Inheritance Flashcards
genes
hereditary units found in chromosomes
gametes
reproductive cells, eggs, sperm
somatic cells
body cells (not gametes)
locus
a gene’s specific location along the length of a chromosome
karyotype
an ordered display of chromosomes from microscope images
sex chromosomes
chromosomes that determine an indiviudal’s sex (X,Y)
autosomes
chromosomes that aren’t sex chromosomes
diploid cells
having 2 of each chromosome
haploid cells
having 1 of each chromosome
meiosis
the process that creates 4 haploid gametes from 1 germ cell
phases of meiosis
meiosis 1 and meiosis 2
homologous chromosomes
the pair of sister chromatids that attach to each other in prophase 1 of meiosis
synapis
when the paired homologs become physically attached in prophase 1 of meiosis
crossing over
a genetic swap between homologous non-sister chromatids in prophase 1
chiasmata
a point where crossing over has occured
recombinant chromosomes
the chromosomes that swapped genes during crossing over
character
a heritable feature that varies among individuals; ex: eye color, height
trait
each variant of a character; blue eyes, tall
allele
a version of a gene
phenotype
an organism’s observable traits
genotype
an organism’s genetic makeup; affects phenotype
law of segregation
the two alleles separate in gamete formation; you only get one allele from each parent
heterozygous
having two differnt alleles
homozygous
having two of the same allele
true-breeding
crossing two homozygotes will always result in another homozygote
dominant vs recessive
the expression of the dominant allele maks the phenotypic effect of the recessive allele
law of independent assortment
the pair of alleles for a given gene segregates independently of the pair of alleles for another gene (only true for genes on different chromosomes, or far away on the same chromosome)
monohybrid cross
a breeding experiment for an organism that differs in one trait
dihybrid cross
a breeding experiment for an organism that differs in two traits
monohybrids
individuals heterozygous for one trait
dihybrids
individuals heterozygous for two traits
complete dominance
one allele is completely dominant over the other; heterozygous phenotype is the same as homozygous dominant; ex: red and white gives red
incomplete dominance
heterozygous phenotype is intermediate; ex: red and white gives pink
codominance
both phenotypes are expressed in a heterozygote; ex: A and B give AB
multiple alleles
in the whole population some genes have more than two alleles; ex: A, B, O
pleiotropy
one gene is able to affect multiple phenotypic characters; ex: sickle-cell disease
epistasis
the phenotypic expression of one gene affects that of another; ex: baldness and hair color; yellow labs
polygenic inheritance
a single phenotypic character is affected by two or more genes; ex: eye color, skin color
norm of reaction
the phenotypic range of a particular genotype (the phenotype can be influenced by the environment)
multifactorial characters
polygenic characters that are also influenced by the environment; ex: skin color and tanning
carriers
heterozygotes that carry a recessive gene (for some disorder)
