ANT 201: Week 2

Hypothesis

A prediction made based on prior knowledge or observations.

Prediction

Specific outcomes that are expected to happen based on a hypothesis

People believed that you got each gene from parents that blended together until what experiment

Mendel’s Pea Plant Experiment

• you inherit two but one can mask the other

Law of Segregation

Genes are inherited in pairs and these pairs are randomly separated in sex cells so that each parent only passes one allele to the offspring

*Segregate = separate genes —> eventually leads to equality

Law of Independent Assortment

Genes for different traits are inherited independently of one another

*Different traits = Diff lifestyles (assort.)

Law of Dominance

When there are alternate forms of a gene, a dominant allele will mask the presence of a recessive allele.

Pedigrees

Used to trace the inheritance of traits, especially medical conditions.

• Shaded will always have either AA or Aa and not shaded is always aa

Codominance

Two alleles are expressed equally in the phenotype

• Flower with both pink + red

Incomplete Dominance

both alleles of a gene are partially expressed, often resulting in an intermediate or different phenotype

• red and white flower made pink flower

Ex: Tay-Sachs (enzyme improper function)

Pleiotropy

One gene impacts/effects multiple phenotypes

• marphan syndrome

-tropy ..”trophy” —> one person trumps + wins all

Polygenic

Several genes contribute to one phenotype or effect

• height, skin + eye color, Alzheimers

“Poly” “i in team”.. multiple people affect me

Epistasis

A gene can mask or interfere with the expression of another gene

• albinism

*Stasis “status”… status of your condition after surgery (facial expression)

Epigenetics

Changes to the expression of genes based on environmental factors

• Methylene (long-term exposure to cigarettes)

• Dutch famine (smaller bodies)

*Epi -demic… environment factors

Phenotype Plasticity

Genotypes can produce different phenotypes depending on environmental input

• Height: 80% genetic, 20% nutrients

Developmental Plasticity

develops phenotype in response to childhood stressors + can’t be changed in adulthood

Development… developing as a child

Acclamatory Adjustments

temporary changes to phenotypes in response to stressors

• altitude changes

+ Phenotype changes associated w/ plasticity are not evolutionary

Phenotype Equation

Genotype + Environment

Modern Synthesis

Unification of genetic and evolutionary theories

• collab of genetic + evolutionary theories

Main Forces of Evolution

• Natural Selection

• Mutation

• Gene Flow

• Genetic Drift

Mutation

• changes in the genetic code

• the only source of new variation

• can be negative, beneficial, neutral

Gene Flow

Movement of alleles between populations, making two populations genetically similar

*Flows easily b/w people

Genetic Drift

Random changes in allele frequencies through time

*Drift … random fallout/changes in relationships as it goes on

Natural Selection

Individuals with traits better adapted to a specific environment are more likely to survive and pass them on to the next generation

• NOT survival of the fittest

  • doesn’t focus on reproduction

• Selection can be weak so less fit still survive

  • Herbert Spencer -eugenicist who believed poverty was due to NS

Point Mutations

a change in a single nitrogen base

Synonymous: change doesn’t affect what it is coded for

Non-Synonymous: leads to the coding of a diff allele

Synonymous

change doesn’t affect what it is coded for

Non-Synonmous

leads to the coding of a diff allele

Two Types: Missense + Nonsense Mutations

Frameshift Mutations

• inversion (flip)

• deletion

• duplication

• insertion

• Translocation

INDELS: insertion + deletion of bases

Nondisjunction

during meiosis, sister chromatids are not separated

Ex: down-syndrome

Hardy-Weinberg Equilibrium

Under certain conditions, allele frequencies will remain constant from generation to generation

Calculating Hardy-Weinberg

1) Divide AA,Aa, + aa by total population

2) plus AA + aa into this equation: (AA/aa) + 0.5(aa)=

*P= AA q= aa

3) Finally plug into equation

P2 + 2pq + q2 =1

P2= 2pq= q2=

• should all equal to 1

• if each answer is similar to the original set then tit in equilibrium but if its off its not

• 0.4 = evolution has NOT occured

Heterozygous Advantage

phenotypes are different + from both homozygous sets

• one of each is beneficial

Ex: sickle cell