BSI Lecture 20 Cell Cycle Flashcards
How does APC trigger anaphase?
Ubiquitilate of securin
How does activation of the APC complex lead to separation of the sister chromatids?
The APC complex causes ubiquitylation and degradation of securin, activating ubiquitin separase, which separates the chromatids
DNA Replication; what are the 3 steps?
1) Unzipping
2) Complementary base pairing
3) Sugar-phosphate backbone formed connecting nucleotides in the 2 new strands
Segregation of the sets of chromosomes to opposite ends of the spindle occur in which phase?
Anaphase
Nucleus expands and chromosomes decondense to interphase state, what phase does this occur in?
Telophase
Assembly of contractile ring necessary for cytokinesis occurs in which phase?
Telophase
Which enzyme replicates DNA?
DNA Polymerase
What are the phases of mitosis?
Prophase Prometaphase Metaphase Anaphase Telophase
What are the two general phases of the cell cycle?
Interphase and M-phase
Interphase consists of which phases?
G1, S, G2
Where on the chromosomes are kinetochores located?
On the centromeres of sister chromatids
What is cytokinesis?
Division of cytoplasm (including all organelles) by the contractile ring which pinches the two daughter cells part.
How is APC activated?
M-Cdk phosphorylates APC, then Cdc20 binds to APC, activating it.
Give two examples of cell types that remain in G0 permanently?
Differentiated nerve and muscle cells.
Replicated chromosomes condenses in what phase?
Prophase
T or F? The nuclear envelope is still intact during prophase.
True
Nuclear envelope breaks down during which phase?
Prometaphase
_______ are protein complexes which assemble on the condensed chromosomes.
Kinetochores
How many chromosomes are copied?
46
In what phase do the sister chromatids separate?
Anaphase
Mitosis and cytokinesis are a part of which phase?
M-phase
What occurs in G1 phase?
Cell growth (organelles)
What event occurs during S phase?
Replication of genome (DNA synthesis)
What proteins bind together the sister chromatids?
Cohesin
What occurs during G2 phase?
Cell growth (produces proteins and enzymes necessary for cell division)
What is mitosis?
Nuclear division
What is the mitotic spindle?
Microtubules that extend from centrosomes and bind to the kinetochores
What are kinetochores?
Kinetochores are protein complexes which assemble on the condensed chromosomes.
What phase(s) of M phase does cytokinesis occur?
Begins in anaphase and is complete by the end of telophase
What is the function of the contractile ring and what is it composed of?
Contractile ring is composed of actin and myosin filaments which pinch the cell in two. This divides them into two daughter cells, each with one nucleus.
Describe G0 phase.
Cells that remain in G1 phase for long periods of time or permanently.
Some cells remain in this phase for long periods of time or permanently is then called _______
G0
Centrosomes start to move to the opposite sides of the nucleus occurs in what phase?
Prophase
_____ shoots out microtubules to form mitotic spindles.
Centrosomes
Nuclear envelope breaking down allows the spindle microtubules to contact the condensed ________
Chromosomes
Microtubules binds to _________ located at centromeres of sister chromatids
Kinetochores
Mitotic spindles gathers all the chromosomes to the _____ of the spindle.
Center (equator)
The phase when two sister chromatids in each replicated chromosome synchronously split apart.
Anaphase
What draws the sister chromatids to opposite poles of the cell?
Spindle fibers
______ begins abruptly with the release of the linkage that hold the sister chromatids together.
Anaphase
Chromatids are pulled to the spindle pole to which it is attached occurs in which phase?
Anaphase
Nuclear envelope reassembles around each of the two sets of separated chromosomes to form two nuclei, this occurs in which phase?
Telophase
Division of the cytoplasm (including all organelles) by contractile ring which pinches the two daughter cells apart is what process?
Cytokinesis (Cytoplasmic Division)
What begins in anaphase and is completed by the end of telophase?
Cytokinesis
What can promote cell division?
Growth factors
