The Cell Cycle Flashcards
(25 cards)
What is the cell cycle
an orderly sequence of events that describes the half life of a cell
When does interphase occur
occurs between successive divisions of a cell and it is the longest portion of the cell cycle
What are the 3 phases of interphase
G1 “gap” phase; S “synthesis” phase; G2 “gap” phase
What happens during the G1 phase
the cell duplicates its organelles, synthesizes proteins, grows and carries out its metabolic activities. DNA duplicating; Preparation; G1=life of cell
How long does a typical somatic cell spend in G1
8 to 10 hours
What happens during S phase
DNA molecules are replicated in order to produce two identical copies of DNA; replication
How long does a somatic cell spend in the S phase
6 to 8 hours
What happens during G2 phase
cell growth continues, proteins that are needed for cell division get synthesized and centrioles are replicated; Prepare to divide
How long does a somatic cell spend in G2 phase?
4 to 6 hours
How many hours total does a somatic cell spend in interphase.
24 hours
What does Mitosis describes
it describes the division of the of the nucleus, which is followed by division of the cytoplasm
What are the three different lengths of the cell cycle.
Some divide continuously (skin); some divide very slowly unless the organ is damaged (liver); some lose ability to divide and get replaced by scar tissue when they die( nerve cells, heart muscle)
How many stages are in Mitosis
5 - Prophase; Prometaphase; Metaphase; Anaphase; Telophase
What is the first stage of Mitosis and what happens during this stage
Prophase- It prepares the cell to divide;
What happens during Prophase?
- Chromatin in the nucleus condenses into thick, rod-shaped chromosomes. 2. Nuclear membrane starts to disintegrate. 3. nucleoli disappears. 4. Paris of centrioles migrate toward opposite poles of the cell (mitotic spindle)
What is the 2nd phase of Mitosis and what happens during it?
Prometaphase - pre-curser for metaphase
what happens during Prometaphase?
- the microtubules form a spindle apparatus with fibers that attach one identical chromatid to one pole of the cell and the other identical chromatid to the opposite pole. 2. the chromosomes migrate toward the center of the cell as pairs of chromatids
What is the 3rd phase of Mitosis and what happens during this phase?
Chromosomes line up RANDOMLY along a metaphase plate at the center of the cell with one chromatid located on each side of the cell’s “equator”
What is the 4th stage of Mitosis and what is the main purpose?
Anaphase - Cleavage furrow begins to form
What are the steps in Anaphase
- Chromosomes split and microtubules pull the identical chromatids apart. 2. chromatids migrate toward opposite poles of the cell as they become daughter chromosomes.
What is the final stage of Mitosis and what main thing that happens?
Telophase- reverse of prophase
What are the steps of Telophase?
- Daughter chromosomes decondense and form a tangled mass of chromatin. 2. a nuclear envelope forms around each tangled mass of chromatin.3. spindle apparatus is dissassembled. 4. nucleoli reappear —- offspring grow and reassemble
What is cytokinesis and when does it happen?
it is where the cleavage furrow split the cell into two cells and is formed from actin microfilaments and happens during the late anaphase and early telophase as the cytoplasm divides.
What are the factors needed to initiate cell division?
- sufficient cytoplasm must exist to be distributed to the daughter cells. 2. DNA replication must be completed. 3. an adequate supply of nutrients must be available to the cell. (Glucose and other important molecules) 4. maturation promoting factor, CdC2, proteins, and cyclin must be present. 5. adjacent cells die and create space for new cells to occupy.
