Building A Secure Virtual Biology Classroom With VPN

Virtual Biology Classroom VPN Safety
Building a virtual Biology classroom safely using a VPN

Everyone will unhesitatingly agree that providing strong encryption while surfing the Internet is a primary concern for every user. We are always afraid of our data privacy when connecting to Wi-Fi in a public place or transmitting meaningful materials. The list of various ways to implement this includes using a VPN that has long been proven effective.

However, in addition to the need to provide internet security for your data, there are several areas where an online virtual private network connection plays a major role. Among them is secure teaching, requiring a suitable platform and taking into account various points to ensure the comfort of students and tutors.

Why Is It An Essential Tool For Online Learning

Nowadays, more and more educational institutions pay tribute to distance learning, tirelessly working on improving various components of the latter. The recent rise in popularity of online studying is due to the prolonged outbreak caused by the COVID-19 pandemic.

Nonetheless, it is necessary to consider various aspects to ensure private browsing for remote learning. Installing a network extension for Firefox, Safari, Chrome, Opera, and any other browser will help build a virtual Biology classroom safely and with many additional benefits.

Internet security is above all

Although online learning keeps up to date, scammers and various enemies of each user have expanded the range of their atrocities without missing the opportunity to try their strength in this area. Based on this, even at home, your devices can be subjected to various attacks by scammers. For this reason, your first task is setting up a browser network to get rid of any worries about personal data.

The latter will help protect sensitive content transmissions, Zoom meetings, and any other part of distance learning. In this context, it is necessary to emphasize another advantage of using this privacy tool since VeePN and other services will help you bypass various network restrictions. Check out the specifics of different providers to find the best one for building a virtual classroom.

Multiple possibilities for you

An extension for Firefox will be useful for every student, helping to overcome limitations and gain access to many other features. You will be able to avoid several dangers and difficulties, including plagiarism, one of the most serious violations of academic integrity.

Install a virtual private network add on and open many resources that limit the ability to familiarize and use. Thanks to a strong protection, you will be able to get to them, scoop information for academic papers and get the highest grades.

Reliable and legal privacy tool

As long as your activities in cyberspace do not violate any law, using one of these is a legal solution to protect your data. Permission to use this is due to the purpose of a virtual private network aimed at preventing any actions similar to criminal and terrorist offenses.

However, the latter is only effective if your educational institution does not prohibit this way of encrypting traffic. It should also be taken into account that several countries consider installing an add on and other tools as an illegal activity for which the student will be punished.

All-around classroom protection

Students use different devices to attend a virtual classroom, often connecting to public Wi-Fi at a library or other public place. It determines their need for protection and limits to track traffic for intruders. However, there are several reasons to start looking into Firefox settings and other ways to secure your identity. A virtual private network will be the best choice to provide secure teaching anytime and anywhere.

Encrypting your network activity is the primary benefit of a browser network, divided into many aspects related to distance learning. It is necessary to carefully understand all the details of building a secure biology classroom with one of these private networks to get everything it can offer.

A Few Recommendations

Although there is a long list of benefits of installing an extension for Firefox or a router, it is necessary to be attentive to details and keep in mind several pitfalls. Once you understand all the nuances and risks, you can find the best way to use one of these for distance learning. Among the specific tips regarding this are:

  • familiarization with Firefox VPN settings highlighting the most significant points to remember
  • backing up network files and data will not be superfluous
  • downloading content from illegal resources would not be a good idea
  • do not neglect the security of the school email account
  • be aware while surfing the Internet and so on.

A good source of information based on which you decide which VPN servers are best for secure teaching will be other users’ experience. Take the time to familiarize yourself with the reviews presented in the public domain.

Final Thoughts

All of the above aspects indicate that using a virtual private network in distance learning is worth it. It can not only provide private browsing but also open up many significant features aimed at improving the student’s academic performance. However, the latter requires learning about different subtleties to avoid difficulties or know how to act when faced with them.

The choice of private extension for Firefox and other browsers is not the last factor in this list. Therefore, it is significant to pay attention to the consideration of the specifics of each. Remember that although no tool is perfect, understanding the modus operandi and possible complications will make the use as efficient as possible.

Simple tips for writing a paper on aging biological changes

Nowadays, gerontological science attracts many researchers. There is still enough time to not worry about aging, whether you are young. For older people, biological and functional changes in their bodies are becoming crucial year by year as they influence their everyday lives.

The demand for exciting and actual articles and essays about aging is high as science moves toward new revolutionary inventions that prolong people’s lives. Students at colleges and universities who study specific disciplines also get assignments on a topic related to aging and biological changes. Being vast and complex, the subject may be embarrassing for those not very familiar with the actual problems of aging.

If you have some questions on how to write a paper on biological changes, there are several ways out of this situation. The easiest way is to ask your friend or family member with needed skills to help you out. Also, you can reach for the help of a teacher.

Another effective option is finding a reliable online site that helps students write papers. AnyHomeworkHelp.com homework help service is an excellent example of a dependable site created and supported by solid specialists. Professional writing services aim to support students with essays, case studies, and other papers. You can order work on any topic, not only on aging biological changes and get many benefits from collaboration with proficient authors. The article below will provide several effective hacks on writing an excellent paper on aging from writers with experience. We recommend you read the tips we offer and apply them in practice.

