BIO Chp. 9
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BIO Chp. 9
Biology Genetics Cell Division
Chapter 9 of the biology textbook that goes over genetics and cell division
Contains an organism's genome
complete collection of an organism's genetic information.
-It's coade controls reproduction, development, and everyday functioning of living things
- a cell's 'recipe book'
-each individuual recipe = a gene
Where are genomes stored?
almost all DNA is stored in the nucleus
-each cell has a copy of the entire genome
What do DNA have instructions for?
protein production: DNA has the instructions and makes proteins to actually carry out necessary tasks.
How is the information in DNA stored?
encoded in chhemical substances
-4 different bases make DNA
: ADenie, Thymine, Guanine, Cytosine
sequence detemines genetic characteristics
-In the nucleus, DNA makes a copy of itself onto mRNA
-mRNA leaves nucleus, heads for a ribosome in the cytosol
-a string of amino acids are put together according to directions in mRNA
Why do cells divide?
replace dead cells
for growth of an organism
-cells can only grow so big before they are dysfunctional
-therefore to grow, we need more (not BIGGER) cells
What are the 3 components of cell division?
Duplication of DNA
Separting DNA copies within the parent cell
Physical splitting of parent cell into 2 daughter cells
double helix unwinds
each strand serves as a template for constructing its new complementary strand
makes up chromosomes that DNA is packaged into.
Chromatin = DNA + associated proteins
Remain in an unduplicated state until DNA is replicated
Once DNA is duplicated, chromosomes become
2 identical sister chromatids
Chromosomes and DNA replication
What are the ways in which DNA can be found arranged?
: remains loose in the nucleus
: chromosomes consisiting of 2 identical sister chromatids take shape
Chromosomes come in matched pairs
-one member of the pair in inherited from each parent
-they contain same genes but are NOT identical
: homologous chromosomes
There are 46 chromosomes in humans, therefore 23 pairs
The cell cycle
Mitoctic Phase (M phase):
: cell is carrying out its job and preparing for cell division
: includes mitosis and cytokinesis
how a cell divides.
This is a multi-step process
chromatin condenses into chromosomes
double structure formed-composed of 2 indentical sister chromatids
mitotic spindle begins to form
chromosomes migrate toward center of nucleus
nuclear envelope breaks down
chromosomes line up on metaphase plate (attach to spindle fibers, microtubles)
sister chromatids uncouple into individual chromosomes
spindle pulls separated chromatids to opposie spindle poles
nuclear envelope reforms
completes cell division by dividing the cytoplasm between the 2 daughter cells
cell furrows and splits in two
Cell division in plant cells