Date post: | 31-Dec-2015 |
Category: |
Documents |
Upload: | alexis-newman |
View: | 214 times |
Download: | 0 times |
CELL DIVISION
Cell Division/Reproduction
Why?
Cells divide for many reasons: In order to stay
small Diffusion occurs
at a faster, more efficient rate in smaller cells.
Why would diffusion rate matter in cells?
Remember what materials need to enter and exit the cell.
DNA limits their size DNA can only
control cells up to a certain size.
Repair/replace old or damaged cells.
Growth and Development We start out as one
cell, mitosis allows that 1 cell to turn into billions of cells.
Cell Cycles
No nucleus No membrane bound
organelles (ex. mitochondria, vacuole, chloroplast) A.) Cell division takes
place in 2 steps: 1.) DNA is copied 2.) Cell splits by
binary fission
Prokaryotic Cells
Cell Cycles
Contain a nucleus and organelles. Repeating
sequence of growth and division
Occurs in two cycles for two purposes
Mitosis Occurs in somatic
(ordinary body cells) for growth and repair
Creates 2 identical cells
Meiosis Occurs in germ cells
(ovaries and testes) to make gametes (sex cells).
Creates 4 similar cells.
Eukaryotic Cells
Eukaryotic Cell Cycle
3 Stages Interphase
G1: First growth phase
S: Synthesis phase G2: Second growth
phase Mitosis
nuclear division Prophase Metaphase Anaphase Telophase
Cytokinesis Division of cytoplasm
Centromere
Interphase
This is when the cell is preparing to divide.
The LONGEST phase of the cell cycle
90% of the cell’s life is spent in Interphase.
G1 – first growth phase: The cell doubles in
size and the organelles double
S – synthesis phase: the DNA that makes
up the chromatin is copied (DNA replication) this is the longest phase of interphase.
G2 – second growth phase: Growth and
preparation for mitosis, second check-point.
Interphase (G1, S, G2)
Terms to know: (Start a VOCAB page)
Chromosome Single piece of coiled
DNA Diploid
A cell that contains a set of chromosomes from mom and dad. (46 in Humans)
Replicated Chromosome A single piece of DNA
that has been copied through DNA replication
Sister Chromatids 2 identical strands of
DNA Non-Replicated
Chromosome Single strand of DNA
before it is copied
Spindle Fibers Fibers that are
attached to centrioles to help pull apart chromosomes
Centrioles Organelles that aid in
pulling apart chromosomes
Centromere Structure that holds
the replicated chromosomes together
DNA related terms Structural Terms
Mitosis (PMAT)
Mitosis The nucleus of a cell
is divided into two nuclei with the same number of chromosomes.
Cell Stays diploid Consists of 4 phases
ProphaseMetaphaseAnaphaseTelophase
Mitosis Step1: Prophase
Longest phase of MITOSIS Chromatin coils and
forms chromosomes
Nuclear envelope breaks down
Spindle fibers form and stretch from one end of the cell to the other They attach to the
centrioles They help to pull
the cell apart
Mitosis Step2: Metaphase
Chromosomes line up in the middle of the cell
Mitosis Step3: Anaphase
Centromere of each chromosome splits
Two sister chromatids separate and move to opposite poles
Each chromatid becomes separate (non-replicated) chromosome in each daughter cell.
Mitosis Step4: Telophase
Last stage of Mitosis
Chromosomes at each pole uncoil and become chromatin
Nuclear envelope reforms
Spindle fibers break down
Cytokinesis
NOT part of mitosis
The cytoplasm divides into two cells
Cell membrane reforms
In plant cells the cell wall reforms