Finals Genetics/ Inheritance

Genetics

the science that studies how genes are transmitted from one generation to the next

Gene

a segment of DNA that controls a hereditary trait

Chromosome

a long chain of genes

Trait

characteristics that an organism has

Gregor Mendel

father of genetics, responsible for discovering the three laws of genetics

Cross-pollination

pollinating one flower with the pollen from another and producing offspring with 2 different parents. What Mendel used when experimenting with pea plants

P generation

parental generation (pure-true breeds)

F1 generation

first generation of offspring

F2 generation

second generation of offspring

Hybrids

the offspring of parentals with different traits

Alleles

different forms of a gene

Principle of Dominance and Recessiveness

Mendel's law states that some alleles are dominant and others are recessive. When both are present, a dominant allele will mask the recessive one.

Principle of Segregation

Mendel's law that states that every individual carries 2 alleles for each trait. These 2 alleles separate/ segregate during the formation of gametes (each parent gives one)

Homozygous

the 2 alleles are the same (both dominant or both recessive)

Heterozygous

the 2 alleles are different (hybrid)

Genotype

the genetic makeup of an organism

Phenotype

the physical characteristics of an organism

Punnett Square

a diagram showing the allele combinations that might result from a genetic cross between 2 parents; can be called a testcross

Dihybrid or Two-factor cross

a cross that uses 2 genes and predicts the possible makeups for them being passed (has 16 squares instead of 4)

The principle of independent assortment

Mendel's law that states when gametes are formed, the alleles of a gene for one trait segregate independently of the alleles for a gene of another trait

Autosomal genes

genes found on chromosomes other than sex chromosomes

Autosomal dominant

traits will be expressed if HH or Hh (no carriers)

Autosomal Recessive

traits will be expressed if hh; Heterozygotes are carriers ( Cystic fibrosis, sickle cell anemia, Tay Sachs Disease

Sex linked genes

genes found on sex chromosomes (mainly X) are recessive; females can be carriers due to 2 X chromosomes, while Males can't

Incomplete or Nondominance

no allele is dominant or recessive, they just blend in the offspring (ex, red flower + white flower = pink flower)

Co- dominance

both alleles appear in the phenotype of the heterozygous offspring (E, Blood type A & B)

Polygenic Inheritance

the determination of a characteristic is the result of the interaction between many genes

Pedigree Chart

shows the passing of traits from one generation to another

Squares

in a pedigree chart represent males

Circles

in a pedigree chart represent females

Filled in

in a pedigree chart means a trait expressed

Empty

in a pedigree chart, means trait not expressed

Half-filled

in a pedigree chart, means the individual is a carrier

Wild-type traits

traits that are most often seen in nature, most common and natural, not necessarily dominant

Linked Genes

located near each other on the same chromosome and tend to travel together during meiosis and fertilization; inherited as a set, not following Mendel's laws of independent assortment

Locus

genes' specific location on a chromosome

Rule of multiplication

states that the probability of a compound event is the product os separate probabilities of the independent events

Pliotype

is when one gene influences several characters; Ex, sickle cell, which results in abnormal hemoglobin proteins and causes red blood cells to deform into a sickle shape

Linkage Map

a type of genetic map that shows the relative positions of genes or genetic markers on a chromosome, based on the frequency of recombination between them