Bio: chapter 16
one
A critical characteristic of DNA polymerases is that they can only work in________ direction
Telomeres
Act as insulators No genes Short repeating stretches of nucleotides example: "TTAGGGTTAGGGTTAGGG"
thymine (T)
Adenine (A) hydrogen bonds with .
Proofreads: check for errors Requires a primer : Adds nucleotides in the 5'→ 3' direction: actually connects to the 3 prime end
Characteristics of DNA Polymerases
reduces
DNA Polymerase III proofreading process _______ the error rate
last, cannot
DNA Polymerase III proofreading process can only fix the ______ nucleotide placed. Once another nucleotide is placed it______ go back and fix it.
paired bases
DNA Polymerase Proofreadsby checking the match between _______ __________, and can correct mismatched bases when they do occur.
thymine dimers
DNA can be broken or altered by various chemicals and types of radiation. For example, UV light can cause ______ _____ to form, causing a kink in the DNA strand.
proofread
DNA polymerase can _________ its work—it checks the match between paired bases, and can correct mismatched bases when they do occur.
primer
DNA polymerase requires a_______ to synthesize DNA
3′ end
DNA polymerases can add deoxyribonucleotides to only the ___ ____ of a growing DNA chain
5′ → 3′
DNA synthesis always proceeds in the _____ direction.
DNA, bases
DNA synthesis occur when existing strands of ______ served as a template for the production of new strands, with_______ being added to the new strands according to complementary base pairing.
cytosine (C).
Guanine (G) hydrogen bonds with
Proofreading Mismatch Repair nucleotide excision repair
How does the cell Repair Mistakes and Damage? (3 ways)
Proofreading
If it doesn't't catch it immediately it cant go back to fix the problem It can only remove the very Last nucleotide.
bacteria (prokaryotic)
In_____________ chromosomes, the replication process begins at a single location (circle)
DNA polymerase I
Lagging synthesis: ____ _________ __ removes the RNA primer at the beginning of each Okazaki fragment and replaces it with DNA.
section
Mismatch repair enzymes recognize the mismatched pair, remove a _______ of the newly synthesized strand that contains the incorrect base, and fill in the correct bases.
replisome
Most of the enzymes responsible for DNA synthesis around the replication fork are joined into one large multi-enzyme machine called the __________.
bidirectional
Replication bubbles grow as DNA replication proceeds, because synthesis is____________.
RNA template
Telomerase has its own _________ ________
nucleotide excision repair
The __________ _______ _______ system recognizes physical types of damage. Its enzymes then remove the single-stranded DNA in the damaged section.
double helix.
The antiparallel strands twist to form a ________
DNA ligase
The enzyme ______ __________ then joins the Okazaki fragments to form a continuous DNA strand.
helicase
The enzyme ________ catalyzes the breaking of hydrogen bonds between the two DNA strands to separate them
topoisomerase
The enzyme__________ cuts and rejoins the DNA downstream of the replication fork, relieving this tension.
template
The presence of a DNA strand complementary to the damaged strand provides a _____ for resynthesis of the defective sequences.
complementary base pairing
The secondary structure is stabilized by _____________ _________ ________.
DNA Polymerases
These are characteristics of what enzyme: Proofreads: check for errors Requires a primer : Adds nucleotides in the 5'→ 3' direction: actually concects to the 3 prime end
Telomeres (process), Telomerase (enzyme)
This prevents the lagging strand from getting shorter with each replication.
lagging strand
What DNA synthesis strand is this?
DNA polymerase III
What enzyme catalyzes DNA replication???
topoisomerase
What helps alleviate tension as the DNA unwinds farther down the helix?
circle
What shape does Bacteria chromosome have?
elongated
What shape does Eukaryotic chromosome have?
Telomere replication process (4 steps)
Whats this process 1. unreplicated end 2. Telomerase extends unreplicated end 3. Again Telomerase extends unreplicated end 4. Lagging strand complete
replication fork
______ ______ is the Y-shaped region where the DNA is split into two separate strands for copying.
Mismatch repair
________ ______ occurs when mismatched bases are corrected after DNA synthesis is complete.
Primase, ligase
_________ makes an RNA primer, which DNA polymerase uses to synthesize the lagging strand. _______ connects the new sequence.
Eukaryotes
____________ have multiple origins of replication and thus have multiple replication bubbles. (linear)
primary structure of DNA
_________________ has two major components: A backbone made up of the sugar and phosphate groups of deoxyribonucleotides. A series of nitrogen-containing bases that project from the backbone.
Origin of replication
a particular sequence the chromosome at which replication is : In bacteria chromosomes, the replication process begins at a single location. (circular) Eukaryotes have multiple origins of replication and thus have multiple replication bubbles. (linear)
Primase
a type of RNA polymerase, synthesizes a short RNA segment that serves as a primer for DNA synthesis
Semiconservative replication
all cells use ______to replicate
Telomeres
are the regions at the ends of linear chromosomes (doesn't code for anything)
lagging strand
discontinuously in the direction away from the replication fork and so lags behind the fork.
replication bubble
forms in a chromosome that is actively being replicated
Okazaki
fragments called in the lagging strand
discontinuous, moves away from the replication fork
how is the Lagging strand synthesis different from leading stand synthesis ?
primase (synthesizes a RNA primer) DNA polymerase III (then adds bases to the 3' end of the primer. )
how is the Lagging strand synthesis similar to leading stand synthesis?
DNA polymerase III
main enzyme of DNA replication
leading strand
or continuous strand, leads into the replication fork and is synthesized continuously in the 5′ 3′ direction.
Primer is unable to attach at the beginning. Enzymes come in and cut those ends off. Linear chromosomes shorten after each replication
problem with DNA synthesis?
semiconservative replication
the parental DNA strands separate and each is used as a template for the synthesis of a new strand. Daughter molecules each consist of one old and one new strand.
helacase, single-strand DNA-binding proteins (SSBPs)
two proteins are responsible for opening and stabilizing the double helix.
Telomerase
used in cells who frequently divide Enzyme Adds nucleotides to the lagging strand Carries its own primer
leading strand
what DNA synthesis strand is this?
single-strand DNA-binding proteins (SSBPs)
what attaches to the separated strands to prevent them from closing.
Watson and Crick
who proposed that two DNA strands line up in the opposite direction to each other, in what is called antiparallel fashion.