Semester 2 finals

Relative fitness

the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

Theory

A hypothesis that has been tested with a significant amount of data

Evolution

Living species are descendants of ancestral species

Natural selection

Better adapted individuals more likely to survive and reproduce.

Adaptation

Evolution that results in better fit between organism and environment

Strata

Rock layer form when new layer/sediment converse old one & compresses it

Homologous structures

Features that have different functions, structurally similar to common ancestry

Vestigial structures

Remnants of features that served important function in ancestor

DDT pesticide use resistance (describe)

When mosquito population gets sprayed with DDT, the allele that has an enzyme that breaks it down will increase by each generation.

Hardy

Weinberg Equilibrium

Genetic drift

Chance events cause allele frequency fluctuation for generations

Bottleneck effect

Drastic decrease in population

Founder effect

Genetic drift from a few individuals being isolated which forms a new population that isn't the original.

Gene flow

Transfer of alleles from 1 population to another from movement of individuals or gametes

Directional selection

Favors intermediate variants, against extreme phenotypes

Disruptive selection

Environmental conditions favor individuals at both ends of the phenotype range over intermediate phenotypes

Sexual selection

Form of natural selection, certain traits more likely than other individuals to obtain mates

Sexual dimorphism

Marked differences between secondary sex charecterisitscs of males & females

Balancing selection

Natural selection, maintains stable frequencies of 2 or more phenotype forms in population.

Heterozygote advantage

Type of balancing selection, heterozygous individuals have better reproductive success than homozygous

Why are there organisms that exist that seem less than ideally selected for their environment?

1. Natural selection favors fittests variants, may not be ideal traits
2. Evolution doesn't scrap ancestral anatomy, rather it builds off it
3. Every adaption has compromises E.g. webbed feat good for swimming on water,
4. Events can affect genetics of population, e.g. individuals may be blown to other population by storm.
5. Genetic drift in small populations may get rid of beneficial alleles
6. Environment changes every year, may change effectiveness of allele.

Speciation

emergence of a new species from natural selection

Biological species concept

species as a group of populations who have potentially interbreed in nature, produced fertile offspring

Reproductive isolation

Barrier that stops members of 2 species from producing fertile offspring

Hybrids

Offspring of pairs who are a different species

Morphological species concept

Definition of species in measurable anatomical criteria (looks)

Ecological species concept

Identifies species for their ecological niches (unique adaptions than roles in community)

Phylogenetic species concept

Species as smallest group of individuals, share common ancestor, one branch on tree of life

Prezygotic barriers

Hinders fertilization between 2 species.

Postzygotic barriers

Hinders fertilization by preventing the creation of fertile adults

Allopatric speciation

Population is divided into geographically isolated subpopulations

Adaptive radiation

Evolution of diverse species from a common ancestor

Hybrid zones

Regions where different species mate and produce hybrid offspring

Reinforcement

Natural selection strengins, reinforce reproductive barriers eventually reducing formation of unfit hybrids.

Fusion

two hybritized species turn into 1 species

Stability

Tendency for 1 or more species to maintain character over long time

Conditions of early Earth (list)

Thick water vapor & volcanic eruptions

Lightning

UV radiation

Stromatolites

Layered rock from past activities of prokaryotes which binds sediment together

Four main stages of simple cell evolution (list)

1. Abiotic (non living) synthesis of small organic molecules, (amino acids & nitrogenous bases)
2. Small molecules to polymers (proteins & nucleic acid)
3. Packaging of molecules into "protocells", droplets with membranes maintain internal chemistry different than environment
4. Origin of self replicating molecules made inheritance possible

Macroevolution

Evolutionary change above species level

Radiometric dating

Method, determines age of fossils & rocks on half life radioactive isotopes

Geologic record

Time scale by geologists, divies Earths history into 4 eons (Hadean, Archean, Proterozoic, Phanerozoic)

5 mass extinction events (list)

1. Ordovician Extinction
2. Late devonian extinction
3. Permian Extinction
4. Triassic extinction
5. Cretaceous Extinction

Sixth mass extinction

Human activities modifying global environment making species close to extinct

Exaptations

Structure that evolved who had 1 function change to another function

Goal

directed evolution (why is it incorrect?)

