Chapter 11: DNA Replication and Cell Division Flashcards
What is the difference between prokaryotic and eukaryotic cell division?
Prokaryotic Cells: Binary Fission
- cell elongates
- DNA replicated
- call wall and membrane divide
- cell walls close
- 2 new cells (VERY SIMPLE)
Eukaryotic Cells: Mitosis
What are the two main stages in the “Cell Cycle”?
Interphase: cells are growing, replicating DNA, and performing important functions
M Phase: Mitosis and Cytokinesis resulting in 2 daughter cells (much shorter than interphase)
What are the 3 phases of Interphase? What happens during each phase?
G1 Phase:
Gap phase where the size and protein content of the cell increases. Regulatory proteins are made and activated.
S Phase:
Entire DNA content in the nucleus is replicated (DNA is “synthesized”)
G2 Phase:
Cell prepares for Mitosis and Cytokinesis
(G0 Phase: Resting phase. Present in cells that will not divide)
How is the Cell Cycle regulated? What are the “Checkpoints”? What happens if a cell does not pass it’s checkpoint test? What is p53 and why is it so important?
Cyclin-CDK Complexes: Proteins that come and go in cycles. Cyclins activate the Cyclin-Dependent Kinases (CDKs) which promote cell division.
3 Checkpoints:
(G1/S checkpoint,
Intra-S checkpoint,
G2/M checkpoint)
- If cell does not pass:
- “Cell Limbo” if it can be fixed
- “Apoptosis” if problem can’t be fixed. ENSURES THAT A DAMAGED CELL WILL NOT DIVIDE
P53: Negative regulator that is involved in the first checkpoint and is vital for initiating apoptosis (CRUTIAL IN PREVENTING CANCER)
What are Homologous Chromosomes?
Pair of two chromosomes (1 from mom and 1 from dad)
What is the difference between “Diploid” and “Haploid” cells?
Diploid: 2 complete sets of chromosomes
Haploid: 1 complete set of chromosomes
What is the difference between “Autosome” and “Sex” chromosomes?
Autosomes: carry the genes for general body characteristics
Sex Chromosomes: determine an individual’s sex and carry genes for certain sex-linked traits and disorders.
What are the different steps of “Mitosis”? What happens during each step? How is cytokinesis different between animal and plant cells? What are the end results of Mitosis?
PMAT
- Prophase: chromosomes condense and become visible
- Prometaphase: Nuclear membrane breaks down and the microtubules of the mitotic spindle attach to the chromosomes
- Metaphase: Chromosomes (each is a pair of sister chromatids) are lined up in the middle
- Anaphase: Sister chromatids separate and centromeres split as individual chromosomes move apart
- Telophase: Microtubules of the mitotic spindle break down, and nuclear envelopes reappear around chromosomes
Cytokinesis: Contractile ring forms and splits the cell in half (in animal cells). The cell wall is just formed in plant cells.
- TWO IDENTICAL DIPLOID DAUGHTER CELLS
What are the different steps of Meiosis I?
MEIOSIS I
- Prophase I: chromosomes match up with homologous pairs and begin “Chiasmata” (crossing over)
- Metaphase I: Chromosome pairs meet in the middle
- Anaphase I: Chromosomes are pulled apart (instead of sister chromatids)
- Telophase I: Microtubules of the mitotic spindle break down, and nuclear envelopes reappear around chromosomes
- Cytokinesis: Contractile ring forms and splits the cell in half
What are the different steps of Meiosis II?
MEIOSIS II
- Prophase II: Chromosomes condense in both cells
- Metaphase II: Single-file line of chromosomes meet in the middle
- Anaphase II: Unique chromatids are pulled away from eachother
- Telophase II: Microtubules of the mitotic spindle break down, and nuclear envelopes reappear around chromosomes
How is “Meiosis” different from Mitosis?
Only “Germ” (sexual reproduction) cells:
- perform prophase, metaphase, anaphase, and telophase TWICE
- “Chiasmata”
- Results in FOUR UNIQUE HAPLOID CELLS
How is the formation of an “Oocyte” different than “Sperm”?
The cytoplasm divides unevenly in females resulting in an oocyte (immature egg)
In males, the 2 cells divide evenly, resulting in 4 functional sperm cells
Why do we have crossing over?
In order to create gametes that contain new combinations of genes -> GENETIC DIVERSITY
What are “Centromeres”?
The region of a chromosome to which the microtubules of the spindle attach. Centromeres are the specific chromosomal regions that serve as the platform on which kinetochores assemble.
What are “Kinetochores?”
The large protein assemblies that connect centromeres of chromosomes to microtubules of the mitotic and meiotic spindles.
