DNA and genetics Flashcards
what isomers are used to show that DNA is semiconservative (meselson stahl experiment)
Nitrogen 15 and 14
replicon
region of DNA, that replicates from a single origin of replication.
how many starting points does circular DNA have
one
what is the oric
origin of replication i.e. initiation point
oric is rich in……
adenine and thymine
how many sequences are there in the oric and how many base pairs
11 and 245. three repetitions of 13 base pairs and four repetitions of 9 base pairs
what protein complex helps recognize site of replication
origin recognition complex (ORC)
what initiation factors bind to the ORC
cdc6 and DUP/Cdt1
what do the initiation factors help load
MCM2–7 helicase complex
what do S-CDK and DDK do
recruitment of the helicase components Cdc45 and the GINS complex and other functions
what is activated at the start of S phase to begin replication
replicative helicase (composed of MCM2–7, Cdc45, and GINS)
what enzyme begins dissolution
helicase
what maintains the replication fork
single-stranded DNA binding proteins
name four DNA polymerase substrates and four RNA and polymerase substrates
dATP, dGTP, dCTP, dTTP and ATP, GTP,CTP,UTP
function of DNA polymerase I
replaces the primer with DNA
function of DNA polymerase II
repair
function of DNA polymerase III
main addition
what enzyme seals the gap during replication
ligase
what enzyme synthesizes primers
primase
what helps hold DNA pol in place during addition
sliding clamp
what enzyme helps relieve stress on DNA during unwinding
topiosomerase
how does topiosomerase work
catalyzes the removal of superhelical turns from covalently closed DNA by a transient breakage and rejoining of phosphodiester bonds.
what is the difference between TOP1 and TOP2
TOP1 cuts and repairs one strand while TOP2 cuts two
where do we fine replication fork traps
in bacteria for termination of protein synthesis
what repetitive sequence does telomerase add
TTAGGG
what is TERT and TERC
TERT gene provides instructions for making one component of an enzyme called telomerase
TERC is a component of telomerase
what is telomerase composed of
ribonucleoprotein
what chemical group is obtained during telomerase adding
free 3’OH groups due to hydrogen bond formation between the Gs
what cells have high telomerase activity
cancer and germ cells
what is retrovir (Zidovudine) used for
controls HIV
what term is used to describe cells are only
capable of a limited number of
population doublings in culture
hayflick limit
out of different types of DNA which has a low mutation rate
single copy DNA
what type of DNA has a high degree polymorphism
repetitive DNA
what sequences have no genes
highly repetitive DNA
where are highly repetitive sequences found
heterochromatin in telomeres or centromeres
for highly repetitive sequences the repeating unit is not conserved. true or false
false. it is conserved
which sequences are the shortest
a) moderately repetitive
b) highly repetitive
c) single copy
highly repetitive
which sequences are involved
in organizing chromosome pairing during meiosis and recombination
highly repetitive
what sequences are found in pericentromeric and telomeric heterochromatin regions
satellite DNA (highly repetitive)
satellite sequences are
a) unique to individuals
b) unique to species
c) same among all species
unique to species
what sequences are dispersed through euchromatin
moderately repetitive
which sequence regulates gene expression
moderately repetitive
what do interspersed DNA have ability to
jump from one place to another in the genome
what advantage to plasmids provide
antibiotic resistance
what are the types of interspersed DNA
RNA and DNA transposons
what is the difference between RNA and DNA transposons
RNA transposons require conversion of DNA to RNA and back to DNA again while DNA trasnposons do not require an RNA intermediate
what are the two groups of RNA transposons
LTR and non-LTR elements
DNA transposons are retroelements while RNA transposons are not
false. other way around
are endogenous retroviruses(ERVs) LTR or non LTR elements
LTR elements
what are endogenous retroviruses
These are retroviruses integrated into the vertebrate chromosomes and inherited from generation to generation as part of the host genome
what are the types of non LTR elements
LINEs and SINEs (short and long interspersed nuclear elements)
which of these has reverse transcriptase, SINEs or LINEs
LINEs, SINEs borrow them from other retroelements
Alu sequence is a example of what
SINEs
what type of transposons are in Ac/Ds elements of maize
DNA transposons
what are the types of tandem repeats
micro, mega and mini satellite DNA
what is another name for microsatellites
short sequence repeats (ssr)
majority of minisatellites are
1) A-T rich
2) G-C rich
3) A-U rich
G-C rich
where are minisatellites clustered in chromosomes
subtelomeric regions
variable number of tandem repeats
(VNTR) are also known as
minisatellites
telomeric repeats are
1) A-U rich
2) G-C rich
3) G-T rich
4) G-G rich
G-T rich
where are subtelomeric repeats located
adjacent to the telomere
where are hypervariable repeats located
within nuclear DNA or the D-loop of mitochondrial DNA
hypervariable repeats are moderately polymorphic, true or false
false. they are highly so
what is an examples of mega-satellites composed of coding repeats
RNA genes, and the deubiquitinating enzyme gene USP17
what is another name for microsatellites
simple sequence repeats (SSRs)
