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MBG 2040 Study Guide - Final Guide: Trp Operon, Transversion, Dna Mismatch Repair

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salmonimpala884
25 Apr 2016
School
University of Guelph
Department
Molecular Biology and Genetics
Course
MBG 2040
Professor
James Uniacke

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Document Summary

It is not a complete study guide, i"m merely giving you guys some review of the key concepts as well as pointing out some things to watch for, common mistakes etc. It is meant to help you in conjunction with your lecture notes and the textbook. This is the type of thing i would present in a review tutorial. All the figures in these notes are right out of your lecture slides, i may have added text to them or changed them a tiny bit but for the most part they are the same. Famous scientists and their contributions (good chance of a matching question with some or all of these): Avery, macleod, and mccarthy -> proof that the transforming principle is dna. Alfred hershey and martha chase (sometimes just hershey and chase) -> genes are made of dna dna was taken up by the bacterial cells, not the protein of the viral coat.

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Related Questions

Please help answer 4 questions:

1. Using the information provided thus far by both Parts I and II, answer the following questions.

What problems both stated and unstated does Phyllis seem to be experiencing? What pieces of background information (patient environment and social/family history) have been provided by the family?

2. Distinguish between the relevant and non relevant symptoms/lab results needed to form a diagnosis. Of the relevant symptoms/lab results, rank them in priority and defend your answer.

3. Given what you know about the role of myelin in action potential propagation and the key information previously identified in questions 1 and 2, explain why multiple sclerosis is the appropriate diagnosis.

4. Consider you are the physician, what would be your strategy to slow progression of the disease and compensate for reduced neuronal function? What is the long-term prognosis with treatment?

The Soccer Mom:

A Case Study on the Nervous System

by

Jennifer Bolognese, Misti Coronel, Anita Intorre, and

Phil Stephens Biology Department Villanova University

Part I—At the Soccer Game

Thirty-two-year-old Phyllis Jackson was sitting on the bench at the side of the soccer ?eld, sipping a bottle of

Gatorade. Her husband, Steven, sat next to her with a concerned expression. “I’m really worried about you, honey,” he said.

“I’m just a little dehydrated; I’ll be ?ne.”

“If this were the ?rst incident, then maybe I’d agree with you. But your boss has been on your case about your lack of concentration at work, you forgot to pick up the kids from school last week, and quite frankly, you haven’t exactly been yourself with me lately. Now you’re having fainting spells during games? Something doesn’t seem right.”

“I know things haven’t been going well for me lately, but I don’t know why. I try so hard at work, at home, with the kids, to be a good wife. So maybe all this stress has made me a little unfocused and disoriented. What do you want me to do about it?” Phyllis said, blinking back tears.

“I think you should see a doctor,” Steven replied, putting his arm around her and drawing her close. “The kids are getting worried, too.”

Phyllis sighed. “Alright, if it will make you feel better. I really just think I need some time to relax, though.” “Well… I could drop the kids of at my sister’s tonight; that would give us a little free time…”

“That’s really thoughtful of you. I could de?nitely use a quiet night at home, maybe even go to bed early.” Steven seemed disappointed.

Part II—The Doctor Visit

“So, what seems to be the problem, Mrs. Jackson?” Dr. Warner asked Phyllis.

“My husband wanted me to come in and see you after I fainted during my soccer game Saturday. I’ve also been having some problems at work, but I think I’m just stressed.”

“What kinds of problems have you been having at work?”

“It’s been hard to concentrate on tasks. I’ve also had some problems typing—I’ve been making more errors than usual, and oftentimes my ?ngers will go numb.”

“I see,” said Dr. Warner, taking a few notes on his clipboard. “According to my records you are not on any long term medication. Have you noticed any problems outside of work?”

“Well, my husband has been complaining about our personal life lately. And last week, I completely forgot that I was supposed to pick up our two daughters after school. I’ve been feeling really tired lately; even my coordination seems of.”

“How long has this been going on for?”

“A few weeks, but this isn’t the ?rst time. These problems seem to come and go, but it’s getting to the point where I can’t just ignore them anymore. I don’t know, maybe I’m just depressed.”

“Why do you say that?”