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Aging Biological Changes

The Main Points Of Aging Are Biological Changes

Before we start informing you about the working hack on writing, go through the essential aspects of aging biological changes. The information below will suit anyone who will write an effective and actual paper on aging. By reading about the main points, you will prepare yourself for writing.

Bones

*Less calcium containment leads to losing bones density

*Bones become weaker

*Losing strength in bones often leads to osteoporosis.

Muscles and fat

*After 30, the amount of tissue and muscle strength starts decreasing.

*Levels of hormones decline with age and stop stimulating muscle growth.

*Aging reduces overall muscle mass by up to 15%.

*Physical inactivity speeds up the loss of muscle mass.

*The percentage of fat almost doubles by the age of 75.

*The risk of diabetes increases accordingly to fat and weight boosting.

Cells

*A genetic code programs the limit of a cell’s division.

*After a cell finish dividing, it grows bigger and after dies.

*With aging, cells start functioning worse.

Organs Aging With Biological Changes

*The number of cells in organs decreases with age.

*Some organs lose fewer cells than others if an elderly is healthy.

*Many organs have a functional reserve from birth, so many of their functions remain adequate with age.

*The kidneys, the heart and blood vessels, and the brain are more likely to be damaged with age because of stress. 

Define the type of a paper

The preparational stage of writing a good paper on aging biological changes must obligately include reading instructions (if any) and defining the type of a paper. For example, you might be assigned to write an article for a magazine, a blog post, or a college paper. Each type of task will differ on such points as word count, formatting, audience, tone of voice, and other vital aspects. If you are a student who needs to write a term paper or an essay, you might get manuals from a teacher and read them.

Choose a topic

Depending on the type of task, you may need to generate a topic by yourself or choose one from several offered cases. For example, you can write about changes in skin or bones, psychological aspects related to biological changes, etc. We recommend you select a topic that will excite you and make you desire to research the topic deeply. 

Collect information

Now, after you are happy and excited about the topic for your paper, start researching to gather actual data. Any paper will benefit from using various sources. Ensure to use only reliable databases and encyclopedias. One should get access to paid and closed online libraries for some topics. It would be best to include dissertations, scientific articles, interviews, official websites, laws, and other types of sources.

Create the main thesis

Once you have all the needed data collected, proceed with generating the central idea for your work. The main thesis is a summary of your core statement on the topic. Any paper must be built around one or two significant thoughts to be readable and exciting. Thus, it would be best to start with a presentation of the main thesis in the first part of the paper. While writing the body, remind the main thesis and add some approvals. When finalizing, restate the main thesis.

Outline a Biological change paper

One should structure a paper by adding some core elements. The structure will depend on the type of paper you are about to create. A standard college essay or a term paper contains an introduction, the body, and a conclusion. Following the concrete sequence of placing the paper’s elements will help make it logical and practical. When you transition between paragraphs, use cohesive words to connect your thoughts.

Reduce mistakes

After you finish writing a paper, leave it for some time and have some rest. You will be ready to proceed with the final essential stage of writing – proofreading. Ensure to read a paper several times, looking for errors and mistypes. Ensure you are okay with grammar and punctuation. Check the tone of voice and overall style of the text—double-check the names, dates, numbers, etc.

Recap

To master a meaningful and readable paper on aging biological changes, you need to start by defining the type of paper. The next crucial step is choosing a perfect topic that inspires you. The research stage will determine the quality of your paper and help to formulate an effective main thesis. The outlining stage will help you arrange your thoughts and make a paper convincing. Please, do not forget to proofread the text. We hope these tips were helpful! Good luck!

How To Get Help With Biology Homework

How To Get Help With Biology Homework
Biology Homework

Biology is an integral part of many sciences. If you plan to connect your career with pharmaceuticals, medicine, veterinary medicine, criminology, or other natural sciences, you need a strong background in biology to succeed. However, even those students who have advanced knowledge in biology are still looking for biology homework help when they encounter problems in learning the subject.

There are many services which offer to do your homework for you. However, blindly buying ready-made homework assignments is unlikely to help you gain fundamental knowledge. In this article, we will review how to get help with homework in biology and not impair your academic success. 

Why do students face problems with studying biology?

Each student has their specific reasons why it is challenging to study a particular subject. Most often, problems with learning biology are due to gaps in knowledge and poor mastery of the subject. What to do about it?

Identify gaps in knowledge

You must first identify gaps in your knowledge before understanding how to do biology. Some students only need to repeat a couple of topics, while others have serious problems because they are completely unoriented in the subject. So, it is worth understanding what exactly causes you difficulties, and you should study the topic, which slows down your learning process again. 

Theory

It is hard to learn theoretical knowledge when the student faces dry information in the form of a text with no extra details. It is best to use vivid and interesting images. For example, when students try to understand the types, classes, and animals, choosing a picture or an association for each section is necessary. The additional materials or practical tasks will help you learn the Scientific method and theoretical material more effectively. Thus, there are many applications for tablets, phones, and computers, where you can perform practical tasks even in the form of a game. 

