Exam 1

Question 1

What is molecular genetics?

Answer 1

the study of structure and function of genes at the molecular level

Question 2

Differentiate between sister chromatids and homologous chromosomes.

Answer 2

Homologous-one from mom one from dad

Sister chromatids- an identical allele made prior to cell division through replication

Question 3

Define a gene.

Answer 3

A hereditary factor that influences a particular trait

A region of DNA on a chromosome that codes for a particular protein or RNA

Question 4

When can chromosomes be seen as condensed Xs?

Answer 4

During m-phase of cell cycle. This X is representative of the completion of s phase and represents sister chromatids.

Question 5

Which type of chromosomes lack homologs?

Answer 5

Sex chromosomes x,y

Question 6

How do genes relate to the number of kb?

Answer 6

The number of genes is related to areas that encode for protein and is often much less than the number of kb

Question 7

Explain the reason why no. of proteins> no. of genes

Answer 7

alternative splicing

Question 8

Other than proteins (which type of RNA), what else do genes encode?

Answer 8

Proteins are mRNA, but genes also encode for tRNA, rRNA, miRNA, snRNA.
siRNA not included bc not coded for by gene

Question 9

What is a allele?

Answer 9

different versions of a gene

Question 10

Do homologous chromosomes contain the same genes? same alleles?

Answer 10

Carry same genes, not always same alleles

Question 11

How many alleles are passed on in one gamete? one somatic cell?

Answer 11

One allele in gametes, two in somatic cells.

Question 12

What does n stand for in a 2n diploid organism

Answer 12

number of chromosome

Question 13

Describe the principle of segragation.

Answer 13

each gamete carries only one allele because of segregation of sister chromatids in meiosisII

Question 14

When does reduction division occur?

Answer 14

In meiosis I

Question 15

Describe the principle of independent assortment.

Answer 15

If two genes are on different chromosomes, their inheritance is independent of each other and alleles are not always inherited together. Each chromosome arrangement has an equal possibility.

Question 16

When performing a dihybrid mating of the f1 generation what is the ratio of phenotypes in the f2 generation if genes are on separate chromosomes

Answer 16

9D:D 3D:R 3R:D 1R:R

Question 17

Which chromosome is being referred to when sex-linked?

Answer 17

the X chromosome

Question 18

Describe incomplete dominance.

Answer 18

Heterozygous individual is an intermediate of homo dom and homo rec.

Question 19

Describe co-dominance.

Answer 19

2 alleles shown in phenotype

Question 20

What is a polygenic trait?

Answer 20

One whose phenotype is influenced by more than one gene.

Question 21

Explain dominant epistasis.

Answer 21

Dominant allele of one gene masks the action of either alleles of the other gene

Question 22

Explain recessive epistasis

Answer 22

recessive allele of one gene masks the action of either alleles of the other gene

Question 23

What type of inheritance does CF follow?

Answer 23

autosomal recessive

Question 24

What does it mean for a gene to be pleiotropic?

Answer 24

The phenotypic expression involves many organs

Question 25

Describe penetrance.

Answer 25

the extent to which an allele is phenotypically expressed in the population

Question 26

Describe expressivity

Answer 26

variation in phenotype shown in population

Question 27

Function of CFTR protein

Answer 27

transport chloride ions in and out of epithelial cells to help control movement of water in tissues, chloride ions create osmotic gradient for water to enter tissue and thin mucus.

Question 28

What are the p arm and q arm

Answer 28

The P arm is the short arm of the chromosome while the q arm is the long arm.

Question 29

List the five domains of the CFTR protein

Answer 29

two transmembrane domains
two nucleotide-binding domains in cytoplasm
regulatory domain that anchors channel to cytoskeleton

Question 30

What is meant by gene expression

Answer 30

creation of functional gene product such as a (protein, tRNA, etc.)

Question 31

During translation, in which direction are mRNA read?

Answer 31

In the 5’ to 3’ direction

Question 32

Explain the most common mutation in CF.

Answer 32

It is a deletion mutation resulting in deletion of three NT resulting in loss of AA phenylalanine causing protein folding to not occur and eventually be degraded.

Question 33

There are multiple classes of F508 mutations in CF. Describe class 2

Answer 33

few to no CFTR are present at apical cell surface

Question 34

Explain class 3 mutation of F508del

Answer 34

CFTR protein with reduced opening probability

Question 35

Describe class 4 mutatuion of F508

Answer 35

Decreased stability of CFTR at surface

Question 36

Trikafta contains three different drugs, what are they?

Answer 36

tezacaftor
elexacaftor
ivacaftor

Question 37

Explain tezacaftor.

Answer 37

corrects positioning of CFTR protein on cell surface to permit proper channel formation and improved flow, modulator

Question 38

Explain elexacaftor.

Answer 38

increases amount of mature protein that reaches cell surface by targeting processing defects, corrector

Question 39

Explain ivacaftor.

Answer 39

improves fn of protein in body to decrease the build-up of thick mucus