cell division and differentiation Flashcards
what are the 2 main checkpoints in the cell cycle and what are the roles of checkpoints?
- G1/S checkpoint (restriction checkpoint)
- G2/M
Checkpoints aims to prevent uncontrolled division that would lead to cancer, to detect and repair damage to DNA (for example damage caused by UV light)
what are the main components in the cell cycle- draw a diagram
- M phase
- S phase
- G1 phase
- G2 phase
during the m phase what are the events within the cell
- cell growth stops
- nuclear division consisting of 4 stages- prophase metaphase anaphase telophase
- cytokinesis
during the m phase what are checkpoints and phases
- checkpoint chemical triggers condensation of chromatin
- halfway through the cycle, metaphase checkpoint ensures that the cell is ready to complete mitosis
during the G0 phase what are the events within the cell
- cells may undergo apoptosis, differentiation or senescence
- some types of cells such as neurons may remain in this phase indefinitely
what does the g1 checkpoint mechanism do?
- g1 checkpoint control mechanism ensures that the cell is ready to enter s phase and begin dna synthesis
what are the events within the cell during the g1 phase
- cells grow and increase in size
- transcription of genes to make RNA occurs
-organelles duplicate - biosynthesis
what happens during the s phase?
every molecule of DNA is replicated, housekeeping genes are duplicated first due to specific sequence to replication of genes
events in cell during s phase
- dna replicates
- when all chromosomes duplicated, each one consists of a pair of identical sister chromatids
- rapid to reduce chances of spontaneous mutations
what are the events in the cell during G2 phase
- cells grow
what happens at G2 checkpoint
- special chemicals ensure cell is ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and spindle formation
what is mitosis used for
- asexual reproduction
- growth
- tissue repair
what are the main stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
what happens during prophase?
- sister chromatids shorten and thicken as dna supercoils
- nuclear envelope breaks down
- centriole divides and move to opposite poles of the cell
- tubulin threads form between centrioles
what happens during metaphase?
- pairs of chromatids attach to the spindle threads at the equator region
- attach by centromeres
what happens during anaphase?
- centromere splits
- motor proteins pull each sister chromatid to opposite poles
what happens during telophase?
- separated chromosomes reach the poles
- nuclear envelope forms around each new set of chromosomes
- cell starts to split into two (cytokinesis)
what is the significance of meiosis
- sexual reproduction
- creates genetic variation
how does meiosis differ from mitosis
- two divisions (eg prophase 1 and prophase 2)
- during prophase 1 crossing over of the non sister chromatids occurs where non sister chromatids wrap around each other and alleles may become shuffled
- during metaphase independent assortment occurs where homologous pairs of chromosomes are arranged randomly
- during anaphase 1 the crossed over areas separate resulting in allele shuffling
- in telophase 2 four haploid cells are formed
what are the four types of animal tissue?
- epithelial (lining tissue)
- connective tissues
- muscle tissue
- nervous tissue
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