BIOL 102 VOCAB TEST 2 Flashcards
genetic variation
differences in genotype among individuals in a population
mutations
any heritable change in the genetic material, usually a change in the nucleotide sequence of a gene
genotype
the genetic makeup of a cell or organism; the particular combination of alleles present in an individual
polymorphism
any genetic difference among individuals that is present in multiple individuals in a population
alleles
the different forms of a gene, corresponding to different DNA sequences in each different form
homozygous
describes an individual who inherits an allele of the same type from each parent, or a genotype in which both alleles for a given gene are of the same type
heterozygous
describes an individual who inherits different types of alleles from the parent, or genotypes in which the two alleles for a given gene are different
phenotype
the expression of a physical, behavioral, or biochemical trait; an individual’s observable phenotypes include height, weight, eye color, and so forth
genetic risk factor
any mutation that increases the risk of a given disease in an individual
Does a risk factor cause the disease?
no it does not cause the disease, but rather makes the disease more likely to occur.
neutral mutations
genetic changes that have no effect or negligible effects on the organism, or whose effects are not associated with differences in survival or reproduction.
what is the most frequent allele?
the A allele
what determines a genotype?
a genotype is the genetic composition of a cell or organism, which can differ based on the nucleotide sequence in the region(s) of interest. Although there can be many different forms (alleles) of a gene or sequence, each cell or individual normally has only two copies of each sequence, and they can either be identical to each other (homozygous) or different from each other (heterozygous)
What determines a phenotype?
A phenotype of a cell or organism refers to its observable features, which are determined in part by its genotype, but can also be influence by environmental factors. Some phenotypes are easily seen and vary widely among individuals, such as hair color or height, but a phenotype may also involve less easily observable characteristics such as blood type, which fall into a few distinct groups.
With regards to mutations, what is meant by the terms “harmful,” “beneficial,” and “neutral”?
Beneficial mutations are those that provide some sort of advantage to the organism in its environment.
Neutral mutations provide neither benefit nor harm to the individual
Harmful mutations are those that may cause genetic disorders
A mutation arises in a bacterium that confers antibiotic resistance. Is this mutation harmful, beneficial, or neutral?
mutations that cause antibiotic resistance are clearly beneficial to bacteria when antibiotic is present, but are neutral or can even be harmful in the absence of antibiotic. The effect of a mutation on an organism often depends on the environment
spontaneous mutations
occurring in the absence of any assignable cause; most mutations are spontaneous
Most mutations are __________, occurring by chance in the absence of any assignable cause.
spontaneous
Are mutations random?
yes, that are unconnected to an organism’s needs and makes no difference whether a given mutation would benefit the organism.
what is the most common mutation?
the substitution of one nucleotide for a different nucleotide
hotspots
a site in the genome that is especially mutable
germ cells
the reproductive cells that produce sperm or eggs and the cells that give rise to them
somatic cells
a non-reproductive cell, the most common type of cell in the body of a multicellular organism
germ-line mutations
a mutation that occurs in eggs and sperm or in the cells that give rise to these reproductive cells and therefore is passed on to the next generation
what are germ-line mutations important to the evolutionary process?
they are passed from one generation to the next and may eventually come to be present in many individuals descended from the original carrier
what are somatic mutations?
a mutation that occurs in somatic cells
are somatic mutations transferred to offspring?
no they are not transmitted to future generations, they are transmitted to the daughter cells in mitotic cell divisions
Mutations in which types of cell are most likely to contribute to evolutionary change in populations of organisms?
Mutations that contribute to evolutionary change must be capable of being transmitted from generation to generation. Thus, they must be mutations in cell lineages that give rise to reproductive cells.
If mutations occur at random with respect to an organism’s needs, how does a species become more adapted to its environment over time?
Mutant genes that are harmful or neutral are much less likely to persist in a population than ones that result in increased survival or reproduction, because the latter mutations result in greater fitness.
