BIO Chp. 9

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

almost all DNA is stored in the nucleus

-each cell has a copy of the entire genome

protein production: DNA has the instructions and makes proteins to actually carry out necessary tasks.


-mainly enzymes

• encoded in chhemical substances
• -Nitrogenous Bases
• -4 different bases make DNA: ADenie, Thymine, Guanine, Cytosine
• (A,T,G,C)

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

• 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

• 1. Replication
• 2.Mitosis
• 3. Cytokinesis

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
• SEMI-CONSERVATIVE MODEL

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

• unduplicated state: remains loose in the nucleus
• duplicated: 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
• -each pair: homologous chromosomes

There are 46 chromosomes in humans, therefore 23 pairs

• Interphase
• Mitoctic Phase (M phase):

• Interphase: cell is carrying out its job and preparing for cell division
• Mitotic phase: includes mitosis and cytokinesis

• how a cell divides.
• This is a multi-step process
• -prophase
• -metaphase
• -anaphase
• -telophase

• 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
• 

• spindle disassembles
• nuclear envelope reforms
• chromosomes decondense
• 

• completes cell division by dividing the cytoplasm between the 2 daughter cells
• cell furrows and splits in two