Bio Exam 4 - Section 20 and Section 21 (Predicting Phenotypes and Genotypes) and (Pedigrees and multiple alleles)

Dihybrid cross

a genetic cross used to track the inheritance of two traits

Rule of Addition

if an event can occur more than one way, the probability of that event occurring is the sum of of the probabilities of each way the event can occur

Rule of multiplication

probability of two or more independent events in a specific order, multiply the individual probability events

Monohybrid crosses

a cross between two organisms with different variations at one genetic locus of interest

Punnett Square

a diagram used to predict the possible allele combinations for offspring from two parental individuals; illustrating the inheritance of specific genetic traits

Test crosses

performed to determine the genotype of an organism showing the dominant trait

Monohybrid cross

a breeding experiment that examines inheritance of a single pair of alleles

Dihybrid cross

a breeding experiment that examines inheritance of two independent pairs of alleles

Law of Segregation

each gamete receives one allele of a gene pair

Law of Independent Assortment

alleles of different genes segregate independently when the genes are not linked

Probability

get an answer in genetics quickly and without punnett

Carrier

a person (or other organism) who is heterozygous for a recessive trait and does not display the trait or show symptoms of the condition

Codominance

a relationship between the alleles of a gene wherein the alleles in a heterozygote are both fully expressed. This results in offspring with a phenotype that is neither dominant nor recessive and is a unique phenotype

Complete Dominance

a relationship between the alleles of a gene wherein the allele that is dominant completely masks the effect of the allele that is recessive in the heterozygote

Epistasis

the phenomenon where the effect of one gene is dependent on the presence of one or more other genes.  In other words, one gene influences the expression of another gene

Heterozygote advantage

a phenomenon wherein the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype

Incomplete dominance

a relationship between alleles in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles

Multiple alleles

the condition wherein a gene has three or more possible alleles

Pedigree

a diagram that shows the occurrence of phenotypes of a particular gene from one generation to the next

Pleiotropy

a phenomenon where one gene influences two or more seemingly unrelated phenotypic traits

Polygenic inheritance

occurs when one characteristic is controlled by two or more genes

Quantitative character

a phenotype that depends on the combined actions of many genes and the environment

Autosomal recessive traits

skips generations, found in males and females equally

Autosomal recessive

require two carriers (heterozygote) parents when the disease is serious enough to prevent reproduction

Cystic Fibrosis

• Causes salt imbalance, mucus buildup leads to lung infections

• 1 in 25 white people are carriers

• causes sterility in males

• Used to cause death by 20-25

Sickle-cell Anemia

• 10-40% of indigenous African people are carriers

• Homozygous recessive people experience sickle shaped RBC’s, anemia, body pains, fever, fatigue and death by 30 if untreated

ID the pedigree

Does not skip generations, found in both male and females equally

Brachydactyly

Autosomal dominant condition causing short fingers and toes

Huntington’s Disease

AD disease that causes nervous system detioration over time; Typically starts in 30s but can start in adolescence or much later in life

Pleiotrophy

one gene have multiple effects, depending on the tissue/ cell type

Epistasis

one gene affects the expression of another gene

Polygenic inheritance

when many genes control a single trait, making it a quantitative trait

PKU

is a rare inherited metabolic disorder where the body can't properly break down the amino acid phenylalanine