Cell Cycle and Mitosis Flashcards
Preparing for final
Define Interphase
Cell growth stage where cells increase in size and duplicate DNA in preparation for replication
What are the two parts of the replication stage?
Mitosis and Cytokinesis (meiosis)
What are the 4 phases cell cycle? Which phases are part of interphase?
- G1 Phase
- S phase
- G2 Phase
- Mitosis and Cytokinesis
What happens in the G1 phase? Conditions required to move to next stage? State of DNA
- Growth
- Big cell size, undamaged DNA, favorable environment
- relaxed chromatin (1)
What does the term homologous mean?
Same genes in the same order but the DNA sequence is not identical
What happens in the S phase? Conditions required to move to next stage? State of DNA
- DNA synthesis/replication
- 2 copies of DNA from replication
- relaxed chromatin (1–>2)
What happens in the G2 phase? Conditions required to move to next stage? State of DNA
- More growth, preparation for cell division
- No DNA damage, if environment is still favorable
- relaxed (2)
What is the use of cell cycle checkpoints?
Ensure that cells only move to next phase if everything ready
What happens at the G1/S Checkpoint?
- Is the environment favourable?
- Check for undamaged DNA, is the cell big enough?
if yes move to S phase
G2/M Checkpoint?
- are chromosomes replicated?
-DNA undamaged?
if yes start mitosis
M-Phase Checkpoints
-Are chromosomes attached to spindle apparatus?
-If yes are chromosomes properly segregated?
If yes finish mitosis
What is the G0 Phase?
Mature cells and cells that can’t divide again leave the cell cycle and enter G0 phase
Is chromosome number duplicated in S phase? If not what is?
No, DNA is replicated but chromosome number stays the same.
A cell can be experimentally made top move through the cell cycle more quickly but if it hasn’t passed through the _ phase, then it has no hope for survival?
s-phase because if you have not replicated your DNA then mitosis cannot be an option.
What do we call the protein structure that helps join the mitotic spindle to the chromosome?
kinetochore
What is the difference between mitosis and cytokinesis?
Mitosis is the separation of the DNA and cytokinesis is the division of the rest of the cytoplasm
Mitosis
What is separated in mitosis?
Sister chromatids
First Phase of Mitosis
Prophase
- chromosomes condense and become visible
- nucleolous dissapears
- centrosomes move to opposite sides of the cell
- spindle fibres emerge from centrosmes
- nuclear envelope breaks down
- the sister chromatids coil more tighlty with the help of condesin protein
Second Phase of Mitosis
Prometaphase
- mitotic spindle continues to develop as the microtubules enlarge
- chromosomes become more condensed
- kinetochores appear at the centromeres
- mitotic spindle microtubules attach to kinetochore
Metaphase
- Mitotic Spindle is Fully Developed
- chromosomes are lined up at the metaphase plate
- each sister chromatid is attached to a spindle fiber originating from opposite poles
Mitosis
Anaphase
- condesin protein binding sister chromatid breaks down
-sister chromatids separate at the centromere - sister chromatids (now chromosomes) are pulled to opposite poles
non-kinetochore spindle fibres lengthen, elongating the cell
Mitosis
Telophase
- Chromosomes arrive at opposite poles and begin to decompose (relaxing back int chromatin
- nuclear envelope material surrounds each set of chromosomes
- The mitotic spindle breaks down
Cytokinesis
Animal Cells: a cleavage furrow separates the daughter cells
Plant Cells: a cell plate separates the daughter cells
Mitosis
What is Non-disjunction?
Imporoper separation of chromosomes, usually fatal to both cells but minimal impact to organism.
Haploid Versus Diploid
Haploid: one complete chromosome set / one copy of each chromosome (none homologous chromosomes)
Diploid: Two copies of each chromosome (pairs of homologous chromosomes)
