e x a m II Flashcards
incomplete dominance
heterozygous allele is intermediate
Hh = pink. intermediate between red & white
codominance
expression of both alleles as heterozygote
both A & B are dominant in blood type
recessive lethal alleles
AyAy = lethal
AyA = yellow
AA = black
WOULD be 3:1 ratio, but is only 2:1 due to lethality.
pleiotropic traits
one gene affects many traits
-hormone binding receptors
polygenic traits
many genes affect a trait
- height in humans
9: 3:3:1 ratio
complementation
two organisms have 2 dif mutations
occurs when they are on DIFFERENT genes
9:7 ratio
penetrance
% of individuals who exhibit the phenotype of that allele
how many people get breast cancer with a BRCA-1 gene mutation
expressivity
the degree to which phenotype is expressed (intensivity)
different shades of blue
percent of volume ejected from the heart w/ CHF
how can someone with an allele for a trait or disease not develop the disease?
there are many factors that contribute to expressivity & penetrance. having the allele doesn’t necessarily guarantee it will be expressed
griffith & avery’s experiments
s-strain bac transforms r-strain back into a-strain bac.
dna is transforming agent.
hershey-chase experiment
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
components of dna
deoxyribose sugar, phosphates, nitrogenous bases
purines
A & G
pyrimidines
T & C
how is a single strand of DNA formed?
phosphodiester bonds between adjacent nucleotides
aka sugar-phosphate backbone
dna shape
double helix with complimentary anti-parallel strands
base pairing
A-T
C-G
dna replication is…
semi conservative
meselson-stahl experiment
used different densities of N (14 & 15)
created an intermediate band between 14 & 15 in test tube after centrifuging
consistent with semiconservative hypothesis
how does dna replication begin?
DNA polymerase catalysis synthesis
starts at RNA primer
what direction is DNA synthesized in?
5’–>3’ direction
leads to leading & lagging strand replication
DNA polymerase III
elongates RNA primers with new DNA
DNA polymerase I
removes RNA @ 5’ end fragment; fills gap
primase
synthesizes a stretch of RNA complementary to that specific region of the chromosome
DNA ligase
joins the gap-filling dna to ogazaki fragment
telomerase
adds short repeats to 3’ ends of DNA (overhang on end of DNA; telomere)
helicase
disrupt H bonds; unzips double helix
topoisomerase
removes super-coiled regions of dna allowing them to rotate
rna is…
the intermediate between DNA & protein
RNA polymerase is similar to…
DNA polymerase
differences between RNA & DNA:
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
which direction does rna polymerase synthesize rna?
5’–>3’
dna is template
rna synthesis
intitiation:
rna binds to promoter
rna synthesis:
elongation-
rna polymerase synthesizes complementary strand of rna
rna synthesis:
termination-
terminators signal the end of the polymerase is done.
releases rna from rna polymerase
TATA box
site of first event in transcription- TATA-binding protein binding (lol)
TATA-binding protein
when bound, it attracts other GTFs to form pre-initiation complex
GTFs
general transcription factors; bind before RNA polymerase II to ATTRACT it to start transcription
RNA polymerase II
transcribes all protein-encoding genes
transcribes some snRNAs
carboxy tail domain
Allows other proteins to bind to RNA
is prokaryotic rna functional after transcription?
yes, immediately after transcription
is eukaryotic rna functional after transcription?
no, it requires further processing before it is translated into a protein
which end is capped?
5’ by methylguanosine
what does splicing do?
remove introns, glues extrons together
where is the polyA tail added?
the 3’ end
alternative splicing?
different proteins are made from the splicing together of different combinations of exons
snRNAs
small nuclear RNAs
Small protein localized in the nucleus
Bind to areas in the intron to recruit snRNPs
SnRNPs
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
