2nd Semester 39 - BIOLOGY JUNCTION

Antibiotic Resistant Lab

Antibiotic resistance of bacteria

Procedure Using a sterile loop, pick an isolated colony from you bacterial plate. Try to find one that grew well but is all by itself. Move the colony (don’t scoop up the agar) to a new plate. Using a moist, sterile, cotton swab, spread the bacteria around on the plate.

The goal is to get an complete, even, coverage of bacterial growth on the plate (called a “lawn”). Remember to open the plate only minimally, using the lid as an “umbrella” to prevent contamination (see image below). Label each plate on the bottom (agar contaning side) and store it for examination during next week’s lab.Each new prepared plate will receive four paper discs containing antibiotics. We will be using several different types of Antibiotics and/or antimicrobials.

(please fill in which antibiotics you used below)

The antibiotic discs come in a little tube-like dispenser. To remove the discs take a sterile toothpick and push out a disc into your plate. Use the toothpick to gently press the disc onto the agar. Once you have added the five antibiotic discs to your plates, make sure the plates are labelled and store them in the back of the lab until next week.

If the bacteria are susceptible to the antibiotic a zone of inhibited growth will be evident next week. Measuring the size of this zone is a relative indication of the effect of the antibiotic on the particular bacteria.

Bacteria possess several characteristics that enable them to become resistant to antimicrobial drugs:

Asexual reproduction
Short generation times
High mutation rates

Some Information on Antibiotics

Questions –

1. Name two ways (1. and 2. ) that common human practices towards antimicrobials aids bacteria in becoming resistant.

2. Name two reasons your Physician will perform cultures such as the ones you have done in this lab.

4. How are materials are collected for cultures?

5. Why is neccesary to use sterile technique when obtaining cultures?

Animal Concept Map

Floating Leaf Disk Assay

The Floating Leaf Disk Assay for Investigating Photosynthesis

Brad Williamson

Introduction:

Trying to find a good, quantitative procedure that students can use for exploring photosynthesis is a challenge. The standard procedures such as counting oxygen bubbles generated by an elodea stem tend to not be “student” proof or reliable. This is a particular problem if your laboratory instruction emphasizes student-generated questions. Over the years, I’ve found that the floating leaf disk assay technique to be reliable and understandable to students. Once the students are familiar with the technique they can readily design experiments to answer their own questions about photosynthesis. I plan to add to this page as I have time to elaborate on the technique and provide suggestions for modifications.

Materials:

1. Sodium bicarbonate (Baking soda)

2. Liquid Soap

3. Plastic syringe (10 cc or larger)—remove any needle!

4. Leaf material

5. Hole punch

6. Plastic cups

7. Timer

8. Light source

Optional:

Buffer Solutions

Colored Cellophane or filters

Leaf material of different ages

Variegated leaf material

Clear Nail polish

Procedure:

Prepare 300 ml of bicarbonate solution for each trial.
1. The bicarbonate serves as an alternate dissolved source of carbon dioxide for photosynthesis. Prepare a 0.2% solution. (This is not very much—it’s about 1/8 of a teaspoon of baking soda in 300 ml of water.) Too much bicarbonate will cause small bubbles (CO2)to form on the surface of the leaf which will make it difficult to sink the leaf disk.
2. Add 1 drop of dilute liquid soap to this solution. The soap wets the hydrophobic surface of the leaf allowing the solution to be drawn into the leaf. It’s difficult to quantify this since liquid soaps vary in concentration. Avoid suds. If your solution generates suds then dilute it with more bicarbonate solution.

Cut 10 or more uniform leaf disks for each trial

1. Single hole punches work well for this but stout plastic straws will work as well
2. Choice of the leaf material is perhaps the most critical aspect of this procedure. The leaf surface should be smooth and not too thick. Avoid plants with hairy leaves. Ivy, fresh spinach, Wisconsin Fast Plant cotyledons—all work well. Ivy seems to provide very consistent results. Any number of plants work. My classes have found that in the spring, Pokeweed may be the best choice.
3. Avoid major veins.