Taxonomy

Branch of biology dealing with identifying, naming, & classifying species

Binomial

2 part scientific name

Linnaeus system of classification (list categories)

1. Species
2. Genus
3. Family
4. Orders
5. Classes
6. Phyla
7. Kingdoms
8. Domains

Phylogenetic trees

Branching diagram, represents hypothesis about evolutionary history of organism groups

Convergent evolution

Similar environments & natural selection produce similar adaption in different organisms.

Analogy

Similarity from convergent evolution

Cladistics

A character members of particular clade from ancestor that isn't part of a clade

Parsimony

Simplest explanation for observed phenomena

Molecular systematics

Method, uses DNA/ other molecules to infer how organisms are related(E.g. evolution)

Molecular clocks

Estimates actual time of evolutionary events from DNA changes

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

Gametes

sex cells

Haploid

1 set of chromosomes

Diploid

2 sets of chromosomes

Independent Assortment

the random distribution of the pairs of genes on different chromosomes to the gametes

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Chiasma

site of crossing over in chromosomes

Homologous Chromosomes

Chromosomes that have the same sequence of genes and the same structure

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Inversion Mutation

Mutation in which a chromosome piece reattaches to original chromosome but in reverse orientation

Translocation Mutation

mutation in which one part of one chromosome breaks off and attaches to another

Insertion Mutation

a mutation in which one or more nucleotides are added to a gene

Duplication mutation

a mutation that involves duplication of a region of DNA on the same strand

Homozygous

An organism that has two identical alleles for a trait

Heterozygous

An organism that has two different alleles for a trait

Alleles

Different forms of a gene

Dominant Allele

An allele whose trait always shows up in the organism when the allele is present.

Recessive Allele

An allele that is masked when a dominant allele is present

Law of dominance

In many traits one allele is dominant over the other allele. The "weaker (recessive" allele is only expressed when it is paired with another recessive allele

Phenotype

An organism's physical appearance, or visible traits.

Genotype

genetic makeup of an organism

Gene Loci/locus

specific locations of genes along the chromosome

Carrier

A person whose genotype includes a gene that is not expressed in the phenotype.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

Autosomal

all the other genes in the body that are not sex

Sex

linked

Incomplete dominance

A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.

Codominance

A condition in which both alleles for a gene are fully expressed

Pleiotrophy

The ability of a single gene to have multiple effects.

Polygenic inheritance

combined effect of two or more genes on a single character

What are the phases of meiosis?

Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II

What happens during Prophase I of meiosis?

Spindle forms, homologous chromosomes pair up, crossing over occurs

What happens during Metaphase I of meiosis?

Homologus pairs line up at mid, independent assortment occurs because chromosomes are independent of each other

What happens during Anaphase I of meiosis?

Spindle fibers pull homologous pairs apart and chromosomes are pulled to opposite sides of the cell, ratcheting occurs

What happens during Telophase I of meiosis?

Centrosomes break down, nuclea membrane reforms, chromosomes become chromatin

What happens during Prophase II of meiosis?

Chromatin reform to chromosomes, spindle fibers regrow

What happens during Metaphase II of meiosis?

Spindle fibers pull chromosomes and they line up at mid

What happens during Anaphase II of meiosis?

Spindle fibers pull chromatids to polar ends of cell

What happens during Telophase II of meiosis?

Nuclear membrane rebuilds, chromatids become chromatin *4 unique cells if sperm, *i big plump cell if egg and 3 polar bodies disentigrate

What is the difference between mitosis and meiosis?

Mitosis is cell division for skin/somatic cells to multiply and repair, while meiosis is cell division for sex cells (half the amount of chromosomes in gametes)

What is nondisjunction?

Failure of a pair of chromosomes to separate can happen in Anaphase I or II when the spindle fibers are pulling apart the chromosomes/chromatids

What is translocation and when does it happen?

Fragment to join a nonhomologous chromosome, prophase 1

Who is Mendel and what did he study?

Mendel is a biologist and he studied peas and their inheritance patterns

What are Mendel's laws/rules of inheritance?

Law of segregation and law of independent assortment