UW Bio 180 Exam 1

Organism

A living entity made up of one or more cells

Theory

An explanation for a very general class of phenomena or observations

Cell Theory

All organisms are made of cells and all cells come from preexisting cells

Null Hypothesis

Specifies what we should observe when the hypothesis being tested isn't correct

Control Group

A group that checks for other factors which are not being tested

Two components of scientific theories

Pattern and process

Population

Individuals of the same species that are living in the same area at the same time

Descent with modification

Evolution

Pattern component of Evolution

1) Species change through time

2) Species are related through common ancestry

Fossil Record

All fossils that have been found and described in the scientific literature

Extant Species

Living species

Extinct Species

No longer existing species

Transitional Feature

A trait in a fossil species that is intermediate between those of older and younger species

Vestigial Trait

A reduced or incompletely developed structure that has no function or reduced function but is clearly similar to functioning organs or structures in closely related species

Phylogeny

A family tree of populations or species

Homology

Similarity that exists in species because they both inherited the trait from a common ancestor

Genetic Homology

Similarity having to do with similar DNA structuring

Developmental Homology

Similarity in the embryonic stage

Structural Homology

Similarity in adult morphology (form)

Darwin's Four Postulates

1) Individuals vary in the traits they posses

2) Some trait differences are heritable

3) More offspring are produced than can possibly survive in one generation

4) The individuals who survive best and produce the most offspring is not a random subset of the population

Theory of Evolution by Natural Selection (in two parts)

1) Heritable variation leads to...

2) Differential reproductive success

Biological Fitness

The ability of an individual to produce surviving offspring, relative to that ability in other individuals in the population

Adaptation

A trait that increases the fitness of an individual in a particular environment

Speciation

A population of one species splits into two different species because of natural selection

Tree of Life

A family tree or organisms

Genetics

The branch of biology that focuses on the inheritance of traits

Heredity

Transmission of traits from parent to offspring

Trait

Any characteristic of an individual

Model Organism

A species that is used for research because it is practical and because conclusions drawn from studying it turn out to apply to many other species as well

Phenotype

The distinct physical display of the genetic makeup of an organism

Pure Line

Consists of individuals that produce offspring identical to themselves when they are self-pollinated or crossed to another member of the pure-line population

Hybrids

Offspring from matings between true-breeding parents that differ in one or more traits

Parental Generation

The first cross between two individuals

F1 Generation

The products of the Parental Generation

Monohybrid Cross

Mating between parents that carry two different genetic determinants for the same trait

Recessive Trait

The trait temporarily becomes latent or hidden when paired with a different version of the same trait

Dominant Trait

The trait is always displayed even when paired with a different version of the same trait

Reciprocal Cross

A set of matings where the mother's phenotype in the initial cross is the father's phenotype in the subsequent cross and the father's phenotype in the initial cross is the mother's phenotype in a subsequent cross

Gene

Hereditary determinant for a trait

Allele

Different versions of the same gene

Genotype

Alleles found in a particular individual

Principle of Segregation

Each pair of hereditary elements (alleles) separate from each other during the formation of offspring

Homozygous

Having two copies of the same allele

Heterozygous

Having two different copies of the same allele

Genetic Model

A set of hypothesis that explains how a particular trait is inherited

Dihybrid cross

Mating between two individuals who are both heterozygous for both traits

Principle of Independent Assortment

Different genes are transmitted independently of one another

Locus

Location of a gene on a chromosome

Wild Type

The most common phenotype (generally the dominant)

Mutation

Change in a gene

X-Linked Inheritance / X-Linkage

Genes linked to the X chromosome

Y-Linked Inheritance / Y-Linkage

Genes linked to the Y chromosome

Autosomal Inheritance

Genes on non-sex chromosomes

Genetic Map

A diagram showing the relative positions of genes along a particular chromosome

Incomplete Dominance

Heterozygotes have an intermediate phenotype

Codominance

Heterozygotes have the phenotype associated with each individual allele showing simultaneously

Multiple Allelism

The existence of more than two alleles of the same gene

Polymorphic

Two distinct phenotypes are present in a population due to multiple alleleism

Pleiotropic

A gene that influences many traits rather than just one

Discrete Traits

Characteristics that are qualitatively different from each other

Quantitative Traits

Individuals differ by degree when comparing one particular phenotype

Polygenic Inheritance

Each gene adds a small amount to the value of the phenotype

Epistasis

The interaction of genes that are not alleles, particularly the suppression of the effect of one by another.

Meiosis

The production of gametes (sperm and eggs)

Somatic Cells

Body cells (not reproductive)

Asexual Reproduction

Producing offspring genetically identical to the parent

Centromere

A particular portion where the chomatids are attached

Chromatid

Each of the DNA copies in a replicated chromosome

Sister Chromatids

Chromatids from the same chromosome

Mitosis

Cell replicaiton

1) Prophase

2) Metaphase

3) Anaphase

4) Telophase

5) Cytokinesis

Prophase

Chromosomes condense into compact structures

Spindle Apparatus

Structure that produces the mechanical forces that pull chromosomes to the poles during mitosis and push the poles of the cells away from each other

Metaphase

Chromosomes complete migration to the middle of the cell or the metaphase plate

Metaphase Plate

Imaginary plane in the center of the cell where the chromosomes line up

Anaphase

The centromeres pull apart the sister chromatids toward opposite poles

Telophase

A nuclear envelope begins to for around each set of chromosomes, chromosomes de-condense, and spindle apparatus disintegrates

Cytokenisis

The one cell becomes two separate cells

Homologous Chromosomes / Homologs

Two chromosomes of each type

Karyotype

The number and type of chromosomes present

Diploid

When an organism has two versions of each type of gene

Haploid

When organisms have only one version of each type of chromosome

Haploid Number

Number of unique chromosomes

Ploidy

Number of sets of the same chromosome

Meiosis I

The homologs in each chromosome pair separate from each other

Meiosis II

The sister chromatids separate from each other to form four daughter cells

Non-Sister Chromatids

Chromatids belonging to homologus chromosomes (but not an identical genetic replication)

Tetrad

Homologous replicated chromosomes that are joined together

Prophase I

The spindle apparatus forms and homologous chromosomes synapsis to form a tetrad, genetic recombination in the form of crossing over occurs, and the tetrads move towards the metephase plate

Synapsis

The physical pairing of tho homologous chomosomes during prophase I of meiosis

Crossing Over

An event during synapsis where portions of the maternal and paternal chomosomes swap

Metaphase I

The tetrads are on the metephase plate

Anaphase I

The homologous chromosomes separate and begin moving to opposite sides of the cell

Telophase I

The homologous chromosomes finish moving to the opposite sides of the cell, a nuclear envelope forms around the chromosomes, and cytokinesis occurs

Prophase II

The spindle apparatus forms and the nuclear envelope breaks apart

Metaphase II

The replicated chromosomes which are now two sister chromatids are lined up at the metaphase plate

Anaphase II

The sister chromatids separate and then begin to move to opposite ends of the cell

Telophase II

Chromosomes finish moving to opposite sides of the cell, and a nuclear envelope forms around each haploid set of chromosomes

Law of succession

extinct species resemble contemporary species found in the same location, it shows that evolution occurs