Visualization 

You should print out the information in the form of tables and hang it above the workplace. You will not even realize how the formula will be saved in your mind. It is also effective to draw schemes on your own. For example, if you need to study the brain’s structure, it is better to depict its parts and sign each of them schematically. Are you studying the bones and the skeleton? Try to draw it and sign each bone by yourself. No one expects you to be an artist, but this exercise will help you grasp the information you need. 

Control

After each unit, it is recommended that you take a short exam. You can take tests to understand what you have mastered and what is worth repeating again. In this way, you can be confident in your knowledge. 

How Can I Get Help With Homework In Biology?

If you cannot do your homework on your own with the materials provided, you need help from others. You must realize that one-time assistance with implementing your homework by a third party will only worsen the situation. As a result, you will get a good grade, but you still do not understand the topic, and you will have to ask for help again and again. We offer valid and efficient ways to improve your knowledge of biology.

Find a tutor 

If finances allow, you can turn to a professional tutor who can identify your weaknesses and present you with structured content in a timely and efficient manner. Working with a tutor does not mean you need to study with them for a long time. I had problems with physics, and one month of tutoring was enough for me to become the best in the class. 

Sign Up For Elective Classes 

Most schools offer elective classes where students can deepen their knowledge or fill in gaps in the subject. Ask if your school has such classes. 

Learn by bartering

You may have trouble learning biology, but you are the best at English or Math. Make an announcement with the proposal to help in solving homework in the subject in which you are an expert in exchange for help with homework in biology. 

Ask for help from senior students or classmates 

Find a person who has a good understanding of biology and can explain topics that you do not know over a cup of coffee or a pizza. 

Create A Club For Learning Biology

Do not assume that you are the only person on campus who has problems with your homework. Post an announcement about starting an online or offline biology study group. You can do your homework together, assist one another, or consult on tasks that you know how to do. You can also share money and ask a tutor to teach you about the topics you are struggling with. It will be cheaper than paying for a tutor on your own. 

Google It….How To Get Help With Biology Homework!

The 21st century offers students benefits not available to people 20 years ago. All the information you need is within one click. You no longer need to go to the library or order expensive books and wait a few days for them. You can easily find the necessary material on Google, online libraries, or cost-free online courses on Coursera. Moreover, YouTube and Instagram have become real helpers in obtaining the necessary information. There are plenty of videos and broadcasts where students like you offer the materials you need and share their ideas on how to solve academic problems. 

Look for ideas in the forums 

There are many educational forums where students help each other and share their advice on homework. You will be surprised, but you can even find the information you need on sites such as Reddit and Quora. 

How to Get Help With Biology Homework
Biology Class and Homework

Consult your teacher 

Don’t be shy to ask for help directly from your teacher. There’s nothing to be ashamed of if you need help. You can sign up for a consultation and ask any questions that cause you difficulty. 

As you can see, there are plenty of ways to enhance your knowledge of biology and not face challenges with doing your homework.

Freshman Biology I Stuttgart Cam

 

General Biology I
Stuttgart Campus
Syllabus
Cheryl Massengale – Instructor
Monday, Tuesday, Wednesday – Lecture Room 109
Thursday – Lab Room C105
Class Time – 5:00 to 7:50

 

Assignments on this site may change so check the site often!

 

TOP

 

WEEK TOPIC LECTURE MATERIALS
B109 MON/TUES/THURS
LAB ASSIGNMENTS
C105 WEDNESDAY
1 BIOCHEMISTRY Identifying Controls & Variables with Homer ACTIVITY

VIRTUAL LAB – Dependent and Independent Variables

ANIMATIONS
Practice Tests:  Chemistry   Biochemistry
Biochemistry Practice Test (hardest)
Online Biochemistry Test
2 CELLS Osmosis & Diffusion in an Egg LAB

 

LAB – Vitruvian Man and
Printable Metric Meter

ANIMATIONS
Practice Tests:  Cells   Membranes
Cell Practice Test (Hardest)
Online Test
3
and
4
METABOLISM MICROSCOPY LAB
ANIMATIONS
VIRTUAL LAB – ENZYME-CONTROLLED REACTIONS

Enzyme Foldable ACTIVITY

Lab: Spinach Chromatography

Lab: Stored Energy in Foods

Practice Tests:  Metabolism   Photosynthesis
Cell Respiration
Metabolism Practice Test (Hardest)
Online Test
5 GENETICS & EVOLUTION Sponge Bob Genetics   1  2  3  4   5

Smith-Magenis Syndrome

Lab: Karyotyping & Genetic Disorders

6 NUCLEIC ACIDS Strawberry DNA  LAB


VIRTUAL LAB – Knocking Out Genes

LAB – What’s the Point?
DNA Template
Mutation Sequence Table

ANIMATION – Additions and Deletions

ANIMATIONS
Practice Tests:  Genetics   Nucleic Acids
Nucleic Acid & Genetics Practice Test (Hardest)
Online Test
FINAL EXAM – July 13 Online Test

 

 
BACK

BACK TO BIOLOGY I HOME PAGE CHAPTER 8

 

CHAPTER 8,  CELL REPRODUCTIONSECTION 8-1, CHROMOSOMES

DNA is a long thin molecule that stores Genetic Information.  The DNA in a human cell is estimated to consist of six billion pairs of nucleotides.

