Bio Chapter 12

Front 1

Genes

Back 1

DNA sequence that code for heritable traits

Front 2

Alleles

Back 2

Alternative form of a gene

Front 3

Dominant Allele

Back 3

Requires only one copy to be expressed

Front 4

Recessive Allele

Back 4

Requires two copies to be expressed

Front 5

Genotype

Back 5

The combination of alleles on has at a given genetic locus

Front 6

Genetic Locus

Back 6

Location on the chromosome of a gene

Front 7

Homozygous

Back 7

Having two of he same allele

Front 8

Heterozygous

Back 8

Having two different alleles

Front 9

Hemizygous

Back 9

Having only one allele (male sex chromosomes)

Front 10

Phenotype

Back 10

The observable manifestation of a genotype

Front 11

Complete Dominance

Back 11

One dominant allele and one recessive allele only show the traits of the dominant allele

Front 12

Codominance

Back 12

More than one dominant allele Ex: blood type AB

Front 13

Incomplete Dominance

Back 13

No dominant alleles rather an intermediate phenotype Ex: Red and white flowers making pink flowers

Front 14

Penetrance

Back 14

The proportion of the population that expresses a phenotype, given a particular genotype Varies from full to high to reduced to low to nonpenetrance

Front 15

Expressivity

Back 15

The differences in expression of a phenotype across affected members of a population Either constant or variable

Front 16

Constant Expressivity

Back 16

All individuals with a given genotype express the same phenotype

Front 17

Variable Expressivity

Back 17

Individuals with the same genotype may have different phenotypes

Front 18

Mendel’s First Law of Segregation

Back 18

An organism has two alleles for each gene, which segregate during meiosis, resulting in gametes carrying only one allele for a trait

Front 19

Mendel’s Second Law of Independent Assortment

Back 19

Inheritance of one allele does not influence the probability of inheriting a given allele for a different trait because of recombination during prophase I

Front 20

Experiments Supporting DNA as Genetic Material

Back 20

Griffith’s mice, Avery-MacLeod-McCarthy degraded DNA vs. proteins, and Hershey-Chase radiolabeled DNA

Front 21

Griffith’s Mice Experiment

Back 21

Non deadly rough strain of virus gains the ability to produce smooth strain from the heat-killed smooth strain

Front 22

Avery-MacLeod-McCarthy Experiment

Back 22

Bacterial transformation does not occur if DNA is degraded suggesting it is the genetic material

Front 23

Hershey-Chase

Back 23

Saw that only radiolabeled DNA was injected by bacteria and not radiolabeled proteins

Front 24

Gene Pool

Back 24

All of the alleles in a given population

Front 25

Mutation

Back 25

A change in DNA sequence

Front 26

Nucleotide Mutations

Back 26

Point mutations: substituting of one nucleotide for another or frameshift mutations: moving the three letter transcriptional reading frame

Front 27

Point Mutations

Back 27

Silent: no affect on codon Missense: substitution of one amino acid for another Nonsense: substitution for a stop codon

Front 28

Frameshift Mutations

Back 28

Deletion or insertion

Front 29

Chromosomal Mutations

Back 29

Deletion, duplication, insertion, inversion, or translocation

Front 30

Genetic Leakage

Back 30

A flow of genes between species through hybrid offspring

Front 31

Genetic Drift

Back 31

When the composition of the gene pool changes as a result of chance

Front 32

Founder Effect

Back 32

Bottlenecks that isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes

Front 33

Consequences of Mutation

Back 33

Advantageous or deleterious (detrimental like defects in metabolism)

Front 34

Punnett Squares

Back 34

Front 35

Monohybrid vs. Dihybrid Cross

Back 35

Punnett square with one gene (Aa) vs. Punnett square with two genes (AaBB)

Front 36

Sex-Linked Crosses

Back 36

Used to indicate sex as well as genotype Sex linked is “x-linked”

Front 37

Recombination frequency

Back 37

Likelihood of two alleles being separated during crossing over in meiosis Can be used to create genetic maps as frequency is proportional to distance between alleles

Front 38

Hardy-Weinberg Principle

Back 38

If a population meets five criteria then the allele frequencies will remain constant

Front 39

Hardy-Weinberg Five Criteria

Back 39

1. The population is very large (no genetic drift) 2. There are no mutations that affect the gene pool 3. Mating between individuals in the population is random (no sexual selection) 4. There is no migration of individuals into or out of the population 5. The genes in the population are all equally successful at reproducing

Front 40

Hardy-Weinberg Equation Term Meaning

Back 40

p: dominant allele frequency q: recessive allele frequency pp: homozygous dominant frequency 2pq: heterozygous frequency qq: homozygous recessive frequency

Front 41

Hardy-Weinberg Equation

Back 41

Front 42

Natural Selection

Back 42

Chance variations exist between individuals and advantageous variations afford the most opportunity for reproductive success

Front 43

Modern Synthesis Model

Back 43

Mutation and recombinations are the mechanisms of variation Differential reproduction is the mechanism of reproductive success

Front 44

Inclusive Fitness

Back 44

Success in the population is based on the number of offspring, success in supporting offspring, and the ability of offspring to then support others ensuring continuation of genes in subsequent generations

Front 45

Punctuated Equilibrium

Back 45

For some species, evolution is a slow process with intermittent rapid bursts of evolutionary activity

Front 46

Types of Selection

Back 46

Stabilizing, directional and disruptive

Front 47

Stabilizing Selection

Back 47

Keeps phenotypes in a narrow range excluding extremes

Front 48

Directional Selection

Back 48

Moves the average phenotype toward one extreme

Front 49

Disruptive Selection

Back 49

Moves toward two different phenotypes at the extremes and can lead to speciation

Front 50

Adaptive Radiation

Back 50

The rapid emergence of multiple species from a common ancestor that occupy their own niche

Front 51

Species

Back 51

The largest group of organisms capable of breeding to form fertile offspring

Front 52

Reproductive Isolation

Back 52

Causes species to not be able to reproduce with each other

Front 53

Pre-Zygotic Mechanisms of Reproductive Isolation

Back 53

Things that stop a zygote from forming Temporal isolation, ecological isolation, behavioral isolation, reproductive isolation, or gametic isolation

Front 54

Post-Zygotic Mechanisms of Reproductive Isolation

Back 54

Allow for gamete fusion but yield either nonviable or sterile offspring Hybrid inviability, hybrid sterility, or hybrid breakdown (second generation hybrid can't reproduce)

Front 55

Types of Evolution

Back 55

Divergent, parallel, convergent

Front 56

Divergent Evolution

Back 56

Two species sharing a common ancestor become more different

Front 57

Parallel Evolution

Back 57

Two species sharing a common ancestor evolve in similar ways due to analogous selection pressures

Front 58

Converging Evolution

Back 58

Two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressures

Front 59

Molecular Clock Model

Back 59

The degree of difference in the genome between two species is related to the amount of time since the two species broke off from a common ancestor