“My mother suffered from depression throughout my childhood.”

“Well, depression certainly could cause some of the symptoms you’re experiencing,” Dr. Warner said thoughtfully. “Is there a history in your family of any neurological disorders?” “I don’t think so. I have some vague recollection of my grandfather in a wheelchair when I was really young, but I don’t know what was wrong with him.”

“Okay,” said the doctor, nodding. “Well, the few preliminary tests we’ve run show that you are not pregnant, and that you are not going through menopause. I’d like to send you to see Dr. Thrush, a friend and colleague of mine. She is a neurologist at the local hospital and she will run a few tests to explore your symptoms a little further.”

Questions: Analyze

1. Using the information provided thus far by both Parts I and II, answer the following questions.

What problems both stated and unstated does Phyllis seem to be experiencing? What pieces of background information (patient environment and social/family history) have been provided by the family?

Part III—Diagnostic Tests

Dr. Thrush looked over the results of Phyllis’s Magnetic Resonance Imaging (mri) and evoked potential tests. She was thinking how glad she was that Steven had accompanied Phyllis on this visit as she showed them the MR images of Phyllis’ brain.

“The machine took pictures of Phyllis’ brain in slices. The dark areas are the brain tissue, Phyllis, and the white areas in the middle and around the outside are the cerebrospinal ?uid.”

“Is that normal? Am I ok?” Phyllis asked. “And what are those little white dots in the tissue?”

“The white dots are what concerned me,” replied the doctor. “So we did another type of mri, called dark ?uid, so that your cerebrospinal ?uid would not show up white.”

“But I still see the white dots in my brain tissue. What does that mean?”

The doctor looked down, knowing that this was never an easy thing to tell a patient.

“I am afraid that this indicates that there are plaques or scars in your brain, and that you may have multiple sclerosis.”

Tears began to form in her eyes as Phyllis squeezed her husband’s hand.

“I am afraid that the evoked potential test and the elevated levels of myelin basic protein in you cerebrospinal ?uid indicate the same thing.”

Questions: Evaluate and Apply

2. Distinguish between the relevant and non relevant symptoms/lab results needed to form a diagnosis. Of the relevant symptoms/lab results, rank them in priority and defend your answer.

3. Given what you know about the role of myelin in action potential propagation and the key information previously identified in questions 1 and 2, explain why multiple sclerosis is the appropriate diagnosis.

Part IV—The Diagnosis

Dr. Thrush informed Phyllis that she was probably suffering from the relapsing-remitting form of multiple sclerosis (ms), in which relapses of symptoms are separated by periods of remission. ms is a disorder in which the myelination of axons is degraded due to unknown factors. The most commonly accepted explanation is that ms is an autoimmune disorder in which myelin in the central nervous system is attacked by the body’s own immune system. There is no known cure for multiple sclerosis. During remission, axons affected by the disorder regain their function. Voltage-gated sodium channels are concentrated in the nodes of Ranvier and the distribution changes at disease onset.

Questions: Create

4. Consider you are the physician, what would be your strategy to slow progression of the disease and compensate for reduced neuronal function? What is the long-term prognosis with treatment?

Thank you for your time with this

The Eye Exam It was a sunny day in 2005, and time for Eric’s annual eye exam. Dr. Tim flipped through his charts. “You know, we really should measure your visual fields. It’s been at least ten years since you had that done!” “I hate them!” Eric grumbled. “I get disoriented and, anyhow, we already know I have a large blind spot.” He raised his hand, squinting through one eye. “Here. I can’t see my finger here.” “I know.” Dr. Tim was sympathetic. “But weren’t you just telling me you haven’t seen stars for a while? It’s important. You had that tumor on your pituitary gland. Your optic nerves cross in that area, right in front of the pituitary, so if anything is happening again we’d probably notice it first by changes in your eyesight. It really is important!” An hour later, Eric was seated in front of a large white screen, staring intently at a light in the middle. “Keep looking at that light, so your eyes don’t move. If you see another light anywhere else, push this button.” Eric began the test by focusing on the light he saw in the center. The machine then successively displayed points of light of varying intensity in different places around the entire visual field. When Eric saw the peripheral light, he pushed a button. He did his best to detect the flashes, but realized he was probably missing some. The machine mapped out where he could see and where he could not. Dr. Tim looked at the printout. His face grew serious. “Eric, we have a problem. You have limited peripheral vision, and it’s bad enough that I don’t think you should be driving! This looks to me like something called retinitis pigmentosa. We should refer you to a specialist.” He pulled out more papers. “Here, look at this. Here are your visual fields. The numbers show how well you can see in that area of your eye, and in the graph on the right the darker the box is the less you can see. Now here are a normal person’s visual fields. Do you see the difference?”

