Biology(Hormone)

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  1. A patient having renal surgery suddenly develops massive hypertension and dies during surgery. An autopsy shows the presence of a pheochromocytoma. In your own words, explain how this incident might have happened.
  2. Your favorite cousin, who is 20 years old, has just been diagnosed with type 2 diabetes. He is overweight and spends most of his time playing computer games or watching television. As a health professional, what advice will you give him?
  3. Your patient has just been diagnosed with SIADH. His mother is asking you what this condition is and what she should expect next. What will you tell her?
  4. Your patient has been admitted to the hospital in preparation for a total removal of her thyroid gland to reverse her hyperthyroidism. She suddenly develops thyroid storm. What manifestations will you find, and what is the pathophysiologic basis of thyroid storm?

Topic Altereations in hormone regulation**

 
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Meiosis Lab

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Cellular reproduction in Eukaryotes involves either mitosis or, in the case of sex cells, meiosis. Mitosis involves the reproduction of a cell into two identical daughter cells. Meiosis, however, is a reduction division where a parental diploid cell produces four haploid gametes. Upon fusion, two haploid gametes (in humans the sperm and the egg) will result in one diploid zygote. In this activity you will track chromosomes through meiosis using colored beads.

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Meiosis

Lab 4

 

 

 

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Lab 4: Meiosis

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Introduc on

Meiosis only occurs in organisms that reproduce sexually. The process generates haploid (1n) cells

called gametes (sperm cells in males and egg cells in fe-

males), or spores in some plants, fungi, and pro sts, that

contain one complete set of chromosomes. Haploid cells

fuse together during fer liza on to form a diploid cell with

two copies of each chromosome (2n).

Genes are the units of heredity that have speciĂžc loci

(loca ons) on the DNA strand and code for inheritable

traits (such as hair color). Alleles are alterna ve forms of the same gene (brown vs. blue eyes). Homol-

ogous chromosomes contain the same genes as each other but o en di erent alleles. Non-sex cells

(e.g. bone, heart, skin, liver) contain two alleles (2n), one from the sperm and the other from the egg.

Mitosis and meiosis are similar in many ways. Meiosis, however, has two rounds of division—meiosis I

and meiosis II. There is no replica on of the DNA between meiosis I and II. Thus in meiosis, the parent

cell produces four daughter cells, each with just a single set of chromosomes (1n).

Meiosis I is the reduc on division– the homologous pairs of chromosomes are separated so that each

daughter cell will receive just one set of chromosomes. During meiosis II, sister chroma ds are sepa-

rated (as in mitosis).

 

 

 

 

 

Concepts to explore:

Meiosis

Diploid cells

Haploid cells

Chromosomal crossover

Concepts to explore:

 

There are over two meters of DNA pack-

aged into a cell’s nucleus. It is coiled and

folded into superhelices that form chro-

mosomes, which must be duplicated be-

fore a cell divides.

Each of the 23 human chromosomes

has two copies. For each chromosome,

there is a 50:50 chance as to which copy

each gamete receives.

That translates to over 8 million possi-

ble combina ons!

 

 

Lab 4: Meiosis

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Meiosis:

Prophase I: The sister chroma ds a ach to their homologous counterparts (same chromo-

some – di erent version). This is the stage where crossing over occurs (homologous chro-

mosomes exchange regions of DNA). Structures which will serve as anchors in the cell

(centrioles) during the division process appear.

Metaphase I: The chromosomes line up in the middle of the cell. The orienta on of each

pair of homologous chromosomes is independent from all other chromosomes. This

means they can “ßip ßop” as they line up, e ec vely shu ing their gene c informa on

into new combina ons. Microtubules (long strands) grow from each centriole and link

them together while also a aching to each pair of homologous chromosomes.

Anaphase I: The microtubules pull the homologous chromosomes apart (the sister chro-

ma ds remain paired).

Telophase I: One set of paired chromosomes arrives at each centriole, at which me a nu-

cleus forms around each set.

