session 10-chromosomal abnormalities

Question 1

What is a nucleosome?

Answer 1

structural unit of eukaryotic chromosome, consisting of a length of DNA coiled around a core of histones

Question 2

what do you called lightly packed and tightly packed chromatin?

Answer 2

lightly=euchromatin

tightly=heterochromatin

Question 3

what is the chromosome representation of a male and female?

Answer 3

• 46,XY

- 46,XX

Question 4

what is polyploidy?

Answer 4

no. of chromosomes more than 46
- e.g. 23 x 3 chromosomes
- multiple of 23

Question 5

give 2 examples of aneuploidy

Answer 5

monosomy (loss of one chromosome.i.e. one chromosome pair only has one chromosome)
trisomy (same as above except there is an addition of one chromosome)

Question 6

name the 5 types of mutation that can occur within a single chromosome

Answer 6

• deletion
• duplication
• inversion (rearrangement of genetic material)
• ring chromosome (loss of ends of chromosome arms and ring formed)
• isochromosome ( 2 non identical chromosomes formed from homologous pair-2 short ends join, 2 long ends join)

Question 7

describe the 3 mutations that occur between 2 chromosomes

Answer 7

• inversion-rearrangement. genetic info transferred to another chromosome
• reciprocal translocation-exchange of material between 2 non homologous chromosomes
• robertsonian translocation-exchange of material between 2 acrocentric (centromere located very near the end of chromosome) chromosomes, where the 2 q arms (long) join to form super chromosome and p arms join together.

Question 8

what is karyotyping?

Answer 8

test to examine chromosomes in a sample of cells

Question 9

what is it called when amniotic fluid is tested for any chromosomal abnormalities?

Answer 9

amniocentesis

Question 10

chromosomes are made up of chromatin. What is chromatin made up of? (4 things)

Answer 10

• DNA
• RNA
• non histone proteins (after basic histone proteins removed)
• histones proteins

Question 11

Describe how FISH works

Answer 11

• DNA probes are made fluorescent
• Probes and chromosome with section that wants to be located denatured. DNA separates into single strand
• then mixed together, allows probes to bind to complementary section of DNA on chromosome
• locates genetic material wanting to be examined

Question 12

Which one, euchromatin or heterochromatin has a beads on a string like structure and which is solenoid shaped?

Answer 12

Eu=beads

Het=solenoid