Download Chromosome Haploid vs Diploid

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Chromosome
1. 
Chromatid
2. 
Centromere
3. 
Short Arm
4. 
Long Arm
  Chromosome
- DNA tightly coiled
  Chromatid - two exact copies of
DNA that make up each
chromosome
  Centromere - attaches the
chromatids
Haploid vs Diploid
 Somatic
Cells - “regular” cells
– Contain two sets of
chromosomes: diploid
 Gametes - eggs and sperm
– Contain one set of
chromosomes: haploid
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Why divide?
 Cells
can only get so large
before diffusion will not work
properly to bring in nutrients or
remove waste.
 Allows organisms to grow and
replace damaged tissue
Cell Cycle Phases
1. 
Interphase
– G1, S, G2
2. 
Mitosis
– 
– 
– 
– 
3. 
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
1) Interphase
 Includes
G1, S and G2 phases
 Chromosomes are not visible
 Cell performs regular functions
 90% of cell’s life spent in
Interphase
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G1 phase
 Cell
grows rapidly
Synthesis (S) phase
 Cell’s
DNA is copied
– Each chromosome has two
chromatids (X shaped now)
G2 phase
 Cell
grows more
 Prepares to divide
2) Mitosis
 A
sequence of cellular division
 In the lifetime of a cell, it is very
short
– Prophase
– Metaphase
– Anaphase
– Telophase
Prophase
 Centrioles
start forming
spindles
 Chromosomes coil up
and become visible
 Nuclear envelope
dissolves
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Metaphase
 Chromosomes
move to
equator (middle) of cell
 Line up in single file
 Spindle fibers pull them there
Anaphase
 Chromosomes
are pulled apart
by spindles
 Chromatids move to opposite
poles
Telophase
 Nuclear
envelop forms around
chromosomes at each pole
 Chromosomes uncoil
 Spindles dissolve
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3) Cytokinesis
 The
cytoplasm and cell
membrane are separated by a
belt of proteins
 Resulting in two new identical
cells
Cell Cycle Summary
 The
nucleus divides
 The two new cells have the
same number of chromosomes
as the original cell
 Allows for growth and repair
Cells That Don’t Divide
 Muscle
and nerve cells do not
divide
 They are in G1 phase forever
 If they die, the body cannot
replace them
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Control of the Cell Cycle
 The
cell cycle has inspection
points which allow the next
phase to take place
 The cycle can be slowed or
stopped, or the cell can be
killed if necessary
When Control is Lost
 Cancer
is the uncontrolled
growth of cells
 Cancer cells do not respond to
signals to stop growing or
signals to die
 They keep dividing and
invading surrounding tissue
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