Cytogenetics

Question 1

what is cytogenetics

Answer 1

structure of DNA within the cell nucleus

Question 2

we study chromsones in what phase

Answer 2

metaphase

Question 3

any cell in the body always has how many autosomes

Answer 3

22 autosomes and 1 sex

Question 4

how many types of chromosomes in human body

Answer 4

24

Question 5

metacentric chromosome

Answer 5

middle

Question 6

submetacentric

Answer 6

distant from middle

Question 7

acrocentric

Answer 7

almost at the end

Question 8

what are the most common banding techniques

Answer 8

G,Q,R,C

Question 9

Describe G banding

Answer 9

stain : geimsa

regions: adenine and thymine rich
procedure: treat with trypsin to digest protein

Question 10

what is the most widely used badning method

Answer 10

g staining

Question 11

describe Q banding

Answer 11

stain : quinarine mustartd
regions : heteromorphism variants
procedure : stain with mustard and examine floresence under microscopre

Question 12

describe R banding

Answer 12

stain : geimsa
regions : regions poorly stained by q or r
procedure : treat with hot salt to denature A and T , stain with geimsa

Question 13

what reions do c banding stain

Answer 13

centromeric regoins or constitunitve region with heterochormoatin

Question 14

what does nor stain banding do

Answer 14

indentifyies genes for ribosomal RNA , uses silver staining

Question 15

what kind of chromosoe is used in a karyotpes

Answer 15

metaphase in mitotic cell

Question 16

what syndrome: 47xxy

Answer 16

kleinfelter

Question 17

what syndrome : 45 x

Answer 17

turner

Question 18

what sydnrome: 47, xx, +21

Answer 18

female with down

Question 19

what are the 3 kinds of fish probes

Answer 19

locus specific - detect presence or absense of a gene , can look for gain loss or translocaiton

satellite DNA probe - detects repetitive sequences of DNA , determines # of copies of a chromosome , trisomomy mnosomy etc

Chromosome paint probe - paints entire p and q arm

Question 20

what does aneuplid and euploid mean

Answer 20

anuelploid = any variation of a multiple of normal set of chormosomes

Euploid = normal mutlple of set of chromsomes

Question 21

triploidy is the result of what

Answer 21

dispermy, fertilization by 2 sperm

Question 22

tertraplody is the result of what

Answer 22

failure of cleavage of zygote

Question 23

what are the 4 viable anuploidys

Answer 23

trisomy 21, 18, 13,

monoploidy - turner syndrome

Question 24

how to tell if non disjunciton occurs in meisosis 1 or 2

Answer 24

meisosis 1 - all cellss will have wrong # ( 2 with 2 and 2 with none)

meiosis 2 - 2 cells are fine , 1 has 2 and one and none

Question 25

what 2 things are required to have a stable chromosome

Answer 25

centromere

2 telomeres

Question 26

what does isochromosome refer to

Answer 26

arms of 2 sister chromatides are joined, reslut of abnormal divison of centromere

Question 27

what does a robertsoninan translocation refer to

Answer 27

exnchage between 2 acrocentric chromosomes

Question 28

how many phases of sex differentiation are there

Answer 28

2
1 primary sex diffferention - produciton and matureation of gonads and gametes

2 secondary sex differentiaton - apprearance of the organisms

Question 29

what does the PAR region refer to on the x and y chromosome

Answer 29

psudoautosomal region , this is what allows the x and y chromsome to be homologous

Question 30

sex differentiantion doesnt occur until what week

Answer 30

7th

Question 31

0-7 weeks is known as the _____ stage

Answer 31

indifferent

Question 32

The ovarian pathway is followed unless ____ diverts development into a male

Answer 32

TDF, tetis determining factor

Question 33

what can we identify in cells to know that an x is inacitve

Answer 33

barr bodies

Question 34

gonadal tissue for both sexes is known as

Answer 34

hermaphroditism

Question 35

gonadal tissue and chromosomes for one sex and genetalia for other sex is known as

Answer 35

psuedohermaphroditism