Cytokinesis: The plasma membrane of the cell folds in and encloses each nucleus into two

new daughter cells.

Prophase II: Before any replica on of the chromosomes can take place, the daughter cells

immediately enter into prophase II. New spindle Ăžbers form as the nucleus breaks down.

Metaphase II: The sister chroma ds align in the center of the cell, while the microtubules

join the centrioles and a ach to the chromosomes. Unlike metaphase I, since each pair of

sister chroma ds is iden cal, their orienta on as they align does not ma er.

Anaphase II: The sister chroma ds are separated as the microtubules pull them apart.

Telophase II: The chroma ds arrive at each pole, at which me a nucleus forms around

each.

Cytokinesis: The plasma membrane of the cell folds in and engulfs each nucleus into two

new haploid daughter cells.

We brießy discussed “crossing over” in Prophase I. Since the chromosomes of each parent undergoes

gene c recombina on, each gamete (and thus each zygote) acquires a unique gene c Ăžngerprint.

The closeness of the chroma ds during prophase I, creates the opportunity to exchange gene c mate-

rial (chromosomal crossover) at a site called the chiasma. The chroma ds trade alleles for all genes

located on the arm that has crossed.

The process of meiosis is complex and highly regulated. There are a series of checkpoints that a cell

must pass before the next phase of meiosis will begin. This ensures any mutated cells are iden Ăžed

 

 

Lab 4: Meiosis

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and repaired before the cell division process can con nue.

 

One of the muta ons that is of par cular concern is a

varia on in the amount of gene c material in a cell. It is

cri cal that the gamete contain only half of the chromo-

somes of the parent cell. Otherwise the amount of DNA

would double with each new genera on. This is the key

feature of meiosis.

Figure 1: The stages of meiosis

Muta ons that are not caught by the cell’s

self-check system can result in chromoso-

mal abnormali es like Down’s syndrome, in

which there are 3 copies of chromosome

21.

 

 

Lab 4: Meiosis

46

 

Experiment 1: Following Chromosomal DNA Movement

Every cell in the human body has two alleles that condense into single chromosomes held together by

a centromere. These “sister” chroma ds replicate and pair with the newly made homologous chromo-

somes. In this exercise we will follow the movement of the chromosomes through meiosis I and II to

create haploid (gamete) cells.

 

 

 

 

 

 

 

Procedure

Meiosis I

A. As prophase I begins, chromosomes coil and condense in prepara on for replica on.

1. a) Using one single color of bead, build a homologous pair of duplicated chromo-

somes. Each chromosome will have 10 beads with a di erent colored centromere

in it.

For example, if there are 20 red beads, 10 beads would be snapped together to

make two di erent strands. In the middle of each of the 10 bead strands, snap

a di erent colored bead in to act as the centromere.

Figure 2: Bead Set-up

Materials

2 sets of di erent colored snap beads (32 of each)

8 centromeres (snap beads)

Blue and red markers*

*You must provide

 

 

Lab 4: Meiosis

47

 

b) Now, repeat these steps using the other color of bead.

2. a) Assemble another homologous pair of chromosomes using only 12 (that’s 6 per

strand) of the Ăžrst color bead. Place another, di erent colored bead in the middle

of each to act is its centromere.

b) Repeat this step (2 strands of 6 beads plus a centromere) with the other color of

beads.

B. Bring the centromeres of two units of the same color and length together so they can be held

together to appear as a duplicated chromosome. Your beads should appear as they do in Fig-

ure 2.

C. Simulate crossing over between the blue and red chromosomes. Bring the two homologous

pairs together (that’d be the two pairs that both have 10 bead strands) and exchange an equal

number of beads between the two. This simulates what occurs during prophase I.

D. ConĂžgure the chromosomes as they would appear in each of the remaining stages of meiosis I.

Use Figure 1 to guide you.

 

Meiosis II

E. ConĂžgure the chromosomes as they would appear in each stage of meiosis II. Use Figure 1 to

guide you.

