Bio Lecture 18 - Meiosis

Diploid

cells that divide by meiosis to produce haploid gametes

Haploid

cells with one set of chromosomes (eg. gametes)

Meiosis

a type of cell division that results in daughter cells with half the

number of chromosomes of the parent cell, as in the production of gametes.

Gamete

a haploid reproductive cell containing only a single set of

chromosomes

Somatic cell

diploid cells containing two sets of chromosomes found in pairs (homologous pairs)

sexual reproduction

reproduction that allows a mixing of genomes from two different parents. Organisms that reproduce sexually by meiosis have offspring that are genetically distinct from either parent

asexual reproduction

a process in which a single parent produces offspring that are genetically identical to itself

maternal chromosome

homologous chromosomes in a diploid cell coming from the mother

paternal chromosome

homologous chromosomes in a diploid cell coming from the father

homologous chromosome

matching chromosomes that carry similar but not identical DNA. they are the

maternal and paternal copies of a chromosome found in diploid cells

karyotype

an ordered display of all human chromosome, arranged in pairs

zygote

the cell produced by fusion of haploid gametes (aka fertilized egg).

fertilization

the process where gametes (sperm and egg) fuse to form a zygote, initiating the development of a new organism

Independent assortment

The results of random alternative arrangements of maternal and paternal homologous chromosome on the metaphase plate in meiosis I

sister chromatid

the two replicas of a single chromosome held together after DNA replication. Sister chromatids have EXACTLY the same nucleotide sequence.

nonsister chromatid

chromatids from homologous chromosomes (one from each parent) that can exchange genetic material during meiosis

Meiosis 1

Homologous chromosomes pair and then are separated. This reduces the chromosome number/cell by half.

Meiosis 2

Sister chromatids are separated. This results in four daughter cells, each with only half as many chromosomes as the parent

heredity

transmission of traits from one generation to the next

gene

the basic unit of inheritance. passed from parents to offspring and contain the information needed to specify physical and biological traits. Most genes code for specific proteins, or segments of proteins, which have differing functions within the body.

locus

The location of a gene on the chromosome

synapsis

the fusion of chromosome pairs at the start of meiosis

chiasmata

the visible points of connection between homologous chromosomes, formed during meiosis

crossing over

intertwined chromatids break at one or more places and exchange (recombine; process = recombination) equivalent bits of DNA with each other. Crossovers are essential for establishing physical connections between homologous chromosomes. Also result in exchange of genetic information.