Category: Curriculum Map

Virus

 

Viruses
All Materials © Cmassengale

Discovery of Viruses

  • Beijerinck (1897) coined the Latin name “virus”  meaning poison for  the substance infecting tobacco plants
  • Wendell Stanley (1935) crystallized sap from tobacco leaves infected with Tobacco Mosaic Virus (TMV) & found virus was made of nucleic acid & protein

 

Wendell Stanley Tobacco Leaf with Virus

 

  • Edward Jenner developed smallpox vaccine using milder cowpox viruses
  • Virology – study of viruses
  • Deadly viruses are said to be virulent
  • Viruses couldn’t be seen until electron microscope invented

Viral Characteristics

  • Not living organisms
  • Noncellular
  • Consist of a nucleic acid core (DNA or RNA) and a protein coat called the capsid
  • Capsid made of protein subunits called capsomeres
  • Cannot grow or replicate on their own (inactive particles)

 

 

  • Can only reproduce inside of a living host cell using its raw materials & enzymes
  • Lack ribosomes & enzymes needed for protein synthesis or metabolism
  • Are extremely small particles ranging from 20 – 400 nanometers on average
  • Largest virus is 1000 nanometers in dimension
  • Some can cause disease (smallpox, measles, mononucleosis, influenza, colds, AIDS, Ebola

Ebola Picture
Ebola Virus

  • Some may also cause cancers such as leukemias
  • Virus free cells are rare
  • Highly host specific (only infect certain cells)
  • Referred to as phages
  • Viruses are classified into 2 main groups by their nucleic acid — DNA or RNA Viruses
  •  DNA & RNA viruses are subdivided by capsid shape & whether they do or don’t have an envelope

Viral Structure

  • DNA or RNA core surrounded by protein sheath called capsid
  • Nucleocapsid  includes the viral nucleic acid & its capsid
  • Some form lipid rich covering around capsid called the envelope
  • Envelope usually formed from host cell membrane
  • Envelope may have spikes to help chemically recognize & attach to the host cell
  • Shaped determined by the arrangement of proteins making up the capsid
  • TMV is rod shaped

  • Adenovirus & polio viruses are icosohedral (20 sided)

Virus Structure

  • Measles & rabies viruses are helical
  • T -phages have a head & tail

Bacteriophage Structure

Bacteriophages or T-Phages

  • Among the most complex viruses
  • Attack bacterial cells
  • Composed of a icosohedral head, tail, base plate, & tail fibers
  • Long DNA molecule is inside the head 
  • Tail helps inject the viral DNA into host cell
  • Tail fibers used to attach to host

Retroviruses

  • Contain RNA
  • Have an enzyme called reverse transcriptase which helps use the RNA to make DNA
  • Use the host cell’s ribosomes & raw materials to make viral proteins
  • Cause some cancers & AIDS


HIV Virus

Viroids

  • Smallest particle able to replicate
  • Made of a short, single strand of RNA with no capsid
  • Cause disease in plants


Viroid Attack on Potatoes

Prions

  • No nucleic acid or capsids
  • Made of protein particles that have folded incorrectly
  • Attacks the central nervous system
  • Cause animal diseases in cows (Mad Cow disease), sheep, & humans

Lytic Cycle

  • Viral replication that rapidly kills the host cell causing it to lyse or burst
  • Involves 5 steps —– Adsorption, Injection, Replication, Assembly, & Lysis
  • Adsorption — phage attaches to cell membrane of host
  • Injection — nucleic acid (DNA) of virus injected into host cell
  • Replication — viral DNA inactivates host cell’s DNA & uses host’s raw materials & ribosomes to make viral DNA, capsids, tails, etc.
  • Assembly — new viral parts are combined to make new phages
  • Lysis — enzymes weaken & destroy the cell membrane causing it to lyse releasing new viruses that infect other cells

 

Phases of the Lytic Cycle of a Virulent Virus:

  • Absorption:
    1. Virus attaches itself to the cell.
  • Entry:
    1. Enzymes weaken the cell wall and nucleic acid is injected into the cell, leaving the empty caspid outside the cell. Many viruses actually enter the host cell intact.
  • Replication:
    1. Viral DNA takes control of cell activity.
  • Assembly:
    1. All metabolic activity of the cell is directed to assemble new viruses.
  • Release:
    1. Enzymes disintegrate the cell in a process called

lysis

    , releasing the new

 

