e x a m II

Question 1

incomplete dominance

Answer 1

heterozygous allele is intermediate

Hh = pink. intermediate between red & white

Question 2

codominance

Answer 2

expression of both alleles as heterozygote

both A & B are dominant in blood type

Question 3

recessive lethal alleles

Answer 3

AyAy = lethal
AyA = yellow
AA = black
WOULD be 3:1 ratio, but is only 2:1 due to lethality.

Question 4

pleiotropic traits

Answer 4

one gene affects many traits

-hormone binding receptors

Question 5

polygenic traits

Answer 5

many genes affect a trait

• height in humans
  9: 3:3:1 ratio

Question 6

complementation

Answer 6

two organisms have 2 dif mutations
occurs when they are on DIFFERENT genes
9:7 ratio

Question 7

penetrance

Answer 7

% of individuals who exhibit the phenotype of that allele

how many people get breast cancer with a BRCA-1 gene mutation

Question 8

expressivity

Answer 8

the degree to which phenotype is expressed (intensivity)

different shades of blue

percent of volume ejected from the heart w/ CHF

Question 9

how can someone with an allele for a trait or disease not develop the disease?

Answer 9

there are many factors that contribute to expressivity & penetrance. having the allele doesn’t necessarily guarantee it will be expressed

Question 10

griffith & avery’s experiments

Answer 10

s-strain bac transforms r-strain back into a-strain bac.

dna is transforming agent.

Question 11

hershey-chase experiment

Answer 11

used sulfur first; no radioactive in bac (protein)

used phosphorus; radioactivity found in bac (DNA) concluding it’s the agent necessary dot production of new phages

Question 12

components of dna

Answer 12

deoxyribose sugar, phosphates, nitrogenous bases

Question 13

purines

Answer 13

A & G

Question 14

pyrimidines

Answer 14

T & C

Question 15

how is a single strand of DNA formed?

Answer 15

phosphodiester bonds between adjacent nucleotides

aka sugar-phosphate backbone

Question 16

dna shape

Answer 16

double helix with complimentary anti-parallel strands

Question 17

base pairing

Answer 17

A-T

C-G

Question 18

dna replication is…

Answer 18

semi conservative

Question 19

meselson-stahl experiment

Answer 19

used different densities of N (14 & 15)
created an intermediate band between 14 & 15 in test tube after centrifuging

consistent with semiconservative hypothesis

Question 20

how does dna replication begin?

Answer 20

DNA polymerase catalysis synthesis

starts at RNA primer

Question 21

what direction is DNA synthesized in?

Answer 21

5’–>3’ direction

leads to leading & lagging strand replication

Question 22

DNA polymerase III

Answer 22

elongates RNA primers with new DNA

Question 23

DNA polymerase I

Answer 23

removes RNA @ 5’ end fragment; fills gap

Question 24

primase

Answer 24

synthesizes a stretch of RNA complementary to that specific region of the chromosome

Question 25

DNA ligase

Answer 25

joins the gap-filling dna to ogazaki fragment

Question 26

telomerase

Answer 26

adds short repeats to 3' ends of DNA (overhang on end of DNA; telomere)

Question 27

helicase

Answer 27

disrupt H bonds; unzips double helix

Question 28

topoisomerase

Answer 28

removes super-coiled regions of dna allowing them to rotate

Question 29

rna is...

Answer 29

the intermediate between DNA & protein

Question 30

RNA polymerase is similar to...

Answer 30

DNA polymerase

Question 31

differences between RNA & DNA:

Answer 31

RNA uses Uracil instead of Thymine ribose is rna's sugar; deoxyribose is dna's sugar dna is double stranded; rna is single stranded dna does not have any catalytic activity

Question 32

which direction does rna polymerase synthesize rna?

Answer 32

5'-->3' | dna is template

Question 33

rna synthesis | intitiation:

Answer 33

rna binds to promoter

Question 34

rna synthesis: | elongation-

Answer 34

rna polymerase synthesizes complementary strand of rna

Question 35

rna synthesis: | termination-

Answer 35

terminators signal the end of the polymerase is done. | releases rna from rna polymerase

Question 36

TATA box

Answer 36

site of first event in transcription- TATA-binding protein binding (lol)

Question 37

TATA-binding protein

Answer 37

when bound, it attracts other GTFs to form pre-initiation complex

Question 38

GTFs

Answer 38

general transcription factors; bind before RNA polymerase II to ATTRACT it to start transcription

Question 39

RNA polymerase II

Answer 39

transcribes all protein-encoding genes | transcribes some snRNAs

Question 40

carboxy tail domain

Answer 40

Allows other proteins to bind to RNA

Question 41

is prokaryotic rna functional after transcription?

Answer 41

yes, immediately after transcription

Question 42

is eukaryotic rna functional after transcription?

Answer 42

no, it requires further processing before it is translated into a protein

Question 43

which end is capped?

Answer 43

5' by methylguanosine

Question 44

what does splicing do?

Answer 44

remove introns, glues extrons together

Question 45

where is the polyA tail added?

Answer 45

the 3' end

Question 46

alternative splicing?

Answer 46

different proteins are made from the splicing together of different combinations of exons

Question 47

snRNAs

Answer 47

small nuclear RNAs Small protein localized in the nucleus Bind to areas in the intron to recruit snRNPs

Question 48

SnRNPs

Answer 48

Small nuclear ribonucleoproteins Complexes of protein and one of 5 snRNAs Help align splice sites at either end of an intron Cleaves off the intron Exon is ligased together