Studied by 3 peopleThe ________ recognize damaged and remove a fragment of the strand that includes the damaged nucleotide (s), and then DNA polymerase and ligase fill the gap.
excision repair proteins
The pyrophosphate is then hydrolyzed into two inorganic phosphates, releasing ________, which makes the overall free energy change of DNA polymerization more negative.
additional energy
________ resulting from meiosis have half the amount of nuclear DNA as somatic cells.
Cells
________ always proceeds in the 5′- to- 3′ direction, but the DNA is read in the 3- to5.
DNA synthesis
Because of ________, the information contained in a DNA molecule is fully contained in each of the two strands.
complementary base pairing
Any of a group of viruses that infect bacteria; mad eof DNA and only a few types of protein
Phage
The repeating deoxyribose then phosphate groups that form a strand of a nucleic acid
Sugar-Phosphate Backbone
Pertaining to molecular orientation in which a molecule or parts of a molecule have opposing directions
Antiparallel
Each strand of the parental molecule could be used as a template for the synthesis of a new strand in each daughter molecule
Semiconservative replication
The two parental strands could remain together (that is, could be "conserved") in one daughter molecule, while serving as a template for another daughter molecule consisting of two newly synthesized strands
Conservative replication
The parental molecule could end up dispersed among both strands in the two daughter molecules
Dispersive replication
The beginning of replication, transcription or translation; involves unwinding (denaturing) the DNA double helix to separate the two strands and synthesizing of RNA primers
Initiation
the addition of monomers to make a longer DNA, RNA, or protein during replication, transcription or translation
Elongation
the end of transcription or translation (after each region has been replicated)
Termination
A DNA sequence at which helicase unwinds the DNA double helix and DNA polymerase binds to initiate DNA replication
Origins of Replication
A point at which a DNA molecule is replicating; The forms by the unwinding of the parent molecule
Replication Fork
An enzyme that catalyzes the unwinding of a nucleic acid double helix
DNA Helicase
A strand of nucleic acid, usually RNA that is the necessary starting material for the synthesis of a new DNA strand, which is synthesized from the 3 end of the primer
Primer
An enzyme that catalyzes the synthesis of a primer for DNA replication
Primase
In DNA replication, the daughter strand that is synthesized continuously
Leading Strand
In DNA replication, the daughter strand that is synthesized in discontinuous stretches
Lagging Strand
Newly formed DNA making up the lagging strand in DNA replication; DNA ligase links these together to give a continuous strand
Okazaki Fragmant
Repeated sequences at the ends of eukaryotic chromosomes that do not encode proteins
Telomeres
An enzyme that catalyzes the addition of telomeric sequences lost from chromosomes during DNA replication
Telomerase
The probability that an incorrect base will be inserted into a new strand during replication
Incorcporation Error Rate
A base pair in which the two bases are not complementary (e.g., AC or AG instead of AT)
Mismatched DNA
During DNA replication, a mechanism that excises a base that is incorrectly inserted according to the template (AG) and inserts the correct base (CG)
Proofreading
A mechanism that scans DNA after it has been replicated and corrects any base-pairing mismatches; looks for abnromal H bonding that changes the helix width
Mismatch Repair
A change of a single base pair in a nucleotide sequence (e.g., AT to GC)
Base-Pair Substitutions
A mutation that results from the gain, loss, or substitution of a single nucleotide
Point Mutation
A genetic change caused by internal cellular mechanisms, such as an error in DNA replication
Spontaneous Mutations
Any agent (e.g., a chemical, radiation) that increases the mutation rate
Mutagens
Changes in the sequence of DNA caused by a mutagen
Induced Mutation
A change in a genes sequence that has no effect on the amino acid sequence of a protein because it occurs in noncoding DNA or because it does not change the amino acid specified by the corresponding codon
Silent Mutations
A mutation that results in the loss of a functional protein
Loss of Function Mutations
A mutation that results in a protein with a new/altered function
Gain-of-Function Mutations
A mutation that results in a characteristic phenotype only under certain environmental conditions (the wild-type phenotype is expressed under other conditions)
Conditional Mutations
A mutation resulting from the loss of a continuous segment of a gene or chromosome; Such mutations almost never revert to wild type
Deletions
A mutation in which a segment of a chromosome is duplicated, often by the attachment of a segment lost from its homolog (One of the two chromosomes produced by this mechanism will lack a segment of (it will have a deletion), and the other will have two tandem copies (a duplication))
Duplications
A rare 180° reversal of the order of genes within a segment of a chromosome; usually causes a loss of function
Inversions
In genetics, a rare mutational event that moves a portion of a chromosome to a new location, generally on a nonhomologous chromosome
Translocations
A repair pathway that functions to join together (ligate) the two ends of a broken chromosome
Nonhomologous End Joining
Hydroxyl groups mark which end of DNA?
3'
Phosphate groups mark which end of DNA?
5'
New nucleutides are added to the ___________ end.
3'
Possible method of replication where each parental strand is a template for a new strand.
Semiconservative
Possible method of replication where the two parental strands remain together in one daughter molecule, while serving as a template for another daughter molecule.
Conservative
Possible method of replication parent molecule is dispersed among both strands in the two daughter molecules.
Dispersive
• E coli were grown with N15 (heay isotope) then transfered to a thing with N14
• Resulting DNA densities could only be explained by the semiconservative model
• After one round of replication, DNA had intermediate weight. After more rounds, lightweight DNA appeared with intermediate
• If it was conservative: The first generation would have high and low density, but no intermediate
• If it was dispersive: all first gen would be intermediate, but everything after would get closer to light
Meselson-Stahl Experiment
The lagging strand is made in the _______ direction
5 to 3
The lagging strand is made in small pieces called...
Okazaki fragments
Protein that protects the rest of the DNA molecule from being wound too tight.
Topoisomerase
Polyamerase only works in what direction of the NEW strand?
5 to 3
DNA polymerase recognizes a mismatch, backs up, removes the wrong nucleutide, then starts synthesis again. 99% effective
DNA Proofreading
After replication, a protein complex scans for mismatched bases and recognized them based on abnormal H binding.
Mismatch repair
Enzymes constantly scan DNA for damaged bases caused by radiation/chemicals. They are exised and DNA polymerase I adds the correct ones.
Excision Repair
UV radiation is absorbed by ________, causing it to form covalend bonds with adjacent nucleotides. Disrupts DNA replication.
Thymine
Bases have two isomers. When a base temporarily forms this, it can pair with a different base.
Tautomeric shift
Loss of an NH2 group in cytosine, forming uracil (A is added instead of G)
Deamination
Mutations that occur in somatic cells and affect the individual but are not passed to offspring.
Somatic
Mutations that occur in the gametes and are passed to offspring. May or may not affect phenotype.
Germ line
Loss of function is usually a _________ gene, but gain of function is usually __________.
Recessive; dominant
Point mutation where a single nucleotide change results in a codon that codes for a different amino acid.
Missense
Mutations that affect the phenotype only under certain environmental conditions.
Conditional
Note
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