Replication and Repair Flashcards
If re-replication occurs before mitosis. Chromosome number may be increased and cause _____.
Polyploidy
If mitosis occurs before replication is complete. Chromosome may be lost and cause ____.
Aneuploidy
Regulate progression through cell cycle
Cell dependent cycle (Cdc) proteins
Another name for cell dependent proteins
Cyclins
In which phase does nucleotide biosynthesis take place ?
late G1
In which phase does histone biosynthesis take place ?
early S
When are pre-initiation replication complexes formed?
late G1
What does Cdc7p phosphorylate?
MCM5
Which phase inhibits re-replication during S phase?
Telophase
Which kinase inhibits mitosis in G1 phase ?
Cdc6
Which enzyme inhibits mitosis in S phase ?
DNAPII
What is ori?
Origin of replication?
What is a DNA segment replication from one ori?
Replicon
Replicated early in S phase (chromatin)
Euchromatin
Replicated late (chromatin)
Heterochromatin
Replicate late
Telomeres
ORC
Origin replication complex (1st complex)
Which complex is the docking point for regulatory proteins and interacts with DNAP ?
ORC
Which complex is formed only during early G1 phase and is phosphorylated by CDK?
Cdc6
Which activated complex associates with ORC when mitotic kinase is absent?
Cdc6p (also platform for MCM)
Which complexes are localized in the nucleus during G1 phase?
Cdc45 and MCM
Which activated complex stabilized MCM proteins to form complex
Cdc45p
Which complex may function as DNA helicase and begin strand separation?
MCM
Which complex exits pre-initiation complex so that Cdc7 can enter?
Cdc6p
Which complex completes the pre-initiation complex?
DNAP
Which proteins serve as “licensing factor” for initiation?
MCM proteins
Removes supercoils in DNA ahead of replication fork
Topoisomerase
Breaks H-bonds to separate strands at replication fork
Helicase
aka single-stranded binding protein (ssb); binds to and stabilized DNA
Replication Protein A (RP-A)
Specific ribonucleotide polymerases that synthesize primers
DNA Primase
Initiates primer synthesis with purine NTP
DNA Primase
Which enzymes in plants only need 1 primer and add bases to 3’ end of leading strand?
DNAPII and DNAPIII
What is the problem with synthesizing the lagging strand with DNAPs?
Lagging strand ends with 5’-PO4 and not 3’-OH
T or F. Multiple primers are needed due to 3’ to 5’ orientation of lagging strand
True!
Short, discontinuous fragment composed of primer and newly added nucleotides between primer and pre-existing lagging strand
Okazaki fragment
Missing phosphodiester bond in sugar-phosphate backbone
Nick
Removes RNA primer, inserts proper deoxynucleotides
RNase H
Seals nicks (forms phoshodiester bonds) to create continuous lagging strand
DNA Ligase
Primary function of DNAPII and DNAPIII
oligonucleotide elongation
Primary function of DNAPI
primer synthesis
Function of telomeres
Maintain stable chromosome length
Physical and chemical stresses on DNA
oxygen, uv radiation, alkylating agents, radicals
By-products of what cellular function can cause deamination and alkyation?
Metabolism
Replacing amine group with a double-bonded oxygen (addition of H2O)
Deamination
A location in DNA that has neither a purine or pyrimidine
Apurinic site/ apyrimidinic site (AP site)
BrdU
Bromodeoxyuracil
In what form does BrdU base pair with A?
keto form (common form)
In what form does BrdU base pair with G?
enol form (ionized form)
Caused by uv radiation, alters the position of bases and does not permit base pairing
Pyrimidine dimers
Long uv, less energetic, more photons reach Earth’s surface
UV-A
Short uv, more energetic, far fewer protons reach Earth’s surface
UV-B
ORF
Open reading frame
URF
Uninterrupted reading frame
Loose base pairing at 3rd position
Wobble codons
Sequence identical to RNA (except for T for U) ; aka sense strand
Coding strand
Opposite strand; template for mRNA synthesis; complementary to RNA; aka anti-sense, template strand
Non-coding strand
Mutation induced by acridine; insert/delete 1 base; fatal for protein
Frame shift mutation
Purine replaced by another purine / pyrimidine replaced by another pyrimidine
Transition
Purine replaced by a pyrimidine / Pyrimidine replaced by a purine
Transversion
Triplet encodes same amino acid
Silent mutation
Codon specifies different but functionally equivalent amino acid
Synonymous mutation
Codon specifies a different and nonfunctional amino acid
Missense mutation
Codon signals chain termination
Nonsense mutation
Spontaneous mutation that restores wild type phenotype in mutant
Reversion
First mutation that creates mutant
Forward mutation
Second mutation that restores wild type phenotype
Reverse mutation
Exact, Equivalent, Suppression
Reversion types
Restores wild type function, but not sequence
Equivalent reversion
Second point mutation that reverses effect on non-sense mutation
Nonsense suppressors
Reversal of UV-induced mutations by high-energy visible light or UV-A
Photoreactivation
Enzyme that repairs mutant dimers, activation regulated by light
Photolyases
Repair mechanism that reads through damaged sites and inserts A’s regardless of original sequence
Error-prone repair (aka SOS repair system)
Types or recombination mechanisms
Homologous, Site-specific, Illegitimate
No information in 2 strands lost; Recombination is reciprocal
Crossover
One duplex donates sequence info; Recombination is nonreciprocal
Gene conversion
Mechanisms for homologous recombination
Single-stranded annealing, Double-strand break repair, One-sided invasion
The type of recombination that occurs during meiosis
Double-stranded break repair
Where does site-specific recombination occur in mammals ?
In the rearrangement of immunoglobulin genes in B and T cells
Where does site-specific recombination occur in plants ?
In chloroplast DNA replication, and rearrangement of mitochondrial DNA
T or F. Plastids and mitochondria are autonomous.
False!!
T or F. Some plants lack IR regions
True!! (certain legumes, conifers, and algae)
Plastid genome sizes vary greatly mostly because of ____.
Inverted repeats
Generally have smaller genomes
Non-photosynthetic plants
Generally have larger genomes
Algae
Which is larger, ctDNA or mtDNA ?
mtDNA
Which has fewer genes, mtDNA or ctDNA?
mtDNA
Mitichondrial genes:
Oxidative respiration (e- transport), ATP synthesis, and Mitochondrial translation
DNA transferred between organelles and nuclei
Promiscuous DNA