Cellular Reproduction The Cell Cycle & Mitosis. 9 - Ch.9 – Cellular Reproduction 9.1 – Cellular...
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Transcript of Cellular Reproduction The Cell Cycle & Mitosis. 9 - Ch.9 – Cellular Reproduction 9.1 – Cellular...
Cellular ReproductionThe Cell Cycle & Mitosis
9 - Ch.9 – Cellular Reproduction 9.1 – Cellular Growth
9 - Ch.9 – Cellular Reproduction 9.1 – Cellular Growth
Genetic MaterialSome key terms…Genome – All of the cell’s
DNA/inheritable traitsChromosomes – Smaller
packages of DNA moleculesSomatic 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 - 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
9 - Ch.9 – Cellular Reproduction 9.1 – Cellular Growth
Cell Cycle (The life cycle of a cell)
Broken into 2 partsInterphase
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.
9 - Ch.9 – Cellular Reproduction 9.1 – Cellular Growth
Cell Cycle (The life cycle of a cell)
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.
Broken into 2 partsInterphase
Mitosis
9 - Ch.9 – Cellular Reproduction 9.1 – Cellular Growth
Interphase
G1 (1st Gap) Phase – Growth & normal cell
function
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
MitosisCan be broken
down into 5 phases
Prop
hase
Prom
etaph
ase Metaphase Anaphase
Telophase
Division of the nuclear material
9 - Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis
PROPHASE•Chromatin condenses•Nucleolus disappears•Spindle fibers begin to form•Centrioles separate
9 - 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)
9 - 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)
9 - 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
9 - Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis
TELOPHASE
•Nuclear membranes form•Nucleoli reappear•The chromosomes become less condensed (unwind)
9 - Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis
Mitosis in Plant Cells
9 - Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis
CYTOKINESIS Starts during telophase
9 - Ch.9 – Cellular Reproduction 9.3 – Cell Cycle RegulationCell 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 (non-dividing) phase
G2 checkpoint•Ensures…
•DNA was copied correctly in the S-phase
M checkpoint•Ensures…
•All sister chromatids are connected properly at the kinetochore
9 - Ch.9 – Cellular Reproduction 9.3 – Cell Cycle RegulationThe 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
9 - Ch.9 – Cellular Reproduction 9.3 – Cell Cycle RegulationThe 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)
ExternalSpace and available
nutrientsAn anchor point (for most
animal cells)
Cancer…
9 - Ch.9 – Cellular Reproduction 9.3 – Cell Cycle RegulationWhat happens when cells lose the
ability to control the cell cycle?
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
9 - Ch.9 – Cellular Reproduction 9.3 – Cell Cycle RegulationThese changes ultimately lead to the mutation of two
types of genes that control the cell cycle… Oncogenes and tumor-suppressor genes
Benign Tumor – does not invade
surrounding tissue
Malignant Tumor – invades surrounding
tissue and spreads via circulatory or lymph
system
10 billion to 100 billion
cells.Usually takes
decades to cause a
problem in humans