OBJECTIVES:  Describe the structure of a chromosome.  Compare prokaryotic chromosomes with eukaryotic chromosomes.  Explain the differences between sex chromosomes and autosomes.  Give examples of diploid and haploid cells.

CHROMOSOME STRUCTURE

1. During Cell Division, the DNA (CHROMATIN) in an Eukaryotic Cell’s Nucleus is coiled into very tight compact structures called CHROMOSOMES.(Figure 8-1)

2. Chromosomes are Rod Shaped structures made of DNA and Proteins.

3. The Chromosomes of stained Eukaryotic cells undergoing cell division are visible as darkened structures inside the Nuclear Membrane.

4. The DNA in Eukaryotic cells wraps tightly around Proteins called HISTONES. They help to maintain the shape of Chromosomes and aid in the tight packing of DNA.

5. Proteins called NONHISTONE Proteins Do Not participate in packing of DNA, they are involved in Controlling the Activity of Specific Regions of the DNA.

6. When preparing for Cell Division, Chromosomes form Copies of themselves, Each half of the Chromosome is called a CHROMATID or SISTER CHROMATIDS. Chromatids form as the DNA makes copies of itself before cell division.  (Figure 8-2)

7. The constricted area of each Chromatid is called a CENTROMERE . The Centromere holds the Two Chromatids together until the separate during Cell Division.

8. Between Cell Division, DNA IS NOT so Tightly Coiled into Chromosomes.  The Less tightly coiled DNA-Protein complex is called CHROMATIN .

9. Chromosomes are simpler in prokaryotes.  The DNA of most Prokaryotes comprises only ONE Chromosome, which is attached to the inside of the Cell Membrane.

10. Prokaryotic Chromosomes consist of a circular DNA Molecule and associated Proteins.

CHROMOSOME NUMBERS

1. EACH HUMAN BODY CELL CONTAINS 46 CHROMOSOMES, (2n) OR TWO COMPLETE SETS.

2. ANY CELL THAT CONTAINS TWO COMPLETE SETS OF CHROMOSOMES IS CALLED A DIPLOID CELL. A Diploid Cell  is commonly abbreviated as 2n.

3.  THE NUMBER OF CHROMOSOMES IN A DIPLOID CELL IS CALLED THE DIPLOID NUMBER.  EVERY ORGANISM HAS A CHARACTERISTIC DIPLOID NUMBER (2n).

4.  EXAMPLES:  FRUIT FLIES – 8, LETTUCE – 14, GOLDFISH 94, AND HUMANS 46.

5.  A CELL WITH ONLY ONE COMPLETE SET OF CHROMOSOMES IS CALLED A HAPLOID CELL.
A Haploid Cell is abbreviated as 1n.

6.  GAMETES, EGGS AND SPERM CONTAIN ONLY ONE COMPLETE SET.  EACH HUMAN SPERM OR EGG (GAMETE) CONTAINS 23 CHROMOSOMES, THE HAPLOID NUMBER (1n) FOR ALL HUMANS.

7.  WHEN AN EGG AND A SPERM OF THE SAME TYPE OF ORGANISM JOIN TO PRODUCE A NEW INDIVIDUAL, THE PROCESS IS CALLED FERTILIZATION.

8.  THE SINGLE CELL THAT RESULTS FROM FERTILIZATION IS KNOWN AS A ZYGOTE. THE ZYGOTE CONTAINS TWO COMPLETE SETS OF CHROMOSOMES, ONE SET FROM EACH GAMETE, FORMING A DIPLOID CELL.  IN MOST MULTICELLULAR ORGANISMS, THE ZYGOTE IS THE FIRST CELL OF THE NEW INDIVIDUAL.

9.  The Chromosomes in the Zygote exist in PAIRS.  For every Chromosome that was in the egg, there is a matching Chromosome from the sperm.

10. Human and Animal Chromosomes are categorized as either SEX CHROMOSOMES or AUTOSOMES.

11. SEX CHROMOSOMES are Chromosomes that Determine the SEX of an Organism.

12. In Humans, Sex Chromosomes are either X or Y.  Females have TWO X Chromosomes and Males have an X and Y Chromosome.

13. All the Other Chromosomes in an Organism are called AUTOSOMES.

14. TWO of the 46 Human Chromosomes are Sex Chromosomes, while the reaming 44 are Autosomes.

15. MATCH SET OF AUTOSOMES IN A DIPLOID CELL ARE CALLED HOMOLOGOUS PAIRS.  BOTH CHROMOSOMES IN A HOMOLOGOUS PAIR CONTAIN INFORMATION THAT CODE THE SAME TRAIT (GENES).  Example Eye Color.

SECTION 8-2, CELL DIVISION

All cells are derived from preexisting cells.  Cell division is the process by which cells produce offspring cells.  Cell division differs in prokaryotes and eukaryotes.  In eukaryotes, cell division differs in different stages of an organisms life cycle.

OBJECTIVES:  Describe the events of binary fission.  Describe each phase of the cell cycle.  Summarize the phases of mitosis.  Compare cytokinesis in animal cells with cytokinesis in plant cells.

