Lecture 13: Cell Cycle and Replication Flashcards
How many phases are in the cell cycle? Name them
- there are four phases
- Mitotic (M Phase)
- Interphase (G1 Phase)
- DNA synthesis (S Phase)
- Cell growth (G2 Phase)
How can you roughly organize the cell cycle phases?
Into M Phase and Interphase (everything between cell division)
When one cell splits, what is the result called?
daughter cells
In how many stages of the cell cycle does cell division occur?
one
Describe G1 Phase
growth after being newly formed, emphasis on obtaining energy and forming protein.
What occurs often in the G1 Phase?
Lots of transcription and translation to make a lot of protein
Describe S Phase
Synthesis phase is when the full genome of the organism is copied
What do you call the copying of the genome?
Replication
Describe G2 Phase
Focuses on further growth and preparation for cell division and production of new organelles and proteins for mitosis
What happens in the M Phase?
Mitosis and cytokinesis
Describe Mitosis and Cytokinesis (General)
when the cell actually splits its DNA copies along the cytosol between the cells
What is the G0 Phase?
a pause to the cell cycle, when they stop growing and just live
How much time can the cell stay in the G0 Phase? Give an example
- they can stay there all of their life
- neurons
Is a cell in the G0 Phase alive?
yes, just not dividing anymore
How do you regulate the cell cycle?
with checkpoints
What do checkpoints in a cell ensure and what does it avoid?
- ensures that it is ready for the next stage
- avoids mitosis without enough DNA, cytosol or organelles
What type of cell doesn’t care for the cell cycle?
Cancer cells
What is replication and what phase does it belong to in the cell cycle?
- replicating DNA
- the S phase
What is replication similar to?
Transcription, but on both strands at the same time
What must always happen in replication?
there must be a permanent separation of two strands of DNA
Is each new DNA molecule completely new?
No, they all have an old half and a new half
How many steps are in replication? name them
- there are two steps
- Step 1: separating the two strands of DNA
- Step 2: use both DNA strands as templates
What does step 1 of replication do to the DNA strands?
a permanent separation
What do the separation stretches create in replication?
The Replication Fork
What is the major protein involved in step 2 of replication?
DNA Polymerase
What does DNA Polymerase do in step 2 of replication?
It attaches to each strand and use it to produce the complimentary strand
What are the strands referred to as in replication? Do they have a difference in speed?
Leading and lagging strands, the leading one is copied faster
Is there only one protein involved in replication?
No, there are many
When can errors occur?
during replication or during the life of the cell
Can errors be passed on to offspring?
Yes, there is a chance, if the mutation is in the gamete
What do you call an error in the genome?
Mutation
Are all mutations fatal?
No, they can be unimportant to survival
What is involved in DNA repair?
Proteins
that find mistakes, remove mistakes and then refill the removed nucleotides
What happens if there isnt any repairs done?
genetic mutations arise
How is the DNA normally organized?
uncondensed in the nucleus, a bundle of 46 DNA molecules
Are the DNA copies identical? What are they called?
No, but they are very similar and are called homologous chromosome
When do the chromosomes compact?
when cell division is about to begin
When are the chromosomes clearly visible?
when the cell division is about to begin
When do you have 92 DNA molecules in the nucleus?
after S phase
how many chromosomes are there after S phase?
46
What are the identical copies called after S phase?
sister chromatids
How many chromosomes are in one X shaped structure seen in diagrams?
2
Define the centromere and where it is located.
A region of a the chromosome where it can attach to its sister chromatid.
What is the kinetochore?
a protein that holds the centromere onto the cell’s microtubules
