Honors Bio chapter 9 genetics

Heredity

transmission of traits from one generation to the next

Genetics

study of heredity

Gregor Mendel

Father of Genetics, deduced the fundamental principles of genetics by breeding garden peas

Character

a heritable feature that varies among individuals

Trait

each variant for a character

Self-fertilization

fertilization of the same variety

Cross-fertilization

fertilization of one variety with another variety

True-breeding

varieties for which self-fertilization produced offspring all identical to the parent

Hybrids

the offspring of two different varieties

P generation

true breeding parents

F1 generation

hybrid offspring of the P generation

F2 generation

offspring of the F1 generation

Monohybrid Cross

the cross between two parents that differ in only one character

Alleles

The alternative versions of genes that account for variations in inherited characters

Homozygous

an organism that has two identical alleles for a gene

Heterozygous

an organism that has two different alleles for a gene

Dominant

the allele that determines the organism's trait

Recessive

the allele that has no noticeable effect on the organism's trait

Law of Segregation

A sperm of egg carries only one allele for each inherited character because allele pairs separate from each other during the production of gametes

Punnett Square

a diagram that shows the four possible combinations of alleles that could occur when gametes combine

Phenotype

the physical, observable traits

Genotype

the genetic makeup of a trait

Dihybrid Cross

a mating of parental varieties differing in two characters

Law of Independent Assortment

the inheritance of one character has no effect on the inheritance of another

Testcross

a mating between an individual of unknown genotype and a homozygous recessive individual to determine the unknown genotype with the offspring

Rule of Multiplication

multiply the two individual event probabilities to determine the probability of a compound event; AND

Rule of Addition

add the separate probabilities to determine the probability of an event that can occur in two or more alternative ways; OR

Pedigree

family tree for genotypes and phenotypes of a character

Carriers

people who are heterozygotes of the recessive disorder

Complete Dominance

when the next generation is the same phenotype as the parents

Incomplete Dominance

hybrids that fall between the phenotypes of the two parental varieties

ABO Blood Group

a phenotype in humans that is controlled by three alleles that produce a total of 4 phenotypes

Codominance

when two different dominant alleles of the same gene are both expressed in the phenotype

Chromosome Theory of Inheritance

genes occupy specific loci on chromosomes, and it is the chromosomes that undergo segregation and independent assortment during meiosis

Linked Genes

genes that are located close together on the same chromosome and tend to be inherited together

Recombination Frequency

% of recombinant offspring among the total offspring

Sex-Linked Gene

a gene located on either sex chromosome