CELL DIVISION IN PROKARYOTES

1. BINARY FISSION is the Division of a Prokaryotic cell INTO TWO Offspring Cells.

2. Binary Fission consist of THREE General Stages: (Figure 8-4):

STAGE 1 – The Chromosome, which is attached to the Inside of the Cell Membrane, makes a COPY of Itself, Resulting in Two Identical Chromosomes Attached to the Inside of the Inner Cell Membrane.

STAGE 2 – The Cell continues to grow until it reaches approximately TWICE its Normal Size. Then a CELL WALL Begins forms between the Two Chromosomes.

STAGE 3 – The Cell SPLITS into TWO NEW CELLS.  Each New Cell contains on the Identical Chromosomes.

CELL DIVISION IN EUKARYOTES

1. The trillions of cells that make up your body came from just ONE ORIGINAL CALLED: A FERTILIZED EGG (Zygote).  The Cell Theory states “CELLS COME ONLY FROM THE REPRODUCTION OF EXISTING CELLS” Chapter 4.

2. Each time A Cell Reproduces, the NEW Cells that are formed contained all the ESSENTIAL CYTOPLASM, ORGANELLES, AND NUCLEIC ACIDS NEEDED TO SURVIVE AND FUNCTION.

3. A Cell typically goes through PHASES during its Life, performing life processes of GROWTH AND DEVELOPMENT before it divides into new cells.

4. THE PHASES OF LIFE OF A CELL ARE CALLED THE CELL CYCLE . THE CELL CYCLE CONSISTS OF THREE PHASES:
      A. INTERPHASE
        B. MITOSIS
        C. CYTOKINESIS.

5. The CELL CYCLE is the Repeating Events that make up the Life of a Cell. (Figure 8-5)

6. Cell Division is One Phase of the Cell Cycle.  Cell Division consists of MITOSIS AND CYTOKINESIS.

7. MITOSIS is a Series of PHASES in Cell Division during which the NUCLEUS of a Cell Divides into TWO NUCLEI WITH IDENTICAL GENETIC MATERIAL.  MITOSIS OCCURS ONLY IN EUKARYOTES.

INTERPHASE

1. INTERPHASE IS THE PORTION OF THE CELL CYCLE BETWEEN DIVISION.

2. Interphase is the LONGEST Phase in the Cell Cycle of a typical Cell.  Interphase used to be referred to as the “RESTING PHASE”.

3. During Interphase, calls carry on all their usual functions, such as respiration and enzyme production.  The Cell also GROWS and DEVELOPS into MATURE FUNCTIONING Cells while in Interphase.  It is the period of normal metabolic activity.

4. INTERPHASE CONSIST OF THREE PHASES:

A. G1 PHASE – PERIOD OF NORMAL METABOLIC CELLULAR ACTIVITIES: THE NUMBER OF ORGANELLES AND AMOUNT OF CYTOPLASM IN A CELL INCREASE. Offspring Cells Grow to Mature Size.

B. S PHASE – THE GENETIC MATERIAL (DNA) IS DUPLICATED (COPIED).  THE CHROMOSOMES OF THE CELL REPLICATE.

C. G2 PHASE – Structure directly involved with mitosis are formed.  The Cell makes the Organelles and substances it needs for Cell Division.  A time during which the Cell prepares to divide.

5. REPLICATION IS THE PROCESS OF COPYING GENETIC MATERIAL.

6. REPLICATION RESULTS IN TWO IDENTICAL COPIES OF A CHROMOSOME CALLED SISTER CHROMATIDS.

7. CHROMOSOMES MUST REPLICATE DURING INTERPHASE SO THERE WILL BE A COMPLETE COPY OF EACH CHROMOSOME IN EACH NEW CELL.

8. BECAUSE THE DNA CONTAINED IN CHROMOSOMES CONTROL GROWTH DEVELOPMENT, AND FUNCTION OF EVERY CELL, EACH NEW CELL MUST HAVE AN EXACT COPY OF THE ORIGINAL SET OF CHROMOSOMES.
CELL DIVISION

1. CELL DIVISION IS THE PROCESS BY WHICH ONE CELL PRODUCES TWO NEW IDENTICAL DAUGHTER CELLS.

2. CELL DIVISION INVOLVES TWO STEPS: CALLED MITOTIC CELL DIVISION.

A.  MITOSIS – FIRST STEP. A SERIES OF  PHASES IN CELL DIVISION DURING WHICH THE NUCLEUS OF A CELL DIVIDES INTO TWO NUCLEI WITH IDENTICAL GENETIC MATERIAL.

B. CYTOKINESIS – SECOND STEP. THE CYTOPLASM OF THE CELL DIVIDES INTO TWO NEW CELLS CALLED DAUGHTER CELLS.

3. DAUGHTER CELL NUCLEI ARE IDENTICAL TO THE PARENT CELL NUCLEUS IN EVERY WAY.  LIKE THEIR PARENT CELL, SOME DAUGHTER CELLS WILL PASS THROUGH THE CELL CYCLE OF GROWTH, DEVELOPMENT, AND CELL DIVISION.

