Exam 3 (Most)

Why is it hard to study human genetics?

Ethics, low generation, few offspring, can’t experiment on humans

Pedigree

Family tree that shows inheritance over several generations

Autosomal Recessive

Dominant allele makes enough protein

Heterozygote

carriers

To Have Disorder

homozygous recessive

Autosomal Dominant

Much rarer, Only one allele required, Phenotype often only apparent late in life- after reproduction

Disomy

having 2 copies of each chromosome (1 homologous pair)

Aneuploidy

Presence of atypical # of a particular chromosome, Extra or missing copy

Trisomy

having 3 of a chromosome —> 2n+1

Monosomy

Lacking 1 member of pair of chromosomes —> 2n-1

What is the event that occurs during meiosis  that leads to aneuploidy usually?

Nondisjunction

What is the tool we can use to study human genetics?

DNA sequencing and pedigree

What are the 4 types of mutations in chromosomes?

Deletion, Duplicate, Inversion, Translocation

Deletion

A deletion removes a chromosomal segment

Duplication

A duplication repeats segment

Inversion

An inversion reverse a segment within a chromosome

Translocation

A translocation moves a segment from one chromosome to a nonhomologous chromosomes

Turner Syndrome XO

44 autosomes of 1 X chromosome, Denoted as “XO” or “4s, XO” - O indicates absence of 2nd sex chromosomes

Klinefelter Syndrome XXY

44 autosomes, 2 chromosomes, 1 Y, Denoted XXY or 47 XXY, Common Symptoms: Tall structure, often learning disability, sterile, Barr bodies present

Jacobs Syndrome XYY

44 autosomes, 1 X chromosomes, 2 Y, No specific phenotype, Usually fertile —> do not transmit extra Y, Discredited theory - “supermales”

Fetal Testing

Genetic tests done before birth

Newborn Screening

Some genetic disorders detected at birth

Who was the naturalist who came up with the hierarchical system of classification?

Carolus Linnaeus

What ideas did geologists contribute (Two ideas one old and one new)?

Gradualism (Old) and Uniformitarianism (New)

Gradualism

Observable processes produce small changes, accumulate over time

Uniformitarianism

Geological process uniform over time → Earth must be old

Who was the earlier naturalist who came up with his own theory of evolution before Darwin?

Jean-Baptiste Lamarck

What are Jean-Baptiste Lamarck 2 ideas?

Use and Disuse and Inheritance of Acquired Traits

Use and Disuse

Body parts used —> larger and stronger, Not used —> deteriorate, Example: Giraffe stretch neck —> Neck gets longer, If giraffe doesn’t stretch the neck and doesn’t use, it won’t get taller.

Inheritance of Acquired Traits

Traits acquired during lifetime passed to offspring, giraffe neck stretches/grows —> passes on longer neck

According to Lamarck, who evolves?

Individuals

According to Darwin, who evolves?

Populations

What were the four observations that Darwin made?

Overproduction, Unequal Survival and Reproduction, Heritable Variation, Nonrandom Survival and Reproduction

Overproduction

More offspring born each generation than will survive and reproduce

Unequal Survival and Reproduction

Some survive longer and have more offspring than others

What’s the idea of Overproduction and Unequal Survival and Reproduction lead to?

Competition

Who came up with the idea of compeition?

Thomas Malthus

Heritable Variation

Individual have variations, offspring tend to resemble parents

Nonrandom Survival and Reproduction

Survival and reproduction is based on phenotype, Best adapted individuals —> More offspring

With all of Darwin’s observation, what is this called?

Natural Selection

Natural Selection

Non-random change in allele frequencies in a population, where beneficial traits become more frequent overtime and less beneficial becomes less frequent.

What word do we use to describe an organism’s success or ability in passing on their alleles?

Evolutionary Fitness

Evolutionary Fitness

Not physical fitness, it is survival and reproduction, differences on fitness due to heritable traits, so over time, less favorable traits decrease in frequency, population evolves

What are the example of evolution?

Artificial Selection, Direct Observation, Homology, Fossil Records

Homology

Similarity due to common ancestry, structure inherited from common ancestor

Evolution

Changes in allele frequencies in populations over generations

What are the 5 mechanisms of evolution?

