WEEK 2: cell division and differentiation Flashcards
2 types of cell division are?
mitosis and meiosis
Cell division is essential for?
tissue development/growth + restoration/regenration of damaged tissues
cell division can lead to what type of diseases?
neurodegenration, autoimmune diseases, metabolic diseases, cardiovascular diseases, haematological and malignancy
how many chromosomes in the human body?
23
what is a chromatid?
a chromatid is one of two identical halves of a replicated chromosome- they are referred to as sister chromatids
Mitosis
Cell DNA content is duplicated & cell divides into 2 identical diploid daughter cells
Diploid VS Haploid
diploid= paired chromosomes, one from each parent
haploid= single set of chromosomes
Cell Cycle consists of?
Interphase, Mitosis, Cytokinesis
Interphase
cell performing normal function, not actively focused on division, can be indefinite, preparation for mitosis, most cells are in interphase- consists of G1, S and G2 -> end of interphase is preparation for mitosis
Mitosis
replicated chromosomes are separated into new daughter cells, 1-3 hours
cytokinesis
the physical separation into two daughter cells
G1 phase
step between division and synthesis
normal cell function
generation of organelles
8-12+ hours
S phase
- duplication of chromosomes
- DNA replication
- synthesis of histones and nuclear proteins
- centriole replication
- 6-8 hours
G2 phase
- 2 - 5 hours
- final protein synthesis
- cell contents organise for mitosis
G0 phase
- normal cell function
- not preparing for division
Prophase
Early:
- DNA coils and chromatin condenses + nuclear membrane disappears
Late:
- centrosomes migrate to opposite sides of the cell
Metaphase
chromosomes align in the centre and attached to microtubules held by centrosomes (centrioles)
Anaphase
microtubules pull the chromatids away from the centre
Telophase
- nuclear membranes reform
- DNA uncoils
Cytokinesis
- cytoplasmic division of the daughter cells
what are the 3 different checkpoints?
G1 -> S: Is your DNA intact?
G2-> M: Have you completed DNA replication?
Metaphase -> Anaphase: Are all your chromosomes aligned at the equator?
What are cyclins?
they are at the core of regulating the cell cycle and their level of fluctuations determine which part of the cell cycle that the cell enters
Cyclin dependent kinase (CDK)
is an enzyme that plays a crucial role in regulating the cell cycle, they are inactive on their own and need to bind to specific cyclins to function , they help in checkpoint regulation as well as regulate DNA replication
G1 Phase
Cyclin D + CDK2/4/6 + helps in cell cycle entry and progression through G1