4. MULTICELLULAR ORGANISMS GROW AS MORE CELLS REPEAT THE CYCLE OF CELL DIVISION AND GROWTH.

MITOSIS

1. Mitosis is the Division of the Nucleus, which occurs during Cell Division.

2. Biologist have named the Steps, or Phases, of Mitosis to help study the process.  The FOUR Phases of Mitosis are called PROPHASE, METAPHASE, ANAPHASE, AND TELOPHASE. (Figure 8-6)

3. THE ACTUALLY PROCESS OF MITOSIS IS CONTINUOUS.

4. MITOSIS IS THE PROCESS BY WHICH A NUCLEUS GIVES RISE TO TWO IDENTICAL NUCLEI.

5. INTERPHASE PRIOR TO MITOSIS, THE PERIOD OF NORMAL METABOLIC ACTIVITY. The Chromosomes REPLICATE and the CYTOPLASM Increases as he cell prepares to divide. Interphase includes G1, S, G2 Phases of the Cell Cycle.

FOUR PHASES OF MITOSIS

PHASE 1- PROPHASE  (Figure 8-6 (a))

1. Chromatin condenses into Chromosomes of TWO Sister Chromatids joined together by the CENTROMERE, and visible when viewed through a microscope.

2. THE NUCLEOLUS AND NUCLEAR MEMBRANE DISAPPEAR.

3. TWO Structures called CENTROSOMES appear next to the Disappearing Nucleus.  In Animal Cells, each Centrosome contains a pair of small, cylindrical bodies called CENTRIOLES. Plant Cells lack Centrioles.

4. In BOTH Animal and Plant Cells, the Centrosomes move toward opposite poles of the cell. As they Separate, SPINDLE FIBERS made of microtubules radiate from the Centrosomes in preparation for Mitosis.  The array of Spindle fibers is called the MITOTIC SPINDLE, which serves to Equally divides the Sister Chromatids between the Two Offspring Cells.

5. There are TWO Type of Spindle Fibers:

A. KINETOCHORE FIBERS – They Attached to the Centromere Region of each Sister Chromatids.

B. POLAR FIBERS – they extend across the dividing cell from Centrosome to Centrosome.

PHASE 2 – METAPHASE  (Figure 8-6 (b))

1. The Chromosomes are moved to the CENTER of the CELL (Equatorial Plane) by the Kinetochore Fibers attached to the Centromeres.

2. The Two Sister Chromatids of each Chromosome are attached to Kinetochore Fibers radiating from OPPOSITE ENDS OF THE CELL.

PHASE 3 – ANAPHASE  (Figure 8-6 (c))

1. The Centromeres of Each Chromosome are pulled by the Kinetochore Fibers toward the ends of the cell (OPPOSITE POLES).

2. THE SISTER CHROMATIDS ARE THUS SEPARATED FROM EACH OTHER.  They are now Considered to be Individual Chromosomes.

PHASE 4 – TELOPHASE (Figure 8-6 (d))

1. After the Chromosomes reach opposite ends of the Cell, the Spindle Fibers Disassemble.

2. The Chromosomes return to less tightly coiled Chromatin State.

3. New Nuclear Envelope begins to form around the Chromosomes at each end of the cell.

4. CYTOKINESIS BEGINS.

5.  THE PROCESS OF MITOSIS IS NOW COMPLETE.  THE CELL MEMBRANE BEGINS TO PINCH THE CELL IN TWO AS CYTOKINESIS BEGINS.

CYTOKINESIS

1. Following the last phase of Mitosis, Cytokinesis COMPLETES the process of Cell Division.

2. During Cytokinesis, the Cytoplasm of a cell and its ORGANELLES SEPARATE INTO TWO NEW DAUGHTER CELLS.

3. Cytokinesis proceeds differently in animal and plant cells.

4. CYTOKINESIS OF ANIMAL CELLS: The Cytoplasm Divides when a GROOVE called the CLEAVAGE FURROW forms through the Middle of the Parent Cell.  The Cleavage Furrow Deepens until the parent cell pinches into TWO New Identical Cells.  The New Cells are Now in INTERPHASE.

5. CYTOKINESIS OF PLANT CELLS: In a Plant Cell, the material for NEW CELL WALL CALLED THE CELL PLATE  AND MEMBRANES GATHER AND FUSE ALONG THE EQUATOR, OR MIDDLE OF THE CELL, BETWEEN TWO NUCLEI. Forming TWO New Identical Cells.

6. In Both Animal and Plant Cells, New Offspring Cells are approximately equal in Size.

SECTION 8-3, MEIOSIS

Meiosis is a process of nuclear division that Reduces the number of chromosomes in new cells to Half the number in the original cell. The Halving of the chromosome number counteracts a fusion of cells later in the life cycle of the organism.  For example, in humans, meiosis produces haploid reproductive cells called GAMETES. Human gametes are sperm and egg cells, each which contains 23(1n) chromosomes.  The fusion of sperm and egg results in a zygote that contains 46 (2n) chromosomes.

OBJECTIVES:  List and describe the phases of meiosis.  Compare the end products of mitosis with those of meiosis.  Explain crossing-over and how it contributes to the production of unique individuals.  Summarize the major characteristics of spermatogenesis and oogenesis.

