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