Genetics Answers

Distinguish between proto-oncogens and tumor-suppressor genes; give one example of each. In

which class of genes does a loss-of-function mutation predispose cancer? A gain-of-function

mutation? Explain your answer.

How can one reconcile the following statements : “Cancer is a genetic disease” and “Most

cancers are sporadic (not inherited)”.

Describe the role of cyclins, cyclin-dependent protein kinases, and protein degradation in the

progression of cells through the cell cycle

Is the formation of large blebs from the cell membrane a characteristic of cell undergoing

apoptosis?

Short summary of a normal cell that leads to cancer cells

3. Why during the PCR is there a temperature change for certain times and what is the function of these cycles of different temperatures? explain.

• During the PCR, the temperature change for certain times is designed in order to carry out the exponential amplification of the small DNA fragment by chain polymerization.

• Cycles are rendered in a basic three step process which is repeated 25-40 times:

• 1st step: separates the DNA double strand for a period of 15-40 seconds at a temperature of 95º C -97º C.

• 2nd step: designed primers react with the single stranded DNA thus sticking complementary to other bases in a period of 0.5-2min. at a temperature of 40º C- 65º C.

• 3rd step: dNTPs are placed between the primers synthesizing complementary sequence to template DNA strands for a period of 1-2 min. at a temperature of 72º C.

Sexual reproduction,on the other hand, permits ________ of traits to arise from the contributions of multiple different ancestor

Consider how DNA transcription is controlled. How could a PNA be used to serve a similar function?

(a)  Mendel did not know of the existence of chromosomes. Had he known, what change might he have made in his Principle of Independent Assortment?

(b)  Consider 4 different genes represented by a, b, c, d.  If a is linked to b, and b to c, and c to d, does it follow that a recombination experiment would detect linkage between a and d? Explain.

A phenotypically wild-type female fruit fly that was heterozygous for genes controlling body color and wing length was crossed to a homozygous mutant male with black body (allele b) and vestigial wings (allele vg). The cross produced the following progeny: gray body, normal wings 126; gray body, vestigial wings 24; black body, normal wings 26; black body, vestigial wings 124. Do these data indicate linkage between the genes for body color and wing length? What is the frequency of recombination?