BIO001 Midterm 2 Vocab

Translation

The process that uses the information in messenger RNA (mRNA) to synthesize a protein.

Alleles

Different versions of a gene that have slight variations in the DNA sequence found in other alleles of the same gene.

Gene

A segment of DNA that contains the information required to produce a product that functions in the organism.

Transcription

The process that creates an RNA molecule from information stored in a gene.

Chromosome

A complex of DNA-binding proteins and DNA; is circular in most bacteria and archae and linear in eukaryotes.

Ploidy

The number of each type of chromosome present in a cell, written as a number before the n that represents haploid number. Humans are 2n.

Replicated chromosome

A chromosome comprised of two identical DNA molecules, joined together.

Haploid number

The number of different types of chromosomes present in a cell, indicated with an n. Humans are n = 23.

Gene

A segment of DNA that codes for a protein or RNA product; comprises both structural and regulatory elements.

Diploid

Having two of each type of chromosome.

Homologous chromosomes (homologs)

Different verisons of the same chromosome type, in the same cell.

Sister chromatids

The identical copies in a replicated chromosome

Haploid

Having one of each type of chromosome

Sexual reproduction

Production of offspring that is based on meiosis and fusion of gametes.

Gamete

Cells that fuse to form a zygote. In many species, these are sperm and egg.

Meiosis

A process in eukaryotes that distributes one of each homologous chromosome pair to daughter cells, resulting in a halving of chromosome number.  

Zygote

A fertilized egg

Asexual reproduction

Production of offspring that is based on mitosis.

Maternal chromosome

Any chromosome inherited from the mother.

Crossing over and recombination

Physical exchange of DNA strands between non-sister chromatids during Meiosis I. Leads to recombinant chromosomes containing alleles from both maternal and paternal chromosomes.

Paternal chromosome

Any chromosome inherited from the father.

Independent assortment

The observation that maternal and paternal homologs line up at random before separating at the end of Meiosis I, producing a wide array of possible combinations in daughter cells.

Principle of segregation

The observation that alleles of the same gene separate from each other prior to gamete formation. Caused by the separation of homologous chromosomes at the end (anaphase and telophase) of Meiosis I.

Homozygous

Having two copies of the same allele for a gene.

F₂ generation

The second generation from an experimental cross—the offspring of F₁s.

Dominant allele

An allele with a phenotype that appears in heterozygous individuals.

Recessive allele

An allele with a phenotype that does not appear in heterozygous individuals.

Principle of independent assortment

The observation that alleles of different genes go into gametes independently of each other, making every combination of alleles from different genes equally likely. Caused by different chromosomes lining up independently of each other in the middle (metaphase) of Meiosis I and holds if the genes in question are found on different chromosomes.

F₁ generation

The initial generation from an experimental cross—meaning, the offspring of the original parents.

Heterozygous

Having two different alleles for a gene.

Wild type

The typical or most common version of an allele or phenotype, as opposed to novel, unusual, or low-fitness forms.

Co-dominant alleles

Heterozygotes have the phenotype associated with both alleles present.

Loss-of-function alleles

Alleles that lead to a protein or RNA product that cannot function normally or is completely absent.

Sex chromosome

A chromosome associated with the sex of the individual.

Autosome

Any chromosome that is not a sex chromosome

Sex-linked genes

Genes found on a sex chromosome.

Linked genes

Genes found on the same chromosome

Polygenic trait

A trait that shows continuous variation—usually normally distributed—due to the involvement of products from many different genes. Also called a quantitative trait.

Genetic locus

The physical location of a gene on a chromosome. The plural form is loci and is pronounced LOW-sigh.

Genome

All of the DNA, and thus all genes, in an individual of a particular species.

Pedigree

A diagram summarizing the incidence of a genetic disease or other trait in a family. Pedigrees are used to identify the pattern of inheritance of specific traits and predict how likely offspring from a particular set of parents are to have a specific phenotype.

Null model

A model that predicts the data you should expect to see if a process is not working—meaning, when a particular causative agent is not impacting the situation.

Hardy-Weinberg Principle

A null model stating that if no selection, drift, gene flow, or mutation occur, and if mating is random with respect to the gene in question, then allele frequencies will not change from one generation to the next and genotype frequencies will be in the proportions p2, 2pq, q2, where p and q are the frequencies of two alleles at that gene.

Assortative mating

Mate choice based on similarities or dissimilarities in phenotype.

Inbreeding

Mating among relatives.

Gene pool

A concept used in predicting the results from random matings among all of the individuals in a population, by supposing that all gametes are tossed into "pool" and then drawn out at random to produce offspring.