Chapter 8 Flashcards
(38 cards)
Why do cells need to divide?
Reproduction
Growth
Repair
*Cell Theory= all cells come from cells**
How do bacteria divide?
1) The DNA replicates, then separates
2) Cell division begins as the plasma membrane grows inward, and a new cell wall is synthesized
3) Binary fission produces two identical daughter cells
Prokaryote cell division (Baccteria):
As the bacteria cell prepares to divide what happens?
As the bacteria cell prepares to divide a ring of protein forms at the centre of the cell
- This ring then constricts, pinching off the cell to form the two new cells
What makes Eukaryotic cell division more complex?
They have more things to separate such as multiple chromosome, nuclear envelope, and organelles
What part of cell division represents most of the cells life?
The Interphase (90% of the cells life)
What happens during the S Phase?
- At the beginning of the S phase, the cell contains one copy of each chromosome
- After being copied, the two copies stay together and are called chromatids
What happens at the end of the S phase?
- All of the DNA has been copied
- A second centrosome is made
- The cell enters the G2 phase
What is the Mitotic Phase?
It is a highly orchestrated process of cell division
- Sister chromatids are pulled apart
- Cell contents are divided up
- Cell splits in two (cytokinesis)
What happens during Interphase? PMAT?
Interphase = cell growth & Component duplication PMAT = Component separation & division
Centromere
A region of DNA beneath kinetochore proteins
What happens during the Prophase stage?
It marks the entry of the cell into mitosis
- Condensation of chromosomes
- Breakdown of nuclear envelope
- Nucleoli disappears
What are the duplicated chromosome composed of?
2 sister chromatids
What happens during the Prometaphase?
- Nuclear envelope is completely dissociated
- Sister chromatids attach to mitotic spindle
What binds to the kinetochore structure? then what happens?
Spindle microtubules
Then the chromosome are attached to each spindle pole through microtubules
What happens during the Metaphase stage?
- The mitotic spindle is fully formed
- Centrioles are polarly localized
- Centromeres of the chromosomes line up at the equator of the cell
- The mitotic spindle anchors a kinetochore(protein) to each pole
What happens during the Anaphase stage?
Chromosome are split apart and moved to the poles of the cell by the kinetochore motor proteins
T or F:
The tighter the microtubules pull, the tighter the kinetochore holds on (chinese finger trap)
True
What happens during the Telophase stage?
- Nuclei begins to reform
- Chromatin unfolds
- Nucleoli reappear
- Mitotic fibres disappear
- Cleavage furrow/ cell plate start to form
Kinetochore
A set of proteins that pull the chromosomes apart
What is the result of cell division?
Results in the sister chromatids being separated, and two genetically identical cells being produced
What happens during the Cytokinesis?
The division of the duplicated cell into two daughter cells
In animal cells, how is the cleavage furrow formed?
The cleavage furrow is formed by a contractile ring
- As the ring shrinks, it pinches off the connection between the two cells until they separate completely
How do plant cells separate?
In plants cells, a new portion of the cell wall must be made to separate the two new cells.
- The cell plate forms from the centre blocking the connection between the two cells
How does a cell know when to divide?
Cellular signals tell the cell when, and when not to divide, regulation is partly due to hormone activity
- The internal systems of the cell will check to make sure the cell is healthy and ready to divide
