Question

1. (2 pts) Homologous chromosomes a. come from different parents b. have the same genes c. may have different alleles d. have very similar DNA sequences e. all of the above f. none of the above 2. (3 pts) List the three ways that sexual reproduction increases the genetic variability of a population more than does asexual reproduction. 3. (2 pts) An organism has six independent (unlinked) genes and the following genotype: aaBbDdEEffag. How many different gametes could this organism produce? Show your work. 4. (2 pts) List one process in prophase of meiosis-l and mitosis that is the SAME and a process that is DIFFERENT SAME: DIFFERENT: 5. (2 pts) The cell shown below is two numbers) n=_ (the answer is in the 1n=14 format, so fill in 6. (3 pts) Briefly describe how cancer can arise and the role of the cell cycle control system.

Answer 1

1) option e, all of above

Homologus chromosome are the chromosomes comes from parents ( mother and father).

They contain similar genes and different alleles.

2) three mechanism cause genetic variation in sexual reproduction are-

a) crossing over- this occur during meiosis I between non sister chromatids of homologous chromosomes.

b) due to random movements of chromosomes during telophase in gamete formation.

c) in large no of gametes, random fertilization between egg and gametes.

3) no of gametes can be easily determined using fork line method.

4) meiosis is a process in which reduction in chromosomes no occur which lead to generation of haploid gametes. Mitosis is equational division and lead to formation of 2n cell similar to parent cell.

2 aaBb D d E Effgg No. of gamettes a none of Letersggols of 4 D - E-f-g AB D E Fg B d - E-fg et bot fg - d -E- f - abd Efa abbe fa ĝ → abdefa

Different between meiosis I prophase and mitosis - in meiosis prophase I there is crossing over occur while it is absent in mitosis.

Similarity between meisis I and mitosis - in both division, no of condensed chromatin are 46 chromosomes.

5) the cell is 1n ( haploid) . = 6 no of chromosomes

6) cancer occur due to uncontrolled cell division.

There are two type of Gene's present in the cell . Which plar an important role in cancer.

Protooncogene- these Gene's normally involve in cell division patway and growth pathway which are regulated. But if there are activating mutation than these pathway activate even in absence of signal and lead to tumor formation. Tumor supressor gene- they supress tumor formation. Like cell cycle regulatory gene , eg p53, chk1 and chk2 etc. These get activated when there is mutation in cell and thus prevent division in a wrong way

Loss of function of these Gene's lead to loss over control of cell division and cause tumor formation.

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