bio Cell division

diploid

A cell or organism that contains two complete sets of chromosomes, one from each parent, typically represented as 2n. Twice the number of chromosomes in a gamete.

Haploid

Number of chromosomes in a gamete.

Gamete

Sperm cell. Contains half the DNA and Chromosomes as its parent cell.

Homologous Chromosomes

A pair of chromosomes that are similar in size, shape, gene arrangement and information. One from each parent.

Synapsis

Pairing of homologous chromosomes

Somatic cell

body cell

Prophase 1

-nuclear membrane dissapears

-chromosomes condense

-chromosomes find each other (synapsis) to for tetrads and cross over

Tetrad

paired up homologous pairs. (4 sister chromatids)

Crossing over

DNA from one homologous pair is exchanged with the other homologous pair in tetrad. Results in a new DNA combination from both parents.

metaphase 1

-tetrads line up in the middle

anaphase 1

tetrads seperate (segregate) and homologous pairs move to opposite poles

Telophase 1

-nucleus reforms

-cytokinesis starts to occur

prophase (prophase 2)

-nucleus dissapears

-spindle fibers form

-chromosomes condense

metaphase (metaphase 2)

chromosomes line up at the equator of the cell

anaphase (anaphase 2)

-sister chromosomes split and move to opposite poles

meiosis

-4 cells form

-2 cytoplasmic divisions

-daughter cells have half the DNA of OG cell

-daughter cells are genetically different from OG cells and eachother

mitosis

-2 cells form

-1 cytoplasmic division

-daughter cells have same amount and kind of DNA as OG cells

-daughter cells are genetically identical

sex chromosomes

-determine the gender

-pair 23

-males XY

-females XX

-only males can give Y chromosomes

Autosomes

-pairs 1-22

-responsible for everything except sex

-ex. eyes, hair, height

nondisjunction

-when homologous chromosomes do not properly seperate during meiosis

-can have 1 too many chromosomes=trisomy(3)

-can have 1 too little chromosomes=monosomy(1)

down syndrome

-extra 21 chromosome

-trisomy 21

turners syndrome

-only one x chromosome

-X0

Klinefelter’s syndrome

-2x and 1y

-XXY

trisomy 13

-extra chromosome 13

-often ends in miscarriage

-if is born either still born or dies within a week

sister chromatids

2 strands of identicle dna in a duplucate chromosome