genetics exam 1

theory of epigenesis

organism develops from the fertilized egg by a succession of developmental events

theory of preformation

fertilized egg contains a complete miniature adult, called a homonculus

cell theory

all organisms are composed of basic structural units called cells that are derived from preexisting cells

theory of spontaneous generation

creation of living organisms from nonliving components

descent with modification

existing species arose from other ancestral species

natural selection

mechanism for evolutionary change

mitosis

chromosomes are copied and distributed with each daughter cell receiving a diploid set

meiosis

chromosomes are copied and distributed with each daughter cell receiving a haploid set of chromosomes

alleles

alternative forms of a gene

mutation

heritable changes in DNA sequence, source of all genetic variation

genotypes

set of alleles for a given trait

phenotype

expression of the genotype that produces an observable trait

codons

triplet nucleotides present in mRNA, the genetic code

vectors

carrier DNA molecules that DNA fragments obtained from restriction enzymes can be placed in

clones

copies of the combined vector DNA and DNA fragments

genome

complete haploid DNA content of a specific organism

genomics

studies the structure, funtion, and evolution of genes and genomes

proteomics

identifies a set of proteins present in cells under a given set of conditions. studies their functions and interactions

bioinformatics

uses hardware and software for processing nucleotide and protein data

reverse genetics

dna sequence of a particular gene of interest (GOI) is known, but the function is not

gene knockout

allows scientists to render genes nonfunctional to investigate the possible role of that gene

how many divisions occur in mitosis vs meiosis?

1 mitosis, 2 meiosis

genes are transmitted through what?

gametes

what produces alleles?

mutation

using ______ geneticists can map the location of genes on chromosomes

mutant gene

what is the product of gene expression?

proteins

which theory served as the basis for mendels principles of segregation and independent assortment?

Chromosomal theory of inheritance

How can we test if a trait is sex dependent?

reciprocal cross

when geneticists rediscovered mendels work, they realized he discovered the basis for:

Transmission of hereditary traits

how can we test if a dominant phenotype is a homozygous dominant vs heterozygous?

test cross

when performing a test cross, you would cross your organism of interest with what?

homozygous recessive

true breeding strands

each trait appeared unchanged generation after generation in self-fertilizing plants

transmission genetics

how genes are transmitted from parent to offspring

monohybrid cross

involves a single pair of contrasting traits

P1 generation

parent gen

F1 generation

offspring to the parentals, first filial generation

F2 generation

offspring of F1 generation (from self-fertilization); second filial generation

reciprocal cross

cross made in both directions

Testcross

determines if individual displaying dominant phenotype is homozygous or heterozygous for that trait; cross between dominant phenotype and homozygous recessive

independent assortment

genes assot independently during gamete formation with equal frequency

product law

used to predict frequency of two independent events occurring simultaneously

trihybrid cross

segregation and independent assortment applied to three pairs of contrasting traits

discontinuous variation

a dominance-recessive relationship

continuous variation

offspring were a blend of parental phenotypes

sum law

calculates probability of oucomes independent of each other

chi-square analysis

evaluates the influence of chance on genetic data

chance deviation

chance events subject to random fluctuations; expected outcome is diminished by larger sample size

null hypothesis

assumes data will fit given ratio; assumes there is no real difference between measured values and predicted values

chi-square

goodness of fit of null hypothesis; analysis used to test how well the data fits the null hypothesis; analysis of observed vs expected deviations

pedigree

family tree with respect to given trait; reveals patterns of inheritance of human traits

what was mendels organism and why did he select them?

pea plants; he selected them because they are easy to grow, grow quickly, have true breeding strains, have observable characteristics, and can undergo controlled matings

what are the criteria for classifying two chromosomes as homologous pairs?

they must be the same size with identical centromere locations, they must form pairs during meiosis, they must have identical linear order of gene loci, andone must be from the paternal cell and the other from the maternal cell

gene interaction

single phenotype is affected by more than one set of genes

x-linkage

genes that are present on the X chromosome

Wild Type allele

occurs most frequently in nature and is usually, but not always dominant

Loss of function mutations

new phenotype results from change in activity, mutation causes loss of wild type function

gain of function mutations

mutation enhances function of wild type; quantity of gene product increases

neutral mutations

no change to the phenotype; no change to evolutionary fitness of the organism

incomplete/partial dominance

indeterminate phenotype; neither allele is dominant

threshold effect

condition where normal phenotypic expression occurs any time a minimal level of wild type gene product is attained

codominance

no dominance or recessiveness, no incomplete or blending, joint expression of both alleles in heterozygotes

multiple alleles

three or more alleles of the same gene; resulting mode of inheritance is unique and can only be studied in populations

essential genes

absolutely required for survival, mutations can be tolerated if heterozygous, mutation behaves as recessive lethal allele

lethal allele

has potantial to cause death of an organism, alleles are result of mutations in essential genes; inherited in a recessive manner

dominant lethal allele

presence of one copy of allele results in death

epistasis

expression of one gene masks/modifies effect of another gene pair

dominant epistasis

dominant allele at one loci masks an allele at second loci

complementation analysis

screens number of individual mutations resulting in same phenotype; can predict total number of genes determining a trait

complementation group

all mutations present in any single gene

pleiotropy

expression of single gene has multiple phenotypic effects

sex limited inheritance

expression of specific phenotype is absolutely limited to one sex

sex influenced inheritance

sex of individual influences expression of phenotype; not limites to one sex or the other

penetrance

percentage of expression of the mutant genotype in a population

expressivity

range of expression of mutant phenotype; result of genetic background differences and/or environmental effects

position effect

physical location of gene influences expression

temperature-sensitive mutation

mutant allele expresses mutant phenotype at one temperature, wild type phenotype at another

genetic anticipation

genetic disease has earlier onset and increased severity with each succeeding generation

what are the three functional activity changes in enzymes that can cause a new phenotype?

eliminating enzyme function, changing relative enzyme efficiency, and changing enzyme function