 


Source: http://science.howstuffworks.com/virus-human.htm

Lysogenic Cycle

  • Replication in which the virus stays inactive inside of the host cell & doesn’t immediately kill it
  • Viruses are called temperate phages
  • Lysogenic steps include adsorption, injection, recombination, cell reproduction, activation, replication, assembly, & lysis
  • Recombination —Viral DNA joins with host cell DNA forming an inactive prophage
  • Host cell reproduces  normally until activated by an external stimuli 
  • External stimuli unknown, but could be ultraviolet radiation, carcinogens, etc.
  • Once activated, prophage forms new viruses & destroys host cell
  • HIV is an example of a temperate phage

 

The Lysogenic Cycle of a Temperate Virus:

  • The virus attaches itself and injects its DNA into the cell.
  • The viral DNA attaches itself to the host DNA, becoming a new set of cell genes called a prophage.
  • When the host cell divides, this new gene is replicated and passed to new cells. This causes no harm to the cell, but may alter its traits.
  • Now there are two possibilities:
    • The prophage survives as a permanent part of the DNA of the host organism.
    • Some external stimuli can cause the prophage to become active, using the cell to produce new viruses.

 

 

 


Source: http://science.howstuffworks.com/virus-human.htm

Viral Control

  • Interferon are proteins made by cells to fight viruses
  • Two types of viral vaccines exist — inactivated & attenuated
  • Inactivated virus vaccines don’t replicate in the host’s system
  • Attenuated viral vaccines have been genetically altered so they can’t cause disease
  • Antiviral drugs (AZT, acyclovir, & azidothymidine) interfere with viral DNA synthesis
  • Protease Inhibitors interfere with viral capsid production
  • New viruses emerge as rain forests are cleared (Ebola virus)
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Who Ate the Cheese

 

Who Ate the Cheese?!

Introduction:

DNA isolation from blood, hair, skin cells, or other genetic evidence left at the scene of a crime can be compared with the DNA of a criminal suspect to determine guilt or innocence. This is due to the fact that every person has a different sequence. Scientists use a small number of sequences of DNA that are known to vary among individuals, and analyze those to get a possibility of a match.  DNA is isolated, cut using restriction enzymes and sorted by size by gel electrophoresis. DNA is placed in a gel and an electrical charge is applied to the gel. The positive charge is at the top and the negative charge is at the bottom. Because DNA has a slightly negative charge, the pieces of DNA will be attracted to the bottom. The smaller pieces move more quickly towards the bottom than the larger pieces. The DNA can then be analyzed.

Objectives:

In this simulation you will examine crime scene evidence to determine who is responsible for eating the Queen’s special imported Lindbergher Cheese (yes, the stinky cheese). You will model the process of electrophoresis and DNA fingerprinting.

ROYAL GUARD INCIDENT REPORT

Incident Data

Incident Type: Theft Complaint Status Pending DNA results
Processed by: Chief Wiggam Other Officers: Officer Li Gase

Property

Property Code: Rare cheese Owner’s Name Queen Elizabeth
Name: Lindbergher Value: $12,000

Burglary Data

Method of Entry: Unknown, no evidence of force on doors or windows.

Narrative: The cheese was allegedly stolen from the Queen’s sitting room the night before the grand ball. The cheese was listed as a gift from the Manchurian diplomat. Officer Li Gase dusted for fingerprints and found none on the table or doors, the maid claimed that they had been wiped clean earlier. The wheel of cheese was on a platform in the sitting room, and half of it had been eaten. We took pictures of the half eaten cheese and sent it to the lab for further tests. Edna N. Zime, the lab technician said that saliva samples could be taken from the teeth imprints of the cheese that was left behind.

Suspect Data

Suspect Number: 1
Name: Princess Dubbah Elix
Description of Suspicion: The princess was seen entering the sitting room earlier in the evening. She is well known for her love of cheese.

Suspect Number 2
Name: Electra Foresis
Description of Suspicion: Electra was recently involved in a relationship with the Manchurian diplomat that sources say ended badly. Her motive may have been to sabotage the diplomat’s gift to the Queen.

