Question

Below (see diagram) is a human karyotype:

A) What is the sex of this individual?

B) Which of the following best describes the chromosomes in the karyotype: 1N, 2N, 4N, 23N, 46N?

C) How many chromatids are present in this karyotype? Explain.

D) The chromosomes here are stained with Giesma stain, and distinct light and dark bands can be seen.

What does the staining pattern help to identify?

E) What chromosomal abnormality/abnormalities do you observe in this karyotype? (Be as specific as

possible in your answer).

F) Which of the following mutagens most likely generated the abnormality seen here?

a. An error by DNA polymerase during replication

b. An error by RNA polymerase during transcription

c. An error by ribosomes during translation

d. Reactive Oxygen Species

e. UV light exposure

f. X ray exposure

g. Incorporation of a 5-Bromo- Uracil

h. Exposure to Ethidium Bromide

i. Depurination

G) Which of the following repair mechanisms was likely involved in the abnormality(ies) seen in this

karyotype?

a. Proofreading by a polymerase

b. Mismatch repair

c. Base Excision Repair

d. Nucleotide Excision Repair

e. Photolyase

f. Homologous Recombination

g. Non-Homologous End Joining

H) Give 3 ways in which the abnormality(ies) in this karyotype could lead to a phenotype.

Explain your choice.

QUESTION 3: Below is a human karyotype L2 s3 14 as 16 1s 20 A) What is the sex of this individual? B) Which of the following best describes the chromosomes in the karyotype: 1N, 2N, 4N, 23N, 46N? Explain your choice

Answer 1

A.As there is no Y chromosome it is a girl.

B. As chromosomes are in pair the best state that can describe it is 2N.

C. Each chromosome has 4 chromatids .Here there are 46 chromosomes .Hence 46x 4= 92 chromatids.

D.Giemsa banding is a technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes. It is useful for identifying genetic diseases through the photographic representation of the entire chromosome complement.

E. Chromosome 12 are of unequal lenght or some part is missing .It may result into some kind of leukeamia.