Cell Cycle Flashcards
Chapter 11
What percentage of the cell cycle is interphase?
90%
What are the phases of interphase?
G1 phase, S phase and G2 phase
What are the events of interphase?
The cell grows and replicates both its organelles and its chromosomes.
Mitotic Phase
This involves both mitosis and cytokineses
What are the two types of cell division?
Mitosis and Meiosis
Cytokinesis
Cytoplasm of cell divides into 2 distinct daughter cells
What are chromosomes composed of?
Histones and DNA
What is the structure of chromosomes in G2?
Chromosomes are unwound and consist of two daughter chromatids (2 DNA helices)
Cohesions
Rings that hold sister chromatids together
Codensins
Rings that compress DNA
Nuclear Lamins
Fragments the nuclear envelope to get it out of the way for division
In what phase of mitosis to chromosomes condense?
Prophase
In what phase of mitosis do spindle apparatus form?
Prophase
What is the role of the spindle apparatus?
To move and separate sister chromatids
What phase comes after Prophase?
Prometaphase
In what phase of mitosis does the nuclear envelope break down?
Prometaphase
Where do microtubules attach to chromatids?
Kinetochores
What are kinetochores?
Located on either side of the centromere. Where microtubules attach.
In what phase is the formation of the mitotic spindle complete?
Metaphase
What phase comes after Prometaphase?
Metaphase
In what phase of mitosis do chromosomes line up on the metaphase plate?
Metaphase - Each chromosome is held by microtubules from opposite plates
What phase comes after Metaphase?
Anaphase
In what phase of mitosis do cohesions holding sister chromatids together split apart?
Anaphase
What phase comes after Anaphase?
Telophase
In what phase of mitosis does a new nuclear envelope form around each new set of chromosomes?
Telophase
In what phase of mitosis doe chromosomes decondense?
Telophase
What step comes after Telophase?
Cytokinesis
Cytokinesis
Cytoplasm splits and 2 identical daughter cells are formed.
Centromere
Where the two sister chromatids are joined after DNA replication
What else is duplicated during interphase besides DNA?
Centrioles
Where are centrioles located?
Inside centrosomes.
What is the different between centromeres and centrosomes?
Centrosomes house centrioles and centromeres join sister chromatids
How does cytokinesis in animal cells occur?
A cleavage furrow forms and a ring of microtubules at that size tightens like a drawstring.
How does cytokinesis in plant cells occur?
Vesicles line up in the middle of the cell and fuse forming a cell plate. The cell plate becomes a wall between the two daughter cells.
When do chromosomes become visable?
During prophase when chromatin fibres condense into discrete chromosomes.
In what phase of mitosis are sister chromatids consider full-fledged chromosomes?
Anaphase
During prophase a homologous pair of chromosomes consists of _____.
2 chromosomes and four chromatids
What method to bacteria use to reproduce?
Binary Fission
Progression through the cell cycle is regulated by oscillations in the concentration of which type of molecule?
Cyclins
Epigentic Changes
Changes to histones that affect gene expression
What is the consequences of DNA methylation?
Epigentic Changes
Mitosis Promoting Factor
It has two distinct parts (2 polypeptides): cyclin and cyclindependent kinase (Cdk)
Cdk
kinase, an enzyme that adds a PO4(P for short) from ATP to a protein. Phosphorylation typically activates or inactivates a protein – it activates mitosis proteins.
When is Cdk active?
When bound to cyclin
What protein is the tumor suppressor in G1?
p53 protein
p53 Protein
auses the cell cycle or initiates apoptosis – programmed cell death – if the DNA is physically damaged.
Ubiquitins
small protein that attach to the cyclin subunit and mark it for destruction by proteasomes
