Cell Cycle & Mitosis Flashcards
Which phase of the cell cycle does DNA replication occur?
interphase of the cell cycle.
What is mitosis?
Mitosis is the part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication.
What can uncontrolled mitosis lead to?
Mitosis is a controlled process.
Uncontrolled cell division can lead
to the formation of tumours and of cancers.
What to cancer treatments target?
Many cancer treatments are directed at controlling the rate of cell division.
Describe the process of binary fission.
- replication of the circular DNA and of plasmids
- division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids
How do viruses replicate?
Being non-living, viruses do not undergo cell division.
Following injection of their nucleic acid, the infected host cell replicates the virus particles.
How do eukaryotic cells divide?
Mitosis and Meiosis (gametes)
What are the 3 stages of the cell cycle?
-Interphase (G1, S, G2)
-Nuclear Division (Mitosis/Meiosis)
-Cytokinesis
Describe what each (G1, S, G2) in Interphase stands for.
G1- Growth - cell doubles and grows in size
S - DNA synthesis
G2 - growth and preparation for mitosis; error checking stage
(And M is mitosis in the cycle)
Name the 4 stages of MITOSIS
Prophase
Metaphase
Anaphase
Telophase
Describe Mitosis from GCSE
One round of division
Genetically identical cells are made
Diploid cells are made
Growth and repair- e.g. clonal expansion of B cells
Describe Interphase
Interphase is the longest stage in the cell cycle.
Interphase is when the organelles double, the cell grows and then DNA replicates.
Describe Nuclear division in cell cycle.
Mitosis:
-creating two identical diploid cells
-identical DNA for growth and repair
Meiosis
- creating four genetically different haploid cells.
- where as meiosis creates gametes.
What is cytokinesis in the cell cycle?
Cytokinesis is the final stage.
It is the division of the cytoplasm to create the new cells.
Describe Prophase, and how it is different in animal cells and plant cells.
- chromosomes condense and become visible
- Animal cells: the centrioles separate and move to opposite poles of the cell
- The centrioles are responsible for creating spindle fibres which are released from both poles to create a spindle apparatus
these will attach to the centromere and chromatids on the chromosome in later stages
- Plant cells: have a spindle apparatus, but lack the centrioles.
Describe Metaphase in Mitosis
The chromosomes align along the equator of cell.
The spindle fibres released from the poles now attach to the centromere and chromatid.
[Chromosomes line up
along metaphase plate
(imaginary plane)]
Describe Telophase & Cytokinesis
Telophase:
The chromosomes are now at each pole of the cell and become longer and thinner again.
The spindle fibres disintegrate, and the nucleus starts to reform.
Cytokinesis:
The final stage in the cell cycle is when the cytoplasm splits in two to create the two new genetically identical cells.
Describe Anaphase in Mitosis
The spindle fibres start to retract and pull the centromere and chromatids they are bound to towards the opposite poles.
This causes the centromere to divide in two and the individual chromatids and pulled to each opposite pole.
These separated chromatids and now referred to as chromosomes.
This stage requires energy in the form of ATP which is provided by respiration in the mitochondria.
