Chapter 19 Flashcards
the complete set of genes (& alleles) in a certain organism
genome
Experimented with Pea Plants
Gregor Mendel
based on predictions from one-trait crosses
Rule of Segregation
two genes of each pair are separated from each other, so they end up in different gametes (occurs in diploid cells)
Rule of Segregation
based on predictions from two-trait crosses
Rule of Independent Assortment
gene pairs of one trait are sorted out for distribution into one gamete or another independently of how the gene pair of another trait are sorted out (meiosis)
Rule of Independent Assortment
~ 3 billion base pairs of this
DNA
specific location of the gene on a chromosome
Locus
Humans have about this many genes
21,500
each version of a gene
Allele
two copies of each gene on pairs of homologous chromosomes
Diploid cells
observable functional or physical traits
Phenotype
inherited alleles
Genotype
Homozygous Dominant
AA
Homozygous Recessive
aa
Heterozygous
Aa
pairs of alleles separated during gamete formation
Law of Segregation
Grid used to determine possible outcomes of genetic crosses
Punnett Square
Measure of the chance that some particular outcome will occur
Probability
traits determined by genes that are on the autosomal chromosomes
Autosomal
Particular ______ for each gene
locus
occurs in meiosis
Crossing over
diploid cells have homologous pairs of these
chromosomes
genes in a diploid cell have how many alleles?
2 alleles
between genes if the distance between them is short
linkage
Genes are distributed into gametes in regular what?
patterns
between individuals heterozygous for two traits yields sixteen different gamete unions
Dihybrid Cross
Occurs during Meiosis
Independent Assortment
identify genes that control common reactions to various drugs
pharmacogenetics
wide-ranging effect of one gene
pleiotropy
heterozygous for a trait, but both alleles are expressed
codominance
a gene that has three or more alleles
Multiple allele system
probability that someone who inherits an allele will have the phenotype associated with it
penetrance
homozygous recessive
100% penetrance
Cystic Fibrosis
Dominant allele for extra digits
incompletely penetrant
Polydactyly
combined expression of several genes
polygenic traits
populations show a range of continuous differences
continuous variation
phenotypes shaped by one or more genes and affect by the environment
multifactorial trait
