12 Flashcards
What are somatic cells?
All other cells than sex cells
Where does mitosis happen?
Somatic cells
What is a cell’s genome?
All of the generic information packaged as DNA
What are chromatin?
Uncondensed chromosomes
What do chromosomes contain?
DNA and proteins
What do prokaryotes contain concerning chromosomes? (Include the type and quantity)
1 circular chromosome
What do eukaryotes have concerning chromosomes? (Include estimated quantity and type)
They have Multiple linear chromosomes
What are the 4 parts of a chromosome?
- Centromere
- Kinetochore
- Sister chromatids
- Telomeres
What is the centromere?
The part where the sister chromatically are attached most closely
(think of the X shape; this is where the X crosses)
What is the kinetochore?
This is where the spindle fibers attach to the chromosome to split them
What are sister chromatids?
Duplicated chromosomes consist of 2 sister chromatids which are identical to each other
What are telomeres?
Do they get shorter or longer after each duplication?
The ends of the chromosome
They are repeated DNA segments
They get shorter after each duplication
Even though we are done growing, why do cells continue to divide?
Reparative purposes
What are the 2 phases of mitosis?
- Interphase
- Mitotic phase
Is cytokinesis part of the mitotic phase? When does it take place in animals?
- No
- Happens Directly after the mitotic phase in animals
What is the first step of mitosis?
Interphase
What phase are cells usually in?
Interphase
What steps occur in interphase? (Hint: think letters)
G1, S, G2
How many checkpoints are in interphase? What are they?
3
G1, G2, and M
What is the purpose of checkpoints?
They act as stop signals; if something is wrong, they prevent the cell from continuing. They are like checkpoints on a machine or computer 🖥
What are the basic components of G1?
- The cell is growing
- The cell must replicate its DNA and divide
What happens if the cell does not pass G1?
It goes into G0 and never divides in its life (rest state)
What happens in S Phase? What is the purpose?
- DNA synthesis (replication)
This is so that the cell can divide and clone itself
What happens during G2?
- The cell continues to grow
- Prepares for mitosis
- Insures that the DNA is replicated
What is the metaphase checkpoint?
- Occurs after G2 checkpoint
- Checks for Chromosome spindle attachment
What are the 4 phases of the mitotic phase?
- Prophase
- Metaphase
- Anaphase
- Telophase
What 3 steps happen during prophase?
- Chromosomes condense (individual chromosomes are now visible and are no longer a blob)
- Mitotic spindles form
- Nuclear envelope disappears, also nucleoli
When do mitotic spindles form?
Prophase
When does the nuclear envelope and nucleoli disappear?
Prophase
What 3 steps occur during metaphase?
- Kinetochore microtubules attach to Kinetochore as and pull chromosomes to middle of cell
- Non-Kinetochore microtubules don’t connect anything, but elongate the cell
- M phase checkpoint (metaphase) checks to make sure all chromosomes are attached before anaphase begins
What are the 3 steps of anaphase?
- Sister chromatids separate
- Sister chromatids, now separate, become daughter chromosomes
- Daughter cells migrate to opposite ends of the cell
What are the 3 steps of telophase?
- Two separate nuclei form and cell structures begin to form
- Microtubules disappear
- Mitosis complete!
What happens during cytokinesis?
Cell cleavage punches the cell to fork 2. This divides the cytoplasm.
Is cytokinesis part of the mitotic phase?
NO!!
When can the cell enter mitosis?
Only when cyclin is present
What is cyclin?
A family of proteins that control progression of a cell through the cell cycle
What controls the cell cycle?
Protein kinase (also known as Cyclin-Dependent Kinase (CDK)).
What allows the cell to pass the G2 phase and progress to the M phase?
The binding of CDK with cyclin (cyclin must be present).
This is known as the M Phase promoting factor (MPF)
What is the M Phase promoting factor? (MPF)
The binding of CDK with cyclin
What is the purpose of MPF? How does it work?
- Phosphorylates other proteins to initiate the process
- Triggers the breakdown of cyclin, which inhibits another division until DNA replication occurs again
