chromosome biology

Question 1

what direction does DNA polymerase work in

Answer 1

5’ to 3’

Question 2

what is the function of telomerase

Answer 2

protects the ends of the chromosome

Question 3

what strand is the strand that has okazaki fragments

Answer 3

lagging strand

Question 4

what are the phases of mitosis

Answer 4

G1, S (replication), G2, M (mitotic phase)

Question 5

whats prophase

Answer 5

Chromosomes condense
Nuclear membrane disappears
Spindle fibres form from the centriole

Question 6

whats metaphase

Answer 6

Chromosomes aligned at the equator of the cell
Attached by fibre to each centriole
Maximum condensation of chromosome

Question 7

whats anaphase

Answer 7

Sister chromatids separate at centromere
Separate longitudinally
Move to opposite ends of cell

Question 8

whats telophase

Answer 8

New nuclear membranes form

Each cell contains 46 chromosomes (diploid)

Question 9

whats cytokinesis

Answer 9

Cytoplasm separates

Two new daughter cells

Question 10

what is the purpose of centromeres

Answer 10

joins sister chromatids

site of kinetochore

Question 11

whats interphase

Answer 11

genes are transcibed and dna replication occurs

Question 12

whats the difference between heterochromatin and euchromatin

Answer 12

heterochromatin - condensed structure and silenced genes whereas euchromatin - open structure and actiive genes

Question 13

what is the extragenic region?

Answer 13

DNA space between two genes of a genome

Question 14

how is chromatin formed

Answer 14

dna packaged with histone proteins

Question 15

what is the charge of histones?

Answer 15

positive

Question 16

what are chromatins packaged into?

Answer 16

nucleosomes

Question 17

what probe is useful for chromosome number?

Answer 17

centromeric probes

Question 18

what probe is useful for detecting subtelomeric rearrangements

Answer 18

telomeric probes

Question 19

whats the difference between meiosis and mitosis

Answer 19

meiosis is cell division in germ cells, diploid cells divide to form haploid (2 divides)

recombined copies as they mix

Question 20

whats Oogenesis

Answer 20

process of egg formation

Question 21

what is Spermatogenesis

Answer 21

process of sperm formation

Question 22

which sexual gametes has more divisions

Answer 22

males

Question 23

how many spermatids are produced per miosis

Answer 23

4

Question 24

what are the three types of chromosomal abnormalities

Answer 24

numerical, structural, mutational

Question 25

what is trisomy 21 and what is it caused by

Answer 25

down syndrome | non dysjunction

Question 26

what is the incident rate of trisomy 21

Answer 26

1 in 650 to 1 in 700

Question 27

what is trisomy 13?

Answer 27

paatau syndrome

Question 28

whats the incidence rate of trisomy 13

Answer 28

1 in 5000

Question 29

whats the cause of trisomy 13

Answer 29

non- dysjunction and unbalanced translocatoin

Question 30

what is triomy 18

Answer 30

edwards syndrome

Question 31

whats the incidence of trisome 18

Answer 31

1 in 3000

Question 32

whats the cause of trisomy 18

Answer 32

non-dysjunction

Question 33

what is 45,X? what is its incidence what are symptoms

Answer 33

turner syndrome and 1 in 5000 to 1 in 10000 | females of short stature and infertile, neck webbing and widely spaced nipples

Question 34

what is 45,XXY and what is its incidence rate

Answer 34

klinefelter syndrome, 1 in 1000 | tall stature, long limbs, male but infertile, small testes

Question 35

what is gynaecomastia

Answer 35

abnormal development of breast tissue in males

Question 36

what are the two types of translocations

Answer 36

Reciprocal: involving breaks in two chromosomes with formation of two new derivative chromosomes Robertsonian: fusion of two acrocentric chromosomes

Question 37

what are the 4 structural abnormalities

Answer 37

translocation, deltiens, insertions and inversions

Question 38

whats the differemce between germline and somatic mutations

Answer 38

Somatic mutations – occur in a single body cell and cannot be inherited Germline mutations – occur in gametes and can be passed onto offspring

Question 39

what are the 4 types of coding mutation

Answer 39

silent, missesnse, nonesense, frameshift

Question 40

what do we need for polymerase chain reaction

Answer 40

sequence information, oligonucleotide primers, DNA, nucleotides, DNA polymerase

Question 41

what are the three steps to PCR

Answer 41

dentaure, anneal, extend

Question 42

what temperature does annealing happen

Answer 42

50-70

Question 43

what are the advantages of gel elcetropheresis

Answer 43

speed, ease of use, sensitive, robust

Question 44

what are the advantages of ARMS (amplification refractory mutation system)

Answer 44

cheap labelling not required electrophoresis required primer design critical

Question 45

what are the disadvantages of ARMS

Answer 45

needs sequence information limited amplification size limited amounts of product infidelity of DNA replication

Question 46

whats the function of restriction endonuclease

Answer 46

protective mechanism, degrades dna of invading viruses

Question 47

what is restriction endonuclease?

Answer 47

enzymes from bacterial cells

Question 48

whats the advantages of restriction digest assay

Answer 48

simple, cheap, no radioactive, requires gel electrophereis, not always feasible

Question 49

what are the advantages/ limitations of DNA sequencing

Answer 49

gold standard for mutation detecting, automation and high throughput expensive equipment poor quality sequence read

Question 50

what would alter your choice of method

Answer 50

``` direct test quick and easy cheap sensitivity specificity ```