IMMS genetics

Question 1

what does giesma stain?

Answer 1

G banding

Question 2

what does quinacrine stain?

Answer 2

Q banding

Question 3

which way does DNA polymerase read?

Answer 3

3’ to 5’

Question 4

what is the function of topoisomerase?

Answer 4

unwinds the double helix- relieves supercoiling

Question 5

what does DNA ligase join?

Answer 5

Okazaki fragments

Question 6

what is a primer?

Answer 6

short strand of DNA that is the starting point for DNA synthesis

Question 7

why does RNA detach from DNA?

Answer 7

hydrogen bonds are broken as DNA has a high affinity for re-bonding with its own complementary strand

Question 8

what enzyme allows peptide bonds to form between amino acids during translation?

Answer 8

peptidyl transferase

Question 9

what is a deletion variant?

Answer 9

out of frame deletion causing absence of a base- disrupts the protein

Question 10

what is a splice-site variant?

Answer 10

nucleotide changes- no longer splice receptor site, affects accurate removal of an intron, intron translated into a protein

Question 11

what is a non-sense variant?

Answer 11

changes codon into a stop codon, out of frame deletion site

Question 12

what is a mis-sense variant?

Answer 12

single-base substitution, results in a change in amino acid- may be pathogenic, polymorphism or no functional difference

Question 13

what happens during prophase?

Answer 13

chromatin condenses into chromosomes, centrosomes nucleate microtubules and move to opposite poles of nucleus

Question 14

what happens during prometaphase?

Answer 14

nuclear membrane breaks down, microtubules invade nuclear space, chromatids attach to microtubules

Question 15

what happens during metaphase?

Answer 15

chromosomes line up along metaphase plate

Question 16

what happens during anaphase?

Answer 16

sister chromatids separate and are pushed to opposite poles of the cell

Question 17

what happens during telophase?

Answer 17

nuclear membranes reform, chromosomes unfold into chromatin, cytokinesis begins

Question 18

what is a spermatogonia?

Answer 18

undifferentiated male germ cell

Question 19

how does the cytoplasm divide during gametogenesis in males?

Answer 19

it divides evenly

Question 20

how does the cytoplasm divide during gametogenesis in females?

Answer 20

divides unequally- 1 egg and 3 polar bodies (which apoptose)

Question 21

what is Mendels second law?

Answer 21

the law of independent assortment states that alleles for separate traits are passed independently of one another from parents to offspring

Question 22

what is gonadal mosaicism?

Answer 22

occurs when precursor germline cells (to ova or spermatozoa) are a mixture of 2 or more genetically different cell lines

Question 23

how does incidence of gonadal mosaicism change w/ paternal age?

Answer 23

incidence increases- more divisions= increased probability

Question 24

what are the 3 groups can diseases be characterised into and which genetic variants fall under these?

Answer 24

• chromosomal
• mendelian- autosomal dominant, autosomal recessive and X- linked
• non-traditional- mitochondrial, imprinting, gonadal mosaicism

Question 25

key characteristics of autosomal dominant conditions

Answer 25

- manifests in heterozygous state - father to son - 50% chance

Question 26

key characteristics of autosomal recessive conditions

Answer 26

- manifests in homozygous state - both parents must have recessive allele - 25% chance - males and females affected equally

Question 27

key characteristics of X-linked conditions

Answer 27

- pathogenic variants on X- chromosome - if mother has it- 50% of being unaffected male, 25% affected - if father has it- all daughters will be carriers, boys will not be

Question 28

what is lyonisation?

Answer 28

one of the females X-chromosomes becomes inactivated

Question 29

what is the dominant negative effect?

Answer 29

an altered gene product is produced that acts antagonistically to the wild-type allele

Question 30

what is Knudsons 2 hit hypothesis?

Answer 30

cancer is a result of accumulated mutations to a cells DNA

Question 31

what is penetrance?

Answer 31

percentage of individuals with a specific genotype showing the expected phenotype

Question 32

what is variable expression?

Answer 32

variable expressivity refers to the range of signs and symptoms that can occur in different people w/ the same genetic condition

Question 33

what is sex limitation?

Answer 33

condition inherited in AD pattern that seems tot affect one sex more than another

Question 34

what is allelic heterogeneity?

Answer 34

situation where different mutations within the same gene result in the same clinical condition (e.g. cystic fibrosis)

Question 35

what is a telomere?

Answer 35

region of repetitive nucleotide sequences at the ends of each chromatid, protects the end of chromosomes from deterioration or from fusion to neighbouring chromosomes