F. Using the space below, and using blue and red markers, draw a diagram of your beads in each

stage. Beside your picture, write the number of chromosomes present in each cell. This work

will help you answer the ques ons in the lab, but does not need to be submi ed for grading.

 

Meiosis I

Prophase I

 

 

Metaphase I

 

 

 

 

 

Lab 4: Meiosis

48

 

Anaphase I

 

 

 

Telophase I

 

 

 

Meiosis II

Prophase II

 

 

 

Metaphase II

 

 

 

Anaphase II

 

 

 

Telophase II

 

 

F. Return your beads to their original star ng posi on and simulate crossing over again. Track

how this changes the ul mate outcome as you then go through the stages of meiosis I and II.

 

 

Lab 4: Meiosis

49

 

Ques ons

1. Why is crossing over important in heredity?

2. Provide two ways that meiosis I and meiosis II are di erent.

3. a) In this lab, how many chromosomes were present in each cell when meiosis I started?

b) How many chromosomes were present in each daughter cell at the end of meiosis II?

4. If humans have 46 chromosomes in each of their body cells, determine how many chromo-

somes you would expect to Ăžnd in the following:

Sperm ___________________

Egg ___________________

Daughter cell from mitosis ___________________

Daughter cell from meiosis II ___________________

5. Why is it necessary to reduce the chromosome number of gametes, but not of other cells of

an organism?

 
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BIOLOGY ESSAY QUESTIONS

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Answer five of the seven essay questions (no extra credit for extra work)

 

Each essay question is worth 20 points. Response should be at least 150 words long. Sentences should be well developed, show logical and independent critical thinking, understanding of the concepts and their application to provided case studies/scenarios. Answers should be written in your own words.

 

1. While working at an excavation, an archeologist found several small skull bones. She examines the frontal, parietal, and occipital bones and concludes that the skull belonged to a child not even one year old. How can she tell the child’s age from examining the bones? Explain the importance of her finding in relationship to the infant’s postnatal development.

 

2. Michael is a thirty year old salesman who spends approximately 4 days each week traveling to visit with customers in his region. During his routine physical he casually mentions to his physician that he seems to be sweating more profusely than normal and most rooms that once were comfortable are now too “hot”. Michael also reports that he seems to be losing weight even though his appetite has increased. He also complains that he has a shortened attention span and that he always wants to be moving around. Despite the fact that he feels fatigued, Michael claims to have difficulty sleeping and seems to have more frequent bowel movements, occasionally accompanied by diarrhea. The physician checks Michael’s medical history and finds that indeed he has lost 15 pounds since his last physical.

 

Results of Michael’s physical examination and tests performed by endocrinologist concluded that Michael had Grave’s disease, a form of hyperthyroidism believed to be autoimmune in nature. Michael was presented with a number of possible treatment options. After considering all the options, especially the possible effects of radiation on gamete development, Michael chose surgical removal of the thyroid gland. Following successful surgery, Michael was prescribed synthetic thyroid hormone to ensure that his body was receiving adequate thyroid hormone and told to return within 2 months for a follow-up evaluation of circulating thyroid hormone concentrations. He was also cautioned to carefully monitor his calcium intake.

 

a. Thyroid hormones exert their effects on cells in a manner similar to steroid hormones; describe the mechanism of action of thyroid hormones.

 

b. Why would an imbalance in thyroid hormones have such widespread effects on the body?

 

3. Charlie is badly burned in a fireworks accident on the Fourth of July. When he reaches the emergency room, the examining physician determines the severity of the incident as a third-degree burn. What therapeutic measures is the physician likely to recommend? What are the major concerns with third-degree burns? Are third-degree burns more or less painful than the second-degree burns? Explain.

 

4. E.M.S. went to bed about 11 PM after a busy evening of entertaining friends and family. He was awakened at 2 AM with chest pain that radiated to his left shoulder, arm and fingers. His son took him to the emergency room, where he was immediately given oxygen by mask and nitroglycerin. His chest pain was relieved in about 39 minutes. An ECG revealed evidence of myocardial ischemia but no evidence of a myocardial infarction. He was admitted to the cardiac intensive unit for further evaluation.

