DNA Repair and How do mutations occur Flashcards
Loss or alterations (mutations) of accessary proteins often leads to _____.
cancer
_____ are involved in the nomenclature of mutations that tells where it takes palce
coordinates
Changes in the nucleotide sequence of a chromosome that caused disease. DNA deletion, insertion, substitution, silent, missense mutations
Gene mutation that is responsible for disorders
Unnatural bases are recognized and removed by a specific _______
DNA glycosylase
A ___ mutation results in no change where the mutation produces the same amino acid
silent
Deamination involves DNA _____ (chemical modification)
substitution
Way that a mutation deamination and depurination, most frequent spontaneous chemical reactions.
hydrolytic attack
Genes at differ loci are transmitted independently
Principle of Independent Assortment
A ____ mutation does not occur in gametes and in not heritable
somatic mutation
_______ guides homologous recombination
DNA base pairing
Rearrangements/Translocations, Deletions, Insertions, Duplications are _____ disorders
Chromosome Disorders
DNA breaks also arise from _____ that become stalled or broken
DNA replication forks
_______ facilitate transcription regulation
nuclear receptors
______ enhance transcription can be further away
Enhancer
About _____ of inherited human disorders are single base mutations
1/3
DNA sequence variants of a gene.
Alleles
A ___ results in an altered protein
frameshift
Sexually reproducing organisms possess genes that occur in pairs and that only one member of this pair is transmitted to the offspring
Principle of segregation
Multiple genes, gene-environment are _____ disorders
Multifactorial or Complex
DNA of each human cell loses about_____ bases (adenine/guanine) everyday due to their deoxyribose hydrolyzation of N-glycosyl linkages, a spontaneous reaction called depurination
5000 purine
____ mutations include radiation and chemicals
Induced mutations
DNA breaks often occur from _____ or ______
radiation damage; reactive chemicals
each member of a chromosome pair carries the same allele, then the individual is called ______ for that gene
homozygous
______ can be repaired by Non-homologous end joining without a template which creates a mutation at the site where the DNA duplexes are joined; Inadvertent joining of two segments from different chromosomes that results in chromosomal translocations, which often give rise to disease; Homologous recombination repairs DNA double strand breaks accurately without loss or alteration of the DNA sequence
Double strand DNA breaks
Holiday junctions are commonly found in what process?
Homologous recombination
Of the thousands of random changes created every day in the DNA of a human cell by heat, metabolic accidents, radiation of various sorts, and exposure to substances in the environment,______ accumulate as mutations in the DNA sequence
only a few
Way that a mutation occurs by the methyl group donor S-adenosyl-methionine
Uncontrolled methylation
DNA repair pathway that is how thymine dimers are repaired; large portion of DNA excisied
nucleotide excision repair
Cells carefully regulate the use of _____ in DNA repair
homologous recombination
each member of a chromosome pair carries a different allele, then the individual is called ______ for that gene
heterozygous
Genetic exchange between a pair of homologous DNA sequences
Homologous recombination
Spontaneous reaction involving the deoxyribose hydrolyzation of N-glycosyl linkages
depurination
The importance of DNA repair is also demonstrated by the ______ that follows the inactivation of a DNA repair gene.
increased rate of mutation
____ and _____ hydrolytic reactions, are the two most frequent spontaneous chemical reactions known to create serious DNA damage in cells.
Deamination and depurination
cytosine to uracil in DNA is estimated to occur at a rate of 100 bases per genome per day.
Deamination
we now know that fewer than one in _____ accidental base changes in DNA results in a permanent mutation; the rest are eliminated with remarkable efficiency by DNA repair.
1000
Depurination involves DNA ____ (chemical modification)
deletion
Disorders that deal with the X and Y chromosome or mitochondrial genome
Sex Linked and Mitochondrial
Is DNA stable or unstable?
Stable
____ mutations arise naturally during DNA replication (mitosis) or during meiosis
spontaneous mutations
Special type of cell division that occurs in sexual reproduction. It involves two successive nuclear divisions with only one round of DNA replication, thereby, producing haploid cells from a diploid cell.
