4.6-7: Cell Cycle (mitosis) Flashcards
The cell division process is an integral part of life. What does it allow for?
- the reproduction of cells, growth of cells, and tissue repair
What is the cell cycle?
The life of a cell from its formation until it divides
Before cell division, cells must organize and package their DNA. Explain this process. (4 steps)
- DNA associates with and wraps around proteins known as histones to form nucleosomes
- strings of nucleosomes form chromatin
- when a cell is not actively dividing, chromatin is in a non-condensed form - After DNA replication, chromatin condenses to form a chromosome
- Since the DNA was replicated, each chromosome has a duplicated copy. So the copies join together to form sister chromatids
What is a centromere?
The region on each sister chromatid where they are mostly closely attached
What is a kinetochore?
Proteins attached to the centromere that link each sister chromatid to the mitotic spindle
What is a genome?
- all of a cell’s genetic information (DNA)
What is the genome for prokaryotes? (Ex. Bacteria, archaea)
Singular, circular DNA
What is the genome for eukaryotes? Or like, how many chromosomes etc. (2)
- one or more linear chromosomes
- every eukaryote has a specific number of chromosomes
Ex. Humans 46, chimps 48, elephants 56
What are homologous chromosomes? Give an example
- carry the same genetic trait, but aren’t identical
Ex. You inherit one copy of chromosomes from mom, and a copy from dad. Both coded for eye colour, but your mom had brown, dad had blue
What are the two types of cells?
Somatic and gametes
What are somatic cells? How do they divide? (5)
- body cells
- Diploid (2n) where n represents the # of unique xmes
— 2 set of xmes, one set from each parent - divide via mitosis
Humans: 2n = 46, 23 From mom and 23 from dad
What are gametes? How do they divide? (4)
- reproductive cells (egg/sperm)
- Haploid (n) so one set of xmes
- divide my meiosis
- humans: n= 23
The cell cycle consists of alternating phases of ___
Interphase and mitosis
Show a line diagram of the cell cycle. Include interphase and it’s phases, mitosis, and cytokinesis.
Interphase (oG1 → S → G2) → mitosis → cytokinesis
What is interphase? What percentage of the cell cycle does it take up?
- The largest portion of the cell cycle (90%)
In order, what are the phases in interphase?
- G1 “first gap” phase
- S “synthesis” phase
- G2 “second gap” phase
What is G1 “first gap” phase of interphase?
The cell grows and carries out normal functions
What occurs in S “synthesis” phase of interphase?
DNA replication and chromosome duplication occurs (single stranded xmes become double stranded sister chromatids)
What occurs in G2 “second gap” phase of interphase?
Final growth and preparations for mitosis
What occurs in M phase? Remember interphase → mitosis → cytokinesis pathway. (3)
Mitosis: nucleus divides
- mitosis results in 2 identical diploid daughter cells
Cytokinesis: cytoplasm divides
What are the 5 stages of mitosis?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase and cytokinesis
What are the key events in prophase? (5)
- Chromatin condenses
- Nucleoli disappear
- Duplicated chromosomes appear as sister chromatids (they are identical)
- Mitotic spindle begins to form
- Centrosomes move away from each other
Chromatin condenses in prophase. What does that mean?
- DNA becomes tightly wound around histones to become chromosomes
What are the key events in prometaphase? (2)
- nuclear envelope fragments (breakdown)
2. Microtubules enter nuclear area and some attach to kinetchores