 

a. What’s the most likely cause of the pain (what’s the name of the condition and what causes it)?

 

b. What kind of medication is nitroglycerin and why does it help to relieve the pain? What are other treatment options for this condition?

 

c. Define the underlined terms.

 

5. Until recently, 6-year-old Billie had no apparent health problems. About 1 week ago, she started to lose weight despite a healthy appetite. She urinated frequently and complained of being tired. Her mom noticed that she was very thirsty and was getting up in the middle of the night to urinate. On examination, her blood sugar was elevated. She was diagnosed with type 1 (juvenile-onset) diabetes mellitus.

 

a. Which homeostatic mechanism is not properly functioning?

 

b. Explain the physiology of this disease, what’s going wrong? Be specific.

 

c. What can happen if the diabetes is not controlled?

 

6. Keith is a college student. He is extremely busy studying and working part-time. Keith sleeps in late and therefore does not take time for breakfast. He rushes off to class. At lunch he has time for only French fries. When he gets home from school, he eats canned corn (only corn, nothing else) and washes it down with water. Then, he goes to work, only to start the same routine the next day.

 

When Keith is confronted about his poor diet, he responds, “The French fries are a good source of carbohydrates. Since they are fried in oil, I get my daily requirement of fat. At supper time, I eat corn and it has a lot of amino acids in it.” You, a medical student, suggest that Keith see a doctor. Keith complies and makes an appointment with a doctor. The doctor’s report looks like this: Keith is pale and underweight, his urine and blood pH are low, and the ketones in the urine and blood are high. The Na+ concentration in the blood is low. Keith seems to have possible nerve problems. The doctor explains that Keith is pale due to anemic conditions brought on by the poor diet. With a poor protein diet, Keith’s erythrocytes may not be making adequate hemoglobin. Because his diet is very low in carbohydrates, his body is metabolizing fat, which is causing the weight loss. By products of fat metabolism are ketones, which are acidic. This accounts for the increase in ketones in the urine and the blood and a drop in the pH. A drop in blood pH will inhibit the small intestine from putting Na+ into the bloodstream. Sodium ions are necessary for proper nerve function. In short, Keith needs to begin eating well-balanced meals.

 

a. Why is corn considered to be an incomplete protein?

 

b. How are ketones formed?

 

c. How are sodium ions involved in the nervous system?

 

d. How does this scenario relate to fad diets?

 

7. Analyze the need of climbers of Mt. Everest to set up camps at various levels and stay in those camps for a predetermined amount of time before proceeding with their climb to the top of the mountain.

 

 
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The Epipelagic Is Divided Into Two Components: The Oceanic Waters And The

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Question

1 of 25

The epipelagic is divided into two components: the oceanic waters and the

photic zone.

neritic zone.

pelagic realm.

upper photic zone.

subtidal zone.

Question

2 of 25

Most of the primary production carried out in the open ocean is performed by

seaweeds.

kelps.

phytoplankton.

seagrasses.

zooxanthellae.

Question

3 of 25

Net phytoplankton consist mostly of

copepods.

diatoms and dinoflagellates.

nanoplankton.

cyanobacteria (blue-green algae).

nanoplankton and diatoms.

Question

4 of 25

Typically the most abundant group in the zooplankton are the.

larvaceans.

krill.

fish larvae.

nanoplankton.

copepods.

Question

5 of 25

Which of these is least likely to be seen in the epipelagic?

Suspension feeders

Deposit feeders

Primary production

First-level carnivores

Second-level carnivores

Question

6 of 25

Which of these groups builds a mucus “house?”

Copepods

Arrow worms

Larvaceans

Planktonic snails such as pteropods

Snail larvae

Question

7 of 25

Which of the following accounts for about 50% of the primary production in epipelagic waters?