1. How do your eyes work? What is the difference between focal vision and peripheral vision?

2. What is the anatomy around the pituitary gland? Why are the optic nerves likely to be affected by pituitary tumors?

3. Eric has retinitis pigmentosa In this disease pigments lining your eye gradually break down, so you can’t sense the light that hits your eye. Why do you need the pigments in order to see the images and light?

Andrea Smith was taking notes for her biology exam. Her professor has told her that the exam would cover, in part, the di erences between sexual and asexual reproduction. As she reviewed her notes and prepared for today’s class, she was thinking about her own reproductive dilemma. If only asexual reproduction were the case for humans, maybe she wouldn’t be in this mess. Or at least there wouldn’t be questions about who was the father of her twins. “Dwelling on it isn’t going to help me prepare for class, and right now I have got to nish this chapter on animal reproduction,” she thought. She tried to concentrate and forget about her current dilemma as she feverishly typed on her notepad:

Asexual or sexual reproduction: 3 types of asexual reproduction: (1) ssion: separation of a parent organism into two or more individuals of equal size, (2) budding: growth of new individuals from outgrowths of existing organisms, and (3) fragmentation accompanied by regeneration: the breaking of the body into several pieces, some or all of which develop into new complete individuals through the regrowth of lost body parts. NOTE: Be able to explain the di erences between sexual and asexual reproduction!

She suddenly let out a long sigh. “It’ll be ne,” she thought. “I just hope that none of my family or friends watches the show. What was I thinking when I agreed to this? But that’s what Xavier wanted, and I will do whatever it takes to prove he is the father. Besides I am going to need the money if I have to take care of these babies on my own!”

e next day in class she was feeling even more nervous and was becoming increasingly angry as she thought about her current situation. Her thoughts were interrupted by the sound of her professor’s voice:

“OK, class,” her teacher was saying, “that wraps up asexual reproduction. Let’s move on to reproductive cycles
and patterns. Most animals exhibit cycles in their reproductive activity. Reproductive cycles are often controlled
by hormonal and environmental cues. Animals may reproduce either exclusively asexually or sexually while other animals alternate between the two methods. For example, some animals can lay eggs of two types, depending on
the environment and/or season. One egg type matures only if it is fertilized while the other type does not require fertilization for development, a process called parthenogenesis. Some animals, and in rare cases humans, have both male and female reproductive systems. Some hermaphrodites can fertilize themselves, but most must mate with a member of the same species. Please look over these handouts and answer the questions that follow.”

As the other students read through the assignment, Andrea was thinking: “I’m dealing with a case of sexual reproduction that no doubt started with the fertilization of my egg with, hopefully, Xavier’s sperm. at reminds me, I need to make sure I go over internal and external fertilization again in my notes. I’m not sure I completely understand it.”

All this started the night Xavier had come came over to talk to Andrea about their break-up. He had smelled and looked so good that evening. e events of that night had left Andrea wondering if there was really some truth to that stu about pheromones, which Andrea has learned in her class were chemical signals released by one organism that in uence the behavior of another individual of the same species. Even though Andrea had met someone else and had

“An Unusual Case of Animal Reproduction” by Powell and Tillman Page 1

been seeing Neo for a while, she hadn’t been able to resist Xavier. Neither she nor Xavier had behaved like themselves that night. It was unlike them not to use some barrier method of contraception. As the class wrapped up, Andrea’s mind was still on her upcoming appearance on a daytime talk show. In some ways she was dreading it; but she was determined to prove what she believed she had known all along: at Xavier was the father of her twins.