Suspect Number 3
Name: Ada Nine
Description of Suspicion: Ada was the maid in charge of cleaning the sitting room. She had access to the cheese.

Suspect Number 4
Name: Gene Tics
Description of Suspicion: Gene is the leader of the local Cheese-Makers Guild, he may not have wished for Queen Elizabeth to have cheese from anywhere but his own guild.

Crime Lab Data

Crime Lab Investigator R. Renee Lab Technician Edna N. Zime
List of Evidence Received Plastic bag with cheese crumbs List of Procedures Used DNA extraction
Polymerase Chain Reaction
DNA restriction Analysis

Narrative: After receiving the package with the plastic bag marked Crime Scene, the DNA was extracted. Because the sample was so mall, the DNA was amplified using the polymerase chain reaction. We isolated the DNA from the four suspects and compared them to the crime scene DNA using DNA restriction analysis.

Results: See attached DNA Results

DNA Evidence Evaluation:

1. Turn your paper strips (DNA sequences) so that the side with the bases is facing you. The restriction enzyme cuts at every point it finds C C G G, always cutting between the C and the G. Label the back of the slips with the suspect number so that you don’t get them confused after cutting. Use scissors to cut the DNA sequence at the C C G G points.

2. Count the number of base pairs (bp) in each piece of DNA that you created. Record the base pair number on the back side of the DNA fragment.

3. Make an enlarged chart like the one shown. Your teacher will give you paper for this. Use a ruler to ensure that the lengths are uniform.

4. Tape your DNA fragments to the chart, using the base pair numbers as a guideline for fragment placement.

5. Compare the crime scene DNA to the suspects and indicate on your chart, which suspect is guilty of eating the cheese.

 

 

 

ANALYSIS:

1. On your chart, label the positive (+) and the negative (-) ends. Circle the suspect’s DNA who matches the DNA at the crime scene and write the name of the suspect.

2. For each of the following tasks performed in the activity, describe what they are actually simulating.

Cutting the DNA into fragments:

 

Taping the DNA onto the large paper:

 

3. For each word below, describe how it relates to DNA Fingerprinting:

Polymerase Chain Reaction:

 

Gel Electrophoresis:

 

Restriction Enzyme:

 


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What is Ecology PPT Questions

 

What is Ecology?
By Susan Lundy

 

1.  Definition:

2.      It ________________ how living organism affect each other and the world they live in.
3.      ____________________ is the place a plant or animal lives in.
4.      ____________________ is an organism’s total way of life (its job)
5.      ____________________ factors are the nonliving parts of an organism’s environment.
6.      4 Examples of abiotic factors are:

 

7.      _____________________ factors are all the living organisms that inhabit an environment.

8.      Some things that organism’s rely on each other are _________________, ______________________, __________________ or _________________

9.      What are the levels of simple organization from simplest to most complex?

10.      _________________________ have organized the interactions an organism takes part in to different levels according to ________________

11.     Level 1 Organism:

12.     Level 2 Population:

13.     Level 3 Biological Community:

14.     Level 4 Ecosystem:

15.     Level 5 Biosphere:

16.      Where can you find life?

 

Where the Hippos Roam

 

Where the Hippos Roam
Holt, Rinehart, Winston

Introduction:

    Millions of years ago, ancestors of modern crocodiles lurked in the shallow waters of lakes and other bodies of water. They hunted fish and other animals, much as their descendants do today. If you could travel back in time to visit one of those lakes, you might see the ancestors of today’s hippos there as well. Antelopes might browse along the edges of the lake, and rodents of various sizes might scurry back and forth. When paleontologists examine the fossil of a prehistoric organism, they may discover clues about the organism’s life. They may also answer questions about the environment it lived in: Was the area hot or cold? Was it humid or dry? Then, by putting all of these clues together, the paleontologists may be able to learn a little more about how organisms and environments change over time. Unfortunately, studying a fossil site is no easy task! Often, a paleontologist may find a few teeth scattered over a very large area. In such cases, keeping track of where the fossils were found is very important. 

    In this activity, you will use the data from a fossil site to create a map of fossil locations at that site. Then you will make some conclusions about the past environment, or paleoenvironment, at that location. The table below shows the locations of fossils that were found spread out over 22,500 m2. A team of paleontologists decided that this site, which measured 150 m x 150 m, was too large to work on all at once. Therefore, they decided to create a grid of 10 m squares.

