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Nuclear division process that halves the chromosome number. Basis of sexual reproduction.
Nuclear division mechanism that maintains the chromosome number. Basis of body growth, tissue repair and replacement in multi-celled eukaryotes; also asexual reproduction in some plants, animals, fungi, and protists
sex cells: eggs or sperm
What is cell division used for?
growth, repair and reproduction
The 23rd pair...homologs can be different XX or XY
every pair of chromosomes except the sex chromosomes. they deal with everything else...homologs are alike
how bacteria reproduce. They duplicate their DNA and split
How many kinds of cell division are there and what are they used for?
Two: mitosis, and meiosis. mitosis reproduces every other body cells (growth (cells added for growth--not just getting cells bigger), repair and reproduction in single-celled organisms). Meiosis is for sexual reproduction
division of the nucleus
division of the cytoplasm
Describe reproduction in bacteria. What is it called?
binary fission. Duplicate their DNA (aka chromatin) then split
What is chromatin?
is DNA and associated proteins in a long, thin, hair-like form, rarely visible with a microscope
What are chromosomes?
A structure that consists of DNA and associated proteins; carries part or all of acell’s genetic information
Compare and contrast chromatin and chromosomes
chromatin is long, thin and hair-like DNA that is rarely visible with a microscope. Chromosomes are the shortened, condensed, coiled DNA that is readily visible with a microscope.
Constricted region in a eukaryotic chromosome where sister chromatids are attached.
Chromosomes that have 2 of each chromosomes. They are two copies of the same chromosome
One of two attached members of a duplicated eukaryotic chromosome
when cells have only half of the homologous pairs of chromosomes (sex cells)
when cells have both members of homologous pairs (mitosis)
chromosomes that have 2 copies of each
pictures scientists take of chromosomes which they cut and paste to match pairs. Example amniocentisis
Describe the cell cycle
- G1 (growth phase)
- S (dna duplicates)
- G2 (2nd growth phase)
- M (Mitosis)
- (G1, S, G2 are interphase. cells stay in interphase most of the time)
4 stages of mitosis
- separate (no centrioles in plants)
- envelope and nucleolus disappears
- thickens into chromosomes
- chromatids line up & down the middle along the cell’s equator
Sister chromatids separate and move towards opposite ends of the cell
runaway cell division
helps cancer cells divide uncontrollably
neoplasm forming masses of abnormal cells
In a sheath, contained
not in a sheath and spreads
tumor suppressor genes
Brac 1 and Brac 2
malignant cells spreads to and disrupts function in other body tissues
- fibers dissappear
- envelope and nucleolus reform
- unwind and uncoil back into chromatin
sex organ cells (testes and ovary)
regular body cells