Infiltrate the leaf disks with sodium bicarbonate solution.

1. Remove the piston or plunger and place the leaf disks into the syringe barrel. Replace the plunger being careful not to crush the leaf disks. Push on the plunger until only a small volume of air and leaf disk remain in the barrel (< 10%).

1. Pull a small volume of sodium bicarbonate solution into the syringe. Tap the syringe to suspend the leaf disks in the solution.

1. Holding a finger over the syringe-opening, draw back on the plunger to create a vacuum. Hold this vacuum for about 10 seconds. While holding the vacuum, swirl the leaf disks to suspend them in the solution. Let off the vacuum. The bicarbonate solution will infiltrate the air spaces in the leaf causing the disks to sink. You will probably have to repeat this procedure several times in order to get the disks to sink. You may have difficulty getting the disks to sink even after applying a vacuum three or four times. Generally, this is usually an indication that you need more soap in the bicarbonate solution. Some leaf surfaces are more water repellent than others are. Adding a bit more soap usually solves the problem.

Pour the disks and solution into a clear plastic cup. Add bicarbonate solution to a depth of about 3 centimeters. Use the same depth for each trial. Shallower depths work just as well.

1. This experimental setup includes a control. The leaf disks in the cup on the right were infiltrated with a water solution with a drop of soap—no bicarbonate.

Place under the light source and start the timer. At the end of each minute, record the number of floating disks. Then swirl the disks to dislodge any that are stuck against the sides of the cups. Continue until all of the disks are floating.

1. The control is on the left in each image. In the experimental treatment, on the right, leaf disks are rising and floating on the surface.

Sample results:

Time (minutes)	Disk Floating
1	0
2	0
3	0
4	0
5	0
6	0
7	1
8	1
9	1
10	1
11	4
12	7
13	8
14	10

The point at which 50% of the leaf disks are floating is the point of reference for this procedure. By interpolating from the graph, the 50% floating point is about 11.5 minutes. Using the 50% point provides a greater degree of reliability and repeatability for this procedure.

Sponge Coloring Diagram and Questions

Found at the Biology Corner Name __________________ Period ______

Sponges – A Coloring Worksheet

Since sponges look like plants, it is understandable why early biologists thought they were plants. Today, we know that sponges are simple, multicellular animals in the Kingdom Animalia, Phylum Porifera. This phylum is thought to represent the transition from unicellular animals to multicellular animals. Most (but not all) sponges are asymmetrical and have no definite shape. Sponges, like all animals, are eukaryotic – meaning their cells have a nucleus. Porifera in Latin means “pore-bearer” and refers to the many pores or openings in these animals. Because of these pores, a sponge can soak up and release water. At one time, real sponges were used for cleaning and bathing. Today, most are artificially made.

All adult sponges are sessile, meaning they are attached to some surface. Since they cannot move, sponges cannot pursue their food. Instead, they are filter feeders, meaning they obtain their food by straining the water for small bits of food like bacteria, algae or protozoans.

Sponges exhibit less specialization (adaptation of a cell for a particular function) of cells than most invertebrates. The primitive structure of a sponge consists of only two layers of cells separated by a non-living jelly like substance. The outer layer of the sponge is the epidermis which is made of flat cells called epithelial cells. Color all the epithelial cells (B) of the epidermis peach or pink.

The inner layer consists of collar cells (A) whose function is to circulate water through the sponge. They do this by swishing their flagella which pulls water through the incurrent pore – water then travels out the osculum at the top of the sponge. As water passes through the sponge in this way, cells absorb food and oxygen and waste is excreted. Color the osculum (D) dark blue, the incurrent pores (C) light blue. Color the inside of the sponge where water circulates the same light blue as you colored the incurrent pores. Color all the collar cells (A) red.

