6.1 The Cell Cycle Flashcards
(30 cards)
Definition of cell cycle
The series of events that take place in a cell leading to its division and duplication
What are the 3 phases of the cell cycle?
Interphase, mitosis, cytokinesis
What are the three stages of interphase?
G1 (growth phase 1), S (synthesis), G2 (growth phase 2)
Where is the majority of the cell cycle spent?
In interphase
What happens during interphase?
-DNA is replicated and checked
-Protein synthesis occurs
-Mitochondria grown and divide
-Chloroplasts grow and divide
-Normal metabolic processes occur
-Cell grows
What happens during G1 stage of interphase?
The cell elongates (increases in size), proteins synthesised, organelles replicate
What happens during S stage of interphase?
DNA is replicated in the nucleus
What happens during G2 stage of interphase?
Cell continues to increase in size (elongate), proteins needed for cell division are made, energy stores increased, DNA is checked for errors
What happens in the mitosis phase?
The division of genetic material, the nucleus divides
What happens during cytokinesis?
The cytoplasms dividing and two separate genetically identical cells are formed
What is the Go phase?
-When the cell leaves the cycle, temporarily or permanently
What are the reasons for a cell being in the Go phase?
-Differentiation: cell becomes specialised to carry out a particular function so it is no longer able to divide
-The DNA of cell is damaged, it is no longer viable, damaged cell can no longer divide and enters a period of permanent cell arrest, most cells only divide a number of times before becoming senescent
-As you age, the number of cells in your body increase, growing number of senescent cells linked to age related diseases eg. cancer, arthritis
-Cells like lymphocytes only enter the cell cycle during immune response
Howe is the cell cycle controlled?
Using checkpoints
What is the role of checkpoints in the cell cycle?
Monitor and verify whether the processes at each phase of the cell cycle have been accurately completed before being progressed into the next phase
What are the different checkpoints?
G1 check point, G2 checkpoint, Metaphase checkpoint (Spindle assembly checkpoint)
Where and what is the purpose of the G1 checkpoint?
-At the end of the G1 phase, before entry to S phase
-Checks for cell size, nutrients, growth factors, DNA damage
Where and what is the purpose of the G2 checkpoint
-End of the G2 phase, before the start of mitosis phase
-Checks for cell size, DNA replication, DNA damage
Where and what is the purpose of the metaphase (spindle assembly) checkpoint?
-At the point in mitosis where all the chromosomes should be attached to spindles
-Checks for chromosome spindle attatchment
Are chromosomes visible in interphase?
No
If cells do not pass checkpoints what happens?
Enters a resting state (Go)
What are the two methods of nuclear division?
Mitosis, Meiosis
What is created through mitosis?
2 genetically identical daughter cells, diploid
What is created through meiosis?
4 genetically variable daughter cells with 1/2 the genetic material/haploid
What are the 3 uses of mitosis by organisms?
-Growth and repair of human cells
-Genetically identical cells
-Asexual reproduction
-Increase in cell numbers
-Embryonic development
