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What is a chromosome?
A structure in cells that contain genetic material and protiens upon which genes are located.
What is cytogenetics?
Special field of genetics involved in the microscopic examination of chromosomes. (ex. Chromosomes in actively dividing cells)
What is a Karyotype?
A method of viewing chromosomes from C1-22 including the two sex chromosomes.
Describe Binary Fission.
- DNA replication
- Cell growth (elongation)
- Segregation of chromosomes
- Cell splitting
- Septum : division site designated by protien FtsZ(equvilant to tubulin in eukaryotic cells)
Describe the G0 phase.
This is the quiescent phase, the cell is arrested in permanent resting state.
- G1 : Increase cell size, RNA, & protiens. 46 Chromosomes.
- S : Chromosomes are doubled. (Sister Chromotids) (92 chromosomes or 42 bivalents)
- G2 : Further cell growth & protien synth.
What happens if checkpoints are broken? Also describe what the break of checkpoint G2 causes.
- Uncontrolled cell division normally follows a broken checkpoint.
- When G2 is broken cancer normally follows.
_____ , part of the mitotic spindle apparatus, are only found in animal cells.
What are the different types of microtubules that make up the Spindle ap. ? (Give a short description of each.)
- Asters : Make sure centrosomes are placed in the correct spots in cell.
- Polar Microtubules : Make the cell elongate so that it can divide.
- Kinetochore Microtubules : attach at the kinetochores.
What is Karyokinesis?
Division of the nucleus.
What takes place in prophase of mitosis?
- Nuclear membrane begins to dissociate into small vesicles.
- Centrosome migrates to opposite poles.
- Mitotic spindles can begin to form.
What happens in prometaphase of mitosis?
- Centrosomes reach the opposite poles.
- All sister chromatics are captured by the kinetochore microtubules from opposite poles.
What happens in Metaphase of mitosis?
- Sister chromotids are pulled in opposite directions by depolarizing kinetochore microtubules.
- Sister chromatics aligned at plate facing opposite poles.
- Polar microtubules are pushing poles apart.
What happens in Anaphase of mitosis?
- Sisters are pulled apart and can now be called chromosomes.
- Depolymerization of kinetochore microtubules pull chromosomes to opposite poles.
What happens in Telophase of mitosis?
- Chromosomes reach opposite poles and decondense.
- Nuclear membrane reforms; two seperate nuclei.
- Nucleolus reappears.
What is Cytokenesis?
Division of cytoplasm.
Discribe cytokenesis in an animal cell.
- Begins shortly after anaphase.
- Cleavage furrow forms. (Contractile ring forms this. Ring is made of myosin motor protiens and actin filaments)
Describe cytokenesis in plant cells.
- Golgi-derived vesicles carry cell wall material to cell plate.
- Vesicles follow tracks of microtubules and actin to site.
- Fusion of vesicles forms plate toward outer walls.