In the jelly-like substance between the epidermis and the collar cells are cells called amebocytes – because they look like amebas. The job of the amebocytes is to travel around distributing food and oxygen to the cells of the epidermis. Because of the amebocytes, scientists believe that sponges evolved from protists. Color all of the amebocytes (E) green – look for them carefully.

The body of the sponge would collapse if it did not have some type of supporting structure. Some sponges have a soft network of protein fibers called spongin. Others have tiny, hard particles called spicules. Many of these spicules also stick out of the epidermis and provide the sponge with protection. Most sponges have a combination of spicules and spongin, the ratio often determines how soft or hard the sponge is. Search for and color all the pointy spicules (F) brown.

Reproduction for sponges can be accomplished both sexually and asexually. There are three ways for a sponge to reproduce asexually: budding, gemmules, and regeneration. Sponges can simply reproduce by budding, where a new sponge grows from older ones and eventually break off. Color the adult sponge (J) pink and all the buds (G) you can find red. Sponges can also reproduce by regeneration, where missing body parts are regrown. People who harvest sponges often take advantage of this by breaking off pieces of their catch and throwing them back in the water, to be harvested later. Finally, sponges can reproduce by creating gemmules – which is a group of amebocytes covered by a hard outer covering. Color the gemmule (H) yellow.

Sexual reproduction occurs when one sponge releases sperm into the water. This sperm travels to another sponge and fertilizes its eggs. The larva form will then swim to another location using its flagella where it will grow into an adult sponge. Most sponge species are hermaphrodites, they can produce both eggs and sperm.

Questions:

1. What did early biologists think sponges were? ______________________

2. Sponges belong to the Kingdom _________________ and the Phylum _______________

3. Sponges are [ unicellular or multicelluar ] and [ prokaryotic or eukaryotic ]

4. What type of symmetry do sponges have? ___________________________________

5. What does it mean to be sessile? ____________________________________

6. How do sponges get their food? ___________________________________

7. Water enters the sponge through the _____________________ and leaves through the
_____________________.

8. What is the job of the amebocyte? ________________________________________

9. What two substances give the sponge support? _________________________________

10. Tiny sponges growing from the main body of the sponge are called _________________

11. What is a gemmule? ___________________________________________________

12. What is a hermaphrodite? ______________________________________________

Label the letters on the diagrams

SciSpongesColoringWSP3.bmp (1403574 bytes)

Label the letters on the diagrams
SciSpongesColoringWSP4.bmp (2585142 bytes)

Found at www.biologycorner.com

Endocrine System

The Endocrine System

Click here to view an animation of the endocrine system

The endocrine system is a set of hormone secreting glands within the body of an animal. The function of the endocrine system is homeostasis, communication and response to stimuli. The endocrine system regulates the internal environment of the animal for growth, survival and reproduction as well as allowing it to respond to changes in its external environment.

The endocrine system’s glands secrete chemical messages we call hormones. These signals are passed through the blood to arrive at a target organ, which has cells possessing the appropriate receptor. Exocrine glands (not part of the endocrine system) secrete products that are passed outside the body. Sweat glands, salivary glands, and digestive glands are examples of exocrine glands.

The other communication method in the body is the nervous system. Although there are differences between them, they complement each other in many responses, e.g., response to danger.

The difference between nervous and endocrine control are as follows:

1. Nervous response is faster.

2. Nervous response is shorter in duration.

3. Nervous response stops quicker.

Nervous response is much more local.
Nerve ‘messages’ are conducted electrically; endocrine ‘messages’ are carried chemically.

Hormones

Most hormones are made of protein. They are called peptides. Peptides are short chains of amino acids; most hormones are peptides. They are secreted by the pituitary, parathyroid, heart, stomach, liver, and kidneys.

Some hormones are steroid based. Steroids are lipids derived from cholesterol. Testosterone is the male sex hormone. Estradiol, similar in structure to testosterone, is responsible for many female sex characteristics. Steroid hormones are secreted by the gonads, adrenal cortex, and placenta.

Hormones are usually slow to act but, once they act, they remain active for long periods of time and, also, their effects remain for a long time.

