DNA Replication_Exam 3 Flashcards
This links nucleotide bases together. The hydroxyl group on one base bind with phosphate on adjacent base
Phosphodiester bond
Components of a DNA’s Structure
Antiparallel and noncovalent interactions
2 strands in double helix run in opposite directions, double helix held together by non-covalent interactions
Antiparallel
DNA structure with hydrogen bonds and hydrophobic interactions
noncovalent interactions
Each daughter cell contains 1 parent strand + 1 new strand
Semiconservative
starts at several points (origins) and its replication ‘bubble’ is formed
bidirectional with multiple origins
Characteristics of Eukaryotic DNA replication
Semiconservative and bidirectional with multiple origins
Primed by RNA is a characteristic for what?
Eukaryotic DNA replication
DNA polymerases cannot cannot synthesize new DNA without short stretches of ___
RNA (primer)
DNA ____ makes small stretches of RNA
primase
DNA polymerases elongate DNA chain by addition of base pairs to ____ end
3’
Sequence of base pairs added is dictated by base pair of ___ ____
coding strand
Semidiscontinuous process: New DNA always synthesized in
5’ –> 3’ direction
Semidiscontinuous process: Parental strand read from
3’ –>5’
Semidiscontinuous process: Continuously synthesized from 5’ –> 3’ on
leading strand
Semidiscontinuous process: ___ ____ is synthesized from 5’ –> 3’, but discontinuous = ___ ____
Lagging strand, okazaki fragments
Proteins involved in DNA replication?
DNA Polymerases, DNA Helicases, DNA primases, Single-stranded DNA binding proteins, DNA ligase, toposiomerases and telomerase
This protein adds nucleotides to 3’ end during replication of new DNA, and some are able to proofread & remove wrong nucleotides in 3’-5’ direction
DNA Polymerases
This protein unwinds parental DNA double helix and requires ATP to form the replication fork
DNA Helicases
This protein synthesizes short RNA primers for DNA synthesis
DNA primases
This protein prevents premature binding & winding of DNA (aka. annealing)
single-stranded DNA binding proteins
This protein joins nucleotide fragments by forming phosphodiester bonds and requires ATP
DNA Ligase
This protein facilitates unwinding of double helix during replication & transcription to release torsional stress and functions ahead of replication fork
topoisomerases
This protein adds TTAGGG repeats to the ends of chromosomes in stem cells, progenitor cells & cancer, giving them immortality
Telomerase
- Steps in DNA replication: ___ unwinds DNA forming replication fork
Helicase
- Steps in DNA replication: ____ prevent DNA from rewinding
Single-stranded DNA binding proteins
- Steps in DNA replication: ___ ads RNA to origin of DNA synthesis
DNA primases
- Steps in DNA replication: ____ adds nucleotides in 5’-3’ direction (to 3’ end of strand)
DNA Polymerase
- Steps in DNA replication: ____ is continuous
leading strand
- Steps in DNA replication: ___ is discontinuous forming okazaki fragments
lagging strand
- Steps in DNA replication: ___ are removed
RNA Primers
- Steps in DNA replication: ___ joins fragments formed
DNA Ligase
This type of damage is internal, spontaneous & is due to errors in DNA replication
Endogenous damage
This type of DNA damage is environmental, and ionizing radiation, polyaromatic hydrocarbons, nitrosamines, free radicals, and chemotherapy
Exogenous mutagens
This type of DNA repair fixes mismatch repair in normal base pairing (AT, GC) and identifed by protiens
Mismatch repair
This DNA repair corrects spontaneous depurination (loss of purines) or deamination (cytosine loses amine to form uracil)
Base excision repair
This type of DNA repair removes mutations formed by UV light and environmental chemicals
Nucleotide excision repair
This type of DNA repair uses info from unaffected chromosome to fix
Double-stranded DNA repair