Chapter 14 - Mutation and Genetic Variation Flashcards
what is genetic variation?
genetic differences that exist among individuals in a population at a particular time
What is the genotype?
the genetic makeup of a cellular organism
WHat is polymorphism?
genetic difference among individuals that is present in multiple individuals in a population
what are alleles?
different form of the same gene
what does homozygous mean?
the same allele for a gene inherited from each parent
WHat does heterozygous mean?
different allele for a gene inherited from each parent
what is the phenotype?
individuals observable characteristics or traits
what is a genetic risk factor?
any mutation that increases the risk of disease in the individual
What are neutral mutations?
have negligible effect on survival or reproduction
What are harmful mutations?
decrease the survival or reproduction in individuals - often eliminated after 1 generation
Where are neutral mutations most likely to occur?
in non coding DNA or in introns
What are beneficial mutations?
mutations that were discovered through their effects oin protecting from infectious disease
What is an example of a beneficial mutation?
mutation to CCRS so it is no longer a HIV receptor so is a lot harder for viruses to invade
What is the nature of mutations?
most are spontaneous and random
what is the most common mutation?
substitution
what are hotspots (mutations)?
sites in the genome that exhibit greater rates of mutation
WHat are germ cells?
haploid gametes and the diploid cells that give rise to them
WHat are somatic cells?
all other body cells (excluding gametes etc.)
What does number of mutations depend on?
rate, size of genome, and amount of replication
Which are the only mutations transmitted to progeny (descendants)?
germ line mutations (as occur in egg and sperm cells)
What cells do most cancers result from?
mutations in somatic cells
What did Joshua and Esther Lederberg study?
replica plating (do mutations occur randomly or are they directed by the environment?)
What did Joshua and Esther Lederberg find?
showed that antibiotic resitant mutant can arise in the abscence of antibiotic
What is a point mutation?
changes in a single nucleotide
what is a synonymous mutation? (silent)
when mutation results in tge same amino acid formation
what is a nonsynonymous mutation? (missense)
when amino acid replacement occurs
What is a nonsense mutation?
when a stop codon is created in the protein
What can be the effect of deletion or insertions in non coding regions?
little or none
What is an example of the effect oa 3 nucleotide deletion?
cystic fibrosis
What are insertions or deletions called?
frameshift mutations
What are transposable elements (or transposons)?
insertion of movable DNA sequences into or near a gene
What did Barbara McCLintock study?
what causes sectoring in corn kernels
What did Barbara McCLintock find?
transposable elements can be excised from original position in genome and inserted into another position