Endocrine Glands

There are 10 endocrine glands. As stated previously, other organs such as the stomach, intestines, kidneys, heart, brain, and placenta also make hormones.

Click here to take an online quiz on the location of the endocrine glands

The Pituitary Gland

The pituitary gland is often called the master gland. That is because the pituitary gland produces hormones that regulate other endocrine glands. Some hormones produced by the pituitary gland are:

1. Follicle Stimulating Hormone (FSH): Will be discussed in a later Chapter of the syllabus.

2. Luteinising Hormone (LH): Will be discussed in a later Chapter of the syllabus.

3. Growth Hormone (GH): Causes body cells to absorb amino acids and form protein for growth. The main function is to cause the elongation of bones.

4. Prolactin: stimulates milk formation by the breast after the birth of the baby.

5. Oxytocin: stimulates muscle contraction of uterus during birth, stimulates muscle contraction in the milk ducts during breast-feeding.

6. Antidiuretic Hormone (ADH): causes increased water reabsorption by kidneys.

7. Thyroid Stimulating Hormone (TSH): Combines with iodine at the thyroid gland to produce thyroxine.

Overproduction of GH causes gigantism and underproduction causes dwarfism.

The Hypothalamus

The hypothalamus links the nervous system with the endocrine system. It produces hormones that control the pituitary gland’s responses to messages from the brain and other hormones. Some these hormones, called releasing hormones, stimulate the pituitary gland to make other hormones. Others, called release inhibiting hormones, prevent the production of pituitary hormones.

An example is growth hormone releasing factor. This causes the production of growth hormone (GH) by the pituitary gland.

The Pineal Gland

This gland is in the brain. One hormone produced there is melatonin. Synthesis and release of melatonin is stimulated by darkness and inhibited by light. But even without visual cues, the level of melatonin in the blood rises and falls on a daily (circadian) cycle with peak levels occurring in the wee hours of the morning. Melatonin is readily available in drug stores and health food stores, and it has become quite popular. Ingesting even modest doses of melatonin raises the melatonin level in the blood to as much as 100 times greater than normal. These levels appear to promote going to sleep and thus help, insomnia to hasten recovery from jet lag, and to not to have dangerous side effects.

The Thyroid Gland

The thyroid gland produces the hormone called thyroxin. Thyroxin controls the rate of all the body’s internal reactions. In other words, thyroxin controls the rate of the body’s metabolism.

Physical conditions related to abnormal thyroid function are:

Hypothyroidism- Under Production of Thyroxine

1. Cretinism– Under production of thyroxin in young children. This results in low metabolic rates and results in retarded physical and mental development.

2. Myxoedema- Under production of thyroxin in adults. Characteristics are tiredness, lack of energy, slow mental and physical activity, and weight gain.

3. Goitre- Swelling of the thyroid caused by myxoedema.

Goitre

In cases of low production of thyroxine tablets are available to increase the thyroxine in the body. Since thyroxine needs iodine to be produced iodine is also administered to boost thyroxine levels.

Thyroxine Excess (Hyperthyroidism)

Thyroxine secretion is above normal. This causes a raised level of metabolism. Symptoms of over production of thyroxin are bulging eyes, weight loss heat production, nervousness, irritability, and anxiety. This condition is called Grave’s Disease. Corrective measures for Grave’s Disease are:

1. Drugs to suppress thyroid activity

2. Surgically remove part of the gland

3. Use radioactive iodine to destroy some of the gland.

The Parathyroids

parathyroids behind thyroid gland

There are 4 parathyroid glands. They are located within the thyroid gland. The hormone they produce is called parathormone. This hormone stimulates the release of calcium from the bones. That is why we must continue to include calcium in our diet even when our bones are fully grown.

The Thymus Gland

This gland is located behind the breastbone. It produces the hormone thymosin. This hormone causes white blood cells (lymphocytes) to become mature and active. These blood cells, as previously discussed in the Blood web page, are involved in the body’s immune system.

