Semester 2 Biology Finals Study Guide

Mrs. Baar's Class

Gene

sequence of DNA that codes for a protein and determines a trait; factor that is passed from parent to offspring

Allele

one of different forms of a gene

Homozygous

having two identical alleles for a particular gene

Heterozygous

having two different alleles for a particular gene

Haploid

term used to refer to a cell that contains a single set of genes

Diploid

a term used to refer to a cell that contains two sets of homologous chromosomes

Gamete

reproductive cell

Ecology

the study of interactions among organisms and between organisms and their environment

Trophic Level

each step in a food chain or food web

Weather

day to day conditions of the atmosphere, including temperature, precipitation, and other factors

Climate

average year to year conditions of temperature and precipitation in an area over a long period of time

Biotic Factor

any living part of the environment in which an organism would interact

Abiotic Factor

physical, non-living factor that shapes an ecosystem

Habitat

where an animal lives

Mutation

random changes in DNA

Evolution

a change in the relative frequency of alleles in a population

Gene pool

all genes that are present in a population for all traits

Genetic Drift

the change in the frequency of an existing allele in a population due to random chance rather than natural selection

Speciation

the formation of new and distinct species in the course of evolution

Natural selection

favors organisms best suited for their environment and they reproduce

Artificial selection

humans choosing what they want from natural variation

Autotroph

Producer: photoautotrophs (sun), chemoautotrophs (chemicals); make their own food

Heterotroph

Consumer: rely on others for energy and food

Climate Change

long term shifts in temperatures and weather patterns primarily driven by human activities

Stages of Mitosis

Prophase, Metaphase, Anaphase, Telophase

Prophase

chromatin condenses forming into chromosomes, centrioles move to the poles, spindle fibers begin to form

Metaphase

spindle fibers attach to the chromosomes, they live up in the center

Anaphase

2 sister chromatids are pulled apart toward opposite ends of the cell

Telophase

nuclear envelope forms around each new set of chromosomes, the nucleus divides creating 2 nuclei with an identical set of centrioles

Why do cells divide?

growth of the organism, repair of damaged tissues, and to maintain a high surface area to volume ratio, which ensures nutrients and waste can move efficiently in and out of the cell

What is mitosis?

the process of nuclear division in eukaryotic cells, it results in two genetically identical daughter nuclei, each having the same number of chromosomes as the original parent nucleus

Parts of a chromosome

Centromere, sister chromatids

Role of spindle fibers

act as a bridge, they attach to the centromeres of chromosomes and physically pull apart sister chromatids to opposite poles of the cell, ensuring each new cell recieves the correct DNA

Factors that affect rate of mitosis

cell type, environmental cues, chemical signals, damage

What is a centriole?

a cylindrical organelle that helps organize the spindle fibers during cell division

Meiosis 1

Prophase 1 (crossing over), Metaphase 1 (homologous pairs line up), Anaphase 1 (pairs seperate), Telophase 1 (two haploid cells form)

Meiosis 2

Prophase 2, Metaphase 2 (chromosomes line up), Anaphase 2 (sister chromatids separate), Telophase 2 (four unique haploid cells form)

What are homologous chromosomes?

Pairs of chromosomes that are similar in length, gene position, and centromere location

What is crossing over? When does it occur?

The exchange of genetic material between non-sister chromatids of homologous chromosomes. It increases genetic diversity

What type of cells go through meiosis? What do we know about the cells at the end of meiosis?

Germ cells undergo meiosis to produce gametes. Meiosis results in 4 daughter cells that are haploid and genetically unique.

How many rounds of interphase and cell division are there in meiosis?

1 round of interphase, 2 rounds of cell division

Mendel Traits (Complete Dominance)

One allele is dominant over the other (e.g. Bb). The dominant phenotype is expressed if at least one dominant allele is present.

Incomplete Dominance

Neither allele is completely dominant. The heterozygote results in a blend of phenotypes (e.g. Red x White = Pink)

CoDominance

Both alleles are expressed equally and simultaneously (e.g., a speckled chicken with both black and white feathers).

Reproductive Linked Traits

Traits located on gametes (usually the X). Remember that males (XY) only need one copy of a recessive X-linked gene to express the trait.

Blood Types

Uses multiple alleles. This is an example of both CoDominance (AB blood) and Complete Dominance (Type A or B over Type O).

Father of Genetics

Gregor Mendel

Pedigree

Circle = Female

Square = Male

Shaded = Individuals with the trait