Biology Answers

During meiosis, genetic recombination results because –

what is the storage organ for an egg yolk

what is the storage organ for an egg white

Judy did a little research on skin cancer on the Internet before the visiting her doctor next morning. She found out what happened with other people, that were significantly older than she. It didn’t make sense that this would happen to her - she was only 20 years old!

The articles talked about how the sun’s ultraviolet light can be cause of DNA mutations. Accumulated DNA mutations over the years can cause genes super-activation. Judy was really grateful for the college biology course she attended. She knew that DNA was hereditary material that acted as a “plan” for everything our cells did, and that the gene was a piece of DNA that contained instructions for synthesizing a single protein. However, she should ask the doctor about these genes.

During the examination Dr. O'Brien was silent, looking at the mole on her leg. Finally, he said kindly: “I want to do a biopsy. All this means that we will remove your mole and look at the cells under a microscope and determine if they look abnormal. "

Judy said with tears: “You mean you can tell me that I have a tumor just by looking at some cells?”

 “It is very possible that your cells will look completely normal. A tumor is not necessarily the same as cancer. ” She looked embarrassed, so he continued: “A tumor means that the cells divide and gather in the same mass. But not all tumors automatically become malignant and life-threatening. A benign tumor is a mass of normal cells. These tumors are not considered as a cancer, and they are usually easily treated - we just remove them”, Dr. O'Brien replied.

The doctor smiled and seemed pleased that Judy read about it herself. “Let's remember! You see, we have tens of thousands of genes in our cells, but this does not mean that mutations in just any of them will lead to cancer. Genes that become mutated and can cause cancer have a specific type called cell cycle genes. Each person has a set of cell cycle genes in each of his cells that encode cell cycle proteins.  In normal healthy cells, cell cycle protein formation is tightly controlled, activating proteins are produced only when we really need more cells, and inhibitory proteins appear only when we don't need more cells. However, mutations in these genes can eliminate this tight regulation and lead to uncontrolled cell division. This is what happens in many types of cancer: the normal cell process, cell division, that is no longer properly controlled. ”

Judy thought for a second. “Okay, but you still haven't said what proto-oncogenes are.”

Issues for discussion:

1. What genes is Judy talking about? What are these genes called?

2. What are the functions of these genes in the cell? Explain.

3. List several genes that belong to this group.

4. In addition to these genes, mutation of what other genes leads to cell transformation?

5. Explain the mechanisms of conversion of proto-oncogenes into an oncogene.

6. What properties are characteristic of benign and malignant tumors.  Describe.

7. What stages of malignant transformation of cells do you know? Describe each stage.

Judy sat down, drank water from her bottle and wiped sweat from her face. She loves to sunbathe every summer. Judy decided that her usually pale skin had become quite tanned, in fact it turned out to be a little red.

Judy paused for a second to scratch her calf of the leg. For several days, the itch had been bothering her, and she decided that she had been bitten by mosquitoes the night before. She leaned over to take a closer look and was surprised to find that this was not a mosquito bite, but a mole. As long as she remembers herself, this mole was, but she had never itched before. She looked more closely and noticed that the "mole" looked a little different than she remembered. She was a little bigger and the edges were jagged. One edge was slightly darker than the other, and in the middle was a rising purple-black dot, which she tried to erase, but could not.

Judy shook her head: “In any case, I just noticed that the mole on the leg looks strange, and it itches, I should think.”

Mariah sat with a worried expression on her face: "Let me see this." When she looked at Judy’s leg, she said quietly: “Maybe you should go to the clinic”? While Judy looked at her, she continued: “My mother sent me a brochure about skin cancer last year. You know, trying to convince me to stop lying in the sun for a long time. I looked at it before throwing it in the bin. I remember some photos of skin cancer, and they looked like your mole. ”

"What are you talking about?" Judy exclaimed defensively. “How can I have skin cancer? I was not so long under the sun rays compared with you. "

"Good good. I'm not a doctor. I just remember these pictures. Well, let's just call the clinic so they can examine you. I’m sure they will tell you that I’m crazy. ”

Issues for discussion:

1. Judy has a change in her mole that occurred under the influence of the sun. What is the name of this process? Explain.

2. What is the reason for Judy's mole color change? What changes in the DNA molecule occurred under the influence of this factor?

3. What other factors can lead to the transformation of normal cells?

4. What type of tumor are moles? Explain the answer.

Task 1. Situational tasks:

A 4-day-old newborn was delivered to the clinic. From the history of the disease it is known: a child from a second pregnancy, full-term, birth weight is 3500g. Pregnancy proceeded normally, childbirth was normal. The child cried immediately. After trying to give the child a drink of sweet water a cough, cyanosis and vomiting appeared. During feeding expressed breast milk from a spoon, vomiting, cyanosis also appeared immediately, and foam flowed through the nose. Vomit is without signs of caseation. On the third day, the doctor suspected a child with a malformation - atresia of the esophagus.

Questions for discussion:

1. What are the mechanisms of this embryopathy?

2. What types of apoptosis and their distinctive features do you know?

3. What type of apoptosis occurs with atresia? Explain.

a man with type A- blood and a women with type B+ blood marry and have 8 children. one of the children has type O- blood. what are the genotypes of the parents. what are probable genotypes and phenotypes of the 8 children.

You test a population of 10,000 teenagers in Kenya for their genotypes of the sickle cell trait. You find

that 1 in 500 teenagers (200 total) have sickle cell anemia, an autosomal recessive disorder.

(a) What is the predicted frequency of the:

-Recessive allele? Show your work. ?

-Dominant allele? Show your work. ?

(b) What is the predicted frequency of the:

-Homozygous dominant genotype? Show your work.

-Heterozygous/carrier genotype? Show your work.

(c) How many individuals should be:

-Homozygous dominant? Show your work.

-Heterozygous/carriers? Show your work.

Choose any wild, existing species of Eukaryote that interests you. Please don’t choose humans and don’t choose a domesticated species. In studying a population of your organism, you focus on a particular gene (this does not have to be an actual gene, just a realistic one). At first it seems that your study sample is uniform at this locus but then you discover a unique, novel mutation. In other words, every single copy of the gene in your sample is identical except for the unique copy of a new variant allele that you have discovered.

In your own words, describe the normal function of the gene at this locus and how the function of the new allele differs, if at all. For the sake of this exercise, we will assume that the new allele is not strongly deleterious and that it will ultimately become fixed (replace the original allele) in the population. In your own words, tell the story of how and why the new variant becomes fixed. To keep your reader informed, be sure to state its frequency at three or more points in time, measured in generations.

why do mammals have a double circulatory system