Foundations of Biology: Inheritance and Meiosis I and II

genome

all the chromosomes in the nucleus of a cell; contains all protein-making information for an organism; the genes and proteins they make determine how well a cell functions

karyotype

number and visual appearance of the chromosomes in the cell nuclei of an organism

phenotypes

characteristics of an organism based on genetic information; observable traits; ex. hair and eye color

gene

code for mRNA that is made into proteins

gene locus

the location of a specific pair of genes

homologous chromosomes

chromosomes that contain the same genes in the same location, but have different alleles

alleles

alternative versions of the same gene

genotype

which alleles are present at a gene locus

maternal chromosomes

chromosomes inherited by the female parent

paternal chromosomes

chromosomes inherited by the male parent

variation

sexual reproduction creates _______ in generations, but is slower and requires 2 different sexes

no

asexual reproduction produces later generations with _______ variation, but is faster and does not require two different sexes

gametes

often haploid reproductive cells that can fuse to form a diploid zygote; often ovum and sperm in eukaryotes

ploidy

the number of sets of chromosomes in a cell

haploid

1n ploidy

diploid

2n ploidy

prophase 1

chromosomes condense, bivalents form, the nuclear envelope breaks down

metaphase 1

homologous pairs align at metaphase plate and crossing over occurs

anaphase 1 and telophase 1

homologous chromosomes are separated on metaphase plate my spindle fibers to form two haploid cells

recombinant

new genotypes formed from crossing over that do not match the genotype of either parental chromosome

bivalent

formed by replicated chromosomes pairing up and attaching to their homologous chromosome in prophase 1

crossing over

the swapping of regions of DNA between non-sister chromatids during bivalent formation

homozygous chromosome

having two of the same alleles

heterozygous chromosome

having two different alleles

number

nondisjunction events during meiosis I or II cause deviations in chromosome __________

dominant allele

an allele that produces the same phenotype in heterozygous and homozygous genotypes

recessive allele

an allele that produces its phenotype only in homozygous genotypes

autosomal inheritance

the patterns of inheritance of any genes not on a sex chromosome; these are the "standard" patterns of inheritance

principle of independent assortment

the genes for one specific trait and another assort independently because: 1. they are located on different chromosomes and 2. these chromosomes have two equally likely ways of lining up before they are segregated

monohybrid cross

a genetic cross that examines only one trait

reciprocal cross

a genetic cross that tests for sex linked traits by flipping the genotypes of the male and female parent; makes no difference in autosomal crosses

dihybrid cross

a genetic cross that examines two genes (traits) with two alleles on different chromosomes; produces 4 possible types of gametes

test cross

tests us the genotype of an organism by crossing an unknown parent with a homozygous recessive parent

hemizygous

genotypes that only have one allele; male X sex chromosomes