Unit 5: Heredity

G1- cell grows

S- DNA replicates into double-stranded chromosomes

nuclear membrane breaks down, centrioles and spindle appear, homologous chromosomes pair as tetrads, crossing over occurs

tetrads move to the equator

tetrads split and chromosomes move to the poles

cell membrane pinches in and nuclear membrane returns; new cells are haploid but double stranded

nuclear membrane breaks down and spindle returns

chromosomes move to the equator

centromere divides and single chromosomes move to poles

cell membrane pinches in and nuclear membrane reforms; results in 4 haploid single stranded cells

meiosis only occurs in ovaries or testes, results in 4 haploid cells, for creation of new gametes

genetic material is swapped b/w two chromosomes in meiosis, important bc it increases genetic diversity

an individual’s complete set of chromosomes; can show sex and genetic disorders based on chromosomal numbers

experimented on pea plants and figured out the fundamental laws of inheritance

the two alleles for each trait separate during gamete formation

each pair of alleles for different traits separates independently during gamete formation

alternate form of a gene

observed physical traits

genetic make up

having 2 of the same allele (HH or hh)

having 2 different alleles (Hh)

fully expressed in heterozygote

no effect on appearance of heterozygote

studies 1 trait

studies 2 traits

P1- parental; breeding

F1- offspring of P1

F2- offspring of F1

expected genotypes and probabilities for each of offspring

the masking of a gene’s expression by another gene

the effect of 2 or more genes acting on a single phenotypic trait (ex. skin color)

gene has more than 2 alleles (ex. blood type- A, B,O)

genes located on the same chromosome, the closer they are the greater chance they will get inherited together; ratio has less recombinant offspring

F1 hybrids have appearance that is between that of 2 parents (ex. red + white → pink)

phenotype of both alleles expressed (ex. red + white → red and white spots)

genes carried on one of the sex chromosomes; men more likely to be affected by X chromosome traits and cannot be carriers

the idea that the same genotype can result in different phenotypes; environment affects

autosomal recessive; lack enzyme that breaks down mucus

autosomal recessive; crescent shaped blood cells

autosomal dominant; CAG repeat in neurons

autosomal recessive; protein builds up in brain

autosomal recessive; brain deterioration

one X and no other sex chromosome

XXY

trisomy 21