The Adrenal Glands

Click here to view an animation of the adrenal glands

Diagram showing the location of the adrenal glands

The adrenal glands are located on top of each kidney. They secrete the hormone called adrenaline (also called epinephrine). This hormone prepares the body for stress and is released when we are frightened or feel stress. It does the following:

1. Increases blood flow to the heart, muscles, and brain.

2. Reduces blood flow to the kidneys. This helps reduce blood loss if we are cut. It causes us to get pale.

3. Opens the bronchioles allowing us to get more air.

4. Increases glucose levels in the blood.

5. Increases heartbeat rate.

6. Increase muscular contraction and strength.

7. Increases mental alertness.

Pancreas

As discussed in the Human Nutrition web page the pancreas secretes pancreatic juice for the digestive system.

In addition, the pancreas produces the hormone called insulin. This hormone is produced in groups of cells called Islets of Langerhans. Insulin is needed because it reduces blood glucose levels in the blood. It causes cells, especially fat and muscle cells, to absorb glucose from the blood. The glucose is needed for cellular respiration or converted into glycogen. The glycogen is stored in the liver or the muscles for future use in cellular respiration.

Diabetes is a serious condition that results from 1 of 2 causes. In type 1 diabetes, the pancreas no longer makes insulin and therefore blood glucose cannot enter the cells to be used for energy. In type 2 diabetes, either the pancreas does not make enough insulin or the body is unable to use insulin correctly. Symptoms of diabetes are high glucose levels in the blood and urine, the production of large amounts of urine, severe thirst, loss of weight, and tiredness.

Injections of insulin, which are taken daily, the control of carbohydrate intake, exercise, and weight control treat diabetes.

Anabolic Steroids

Anabolic steroids are hormone supplements that habe been used. They build up muscle, speed up recovery of muscle from injury, and help strengthen bones. There are many serious side effects such as liver and adrenal gland failure, infertility, impotence, and the development of male characteristics in females that can result if they are misused. They are also, sometimes given to animals to promote increased lean muscle (meat) production. This practice is banned in the EU.

Control of Thyroxine Level

Control of thyroxine level as well as many other hormones is done by negative feedback. If the thyroxine level is normal the pituitary gland is inhibited from releasing thyroid stimulating hormone (TSH). As a result, no further thyroxine is produced. When thyroxine levels are low the pituitary gland produces TSH. This causes more thyroxine to be produced by the thyroid gland.

An Example of negative feedback in the role of the thyroid in maintaining body temperature at 37°C.:

The hypothalamus of the brain detects a drop in blood temperature.
The hypothalamus stimulates the pituitary to secrete TSH (thyroid-stimulating hormone).
This hormone stimulates the thyroid to increase its secretion of thyroxine.
The higher concentration of thyroxine increases metabolism and heat production increases.
The blood is warmed back to normal temperature.

OR:

Hypothalamus detecting raised blood temperature and reduces its stimulation of the pituitary.
High thyroxine levels inhibiting the release of TSH from the pituitary.
The increased level of thyroxine leads to the limitation or reduction of its secretion.
Body’s metabolism slows down as a result of less thyroxin. The body’s temperature goes down.

Review Chart of Major Hormonal Glands

Where the Hormone is Produced	Hormone(s) Secreted	Hormone Function
Adrenal Glands	Adrenalin	Causes Emergency Responses (fight/flight)
Pituitary Gland	Growth hormone	Affects growth and development; stimulates protein production
Pancreas	Insulin	Lowers blood sugar levels; stimulates metabolism of glucose, protein, and fat
Hypothalamus	Growth Hormone Releasing Factor	Causes growth hormone to be made
Pineal Gland	Melatonin	Controls body rhythms
Parathyroid Glands	Parathyroid hormone (Parathormone)	Affects bone formation and excretion of calcium and phosphorus
Thyroid	Thyroxine	Controls Metabolism
Thymus	Thymosin	Matures white blood cells