Unit 5 Genetics Flashcards
fertilization
combines two haploid gamete cells into a new zygote
meiosis
reduces diploid cells back to haploid gametes so DNA can be combined into next generation of organisms
meiosis 1st division
homologs seperate, reductional division where 4c reduces to 2c, crossing over takes place
meiosis 2nd division
sister chromatids seperate, equational division
ploidy
genetic content (n) or number of chromosome copies (c)
reductionol division
decreases the genetic content
equational division
separates sister chromatids
crossing over
in prophase I, parts of each sister chromatid swap places to increase genetic variation
interkenisis
cell rests, reestablishes energy stores and organizes chromosomes, no DNA replication
prophase 2
spindle fibers drag chromosomes to center of cell
metaphase 2
duplicated sister chromatids are separated
anaphase 2
full separation of sister chromatids
segregation
maternal and paternal alleles for a gene are segregated into different gametes
why is genetic variation important?
to face changing environmental conditions
independent assortment
different genes for different traits are inherited independently of one another (unless they are located close to each other on the same chromosome)
synapsis
as homologous chromosomes are condensed and collected they are temporarily bound by synaptimal complex
law of dominance
certain alleles can mask the presence of others
law of segregation
parental genes are randomly separated, offspring inherit one genetic allele from each parent
law of independent assortment
alleles for different genes are inherited independently from one another (exception is linked genes)
punnet square
table used to predict outcome of a genetic cross
genetypic ratio
alleles ratios (ex: PP-1 Pp-2 pp-1)
phenotypic ratio
characteristic ratio (ex: 3 purple flowers, 1 white)
genotype
combination of letters, genetic makeup
phenotype
the way the trait appears, physical characteristic
addition rule
add or subtract the probability of one event happening over the other (either/or)
multiplication rule
multiply probability of two events to calculate the probability of them happening at the same time
mitochondrial dna
from mother only
nonmendalian genetics
study of traits and genes that are not inherited in line of mendel’s law
incomplete dominance
when a heterozygote for a particular trait is a mix of homozygous phenotypes (hybrid doesn’t resemble either parent, ex: red and white flower produce pink)
codominant traits
heterozygote shows both phenotypes (ex: AB blood type)
linked genes
when two genes are not inherited independently because they are located on the same chromosome
polygenic traits
traits controlled by more than one gene (ex: skin color)
pleiotropy
when one gene controls multiple, seemingly unrelated traits
lethal allele
an allele that causes death when inherited
sex-linked traits
traits related to genes on sex chromosomes
nonnuclear inheritance
DNA found in chloroplast and mitrochondria
recombinant frequency
recominants/total offspring x 100 = RF
environmental affects on phenotype
food/nutrients, soil pH (phenotypic plasticity with hydrengaes)
phenotypic plasticity
signals in the environment that change gene expression, environmentally driven variations have evolutionary advantage
fruit fly experiments
discovered recessive problems on X chromosomes with fly’s eye color
heredity
transmission of traits from one generation to the next
somatic cells
all cells in the body minus reproductive cells
locus
a gene’s specific location along the length of a chromosome
asexual reproduction
single individual is the sole parent, passes identical DNA to offspring and gives rise to clone
karyotype
ordered display of chromosomes by length
autosomes
chromosomes that aren’t sex chromosomes
diploid cell
cell with two chromosome sets (maternal and paternal) 2n
homologous chromosomes
2 chromosomes of a pair with the same length, staining pattern, and centromere position
chiasma
hold homologs together as spindle fibers for the 1st meiototic division
hybridization
crossing of two true breeding varieties (creating hybrids)
test cross
breeding an organism of unknown genotype with a homozygous recessive to reveal organism’s genotype