Diatoms

Cyanobacteria

Dinoflagellates

Coccolithophorids

Silicoflagellates

Question

8 of 25

The following are an adaptation to the planktonic way of life except

spines.

small size.

decrease in drag.

substitution of heavy ions by light ones.

gas-filled bladders.

Question

9 of 25

The storage of lipids within the body is an adaptation in plankton since lipids

make cells heavier.

increase body density.

contain air pockets so they help in buoyancy.

contain a larger amount of energy.

are less dense than water.

Question

10 of 25

The neuston consists of animals that

swim against currents.

sink to the bottom portion of the water column.

are top carnivores in the pelagic realm.

spend their entire lives in the plankton.

live at the surface, but remain underwater.

Question

11 of 25

Counter shading is a form of

shading with bioluminescence.

warning coloration.

structural coloration.

protective coloration.

cryptic coloration.

Question

12 of 25

The rete mirabile found in some fishes is involved in.

increasing speed.

decreasing buoyancy.

digesting food.

increasing buoyancy.

conserving body heat.

Question

13 of 25

Zooplankton that migrate vertically

hibernate at night and feed during the day.

feed at the surface during the day, and migrate below the photic zone at night.

feed in the photic zone during the day, and migrate to the surface at night.

stay below the photic zone during the day, and feed at the surface at night.

migrate up and down but always stay below the photic zone.

Question

14 of 25

Most animals in the epipelagic are omnivores. This means that they eat

producers and consumers.

part of the neuston.

zooplankton.

detritus.

phytoplankton.

Question

15 of 25

What is the relationship between dissolved organic matter (DOM) and bacteria in the epipelagic?

Bacteria feed on the DOM, making it available to other animals in the food chain that feed on bacteria.

Bacteria supply most of the DOM.

Bacteria feed on DOM and thus it is unavailable to other animals.

Bacteria cannot utilize DOM and thus feed on detritus, depleting it through most of the epipelagic.

Bacteria cannot utilize DOM, making it available to animals.

Question

16 of 25

The most common limiting nutrient in the ocean is

silicon.

oxygen.

nitrogen.

carbonate.

phosphorus.

Question

17 of 25

The fall bloom in temperate waters is caused when

primary production decreases as nutrients increase.

primary production decreases due to light limitation.

primary production decreases as nutrients decrease.

primary production increases as nutrients increase.

primary production increases as the number of zooplankton increases.

Question

18 of 25

Equatorial upwelling occurs as a result of

temperature changes at the Equator.

the divergence of equatorial surface currents.

the convergence of equatorial surface currents.

winds causing the Ekman transport of surface water offshore.

El Niño conditions north and south of the Equator.

Question

19 of 25

The Southern Oscillation can be best described as

relative changes between two pressure systems.

variation in wind speed over the Pacific Ocean.

relationship between sea-surface and high-altitude pressures.

tidal differences between the Indian and Pacific Oceans.

wind-speed differences along the Equator.

Question

20 of 25

The long spines and projections seen in many epipelagic plankton are used for

feeding.

reproduction.

increasing drag.

increasing buoyancy.

gathering nutrients.

Question

21 of 25

Most epipelagic fish have a tail that is

short and wide.

short and narrow.

short and thin.

high and wide.

high and narrow.

Question

22 of 25

Which of the following adaptations is least likely to be seen in epipelagic fish?

Stiff fins

A smooth, scaleless body

Increased white muscle

Grove in body for fins

Eyes flush with body

Question

23 of 25

The largest source of dissolved organic material (DOM) in the epipelagic is

viruses.

bacteria.

phytoplankton.

zooplankton.

nekton.

Question

24 of 25

The lateral line system in fishes functions in ________________.

sensing vibrations in the water

detecting magnetic lines of force in water

sensing light in aphotic zones

sweeping surrounding water for plankton

bioluminescence

Question

25 of 25

The remote sensing system found in dolphins and some other cetaceans is ___________.

communal mutualistic behavior

extrasensory perception

echolocation

underwater acoustic sensitivity

heightened smell

 

 

 

 
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