Mitose
1. Genome
● Definition: The genetic material (DNA) of a cell.
● Structure: Partitioned among chromosomes.
2. Cell Cycle Phases
Interphase (Growth and preparation for division):
● G1 phase (First Gap):
○ Cell growth.
○ Preparation for DNA replication.
● S phase (Synthesis):
○ DNA replication → Chromosomes now consist of two sister chromatids.
● G2 phase (Second Gap):
○ Further cell growth.
○ Preparation for mitosis.
3. Mitotic (M) Phase (Cell Division):
● Mitosis: Division of the nucleus.
○ Prophase: Chromosomes condense; mitotic spindle forms.
○ Metaphase: Chromosomes align at the metaphase plate.
○ Anaphase: Sister chromatids separate.
○ Telophase: Nuclear envelope reforms; chromosomes decondense.
● Cytokinesis: Division of the cytoplasm (Cleavage in animal cells, cell plate formation
in plant cells).
4. Mitotic Spindle
● Definition: Made up of microtubules.
● Function: Controls chromosome movement.
● Arises from: Centrosomes in animal cells.
● Key Components:
○ Asters: Star-shaped microtubules near centrosomes.
○ Kinetochore Microtubules: Attach to chromosomes.
○ Nonkinetochore Microtubules: Push poles apart for cell elongation.
, 5. Cell Cycle Checkpoints
● G1 Checkpoint ("Restriction point"):
○ Determines if the cell will proceed with division or enter G0 (non-dividing
state).
● G2 Checkpoint:
○ Ensures all DNA is replicated and the cell is ready for mitosis.
● M Checkpoint:
○ Ensures all chromosomes are properly attached to the spindle before
separation.
6. Cell Cycle Control Molecules
● Cyclins: Proteins that regulate the cycle.
● Cyclin-Dependent Kinases (Cdks): Enzymes that, when activated by cyclins, signal
progression through the cell cycle.
7. Cancer and Cell Cycle
● Normal Cells: Density-dependent inhibition, anchorage dependence.
● Cancer Cells: Ignore normal regulation, divide uncontrollably, can metastasize.
Interphase → Mitosis → Cytokinesis.
Meiose
1. Basic Concept: Sexual Reproduction
● Gene Inheritance: Offspring inherit genes located at specific loci on chromosomes.
● Asexual Reproduction: Offspring are genetically identical to the parent (via mitosis).
● Sexual Reproduction: Combines genes from two parents, resulting in genetic
diversity.
2. Human Chromosome Set
● Somatic Cells (Diploid, 2n = 46):
○ 22 pairs of autosomes.
1. Genome
● Definition: The genetic material (DNA) of a cell.
● Structure: Partitioned among chromosomes.
2. Cell Cycle Phases
Interphase (Growth and preparation for division):
● G1 phase (First Gap):
○ Cell growth.
○ Preparation for DNA replication.
● S phase (Synthesis):
○ DNA replication → Chromosomes now consist of two sister chromatids.
● G2 phase (Second Gap):
○ Further cell growth.
○ Preparation for mitosis.
3. Mitotic (M) Phase (Cell Division):
● Mitosis: Division of the nucleus.
○ Prophase: Chromosomes condense; mitotic spindle forms.
○ Metaphase: Chromosomes align at the metaphase plate.
○ Anaphase: Sister chromatids separate.
○ Telophase: Nuclear envelope reforms; chromosomes decondense.
● Cytokinesis: Division of the cytoplasm (Cleavage in animal cells, cell plate formation
in plant cells).
4. Mitotic Spindle
● Definition: Made up of microtubules.
● Function: Controls chromosome movement.
● Arises from: Centrosomes in animal cells.
● Key Components:
○ Asters: Star-shaped microtubules near centrosomes.
○ Kinetochore Microtubules: Attach to chromosomes.
○ Nonkinetochore Microtubules: Push poles apart for cell elongation.
, 5. Cell Cycle Checkpoints
● G1 Checkpoint ("Restriction point"):
○ Determines if the cell will proceed with division or enter G0 (non-dividing
state).
● G2 Checkpoint:
○ Ensures all DNA is replicated and the cell is ready for mitosis.
● M Checkpoint:
○ Ensures all chromosomes are properly attached to the spindle before
separation.
6. Cell Cycle Control Molecules
● Cyclins: Proteins that regulate the cycle.
● Cyclin-Dependent Kinases (Cdks): Enzymes that, when activated by cyclins, signal
progression through the cell cycle.
7. Cancer and Cell Cycle
● Normal Cells: Density-dependent inhibition, anchorage dependence.
● Cancer Cells: Ignore normal regulation, divide uncontrollably, can metastasize.
Interphase → Mitosis → Cytokinesis.
Meiose
1. Basic Concept: Sexual Reproduction
● Gene Inheritance: Offspring inherit genes located at specific loci on chromosomes.
● Asexual Reproduction: Offspring are genetically identical to the parent (via mitosis).
● Sexual Reproduction: Combines genes from two parents, resulting in genetic
diversity.
2. Human Chromosome Set
● Somatic Cells (Diploid, 2n = 46):
○ 22 pairs of autosomes.
