View
2
Download
0
Category
Preview:
Citation preview
1
Mitosis and the
Cell Cycle
2
Cell Division
All cells are derived from pre-existing cells
New cells are produced for growth and to replace damaged or old cells
3
All cells undergo 5 phases of the cell cycle
4
All cells undergo 5 phases of the cell cycle
G1 - primary growth phase
S – synthesis; DNA replicated
G2 - secondary growth phase
M - mitosis C - cytokinesis
collectively these 3 stages
are called Interphase
5
Interphase - G1 Stage
Cells mature by making more cytoplasm & organelles
Cell carries on its normal metabolic activities
6
Interphase – S Stage
Synthesis stage
DNA is copied or replicated
Two identical copies of
DNA
Original DNA
7
Interphase – G2 Stage
All cell structures needed for division are made (e.g. centrioles)
Both organelles & proteins are synthesized
8
Mitosis
Is the division of the nucleus
Only occurs in eukaryotes
Doesn’t occur in some cells such as brain cells
9
The Four Mitotic Stages
Prophase
Metaphase
Anaphase
Telophase
10
Early Prophase Chromatin in nucleus condenses to form visible chromosomes
Spindle fibers form from cytoskeleton or centrioles (animal)
Sister
chromatids
(chromosomes)
Nucleolus Cytoplasm
Nuclear envelope
11
Prophase Nuclear membrane & nucleolus disappear
Chromosomes continue condensing & are clearly visible
Spindle fibers (kinetochore) attach to the centromere of each chromosome
12
Prophase
Nucleus & Nucleolus have disintegrated
Chromosomes
13
Prophase The spindle fibers form from the microtubules in plant cells
Spindle fibers form from 2 centrioles at the centrosome in animal cells
14
Metaphase
Chromosomes, attach to the kinetochore (spindle) fibers and move to the center (equator) of the cell
Pole of the Cell
Pole of the Cell
equator
15
Metaphase
Chromosomes lined at the Equator
Spindle Fibers
16
Anaphase
This phase occurs rapidly
Sister chromatids are pulled apart to opposite poles of the cell via kinetochore (spindle)fibers
Anaphase
Sister chromatids Are pulled
apart
18
Telophase
Spindle disassembles Nuclear envelope begins to form around chromosomes
Nucleolus reappears Chromosomes reappear as chromatin
19
Cytokinesis follows Telophase
The cytoplasm and organelles divide
The cell separated into two identical halves called daughter cells
Animal Cell
20
Cytokinesis
Cell plate in plant cell In plant
cells, cell plate
forms at the
equator to divide
cell
21
Cytokinesis
Cleavage furrow in animal cell In animal
cells, cleavage furrow
forms to split cell
22
Daughter Cells of Mitosis
Have the same number of chromosomes as the parent cell from which they were formed
Are identical to each other, but smaller than parent cell
23
Identical Daughter Cells
Parent Cell
Two
identical
daughter
cells
(Paired
centrioles)
25
Mitosis in Onion Root Tips
26
Eukaryotic Chromosomes
All eukaryotic cells store genetic information in chromosomes
Human body cells have 46 chromosomes or 23 identical pairs
27
Eukaryotic Chromosomes
Each chromosome is composed of a single, tightly coiled DNA molecule
Chromosomes can’t be seen when cells aren’t dividing and are called chromatin
Chromosome
28
Compacting DNA into Chromosomes
DNA is tightly coiled around proteins called histones
29
Chromosomes in Dividing Cells
Duplicated chromosomes are called sister chromatids & are held together by the centromere
Called Sister Chromatids
30
Karyotype
A picture of the chromosomes from a human cell arranged in pairs by size
First 22 pairs are called autosomes
Last pair are the sex chromosomes
XX female or XY male
Chromosomes carry the information which codes for what we are and what we look like.
Widow Peak
Multi-tasking
33
Types of Cell Reproduction
Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells
Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells
34
Uncontrolled Mitosis
If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors
Oncogenes are special proteins that increase the chance that a normal cell develops into a tumor cell Cancer cells
Recommended