Flashcards in The Cell Cycle Deck (31):
How do prokaryotes divide? (4)
- circular DNA molecules are replicated
- DNA molecules attach to different PM parts
- cell elongates
- contraction of PM across the middle of cell produces 2 daughter cells with new cell walls
What is the cell cycle?
A series of events that a cell undergoes, which results in 2 genetically identical daughter cells.
What are the three parts of interphase?
G1: cell growth and checkpoint
S phase: DNA and chromosome replication
G2: cell growth and preparation and checkpoint
What occurs during the G1 phase? (4)
- cell cytosol increase
- protein synthesis for DNA replication
- organelles replicate
- cell will go through check point, of there are any errors cell will either correct them or enter non dividing stage (G0)
What occurs during the s phase of interphase?
- Parent cell replicates DNA
- by the end of s-phase cell will contain double the amount of DNA and chromosomes
What occurs during the G2 stage of interphase? (3)
- cell continues to grow in preparation for division
- synthesis of proteins need for microtubles
- cell undergoes another checkpoint to see if DNA has been correctly duplicated
What occurs during prophase? (3)
- chromosomes condense and become visible
- replicated centrioles move apart
- microtubles extend towards towards centrioles
- nuclear membrane has breaks down
What occurs during metaphase? (3)
- microtubles have have fully formed and are in position
- chromosomes align on the equator of the cell
- nuclear membrane has completely broken down
What occurs during anaphase?
- spindles contract pulling centromeres apart leaving single stranded chromosomes at either end of the cell
What occurs during telophase? (3)
- nuclear membrane forms around each set of chromosomes
- chromosomes de-condense
- spindles begin to break down
What occurs during cytokinesis?
- a contractile ring of protein molecules form a cleavage furrow
- cell splits into two daughter cells
How is cytokinesis different in plant and animal cells different?
During cytokinesis in plants, a cell plate forms in the middle of the cell and it grows towards the cell wall, where as in animals, they form cleavage furrow and the cell membrane constricts.
True or false?
Mitosis is a type of cell division in which a complete set of chromosomes is distributed to each daughter cell.
True. Mitosis does provide a complete set of chromosomes to each daughter cell. They are diploid cells.
True or false?
Binary fission does not require DNA replication.
False. Prokaryotes have a circular DNA chromosomes that needs to be replicated in order to compete mitosis.
What must occur in order for a successful division of sister chromosomes during mitosis?
Mitotic spindles must correctly attach to each sister chromosomes by their kinetochore and contract to pull the sister chromatids to opposite poles.
Why is the cell cycle important?
It plays a crucial role in the following processes:
- growth: new cells produced- increased size
- repair and maintenance: replaces dead cells
- reproduction: gives rise to next generation
What is the purpose of binary fission and mitosis in comparison to meiosis?
Binary fission and mitosis are forms of asexual reproduction. Mitosis is also responsible for replacing dead cells with new ones; repairing damaged tissues, and allowing living organisms to grow. Meiosis is responsible for the production of gametes.
List five differences between an interphase cell and a cell in mitosis.
- chromosomes not distinct
- no spindle
- cell metabolically active in generating ATP
- cell components undergoing duplication
- cytokinesis not occurring
Define the term cytokinesis.
Division of the cell’s cytoplasm
What are checkpoints?
Checkpoints are times in the cell cycle where a cell’s enzyme reviews the state of the cell to determine if the cell is prepared to commit to or continue with cell division.
What are the importance of the checkpoints?
Checkpoints ensure correct genetic info is passed on to new cells. if the info is not passed on accurately all future cells will inherit the defect. If cell division is not controlled, cancer may result.
What would happen if spindle assembly checkpoint did not function?
The centromere of the chromosomes attach to the spindle, if this didn't happen, chromatids may not separate, resulting in some daughter cells having too many chromosomes and some having too little.
What are the differences between mitosis and cytokinesis?
- Mitosis is the division of genetic material/DNA/chromosomes while cytokinesis is division of the
- Mitosis results in two identical daughter nuclei enclosed in one cell, while cytokinesis results in two
daughter cells, complete with plasma membranes (and cell walls in plant cells).
- Mitosis precedes (comes immediately before) cytokinesis.
- Cytokinesis occurs in eukaryotes and prokaryotes, whereas mitosis occurs only in eukaryotes.
Why can radiation be used to control cancer?
Because cancer cells are more susceptible to the damaging effects of x-radiation than normal cells.
How can cancer occur?
Cells reproduce at a rate far in excess of the normal regulated rate of the cell cycle. Genes that normally control the progress of a cell through the cell cycle are changed by mutation and therefore cannot detect errors. Cancerous cells will continue to divide in an unregulated manner.
When does the m checkpoint occur?
Metaphase; it checks if the microtubules are correctly connected to the sister chromatids.
True or false?
Cell production and cell loss are kept in balance by genes.
True or false?
Mitosis is accompanied by the replication of cell organelles such as mitochondria and chloroplasts.
True. Before a cell undergoes mitosis it must replicate its organelles during interphase.
In what way can cancer drugs affect microtubules in order to reduce the spread and growth of cancerous cells?
If the drugs prevent microtubules from separating the chromosomes, replication will be slowed and cells will die due to the dna not separating.
What differences are there in mitosis between plants and animals?
- only a certain type of tissue can undergo mitosis in plants, meristematic
- plants do not contain centrioles/ centrosomes for mitotic spindles to attach onto, it sues its cell wall