Chapter Three: Cell Division Flashcards
What does mitosis function in?
Growth and repair of body cells
What is the difference between mitosis and meiosis?
Mitosis: produces two genetically identical daughter cells with the same chromosome number (diploid 2n) as the parent
Meiosis: produces gametes (sexually producing organisms) with half the chromosome number (haploid n)
What is the structure of a chromosome?
Highly coiled and condensed strand of a DNA molecule
What does a replicated chromosome consist of
Two sister chromatids, where one is the exact copy of the other. A centromere is a specialised region that holds the chromatids together
What is the cell cycle?
A regular sequence of growth and division
What about the phases of the cycle are crucial to an ogransims growth, development and maintenance?
The rate and timing
What is the phase nerve and muscle cells permanently in on losing the ability to divide?
G0
What are internal regulators?
Proteins which make sure that the cell does not undergo mitosis until certain conditons are met
Give an example of external regulators and what they do in the cell cycle
Proteins such as growth factors speed it up, slow it down, or stop it
What happens between stages of the cycle?
There are checkpoints where specialised proteins assess that the cell is ready to proceed to the next phase
What is G1 or the first gap phase?
The newly divided cell enters this p after mito and during G1 the cell increases in size and prepares to replicate DNA
What is G1 checkpoint?
If the cell is healthy, with enough resources, and undamaged DNA, growth factors stimulate it to proceed to S phase.
If not, the cell dies or enters resting state/G0
What is the S phase?
DNA synthesis through the process of replication
What is S checkpoint?
S phase is continuously monitored for replication errors. If it correctly progresses, growth signals stimulate cell to go to G2
What is G2 or the second gap phase?
Cell has to produce organelles/cellular components that will populate TWO new functioning daughter cells
What is G2 checkpoint?
All chromosomes must be fully replicated with no types of damage. Only then can a cell enter M phase and divide
What happens when errors do, though rarely, occur during division?
Development of cancer
90% of cells life spent in interphase. Which phases make up interphase and what is it, and what is seen?
G1, S, G2
Chromosomes replicate in preparation for division.
1/+ nucleoli become visible but nuclear membrane is intact
What is mitosis?
The division of nucleus
What are the 4 phases of mitosis?
Recall acronym
P rophase
M etaphase
A naphase
T elophase
What are the 5 parts of the Prophase?
1) chromosome stands begin to condense and become visible
2) nuceoli disappear
3) spindle fibres begin to form in cytoplasm, extending from one centrosome to other
4) centrosomes begin to migrate to poles
5) nuclear membrane begins to disintegrate
What are the 3 steps in Metaphase?
1) chromosomes line up in a single file on the equator aka Metaphase plate
2) centrosomes are at opp poles
3) spindle fibres run from centrosomes to centromeres of chromosomes
What happens in Anaphase, the shortest?
1)centromeres of each chromosome begin to separate and spindle fibres pull the sister chromosomes apart
What 3 things happen in Telophase?
1) chromosomes cluster at opp ends and the nuclear membrane reforms
2) supercoiled chromosomes begin to unravel and return to their pre-divisiom condition as long threadlike stands
3) nuclear membrane reforms
