biology final exam review

homozygous

An organism that has two identical alleles for a trait

heterozygous

An organism that has two different alleles for a trait

recessive

An allele that is masked when a dominant allele is present

dominant

An allele that is always expressed

monohybrid cross

A cross between individuals that involves one pair of contrasting traits

law of segregation

first law of heredity stating that pairs of alleles for a trait separate when gametes are formed

mitosis

part of eukaryotic cell division during which the cell nucleus divides

meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

natural selection

A natural process resulting in the evolution of organisms best adapted to the environment.

artificial selection

selective breeding of plants and animals to promote the occurrence of desirable traits in offspring

homologous structure

Structures in different species that are similar because of common ancestry.

analogous structure

Similar in feature and function, but do not appear to have the same evolutionary origin.

survival of the fittest

a natural process resulting in the evolution of organisms best adapted to the environment

descent with modification

principle that each living species has descended, with changes, from other species over time

convergent evolution

the evolution of similar features in independent evolutionary lineages

divergent evolution

when two or more species sharing a common ancestor become more different over time forming new species

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

Deoxyribose

A five-carbon sugar that is a component of DNA nucleotides

nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

Chargaff's Rule

equal amounts of adenine bonds with thymine and equal amount of guanine bonds with cytosine

DNA replication

The process in which DNA makes a duplicate copy of itself.

Vestigial organs

Organ that serves no useful function in an organism

Genetics

The scientific study of heredity

heredity

the passing of traits from parents to offspring

Gregor Mendel

The father of genetics - Experimented with pea plants

codon

three-nucleotide sequence on messenger RNA that codes for a single amino acid

codon chart

Device used to determine the amino acid coded for by a codon

RNA

ribonucleic acid; a nucleic acid that plays an important role in the production of proteins

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

transcription

(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA

translation

Process by which mRNA is decoded and a protein is produced

dihybrid cross

A cross between individuals that have different alleles for the same gene

phenotype

An organism's physical appearance, or visible traits.

genotype

An organism's genetic makeup, or allele combinations.

Law of Independent Assortment

Mendel's second law, stating that allele pairs separate from one another during gamete formation

genetic probability

chance of getting certain gene

co-dominance

Situation in which both alleles of a gene contribute to the phenotype of the organism

incomplete dominance

situation in which one allele is not completely dominant over another

complimentary strand

New DNA strand that is formed be pairing nucleotides to the template

cloning

A process in which a cell, cell product, or organism is copied from an original source.

karyotype

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

chromosome

condensed threads of genetic material formed from chromatin as a cell prepares to divide

human chromosomes

humans have 46 of these, males have an XY pair and females have an XX pair

autosomes

Any chromosome that is not a sex chromosome

sex chromosomes

Chromosomes that determine the sex of an individual

pedigree

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

classification

the process of grouping things based on their similarities

taxonomy

the science of describing, naming, and classifying organisms

kingdoms of life

Eubacteria, archaebacteria, protista, fungi, plantae, animalia

crossing over

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

Interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

Anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

Prophase

Chromosomes become visable, nuclear envelop dissolves, spindle forms

Metaphase

phase of mitosis in which the chromosomes line up across the center of the cell

Telophase

the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

cell theory

fundamental concept of biology that states that all living things are composed of cells; that cells are the basic units of structure and function in living things; and that new cells are produced from existing cells

Stages of Meiosis

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

Prophase I (Meiosis)

Each chromosome comes near its replicated chromosome pair. Nucleus dissolves at this stage. Crossing Over (exchange of genetic material) occurs at this phase.

Metaphase I (Meiosis)

homologous pairs (tetrads) align at the equatorial plane and each pair attaches to a separate spindle fiber at the kinetochore

Anaphase I (Meiosis)

Tetrads split up and head to opposite poles

Prophase II (Meiosis)

In each of the daughter cells, a new spindle apparatus forms, the nuclear envelope breaks down, and the chromatin condenses into chromosomes again

Metaphase II (Meiosis)

the chromosomes line up individually along the metaphase plate, with microtubules attached to the kinetochores of each sister chromatid

Anaphase II (Meiosis)

sister chromatids separate and are pulled towards opposite poles of the cell by spindle fibers

gamete

a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote. {Egg or sperm}

human chromosome number

46 in body cells, 23 in egg or sperm (gametes)

homologous chromosomes

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

tetrad

structure containing 4 chromatids that forms during meiosis

Sister chromatids

Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.

haploid

(genetics) an organism or cell having only one complete set of chromosomes

diploid

(genetics) an organism or cell having two sets of chromosomes or twice the haploid number

mutation

a random change in a DNA sequence

protein synthesis

the formation of proteins by using information contained in DNA and carried by mRNA

nucleic acids

DNA and RNA; carry genetic information

DNA polymerase

Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule

Transcription

(genetics) the organic process whereby the DNA sequence in a gene is copied into an mRNA strand

Translation

(genetics) the process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosome in the cytoplasm

semi-conservative model

Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand.

fitness

Ability of an organism to survive and reproduce in its environment

adaptation

inherited characteristic that increases an organism's chance of survival

vestigial structures

A structure that is present in an organism but no longer serves its original purpose

omnivore

organism that obtains energy by eating both plants and animals