Chapter 15 Flashcards
what was the hersey and chase study
t2 virus to see what contribute to gene, if dna or protein. virus infected wirh bacteria
What is chromosome made of
DNA and Protein
backbone of DNA
Phosphate-sugar-phospate-sugar
DNA measures
5’ 3’ double helix antiparallel
3’ 3’ is attached to what
hydroxyl attached to carbodeoxyribose
5’ 5’
phospate attached to a 5-carbon
what are the names of the DNA components
Adine, thymine, guanine, cytosine.
A=t c=g
A-G are …
purines, double ring
C,T,U are…
PurimiDINES, single ring
which is a stronger bond
C and G
what are the 3 hypothesis for DNA replication
conservative
semiconservative
dispersive
semiconservative
half and half. open it, synthesise = 1 new 1 old
conservative
open it up= syntesise= old one stick together
dispersive
a bit of old a bit of new, plucking in
what did meselson and stahl do
grew ecoli in nitrogenous bases to see dna replication. results show semiconservative replication. nitrogeouns to trace the dna
what is the DNA catalyzer
DNA plymerase. catalise dna syntesis, photocopy dna, make polimer of dna. and can only add deoxyribonucleotides to the 3’ end of growing DNA
Which are the monomers
Ribose and the DNTP’s A,G,C,T
what does DNA syntesis do to potential energy
increase it
endergonic
require energy
what is the formation of the phospodiester bonds
dehydration syntesis
what puts the backbone of dna together
dehydration syntesis
Bacteria DNA
circular, bidirectional
DNA helacase
Break hydrogen bonds and open the double helix apart
Binding protein SSBP/s
attach to each single strant and prevent them from closing together again
topoisomerase function in dna
cut dana and rejoints the dna to release the coiled tension
what is the leading strand
the strand that is directional 5’ 3’ towards the fork
the lagging strand
slows down falls behind
Primase function
syntesise new ran on the lagging strand so fork can open
what are the steps for dna replication
split them HELICASE > single strand binding protein to keep them apart> topoise somerase > primase > DNA polymerase
FUnction of Helicase
catalyses the breaking hydrogen bonds between base parings and opens the double helix up.
Single Strand Binding DNA binding Proteins
stablish single strand DNA and prevents from closing down
Topoisomerase function
Cuts to reveal tention and rejoins DNA
Primase
catalyses the syntesis of RNA in the lagging strand
DNA polimerase II
Extend the leading strand
sliding clamp function
Holds Dna polymerase in place during strand expention
DNA polimerase I funcition
Removes the RNA primer and replaces it with DNA
DNA ligase function
catalizes okazaki fragments into continous strand
what are okazaki fragments
lagging strand is sunthesized as short discontinuous fragments
what joins okazaky fragments together
DNA ligase
WHat is a replisome
contrains the enzyme responsible for DNA synthesis around the replication fork
Telomers are what
the end of linear chromosomes
The replisome contains what
the enzyme responsible for DNA synthesis around replication fork
DNA!! polimerase cannot add to the end with no primer so it becomes shorter eveyrtime
shorter chromosomes by 5o and 100 nucleotides
DO telomeres contain genes
no
Telomeres function
replicate telomeres using RNA template
does somatic cells have telomeres ?
No
what happens to cell division if your telomeres are shorter
they do not divide, division is shut
cancer cells have telomeres
!!!
how acurate is dna replication
very acurate. one mistale every 1 billion cases
what is the function of a repair enzyme
Remove defected bases and replace then with correct ones.
recognice
demove incorrect
fill in with correct
what recognices UV light damage
Nucleotide exicion system. DNA ligase link the repaied strand to the original damage dna
who did experiemnt what showed dna copied by semiconservative
meselson and Stah
