Download Ch.9 – Cellular Reproduction 9.3 – Cell Cycle

Cellular
Reproduction
The Cell Cycle &
Mitosis
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Ch.9 – Cellular Reproduction
9.1 – Cellular Growth
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Ch.9 – Cellular Reproduction
Genetic Material
Some key terms…
Genome – All of the cell’s
DNA/inheritable traits
Chromosomes – Smaller
packages of DNA molecules
Somatic Cells – Body cells which
have a full set of chromosomes
(2n)
Gametes – Reproductive cells
which have ½ the number of
chromosomes (n)
Chromatin – DNA and protein
molecules (histones)
9.1 – Cellular Growth
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Ch.9 – Cellular Reproduction
9.1 – Cellular Growth
Cells duplicate their
genetic material
before they divide,
ensuring that each
daughter cell
receives an exact
copy of DNA
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Ch.9 – Cellular Reproduction
9.1 – Cellular Growth
Cell Cycle (The life cycle of a cell)
Broken into 2 parts
Interphase
Mitosis
Period when the
cell grows, carries out its
cellular functions and
replicates DNA in
preparation for cellular
division
Period when the nucleus
& nuclear material
divides.
Cytokinesis occurs near
the end of mitosis. It is
the dividing of the
cytoplasm.
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Ch.9 – Cellular Reproduction
9.1 – Cellular Growth
Cell Cycle (The life cycle of a cell)
Broken into 2 parts
Interphase
Mitosis
Period when the
cell grows, carries out its
cellular functions and
replicates DNA in
preparation for cellular
division
Period when the nucleus
& nuclear material
divides.
Cytokinesis occurs near
the end of mitosis. It is
the dividing of the
cytoplasm.
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Ch.9 – Cellular Reproduction
Interphase
G1 (1st Gap) Phase –
Growth & normal cell
function
9.1 – Cellular Growth
S (Synthesis) Phase –
DNA is copied
G2 (2nd Gap) Phase –
Cell prepares for division
of its nucleus
•Protein for microtubules
is synthesized
•Additional cell growth
•Cell “checks” the DNA to
be sure that it was
copied correctly so that
mitosis can begin
Mitosis
Can be broken
Division
of the
down
into 5
nuclear
phases
material
Mitosis Rap
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Ch.9 – Cellular Reproduction
9.2 – Mitosis & Cytokinesis
PROPHASE
•Chromatin condenses
•Nucleolus disappears
•Spindle fibers begin to form
•Centrioles separate
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Ch.9 – Cellular Reproduction
9.2 – Mitosis & Cytokinesis
PROMETAPHASE
•Nuclear envelope
fragments
•Centrioles near the poles
•Chromosomes begin to
attach to the spindle fibers
at the kinectochore (a
protein located at the
centromere)
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Ch.9 – Cellular Reproduction
9.2 – Mitosis & Cytokinesis
METAPHASE
•Longest stage of mitosis
(~20min.)
•Duplicated chromosomes
align at the metaphase plate
(equator of the cell)
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Ch.9 – Cellular Reproduction
9.2 – Mitosis & Cytokinesis
ANAPHASE
•Shortest stage of mitosis
(~2min.)
•Sister chromatids are
separated and are pulled to
the poles
•The cell elongates
•By the end of anaphase
each pole has one copy of
each chromosome
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Ch.9 – Cellular Reproduction
9.2 – Mitosis & Cytokinesis
TELOPHASE
•Nuclear membranes form
•Nucleoli reappear
•The chromosomes become
less condensed (unwind)
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Ch.9 – Cellular Reproduction
9.2 – Mitosis & Cytokinesis
Mitosis Rap
Mitosis in Plant Cells
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Ch.9 – Cellular Reproduction
CYTOKINESIS
9.2 – Mitosis & Cytokinesis
Starts during telophase
Mitosis Rap
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Ch.9 – Cellular Reproduction
9.3 – Cell Cycle Regulation
Cell Cycle Regulation
G1 checkpoint
•Ensures…
•Enough nutrients
•Large enough to divide
•If “go” signal is given cell
will divide
•If go signal is not given cell
will enter the G0 (nondividing) phase
M checkpoint
•Ensures…
•All sister chromatids are
connected properly at
the kinetochore
Checkpoint Animation
G2 checkpoint
•Ensures…
•DNA was copied
correctly in the S-phase
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Ch.9 – Cellular Reproduction
9.3 – Cell Cycle Regulation
The Cell Cycle Clock
Controlled by cyclins and cyclin-dependent kinases
Proteins that build
up and then
degrade at certain
points in the cell
cycle
(Cdk)
Enzymes the cyclins bind
to in order to initiate the
next the next phase in the
cell cycle
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Ch.9 – Cellular Reproduction
9.3 – Cell Cycle Regulation
The Cell Cycle Clock
Internal and external factors trigger cell division
Internal
Growth factors - proteins
released by certain cells
that stimulate other cells
to divide. (Growth
hormones in mammals)
Cell reproduction stimulation animation
External
Space and available
nutrients
An anchor point (for most
animal cells)
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Ch.9 – Cellular Reproduction
9.3 – Cell Cycle Regulation
What happens when cells lose the
ability to control the cell cycle?
Cancer…
Cells can become cancerous when a mutation occurs
spontaneously or from an outside factor (carcinogen)
As cells multiply a predictable
series of genetic changes occur
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Ch.9 – Cellular Reproduction
9.3 – Cell Cycle Regulation
These changes ultimately lead to the mutation of two
types of genes that control the cell cycle…
Oncogenes and tumor-suppressor genes
10 billion to
100 billion
cells.
Usually takes
decades to
cause a
problem in
humans
Benign Tumor –
does not invade
surrounding
tissue
Malignant Tumor –
invades surrounding
tissue and spreads via
circulatory or lymph
system