    Starting in the northwest corner, they labeled the squares with the letters A-O from west to east. Then the team numbered the squares 1-15 from north to south. In this way, each fossil could be labeled with a letter and a number, depending on where it was found. For instance, the label A1 would signify the 10 m x 10 m square in the northwest corner of the site. Similarly, the label O15 would indicate the square in the southeast corner of the site.

Activity:

Location of Fossils
Layer Hippos Rodents Crocodiles *Bovids
A B11,C6,D3, I15,J10,L7, M6 C14,F7,G13, I3,L13,O2
B F2,J3,K1,K2 B10,B11,F13 H2,I7,K2, N5,N7 G14
C B3,C10,D1, H8,M9,N4 A5,A6,E2, E4,E14,H7, H8,H12,K4, M1,N15

* Bovids are antelopes and other similar animals

Problem:

  1. Create a map of the fossil site. The scale should be 1 cm = 10 m. Label the grid of squares with letters and numbers.
  2. Using letters, show where the fossils were found. (Put an H in each square where a hippo tooth was found; use R to indicate a rodent tooth, use C to show a crocodile tooth, and B for a bovid tooth.
  3. Use a different color for each layer of sediment, and make a key to show which colors are which. (Example: Layer A – red, Layer B – blue, Layer C – green)
  4. Based on the distribution of fossils in level B, what part of this site might have been covered by water? Devise a way to indicate that part on you map. (Example: Lightly shade with a color)

Questions:

  1. Explain why you chose to shade part of your map as once covered in water. (What fossil clues helped you.)

 

 

  1. Describe how the environment at this site changed through time.

 

 

  1. One member of the team wished to look for fossils of dry-climate plants at this site. Which layer or layers do you think would be most likely to yield fossils of this kind? Explain your answer.

 

 

  1. When the paleontologists were analyzing these data, they proposed several hypotheses to explain the changing climate. One of them suggested that tectonic uplift had occurred, causing the area to gain elevation over time. A second paleontologist disagreed, stating that the area probably lost elevation over time. Whom do you agree with? Explain your answer .

 

 

 

Water in Carrot Lab

 

How Much Water is in a carrot?

 

Introduction:

Life exists on Earth because of the abundance of liquid water. Water makes up anywhere from 70 to 90% of the body weight of living things. Living things are composed of atoms and molecules within aqueous solutions (solutions that have materials dissolved in water).  At most temperatures on the surface of the earth, water is a liquid. In this state, water is an excellent solvent, and because there is so much of it available on the earth’s surface, water is home (oceans, lakes and rivers) to much of life. Water has been referred to as the universal solvent. Water is also involved in many metabolic processes within organisms.

Water is a polar molecule and can bond both to itself and to other water molecules by weak attractions called hydrogen bonds. Hydrogen bonding is responsible for the unusual thermal properties of water including a high specific heat capacity and a high heat of vaporization.

Specific heat is defined as the amount of heat energy needed to raise the temperature of one gram of a substance 1°C. Since it takes much more energy that normal to break all the hydrogen bonds in liquid water, water resists rapid temperature fluctuations, adding stability to earth’s environments where liquid water is plentiful.

The heat of vaporization is defined as the energy needed to change the phase of a liquid to a gas. Again, because of the number and relative strength of water’s hydrogen bonds, it takes a great deal of energy to break a molecule free of its liquid partners. Heat of vaporization causes a cooling effect because as the warmer molecules evaporate from your skin they take the heat energy with them, leaving you cooler.

Objective:

Students will design and conduct an experiment to determine the amount of water present in a carrot.

Materials:

Some materials that will be available for you to use are plates, vegetable peelers, knives, graters, knee-hi stockings, foil, microwave, blow dryers, plastic bags, and paper towels.  Any other materials you use must be approved by the teacher first (No dehydrators!).

Procedure:

  1. Begin by weighing and recording the mass of the carrot.
  2. Estimate the water content present in your carrot.
  3. Develop a hypothesis for the amount of water in a carrot.
  4. Write the materials needed and procedure you will be using to extract the water.
  5. After having your hypothesis and procedure approved by the teacher, conduct the experiment.
  6. Be sure to include an introduction, procedure, data, data analysis, and a conclusion in your lab report.