Questions

1. What is the di erence between asexual and sexual reproduction?
2. List and de ne some types of asexual reproduction. Give one example of each. 3. What is the di erence between parthenogenesis and hermaphroditism?
4. What is the di erence between internal and external fertilization?
5. What is the function of pheromones?

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“An Unusual Case of Animal Reproduction” by Powell and Tillman

Page 2

Part II – The Pregnancy

“I can’t believe it has come to this! Airing our dirty laundry on national television. I never thought Xavier would let things get so out of hand.”

It was late and Andrea was so upset she couldn’t sleep. She tried studying for the upcoming exam, but she couldn’t concentrate. She decided to get an early start on packing. She was so angry with Xavier. How could he have left her pregnant and alone, she thought, as she neatly added her new dress to the bag? How could he think that their babies might belong to someone else? She grabbed her journal, about to add it to the bag, but instead sat in her cozy corner chair and began to read:

January 12, 2007

I’m pregnant with twins! Sometimes it’s still hard to believe because it was so unexpected. I feel like I am about to pop! I know that Xavier is the father of my babies and I can’t wait for us to be a family. But he has doubts about it all because he knows that I met someone else during the brief time that we split up. And he wants to be sure that he is the father before we can move on. But what if it is Neo, the new guy I met? ere’s a slight chance but I doubt it. I know the exact time of conception. It was the night Xavier came over to talk about our relationship. It was a little over a week after that night that the pregnancy test detected the increase in HCG. I guess I just missed him so much.

I do regret that Xavier hasn’t been around much during the pregnancy. He has missed the development of our babies. In the past months, I have heard the babies’ heartbeats and felt them moving around. I wish he would come back because it’s obvious that I am pregnant now. Hopefully we can talk through our di erences and get back together before the pregnancy gets di cult—the frequent urination and back pain my OB/GYN keeps warning me about. I know there is no way he will ever let me go through labor alone. I only pray the contractions are not more than I can bear. Xavier seems committed to the idea of a paternity test. Hopefully it won’t come to that, but if it does, we’re going to a daytime show to gure all this out.”

“Wow! at seems like a lifetime ago,” she thought. “Now we have these beautiful twins and we don’t seem any closer to becoming the real family I dreamed about. Well this will all be over in a couple of days. I am 110% con dent that the twins belong to Xavier, not Neo. I can’t wait to see the look on Xavier’s face and hear him apologize once he sees the results of the paternity test!”

Questions

1. What does Andrea mean by time of conception?
2. How is HCG used to determine pregnancy?
3. List some changes that occur with the fetus/mother during the 1st, 2nd, and 3rd trimesters. 4. What hormones are responsible for inducing and regulating labor?
5. What trimester is Andrea in during this journal entry?

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“An Unusual Case of Animal Reproduction” by Powell and Tillman

Page 3

Part III – The Results

Andrea replayed the words over and over again in her mind: “Xavier, you ARE the father!” She was ecstatic. Finally, she could breathe, knowing that Xavier was the father of her babies. en she heard what the host had to say next...

“Neo...YOU ARE the father!”
Andrea looked around in disbelief. She heard herself saying, “What do you mean? You just said Xavier was the father!

If Xavier is the father, how can he be the father?” she asked as she pointed toward Neo.

“Well, this is a rst, even for our show. But it appears that your twins were fathered by both of these men.”

“I can’t believe it. e rst time I do something like this and I end up with twins and two fathers! Not only did I expose myself to potentially deadly STDs, but now I have two children, whom I have no doubt that I will be raising alone, and I have put my school career in jeopardy,” Andrea thought.

She still couldn’t believe this was really happening to her. How was it possible that her TWINS have di erent fathers? What were the events that must have happened within her body that could lead to these circumstances? She grabbed her

journal from her bag and ipped back to the entry describing her feelings the day she found out she was having twins:

August 23, 2006

I just came back from another Dr’s appointment. Dr. Blossom informed me that I am having two babies— twins—fraternal. I don’t know if they are boys or girls yet. One could be a boy and the other a girl. I still can’t believe this has happened. Xavier has to be the father. He has to be! I will have to just play the hand I have dealt myself. How stupid was I? I was going to practice abstinence after Xavier and I broke up...and I certainly wasn’t planning on meeting and getting involved with Neo! I can’t believe that Neo and I didn’t use a condom either. And it’s no excuse that we had been drinking. I just got caught up in the moment with Xavier—going down memory lane and things got all sentimental. I could have at least thought to use the rhythm method and kept track of when ovulation may occur. is has to be the most irresponsible thing I have ever done! Why did I stop taking my birth control pills anyway? And I have no idea where I put that diaphragm. Undoubtedly, some people will judge me as the type of woman who should have a tubal ligation that would permanently prevent any pregnancy.

