McGraw-Hill Ryerson Biology 11 chapter 4 definitions

Cell division and reproduction

Genetics

The study of heredity and the variation of inherited characteristics in living organisms.

Somatic cell

A plant or animal cell that forms the body of the organism- excludes reproductive cells

Chromosome

A structure in the nucleus containing DNA

Sister chromatid

One of two genetically identical chromosomes held together by a centromere

Centromere

The region where two sister chromatids are held together in a chromosome

Spindle fibre

Microtubule structure that facilitates the movement of chromosomes in the cell

Centrosome

Structure that helps form the spindle fibres

Genome

The complete DNA sequence of an organism

Homologous chromosome

A chromosome that contains the same sequence of genes as another chromosome

Gene

A part of a chromosome that governs the expression of a trait that’s passed onto the offspring: it has a specific DNA sequence

Allele

Different forms of the same gene

Karyotype

A photograph of homologous pairs in a cell

Asexual reproduction

Reproduction that requires only one parent and produces genetically identical offspring

Sexual reproduction

Reproduction that requires two parents and produces genetically distinct offspring

Gamete

Male or female reproductive cell

zygote

A cell formed from the fusion of two gametes

Fertilization

In humans, the joining of male and female haploid gametes

Haploid

A cell that contains half the number of chromosomes as the parent cell

Diploid

A cell that contains pairs of homologous chromosomes

Meiosis

The cellular process that produces cells containing half the number of chromosomes as the parent cell

Synapsis

The aligning of homologous chromosomes during prophase I in meiosis I

Spermatogenesis

The process of producing male gametes in mammals

Oogenesis

The process of producing female gametes in mammals

Crossing over

The exchange of chromosomal segments between a pair of homologous chromosomes

Non-disjunction

The failure of chromosome pairs or sister chromosomes to separate in Anaphase I or II

Monosomy

The loss of a chromosome as a result of non-disjunction

Trisomy

The gain of an extra chromosome as a result of non-disjunction

Selective breeding

The process of breeding plants and animals for desirable traits

Artificial insemination

The process by which sperm are collected and condensed before being introduced into the females reproductive system

Embryo transfer

The process by which an artificially fertilized egg is transferred into the uterus

In vitro fertilization

The technique used to fertilize egg cells outside the females body

Cloning

Producing identical copies of genes, cells or organisms

Gene cloning

The use of DNA manipulation techniques to produce multiple copies of a single gene segment or DNA

Recombinant DNA

A molecule of DNA that includes genetic material from different sources

Therapeutic cloning

The process of replacing an egg cells nucleus with a nucleus from a somatic donor cell to produce a cell line of genetically identical cells

Reproductive cloning

The process of producing genetically identical organisms

Stem cell

Undifferentiated cell that can develop to become specialized