1. Most organisms are capable of COMBINING CHROMOSOMES FROM TWO PARENTS TO PRODUCE OFFSPRING.

2. WHEN CHROMOSOMES OF TWO PARENTS COMBINE TO PRODUCE OFFSPRING, THE PROCESS IS KNOWN As SEXUAL REPRODUCTION.

3. THE CHROMOSOMES THAT COMBINE DURING SEXUAL REPRODUCTION ARE CONTAINED IN SPECIAL REPRODUCTIVE CELLS CALLED GAMETES.

4. IN MOST ORGANISMS, GAMETES CAN BE EITHER EGG OR SPERM .

5. EGGS are larger than sperm and contain a lot of Cytoplasm.  An egg is nonmotile.

6. SPERM Cells contain very little Cytoplasm, have Flagella, that helps them swim to the nonmotile egg.

7. The Chromosomes of Two Gametes are added together when they join.  The number of Chromosomes in the offspring DOES NOT DOUBLE WITH EACH GENERATION, BUT REMAINS THE SAME BECAUSE OF MEIOSIS.

8. MEIOSIS IS THE WAY MANY ORGANISMS PRODUCE GAMETES THROUGH A TYPE OF CELL REPRODUCTION.

9. MEIOSIS IS A TYPE OF NUCLEAR DIVISION IN WHICH THE CHROMOSOME NUMBER IS HALVED.  LIKE MITOSIS, MEIOSIS IS FOLLOWED BY CYTOKINESIS.

10. IN HUMANS SPECIALIZED REPRODUCTIVE CELLS WITH 46 CHROMOSOMES (2n) (DIPLOID CELL) UNDERGO MEIOSIS AND CYTOKINESIS TO GIVE RISE TO EGG OR SPERM THAT HAVE ONLY 23 CHROMOSOMES (1N) (HAPLOID CELL) EACH.

11. MEIOSIS ONLY OCCURS IN EUKARYOTIC CELLS IN PHASES SIMILAR TO THE PHASES OF MITOSIS.

12. MEIOSIS IS DIFFERENT FROM MITOSIS IN SOME VERY IMPORTANT WAYS.

A. The process of meiosis results in the production of Daughter Cells that have HALF THE NUMBER OF CHROMOSOMES OF THE PARENT CELL (HAPLOID CELL).

B. Daughter Cell produced by meiosis ARE NOT ALL ALIKE.  THE DAUGHTER CELLS     MAY HAVE DIFFERENT CHROMOSOMES FROM EACH OTHER.

C. The NUMBER OF CELLS PRODUCED BY MEIOSIS IS DIFFERENT.

(1) Mitosis – One Parent Cell PRODUCES TWO DIPLOID DAUGHTER CELLS.

(2) Meiosis – One Parent Cell PRODUCES FOUR HAPLOID DAUGHTER CELLS.

STAGES OF MEIOSIS

1. THE PROCESS OF MEIOSIS SEPARATES THE PAIRS OF CHROMOSOMES IN A DIPLOID CELL TO FORM HAPLOID CELLS.

2. ONE PARENT CELL DIVIDES TWICE TO PRODUCE FOUR HAPLOID DAUGHTER CELLS.

3. DURING MEIOSIS, THE NUMBER OF CHROMOSOMES IN EACH CELL IS REDUCED FROM DIPLOID TO HAPLOID BY SEPARATING HOMOLOGOUS PAIRS OF CHROMOSOMES.

4. MEIOSIS PROCEEDS IN TWO MAIN STAGES:

A. MEIOSIS I HOMOLOGOUS PAIRS ARE SEPARATED.

B. MEIOSIS II THE SISTER CHROMATIDS OF EACH CHROMOSOME ARE SEPARATED.

MEIOSIS I  (Figure 8-9)

1. AT THE START OF MEIOSIS I EACH CHROMOSOME CONSIST OF TWO STRANDS OF SISTER CHROMATIDS CONNECTED AT THE CENTROMERE.

2. HOMOLOGOUS PAIRS OF CHROMOSOMES COME TOGETHER BEFORE MEIOSIS BEGINS, AN EVENT THAT DOES NOT OCCUR IN MITOSIS. THIS EVENT IS CALLED SYNAPSIS .

3. Each Pair of Homologous Chromosomes is called a TETRAD .

PROPHASE I.

1. Chromosomes become thick and visible, the chromosomes of each homologous pair are tangled together.

2. Portions of Chromatids may Break Off and attach to Adjacent Chromatids on the homologous Chromosome – a process called CROSSING-OVER. (Figure 8-10)

3. Crossing-Over results in Genetic Recombination by producing a New Mixture of Genetic Material.

4. Each pair consists of FOUR CHROMATIDS, BECAUSE EACH CHROMOSOME IN THE PAIR HAD REPLICATED BEFORE MEIOSIS BEGAN.

5. The Nucleoli and the Nuclear Envelope disappear and the spindle fibers form.

METAPHASE I.  Homologous pairs (Tetrads) are still together and arrange in the middle of the cell.

ANAPHASE I.  The homologous pairs of chromosomes separate from each other, spindle fibers pull one member from each pair to opposite ends of the cell. The Random separation of the Homologous Chromosomes is called INDEPENDENT ASSORTMENT.

TELOPHASE I.  Cytokinesis takes place; each new cell is haploid, containing one chromosome
from each pair.

