Biology chapter 12,13,14,15,16,17

DNA

Deoxyribonucleic acid; the genetic material of all living organisms, structured as a double helix.

DNA replication

The process of copying the DNA molecule where the DNA strands separate and DNA polymerase uses each old strand as a template to build a new second strand.

Transcription

The process of making RNA from a DNA template.

Translation

The process of making a protein based on the codon sequence of mRNA, taking place on ribosomes.

Start codon

AUG is the start codon that signals the beginning of translation.

Stop codons

UAA, UAG, UGA are the stop codons that signal the end of translation.

Euchromatin

A form of chromatin that is loosely packed and available for transcription.

Heterochromatin

A form of chromatin that is tightly packed and considered inactive.

Clone

An exact genetic copy of a gene, cell, or organism.

Restriction enzyme

An enzyme made by bacteria to cut up foreign DNA at a specific recognition sequence.

DNA fingerprinting

A process that uses PCR to make many copies of short tandem repeats (STRs) for comparison between different DNA sources.

Gene cloning

The procedure of cutting a chromosome and plasmid with the same restriction enzyme to create recombinant DNA.

Transcription factors

Proteins that help RNA polymerase bind to the DNA at the promoter region, promoting transcription.

Transcription activators

Proteins that bind to enhancer regions and increase transcription rates.

Evolution

The change in the gene pool of populations over time.

Natural Selection

The process whereby organisms that exhibit variations better suited to their environment tend to survive and reproduce.

Population

A group of organisms of a single species living together in the same geographical area.

Microevolution

The change in allele frequencies in a population over time.

Gene pool

All the alleles of all the genes in all the individuals in a population.

Stabilizing selection

A mode of natural selection that favors average traits over extremes.

Directional selection

A mode of natural selection that favors one extreme trait over the average and other extreme traits.

Disruptive selection

A mode of natural selection that favors extreme traits over average traits.

Biological species

A group of organisms that can successfully reproduce (interbreed).

Reproductive isolation mechanisms

Mechanisms that prevent two groups from interbreeding, such as habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gamete isolation, zygote mortality, hybrid sterility, and F2 fitness.

Speciation

The process of splitting one species into two or more species.

Allopatric speciation

Speciation that occurs when populations are separated by a geographic barrier.

Sympatric speciation

Speciation that occurs without geographic separation of populations.

Adaptive radiation

The evolutionary process where one species gives rise to several new species when introduced to a new environment.

Gene

The basic unit of heredity, composed of DNA, that carries the instructions for producing proteins.

Allele

Different forms of a gene that can exist at a specific locus on a chromosome.

Phenotype

The observable physical or biochemical characteristics of an organism, determined by both genetic makeup and environmental influences.

Genotype

The genetic constitution of an individual, specifically the alleles present in its cells.

Homozygous

Having two identical alleles for a particular gene.

Heterozygous

Having two different alleles for a particular gene.

Dominant allele

An allele that expresses its phenotype even when heterozygous with a recessive allele.

Recessive allele

An allele that only expresses its phenotype when in a homozygous state.

Genetic drift

A mechanism of evolution involving random changes in allele frequencies in a population.

Natural selection

The process through which populations adapt to their environments; individuals with advantageous traits are more likely to survive and reproduce.