Cytogenetics Oct12 M3

Question 1

morphologic groups of chromosomes

Answer 1

metacentric, submetacentric, acrocentric

Question 2

molecule holding chromosomes until anaphase

Answer 2

cohesins

Question 3

name of structure on chromosomes that the mitotic spindle attaches to

Answer 3

kinetochores

Question 4

important proteins in kinetochore

Answer 4

CENP proteins

Question 5

2 important chromosome regions

Answer 5

centromere, telomere

Question 6

telomere function and how

Answer 6

protect DNA from ligation and degradation. form loop. tell cell not a broken piece of DNA

Question 7

how telomere changes with time

Answer 7

shortens with cell divisions

Question 8

name of the phases in meiosis 1

Answer 8

leptotene, zygotene, early pachytene, late pachytene, diplotene, diakinesis

Question 9

when crossing over occurs at meiosis 1

Answer 9

pachytene stage (early and late)

Question 10

name of crossing over structure inmeiosis

Answer 10

chiasma

Question 11

non-disjunction 3 types

Answer 11

2 homologous chromosomes

2 sister chromatids

Question 12

how mosaicism can happen from non disjunction

Answer 12

if non disjunction at mitosis

Question 13

constitutional mosaicism def

Answer 13

at least 2 cell lines with diff chromosomal complements in a fetoplacental unit derived from a single zygote

Question 14

chimerism def

Answer 14

diff cell lines in diff zygotes

Question 15

common disease where mosaicism taking place

Answer 15

cancer

Question 16

3 cytogenetic techniques

Answer 16

• chromosome banding
• FISH
• chromosomal microarray

Question 17

how to obtain metaphase chromosomes

Answer 17

fix cells at metaphase and put them on slide

Question 18

chromosome banding def

Answer 18

each chromosome has characteristic light and dark bands

Question 19

staining used in chromosome banding

Answer 19

Giemsa

Question 20

Robertsonian translocation def

Answer 20

fusion of 2 acrocentric chromosomes

Question 21

Robertsonian transloc consequence on carrier and progeny

Answer 21

• no conseq on carrier bc normal chrom number

- progeny might get extra copy of a chromosome

Question 22

balanced structural rearrangements of chromosome, give 3

Answer 22

reciprocal translocation, inversion, Robertsonian transloc

Question 23

unbalanced rearrangements conseq

Answer 23

affect dosage sensitive genes

Question 24

banding and karyotyping: good and bad

Answer 24

good: can see balanced and unbalanced rearrangements
bad: limit to resolution

Question 25

FISH steps

Answer 25

denature DNA, hybridize with labelled probe, post-hybridization wash, vew signal on fluorescent microscope

Question 26

FISH good and bad

Answer 26

god: high resolution
bad: only see genome complementary to the probe

Question 27

microarray concept

Answer 27

many FISH at once.patient DNA one colour, test DNA other colour. if mix sequences and colour is in between, shows equal number of genes

Question 28

microarray good and bad

Answer 28

good: very high resolution
bad: balanced rearrangements can’t be seen

Question 29

what techniques used to diagnose down syndrome

Answer 29

all three

Question 30

what banding allows to see in down syndrome

Answer 30

if Robertsonian chromosome (extra copy of chrom 21 on chrom 14)

Question 31

reciprocal translocation carriers

Answer 31

if reciprocal chromatids don’t segregate together, get + copies and deletions too

Question 32

reciprocal translocation between chrom 9 and 22: associated disease

Answer 32

chronic myelogenous leukemia

Question 33

CML cause of problem

Answer 33

BCR and ABL genes rearrangement: constitutively active protein

Question 34

CML name of anormal chromosome 22 (with not much left)

Answer 34

Philadelphia chromosome

Question 35

treatment for CML

Answer 35

TKI (Imatinib, Gleevec)