MEIOSIS II  (Figure 8-11)

1. CHROMOSOMES DO NOT REPLICATE BEFORE BEGINNING THE SECOND PHASE MEIOSIS II WILL DIVIDE CHROMOSOMES INTO HAPLOID CELLS CALLED GAMETES.

2. Each Diploid Cell from Meiosis I will go through a second division, forming the FOUR GAMETES HAPLOID CELL.  (Review Figure 8-11)

CROSSING-OVER

1. CHROMOSOMES OF ALL ORGANISMS CONTAIN REGIONS CALLED GENES .

2. EACH GENE CODES FOR ONE TRAIT, OR CHARACTERISTIC, OF THE ORGANISM.

3. ONE VERY IMPORTANT EVENT THAT CAN OCCUR DURING MEIOSIS I IS CROSSING- OVER.

4. CROSSING-OVER IS THE EXCHANGE OF GENES BETWEEN PAIR OF HOMOLOGOUS CHROMOSOMES.

5. CROSSING-OVER OCCURS ONLY DURING PROPHASE I (ONLY!) WHEN HOMOLOGOUS PAIRS ARE STILL JOINED TOGETHER.  THESE PAIRS CAN SOMETIMES BREAK WHERE THEY MEET AN EXCHANGE GENES. (Figure 8-10)

FORMATION OF GAMETES

1. In Animals, meiosis produces haploid reproductive cells called GAMETES.

2. Meiosis occurs within the Reproductive Organs, in the TESTES or OVARIES.

3. In the Testes, meiosis is involved in the production of Male Gametes known as Sperm Cells or Spermatozoa.

4. In the development of Sperm Cells, a Diploid Reproductive Cell divides Meiotically to form FOUR Haploid Cells called SPERMATIDS.

5. Each Spermatid then develops into a Mature Sperm Cell.

6. The production of Sperm Cells is called SPERMATOGENESIS . (Figure 8-12 (b))
7. OOGENESIS is the production of Mature Egg Cells or OVA.  (Figure 8-12 (c))

8. Notice that the Female only produces ONE EGG (OVUM) under normal circumstances.

9. Although creating 4 Haploid Cells through meiosis, only One Becomes the Egg, the other Three products of meiosis are called POLAR BODIES ,and Degenerate.  This is due to the unequal dividing of the cytoplasm during Cytokinesis I & II.

ASEXUAL AND SEXUAL REPRODUCTION

1. EVOLUTION IS THE PROCESS OF CHANGE IN LIVING POPULATIONS OVER TIME.

2. ASEXUAL REPRODUCTION is the production of Offspring from ONE PARENT.

3. Asexual reproduction DOES NOT Usually involve Meiosis or the Union of Gametes.

4. In Unicellular Organisms, such as bacteria, New Organisms are created by either BINARY FISSION or MITOSIS.

5. Asexual Reproduction in multicellular organisms results from BUDDING OFF a Portion of Their Bodies. (Plants)

6. The Offspring From Asexual Reproduction are Genetically Identical to the Parent.

7. SEXUAL REPRODUCTION is the Production of Offspring through Meiosis and the Union of a Sperm and an Egg.

8. MEIOSIS AND SEXUAL REPRODUCTION RESULTS IN NEW COMBINATIONS OF CHARACTERISTICS WITHIN A POPULATION.

9. ORGANISMS IN A POPULATION THAT REPRODUCE SEXUALLY ARE NOT ALL ALIKE.

10. DIFFERENCES AMONG MEMBERS OF A POPULATION ARE COLLECTIVELY CALLED VARIATION.  WHICH RESULTS FROM THE RECOMBINATION OF GENES DURING MEIOSIS AND FERTILIZATION.

11. MEIOSIS AND FERTILIZATION SHUFFLE THE GENES FROM PARENT ORGANISMS, PRODUCING NEW COMBINATIONS OF GENES IN THE OFFSPRING.

12. AN ORGANISMS CHARACTERISTICS ENABLE IT TO SURVIVE IN IT’S ENVIRONMENT. THE CONDITIONS OF THE ENVIRONMENT DETERMINE WHICH CHARACTERISTICS OR TRAITS BENEFIT THE SURVIVAL AND WHICH DO NOT.

13. THE ORGANISMS WITH THE TRAITS TO SURVIVE WILL THEN REPRODUCE TO PASS THOSE POSITIVE TRAITS ON TO THEIR OFFSPRING.

14. OVER TIME THIS PROCESS LEADS TO THE CHANGE IN THE POPULATIONS, BECAUSE ONLY THOSE WITH POSITIVE TRAITS TO PASS ON WILL REPRODUCE.  NATURAL SELECTION.

15. THE ACCUMULATION OF SUCH GENES AND TRAITS IN EACH GENERATION IS THE BASIS OF EVOLUTION.

16. SINCE ASEXUAL OFFSPRING HAVE THE EXACT SAME GENES AND TRAITS AS THE PARENT, GENETIC VARIATION RARELY OCCURS.

17. A CHANGE IN THE ENVIRONMENT THAT CAN DESTROY ONE INDIVIDUAL COULD DESTROY THE ENTIRE POPULATION.