Chapter 12: Cell Cycle Flashcards
Genome
A cell’s DNA
Chromosomes
Structures containing DNA
Chromatin
Entire complex of DNA and proteins that make up chromosomes
Somatic cells
All the body cells except the reproductive cells. 2 sets of chromosomes, one from each parent
Gametes
Reproductive cells. Half the chromosomes of body cells.
Sister chromatids
Joined copies of original chromosome in a duplicated chromosome
Cohesins
Attach sister chromatids along their lengths (sister chromatid cohesion)
Centromere
Region of chromosome where chromatid most closely attached to sister chromatid
Mitosis
Division of genetic material in nucleus
Cytokinesis
Division of cytoplasm
Mitotic (M) phase
Mitosis and cytokinesis part of the cell cycle (shortest part)
Interphase
Longest part of cell cycle (90%). Cell grows and duplicates chromosomes. Divided into G1 phase, S phase, G2 phase
S phase
DNA is replicated
Mitotic spindle
Structure of microtubules, proteins, asters, centrosomes in cell division. Parts of cytoskeleton disassembles to form mitotic spindle
Polymerize
Elongate (microtubules)
Centrosome
Microtubule organizing center in the cell. Duplicates and then moves apart during cell division.
Aster
Radial array of short microtubules extending from each centrosome
Kinetochore
Structure of proteins on each sister chromatid centromere where spindle attaches. Each faces opposite directions. Depolymerizes spindle microtubules
G2 of Interphase
- nuclear envelope
- 2+ nucleoli
- 2 centrosomes
- duplicated, not condensed chromosomes
Prophase
- chromatin condenses
- no nucleoli
- chromosome appears as 2 sister chromatids joined together
- mitotic spindle begins to form (includes asters)
- centrosomes move away from each other (lengthening microtubules)
Prometaphase
- nuclear envelope fragments (microtubules can enter nucleus)
- chromosomes condense more
- each sister chromatid has kinetochore where microtubules attach
- non kinetochore microtubules interact with those from opposite side
Metaphase
- centrosomes at opposite poles
- chromosomes at metaphase plate
- kinetochores attached to kinetochore microtubules from opposite poles
Anaphase
- shortest stage
- cohesins cleaved, sister chromatids detach
- daughter chromosomes move (centromere first)
- non kinetochore microtubules lengthen, kinetochore microtubules shorten
Telophase
- 2 daughter nuclei, nuclear envelope reforms
- nucleoli reappear
- spindle goes away
Metaphase plate
Imaginary plate in cell
Cleavage
Process of cytokinesis
Cleavage furrow
Shallow groove in cell surface by metaphase plate. Caused by contractile ring of actin microfilaments and myosin. Deepens until cell pinched in 2
Cell plate
Coalescence of vesicles from Golgi apparatus in plant cytokinesis. Enlarges until it fuses with plasma membrane and forms 2 daughter cells
Binary fission
Cell division in prokaryotes. Cell doubles in size and divides.
Origin of replication
Spot where (circular) bacterial chromosome begins to replicate. Results in 2 origins. Each moves to opposite ends and continues to replicate.
Dinoflagellate
Chromosome attaches to nuclear envelope (intact). Microtubules pass through nucleus inside cytoplasmic tunnels.
Diatoms and yeast
Microtubules form within nucleus and separates chromosomes
Cell cycle control system
Cyclic molecules triggering/coordinating events in cell cucle
Checkpoint
Control point in cell cycle where signals can regulate cycle
Cyclin
Protein that activates kinases which drive cell cycle. Accumulates through S and G2 phases. Degrades during G1.
Cdk (cyclin dependent kinases)
Kinases that drive the cell cycle
MPF
Cyclin Cdk complex. Promotes mitosis by phosphorylating various proteins. Peaks during metaphase, degraded during anaphase (Cyclin degrades)
G0 phase
Nondividing phase (exit cell cycle). Most cells in humans in this phase.
Growth factor
Protein that stimulates other cells to divide
PDGF (platelet derived growth factor)
Made by platelets. Stimulate fibroblast division. Fibroblasts help heal wounds.
Density dependent division
Crowded cells stop dividing.
Anchorage dependence
Cell must be attached to substratum. Present in many animal cells.
Transformation
Process where cell becomes able to divide indefinitely and behave like a cancer cell
Benign tumor
Tumor that remains at one site
Malignant tumor
Tumor that can spread to new locations
Metastasis
Spread of cancer cells to new locations