Mutation, Nonrandom Mating, Natural Selections, Genetic Drift, Gene Flow

Mutation

Any heritable change in DNA, Random “probabilistic” or “stochastic”, One allele becomes different allele

Random Mating

Each individual in population equally like to mate with any individuals of opposite sex

Nonrandom Mating

Nonrandom mixing of gametes

Inbreeding

Mating of closely related individuals, genetically similar - increases homozygosity

Polymorphic

For selections to affect population, must be at least two phenotypes

Genetic Drift

Random changes in allele frequency - chance events, reduce genetic diversity with population, Effects inversely proportional to population size-largest effects in small populations.

Bottleneck Effect

Size of population drastically reduced, survival random. Surviving population has different allele frequencies from ancestral population

Founder Effect

Small number of individuals colonize a new environment, Gene pool of new population different from parent population due to small sample size

Gene Flow

Movement of alleles between population, Due to migration, Reduces differences between populations, changes alleles frequencies in each

Hardy-Weinburg Equations

p+q=1

What does p stands for?

Frequency of dominant allele in a population

What does q stands for?

Frequency of recessive allele in a population

What is the 5 requirements for the Hardy-Weinburg Equilibrium?

No mutations, Random mating, No selection, No genetic drift, No gene flow

What is the equation we use to sum all of the genotype frequencies=1?

p²+2pq+q²=1

What is an example of nonrandom mating?

Inbreeding

Speciation

Process by which 1 species splits into 2; the appearance of a new species

Species

Kind of organism

Biological Species Concept

Ernest Mayr, Group of populations whose members have potential to interbred in nature and produce viable offspring

Share common gene pool

gene flow between populations of same species

No gene flow with different species

reproductive isolation

What works very well for biological species concept?

living, extant, sexual

What doesn’t work well with biological species concept?

Extinct/fossil species, viruses/microbes, asexual

Morphological Species Concept

Species distinguished by shape/structure, size, morphology

What is good for Morphological Species Concept?

Living and extinct, asexual and sexual

What is the problem with Morphological Species Concept?

Disagreement over which features and how to divide

Ecological Species Concept

Species define by ecological niche- how individuals interact with living and nonliving parts of the environment

What is good for Ecological Species Concept?

Sexual and asexual, but must be extant

What is the problem with Ecological Species Concept?

Complicated of species can occupy diverse niches

Prezygotic Barrier

Operate prior to zygote formation- prevent fertilization

Habitat Isolation

Overlapping geographic range, but live/breed in different areas —> rarely interact, no opportunities to mate

Temporal Isolation

Overlap but breed at different times- different times of the year, seasons, days

Behavioral Isolation

Species unique behaviors enable mate recognition

What is an example of Behavioral Isolation?

Courtship

Mechanical Isolation

Mating attempted but sexual structures incompatible

Gametic Isolation

Molecular or chemical differences between species egg and sperm incapable, sometimes occur between 2 species

What is Gametic Isolation common in?

aquatic organisms- release gametes into water

Postzygotic Barrier

Operate after ferritization occurs

Reduce Hybrid Viability

Embryo nonviable or offspring do not survive

Reduced Hybrid Fertility

Hybrids viable, but sterile or low fertility, often due to problems during meiosis

Hybrid Breakdown

1st generation hybrids viable and fertile, hybrids can mate with each other or parent species

Allopatric Selection

Geographic isolation —> drift and/or selection—> divergence

Sympatric Selection

“Sym”= together, reproduction isolation without geographic isolation

Process of Speciation

Evolution of a new species, Reproductively isolation of populations of same species —> gene pools diverge

What are the two mechanism of Allopatric Selection?

Mechanism of Separation and Migration

Mechanism of Seperation

Geographic barriers, Mountain range, rivers, land bridge, falling water level

Migration

Small offshoot population —> isolated from parent population

What are the two mechanisms of Sympatric Selection?

Sexual selection and habitat differentiation

Sexual Selection

Selection for different traits in males and females, Can become a barrier to reproduction between subpopulations

Habitat Differentiation

Subpopulation uses habitat or resources not used by rest of population, can lead to habitat isolation, Habitat isolation —> temporal isolation —> postzygotic barriers

Systematics

Study of diversity and evolutionary

Taxonomy

Naming, describing, classiflying

Phylogeny

Evolutionary history of a group of organisms