Cellular Division Flashcards
What are the reasons (4) that cells divide?
- Reproduction
- Growth and Development
- Tissue Renewal
- Maintain Surface Area:Volume (SA:V) Ratio
What are the 2 main types of cellular division?
- Asexual
- Sexual
What are the 2 types of asexual cellular division?
- Mitosis
- Binary Fission
What is the 1 type of sexual reproduction?
Meiosis
What is the term “Genome” referring to?
The DNA of a cell
What is the chromosome structure of Prokaryotes?
Single circular chromosome
What is the chromosome structure of Eukaryotes?
- Linear chromosomes
- Cells often contain 2 copies of each chromosome
What is the term used to describe when cells contain 2 copies of each chromosome?
Homologous chromosomes
What is a chromosome?
Long strand of DNA wrapped around proteins (histones)
What is the name of the protein that DNA wraps around in a chromosome?
Histone
What is chromatin?
A highly condensed form of DNA (DNA is folded and packed tightly)
What is the role of histones?
This protein associates with DNA and helps it condense into chromatin
There are 3 components of chromosome structure. What are those 3 components?
- Centromere
- Telomere
- Kinetochore
What is the Centromere?
Condensed region of the chromosome
What is the Telomere?
Region of repetitive DNA sequences, located at the end of chromosome
What is the Kinetochore?
Disc-shaped protein that spindle fibers attach to
Chromosomes are duplicated before cellular division creating what?
Sister chromatids
Where are the sister chromatids, created before cellular division, held together?
Centromere
When are the sister chromatids pulled apart?
During mitosis
What form of reproduction is bacterial binary fission classified as?
Asexual reproduction
What are the stages (4) of interphase?
- Gap 1(G1)
- Synthesis(S)
- Gap 2(G2)
- G0(Gsubscript0)
What occurs during G1 of interphase?
Growth, protein synthesis, organelle synthesis
What occurs during synthesis of interphase?
DNA is duplicated
What occurs during G2 of interphase?
Growth, synthesis of microtubules, cell cycle checkpoints
What occurs during G0 of interphase?
Quiescent or “resting” state, cells NOT preparing to divide but they ARE metabolically active
What stage of interphase are the majority of human cells in?
G0
Can some cells be called back?
Yes (liver cells)
How much time does a cell spend in interphase? (percent)
90%
What is Mitosis?
Nuclear division
What follows mitosis?
Cytokinesis
What occurs during cytokinesis?
organelles and cytoplasm divide
How many daughter cells are produced during mitosis?
2
True/False: The 2 daughter cells formed by mitosis are identical?
True
How many phases is mitosis divided into?
5
What are the 5 phases of mitosis?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
What happens during Prophase?
- Chromosomes begin to condense
- Spindle apparatus (MTOC) begins to form
What is the spindle apparatus, formed during the prophase, responsible for?
Pulling apart the chromatids
What is the spindle apparatus composed of?
Microtubules and other proteins
What happens during prometaphase?
- Nuclear envelope disassembles
- Spindle fibers attach to kinetochores
What happens during metaphase?
Chromosomes align along the metaphase plate
What causes the alignment of chromosomes during metaphase?
Tug of war between the 2 poles
What happens during anaphase?
Sister chromatids are cut apart
How are the sister chromatids cut apart during anaphase?
Enzymatically, the cohesion that holds them together are cleaved by enzymes
After the cohesion between sister chromatids has been cleaved during anaphase, how are the sister chromosomes pulled to opposite poles?
The microtubules shorten
What happens during telophase?
- Prophase events are reversed
- Nuclear envelopes reform around DNA
- Chromosomes unfold back into chromatin
True/False: Cytokinesis is a part of mitosis
False
During what phase of mitosis does cytokinesis start?
During telophase
True/False: Cytokinesis has the same process in both animal and plant cells
False (review differences in notes)
Review cell cycle regulation slide in notes.
Review slide in notes.
What are the 2 main regulatory molecules in the cell cycle clock?
- Cyclins
- Cyclin-dependent kinases(cdks)
True/False: Cyclin levels fluctuate cyclically
True
How are cyclin-dependent kinases activated?
By attaching to cyclins
True/False: cyclin-dependent kinases are present at constant concentrations but are usually inactive
True
What is the G1 checkpoint?
“restriction point”-most important in mammals
What happens when a cell receives a green light during the G1 checkpoint?
The cell continues to S phase
What happens when a cell receives a red light during the G1 checkpoint?
Exits the cell cycle and enters G0 phase
What determines whether a cell receives a red light or green light?
Cell size, favorable conditions, DNA damage
True/False: Multicellular organisms do not rely on signals from other cells
False
What are the components (2) of a protein dimer?
Cyclin and cyclin-dependent kinase
Review Anaphase Promoting Complex (APC) slide in notes.
Review in cellular division.
What are the external factors (3) of cellular division?
- Growth factors
- Density-dependent inhibition
- Anchorage dependence