lecture 10: the cell cycle Flashcards
3 elements of Cell Theory?
- All organisms are made of one or more cells
- Cell is fundamental unit of structure and functions in organisms
- All cells come form pre-existing cells
What happens during cell division (generally) and it requires the division of… (2 elements)?
- 1 parent cell gives rise to 2 or more daughter cells
- Division of 1. The nucleus (or nucleoid region) and of 2. The cytoplasm
What are the two types of cell division in eukaryotes and what are they based on?
- Mitotic cell division (mitosis)
- Meiotic cell division (meiosis)
- Based on how the nucleus is divided
3 characteristics of mitosis?
- Daughter cells contain same number of chromosomes as parent cell
- Daughter cells are genetically identical
- Produce somatic (body) cells/clones of unicellular organisms
3 characteristics of meiosis?
- Daughter cells contain half the number of chromosomes in parent cell
- Daughter are genetically unique
- Produce gametes/spores for reproduction
Mitosis/meiosis divide the… and cytokinesis divides the…?
- nucleus
- cytoplasm
3 functions of mitosis?
- Asexual reproduction in unicellular and multicellular organisms
- Growth and development of multicellular organisms
- Tissue repair and renewal in multicellular organisms
What is the cell cycle?
Ordered sequence of events in the life of a cell (from origin to its division)
How and why are the steps in the cell cycle monitored?
- Monitored by a molecular regulatory system
- Not well-monitored = lose control = can lead to cancer
What are the 2 major phases in the cell cycle?
- Interphase (90%): G1, S (DNA synthesis), G2
2. Mitotic (M) phase (10%)
What is the mitotic spindle apparatus and what is it composed of?
Dynamic structure formed from cytoskeletal fibers called microtubules that are produced form the centrosome of the cell
What are the 2 functions of the mitotic spindle apparatus and what are used to accomplish those functions?
- Provides forces for moving chromosomes: Kinetochore microtubules –> attach to the kinetochore and pull chromosomes
- Provides forces for cell elongation: Polar microtubules –> interact with polar microtubules from opposite poles and push to elongate the cell
What needs to be done during G1 and G2? (3)
Cell need to make materials to grow
- Proteins
- Plasma membrane and cytoplasm components
- Replicate organelles, duplicate centrosomes
What is done during the S phase?
Replication of all chromosomes
What are the 8 things that are done during the mitotic (M) phase (cell division)?
- Chromosomes need to condense
- Microtubule machinery needs to be made
- Nuclear envelope needs to break down
- Spindle fibers need to contact chromosomes
- Spindle fibers need to pull sister chromosomes to opposite poles of cell
- Nuclear membrane needs to re-form
- Mitotic spindle needs to be dissembled
- Cytoplasm needs to be divided (cytokinesis)