Cell division 1 Flashcards
What are the two different types of reproduction?
Asexual or Sexual.
What is cell division used solely for in unicellular organisms?
Asexual reproduction
What is cell division used for in multicellular organisms?
Tissue growth, tissue repair and sexual reproduction.
What are the four different specific asexual reproduction mechanisms?
Binary fission, budding, fragmentation and sporulation.
Two types of cell division mechanisms in eukaryotic cells?
Asexual - Mitosis and Sexual - Meiosis.
How is cell division meditated?
By external and internal signals.
Favourable environment for cell division.
Nutrient readily available, no damage to DNA and cell size increased sufficiently.
Unfavourable environment for cell division?
Lack of nutrients, DNA damage and cell too small.
When do unicellular organisms grow and divide?
When they have the available nutrients in their environment.
When do multicellular organisms grow and divide?
When more cells are needed by the organism.
What stimulates cell growth and division?
Growth factors and mitogens.
Do growth factors cross the cytoplasmic membrane?
No, they bind and stimulate receptors on the outside of the cell membrane.
What PDGF?
One of the first mitogenic growth factors.
Acts as both growth factor and mitogen.
Stimulates many types of cells to grow and divide.
Many cells secrete it.
Is the size of the cell important in cell division.
Yes.
Binary fission explained?
Described as series of steps but is continuous.
Events of cell growth, DNA replication and cell division occur simultaneously.
Also used by some organelles within Eukaryotic cells like mitochondria.
What is the role of FtsZ proteins in binary fissions.
Polymerizes into a dynamic ring (z-ring) that defines the division site, recruits downstream proteins and directs peptidoglycan synthesis to drive constriction and cell division.
Describe the process of budding?
Small bud forms at one end of mother cell.
As growth proceeds size of mother cell remains constant but bud grows.
When bud is same size as mother cell it separates.
Forms of horizontal gene transfer?
Conjugation, transformation and transduction.
Stages in the cell division of Eukaryotes?
Interphase ( G1/G0 + S + G2)
M phase.
Events of interphase?
Most eukaryotic cells are held in G1/G0 phase until instructed to divide.
Mitogens trigger G1 cells to commit to division.
S phase - DNA replication
G2 phase - Gap
Events of M phase?
Nuclear + cell division.
Different for mitosis and meiosis.
How in cell cycle in Eukaryotic cells controlled/checked?
Restriction checkpoint for start.
G2 checkpoint where cell doubles checks duplicated chromosomes for errors to repair.
M phase or spindle assembly checkpoint.
What process is required to maintain a species?
Cell growth/division.
Role of restriction checkpoint?
Where the cell receives the signal to begin growth and division so ensures cell is able to.
Role of the G2 checkpoint?
Ensured that the DNA has been synthesized efficiently with no information missing.
Role of spindle assembly checkpoint?
Ensures that each spindle fibre has a chromatid each and that there is no duplication or missing bits which could has issues.
Formula for exponential growth?
Nt=N02^tf
Process of fragmentation?
Growing chains of filamentous break apart by fragmentation.
Cell divides while trapped in a cell wall structure which each division getting smaller and smaller until the section breaks off.
Process of sporulation?
If nutrients are in low supple and a cell is in unfavourable conditions.
Induces a cell division type called sporulation which is a form of binary fission.
Parent cell duplicates DNA, the chromosomes separate within the cell creating a forespore with parent cell with a septum wall. Cell develops spore coat. Parent cell then breaks open and leaves spore to float.
After a long term spore eventually re-enters cell cycle through germination the binary fission.
