BIOL_121 Vocab

Genetics

gene

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

alleles

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

transcription

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

translation

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

gene expression

The entire set of processes that results in using the information stored in a gene.

chromatin

The complex of DNA and histones that makes up a chromosome.

nucleosome

A group of eight histone proteins that has DNA wrapped around it.

histone proteins

Proteins that have an abundance of positively charged lysines and arginines in their primary structure, which interact with negative charges on the sugar-phosphate backbone of DNA to form nucleosomes. 

Recessive Allele

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

Dominant Allele

An allele with a phenotype that appears in heterozygous individuals.

Homozygous

Having two copies of the same allele for a gene.

Heterozygous

Having two different alleles for a gene.

Ploidy

The number of copies of each type of chromosome present

Mitosis

A process in eukaryotes that is responsible for distributing a copy of each chromosome to each daughter cell. It occurs after chromosomes have been replicated and prior to the physical division of the parent cell into two daughter cells.

M phase

The portion of the cell cycle when mitosis and cell division occur.

Interphase

The portion of the cell cycle when growth and DNA replication occur.

Prophase

The initial phase of mitosis, when replicated chromosomes condense and the nuclear envelope breaks down.

Metaphase

The middle phase of mitosis, when replicated chromosomes move to the middle of the cell.

Anaphase and Telophase

The late phases of mitosis, when sister chromatids separate and one of each type of chromosome ends up at either end of the parent cell, then nuclear envelopes re-form around each set of chromosomes.

Germ cells

Cells that directly give rise to sperm or eggs, or are sperm or eggs themselves.  Germ cells undergo meiosis to produce haploid daughter cells.

Somatic cells

Cells that form the body, and that only undergo mitosis.

Meiosis

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

Gamete

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

Zygote

A fertilized egg.

Maternal chromosome

Any chromosome inherited from the mother.

Parental chromosome

Any chromosome inherited from the father.

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.

Sexual reproduction

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

Asexual reproduction

Production of offspring that is based on mitosis.

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.