Meiosis
A ___ results in extra or missing amino acids
deletion or insertion
DNA repair pathway where a single base changes
base excision repair
Dominant, Recessive,Codominant are _____ disorders
Single Gene Disorders
Division of the nucleus of a eukaryotic cell, involving condensation of the DNA into visible chromosome, and separation of the duplicated chromosome to form two identical sets. From Greek mitos, a thread, referring to the threadlike appearance of the condensed chromosomes.
Mitosis
Process where Unnatural bases are recognized and removed by a specific DNA glycosylase
base excision repair
Nomenclature of mutations involve what elements?
amino acid, genomic/mRNA/protein, coordinates, and substitutions
T/F: A number of accessory proteins are involved in control of DNA repair
True
A ____ mutation is inherited
germline
_______ is a mechanism to: Accurately repair double strand DNA breaks; Exchange bits of genetic information; Assures accurate chromosome segregation during meiosis
Homologous recombination
Maintaining the genetic stability that an organism needs for its survival requires _______ and ______ the many accidental lesions that occur continually in DNA
an extremely accurate mechanism for replicating DNA and mechanisms for repairing
A ___ mutation results in a stop codon being produced and the protein is truncated
Nonsense
A spontaneous _______ in DNA occurs at a rate of about 100 bases per cell per day
deamination of cytosine to uracil
an encounter with reactive metabolites produced in the cell (including reactive forms of oxygen, H2O2, -OH, and -O2); exposure to chemicals in the environment; ultraviolet radiation from sun can produce a covalent linkage between two adjacent pyrimidine bases in DNA to form thymine dimers (presented later in this lecture) cause _____
DNA damage
T/F: Loss of essential proteins needed for repair generally cause cancer
False; they are lethal
The enzymes catalyzing repair are present at high concentrations in the _____
nucleus
What are the 2 major DNA repair pathways?
base excision repair and nucleotide excision repair
These premutagenic lesions (dimers) alter the structure of DNA and consequently inhibit polymerases and _______
arrest replication
_____ mutations mobile genetic elements that jump around to DNA; can result in protein w altered amino acid sequence or issues with regulation
Transposons
phenotype of a ______ gene will be observed only in the homozygous state
recessive
A ___ mutation results in a base pairing mutation where 2 purines bind or 2 pyrimidines bind
Transition
A ___ mutation results in a single amino acid change
Missense
Two DNA strands switch partners between two double helices
Holliday junction (cross-strand exchange)
covalent linkage of two adjacent pyrimidines by UV light from the sun
Pyrimidine (C or T) dimer formation
Genetic exchange that takes place between a pair of homologous DNA sequences
Homologous recombination
Most such spontaneous changes in DNA are temporary because they are immediately corrected by a set of process that are collectively called _______
DNA repair
______ are sequence variants of a gene. You inherit one _____ of each autosomal gene from your mother and one from your father.
Alleles
An identifiable segment of DNA sequence with a known physical location on a chromosome and enough variation between individuals. Its inheritance and co-inheritance with alleles of a given gene can be traced. Markers can help link an inherited disease with the responsible genes. DNA segments close to each other on a chromosome tend to be inherited together. Markers are used to track the inheritance of a nearby gene
that has not yet been identified but whose approximate location is known. The marker itself may be a part of a gene or may have no known function; used in linkage analysis
Genetic Markers
The importance of DNA repair is evident from the large investment that cells make in ______
DNA enzymes
Variation between individuals in a population at specific nucleotides in their DNA sequence.
Single nucleotide polymorphisms (SNPs)
Dimers may be repaired by _____ or _______ but unrepaired dimers are mutagenic
photoreactivation or nucleotide excision repair
lose 5000 purine bases (A or G) per day in each cell due to thermal disruption of their N-glycosyl linkages to deoxyribose.
Depurination
A ___ mutation results in a base pairing mutation of the incorrect pyr/pur
Transversion
_______ are single base differences at a specific position in the genome; occurring within a gene (can) give rise to an allele. There are hundreds of thousands (millions) in the genome
Single nucleotide polymorphisms (SNPs)
phenotype of a ____ gene will be observed in the homozygous or heterozygous state
dominant
Way that a mutation occurs by reactive oxygen species
oxidative damage
