Molecular Biology Answers

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.

1.     Describe the process of protein synthesis. You answer must include the two major steps, all major enzymes and molecules involved, where each step occurs in the cell and a summary of what happens in each step. (4 marks)

 There are two processes that occur during protein synthesis, transcription and translation. In transcription, DNA is used as a template to make the messenger RNA (mRNA). Transcription occurs in the nucleus of eukaryotic cells. However, translation occurs when the mRNA leaves the nucleus and goes to a ribosome in the cytoplasm of eukaryotic cells. During translation, the genetic code is read by tRNA and the protein is synthesized according to the message present on mRNA. There are three steps in translation: initiation, elongation and termination. Initiation: always starts with the AUG codon therefore, it is always the first amino acid to be added.  Elongation: are amino acids that are added on one at time to the growing protein chain. The tRNA associates the anticodon to the codon of the mRNA and transports each time the correspondent amino acid, the peptidyl transferase forms the peptide bonds between amino acids.

Termination: is when there is a stop codon (UGA, UAG and UAA) the tRNA recognizes it, and it released and the translation ends.

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Mixtures can be homogeneous and heterogeneous,,explain with examples different method used to separate the mixtures

1.     Explain what the term “nondisjunction” means and provide the names of two diseases caused by nondisjunction. (2 marks)

Nondisjunction is best defined as when the chromosomes fail to separate during division. The names of the two diseases that is caused by nondisjunction is Trysomy X and Klinefelter syndrome. Trysomy X, is when a person has 3 X chromosomes and Klinefelter syndrome is when a person has 2 X chromosomes and a Y. 

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1.     Why is a reduction in chromosome number required for meiosis? (2 marks)

A reduction in chromosome number required for meiosis because meiosis creates cells that are destined to become gametes or reproductive cells, this reduction in chromosome number is critical without it, the union of two gametes during fertilization would result in offspring with twice the normal number of chromosomes.

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1.     Describe the process of protein synthesis. You answer must include the two major steps, all major enzymes and molecules involved, where each step occurs in the cell and a summary of what happens in each step. (4 marks)

 There are two processes that occur during protein synthesis, transcription and translation. In transcription, DNA is used as a template to make the messenger RNA (mRNA). Transcription occurs in the nucleus of eukaryotic cells. However, translation occurs when the mRNA leaves the nucleus and goes to a ribosome in the cytoplasm of eukaryotic cells. During translation, the genetic code in mRNA is read and is used to make a protein. There are three steps in translation: initiation, elongation and termination. Initiation: the mRNA and the tRNA bind to the ribosome. Elongation: are amino acids that are added on one at time to the growing protein chain. The tRNA associates the anticodon to the codon of the mRNA and transports each time the correspondent amino acid, the peptidyl transferase forms the peptide bonds between amino acids.

Termination: is when there is a stop codon (UGA, UAG and UAA) the tRNA recognizes it, and it released and the translation ends.

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Chemical elements of tobacco smoke can change the nucleotide sequence in a DNA molecule by replacing adenine with thymine or guanine with cytosine. Which kind of mutation is this one? Draw and explain the mechanisms and consequences of such a change

) When so much damage occurs in DNA that during excision reparation the cell does not have time to completely eliminate them. As a result, after replication of this DNA the daughter chain has “gaps” that are formed at the site of damage of the mother DNA chain,.

1. What type of reparation corrects such damage?

2. What are the molecular mechanisms the cause of this disorder?

3. Feature of postreplication reparation.

4. What other types of postreplication reparation do you know, describe.

) When so much damage occurs in DNA that during excision reparation the cell does not have time to completely eliminate them. As a result, after replication of this DNA the daughter chain has “gaps” that are formed at the site of damage of the mother DNA chain,.

1. What type of reparation corrects such damage?

2. What are the molecular mechanisms the cause of this disorder?

3. Feature of postreplication reparation.

4. What other types of postreplication reparation do you know, describe.