Everything hit her at that very second. She closed her journal and just sat there for a moment. Andrea was reminded that she had stopped taking the pill the month before she became pregnant. She remembered that physicians recommend that a woman wait at least one cycle after she stops taking the pill before becoming pregnant because there is a chance that multiple ovulations may occur. Did it have something to with oogenesis? Andrea was so confused she just couldn’t keep things straight in her mind. She thought about it for a minute to let it all sink in.

Andrea sat back and thought about the lecture on animal reproduction the week before. She pulled out her lecture notes on the menstrual cycle, the basic foundation of everything that she was going through.

Questions

1. Describe the two types of cycles that occur in female mammals (menstrual vs. estrous).

2. Compare and contrast the sterilization techniques (vasectomy and tubal ligation) and the temporary and reversible methods discussed in the case.

3. What are the functions of GnRH, FSH, LH, estrogen, and progesterone?

4. How can the paternity results be explained? Your answer should consider the amount of time before and after ovulation a woman is at risk for pregnancy and how long sperm can survive in the reproductive tract. Your discussion may include the following terms: ova, oogenesis, and fertilization, etc.

•

Image in title block dervied from licensed image © CLIPAREA.com—Fotolia.com, ID #21458691. Case copyright held by the National Center for Case Study Teaching in Science, University at Bu alo, State University of New York. Originally published December 8, 2011. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“An Unusual Case of Animal Reproduction” by Powell and Tillman Page 4

Andrea’s Lecture Notes: The Female Reproductive Cycle

(I) e female reproductive cycle involves both the uterus and the ovaries:

Menstrual cycle = uterine cycle
• Refers to the speci c changes that occur in the uterus

Ovarian cycle
• Cyclic events in the ovaries that regulate the menstrual/uterine cycle

(II) Hypothalamus secretes gonadotrophin-releasing hormone (GnRH) which stimulates the anterior pituitary to secretefollicle stimulating hormone (FSH) and luteinizing hormone (LH) into the blood. FSH and LH regulate the ovarian cycle.

~OVARIAN CYCLE:

Folicular Phase

FSH and LH stimulate a follicle to grow

e growing follicle releases estrogen

Ovulation

• An LH surge triggers ovulation

Luteal Phase

LH stimulates ruptured follicle to become corpus luteum

Corpus luteum secretes estrogen and progesterone, which inhibits LH and FSH secretion from the pituitary

Corpus luteum disintegrates

Estrogen and progesterone levels decrease, releasing the inhibitory e ect on the hypothalamus and the

pituitary

FSH and LH are released and a new cycle begins

(III) Ovarian hormones, estrogen and progesterone, regulate the uterine (menstrual) cycle ~UTERINE CYCLE:

Proliferative Phase

• increasing estrogen levels causes the uterine lining (endometrium) to thicken: prepares the uterus for

implantation of the blastocyst

Secretory Phase
• increased levels of estrogen and progesterone following ovulation maintains the endometrium by increasing

blood supply and growth of endometrial glands that secretes nutrients

Menstrual Flow Phase
• decreased levels of estrogen and progesterone cause the uterine arteries to spasm, depriving the endometrium

of blood: endometrium disintegrates, resulting in menstruation

Based on the information in the case study, Animal Reproduction, please answer the following questions.

Andrea is pregnant and is trying to calculate the time of conception.What is time of conception and how is it determined?

What are the functions of GnRH, FSH LH, estrogen and progesterone in pregnancy?

Andrea is having twins but the babies have two different fathers.Explain the difference between fraternal and identical twins.Which are these?How could the babies have different fathers?