ANT 201 Quiz 2

Gregor Mendel

systematically bred pea plants, focused on traits that have two forms, studied results of crosses

sex chromosomes

X and Y chromosomes (2)

autosomes

all chromosomes except sex chromosomes (22 pairs)

diploid number

total chromosomes in somatic cells

RNA

DNA is the template for the making of

proteins

RNA is the template for the making of

DNA

stuff genes are made of

genes

section of DNA with identifiable structure or function, chromosomes

alleles

one of two or more alternative versions of the same gene

dominant

an allele that results in the same phenotypes whether in the homozygous or the heterozygous state

microevolution

evolution on a small scale - usually within a single population

macroevolution

the evolution of whole taxonomic groups over long periods of time

phenotype

the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences

recessive

an allele that is only expressed in the homozygous genotype

codominance

both alleles are expressed and contribute to the phenotype

incomplete dominance

Both alleles are expressed as a blended phenotype

Evolution

changes in allele frequencies in a population over time

forces of evolution

processes that cause “changes over time”

Natural Selection

• Selection of favored forms through differential reproductive success

• Some individuals leave more offspring than others

• Selection for this advantageous traits will produce adaptations

• Acts on the individual “phenotype”

Mutation

• A change in population allele frequencies by errors in DNA replication

• Some errors may be beneficial, harmful or simply neutral

• Ultimate source of variation in a population for natural selection to act on

Genetic Drift

• A change in population allele frequencies by random change

• Over time, this sampling variation will lead to “fixation” with only one allele remaining

• The “founder effect” is an example of genetic drift, where a daughter population is representative of the original population

• Rare alleles may be overrepresented

Gene Flow

• The exchange of alleles between populations

• Has a homogenizing effect. By making populations more similar to one another

• Disruption of gene flow may eventually lead to speciation (formation of distinct species)

proteins

long strips of amino acids bond together to form long peptide chains

Transcription

DNA unzips and mRNA transcribes information and carries it to the ribosome

translation

mRNA is read at ribosome and tRNA binds specific amino acids

mitosis

somatic cells, produces two exact replicas, basis for cellular proliferation

meiosis

sex cells, produces gametes, crossing over, recombination

independent assortment

the changes of inheriting a certain allele don't depend on inheriting a different allele

linkage

genes on same chromosome tend to stay together

population genetics

study of the processes that change gene frequencies

individual phenotypes

natural selection acts on ...

evolutionary change

occurs when the genetic composition of population changes over time

adaptation

occurs when phenotypes are linked to genotypes and traits are inherited

gene accounting

tracking genetic composition of a population through time

Hardy-Weinberg equilibrium

random mating and inheritance alone do not change allele frequency but stabilize genotype frequency. variation is not lost

polygenic

many genes contribute to a single effect, continuous variations

pleiotropy

one gene with multiple effects

Hardy-Weinberg principle

states that under certain assumptions, both the frequencies of alleles as well as the frequencies of genotypes, will remain constant from generation to generation, no evolutionary forces

heterozygosity

• the state of being heterozygous; having two different alleles of the same gene

• correspond to lower risks of reinforcing rare deleterious variants, leading to protection from disease

founder effect

the reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors

genetic bottleneck

occurs when a population is greatly reduced in size

microevolution

how populations change under the influence of natural selection and other evolutionary forces

macroevolution

how new species and higher taxa are created

evolutionary theory

how new species, genera, families, and higher grouping come into existence

biological species concept

biological species as a group of organisms that interbreed in nature and are reproductively isolated

reproductive isolation

members of a given group of organisms do not ate successfully with organisms outside the group

ecological species concept

emphasizes the role of natural selection in creating and maintaining species

allopatric speciation

occurs when a population is divided by some barrier and different parts of the population adapt to different enviornments

character displacement

may occur if competition over food, mates, or other resources increases the morphological differences between the immigrants and residents

diverge

two 'new' species, reproductive isolation

reinforcement

acts to reduce the extent of gene flow between populations

parametric speciation

selection alone is not sufficient to produce a new species, but new species can be formed if selection is combined with partial genetic isolation

sympatric speciation

strong selection favoring different phenotypes can lead to speciation even when there is no geographic separation and initially there is extensive gene flow among individuals in the population