Karteikarten
Tutorial 3- Cell Cycle and Mitosis
Karten in diesem Stapel (46)
- 1What is the genetic information in the nucleus in the form of?Chromatin
- 2What is chromatin?Ribbon like strands of DNA and a class of packaging proteins called histones
- 3What are the chromatin threads like between divisions?Long and randomly tangled
- 4What are the chromatin threads like when a cell divides?Shorter and very highly folded, and become visible in light microscopes as chromosomes
- 5What is apoptosis?Programmed cell death.
- 6What controls apoptosis?The activation of 'suicide genes' and bcl-2 prevents apoptosis
- 7What is interphase?When the cell isn't dividing
- 8What is the mitotic phase?When the cell is dividing?
- 9What happens to the cell in interphase?The cell grows and prepares itself for division
- 10What are the different phases of interphase?G1 phase, S phase ad G2 phase
- 11What does it mean if an interphase cell is in G0?The cell is not diving or preparing to divide. Most muscles cells and neurones are in this phase.
- 12What happens in G1 phase?Protein synthesis, vigorous growth, most of the organelles are duplicated and centrosome replication begins
- 13What happens in S phase?DNA replicates, synthesis of histones and assembly of new chromatin
- 14What enzyme catalyses the process of DNA replication?DNA polymerase
- 15What happens in G2 phase?Synthesis of enzymes and proteins essential for cell division, their transport to final site and replication of centrioles complete
- 16What are the four phases of the mitotic phase in the correct order?Prophase, metaphase, anaphase and telophase
- 17What happens in prophase?Chromatin coils and condenses into chromosomes. The nucleoli disappear and cytoskeletal microtubules disassemble. Centriole pairs separate and move to opposite ends of the cell due to the growth of new microtubules forming the mitotic spindle.
- 18What does a chromosome consist of?Two identical chromatids held together at a point called the centromere
- 19Why do the chromosomes condense?To prevent them tangling during mitosis
- 20What is needed for spindle attachment?Kinetochore
- 21What happens in metaphase?Chromosomes undergo maximum coiling and arrange themselves along the middle of the cell with the centromeres aligned at the equator of the spindle
- 22What happens in anaphase?The kinetochore of each chromatid splits. The separated chromosomes are now termed as daughter chromosomes and they move towards poles due to interaction between kinetochore and microtubules.
- 23What happens in telophase?Begins after identical sets of chromosomes are at the opposite poles. Chromosomes uncoil and transform into chromatin. Nuclear envelope reforms around the chromatin mass. Nucleoli reappear and spindle disappears. This is the end of karyokinesis (nucleus division)
- 24Which is the longest sub phase of mitosis?Prophase
- 25—Metaphase
- 26—Telophase
- 27—Anaphase
- 28—Prophase
- 29What happens in cytokinesis?The cytoplasm develops a cleavage furrow that deepens, finally separating the two daughter cells, each with the same complement of chromosomes as the parent cell.
- 30When does cytokinesis occur?It starts during late anaphase and continues through telophase and beyond.
- 31How is cell density controlled?Cell growth and division, cell death (apoptosis) and G0 phase
- 32What regulates the initiation of cell growth?Cyclin dependent kinases (Csk's)
- 33How are cyclin dependent kinases switch on and off?The presence of cyclin
- 34What are cell checkpoints ?Control mechanisms that ensure the reliability of cell division. They verify whether the processes at each phase of the cell cycle have been accurately completed.
- 35What happens at the restriction point at the end of G1?Cells that should cease division exit the cell cycle and enter G0
- 36How do continually dividing cells overcome the restriction point at the end of G1?Growth factor induced expression of cyclin D proteins
- 37How does the restriction point at the end of G1 prevent cell division?By the action of CKI p16 & p21. they inhibit CDK4/6 so it can no longer interact with cyclin D1 to cause cell progression.
- 38How do active CDK4/6-cyclinD complexes allow G1-S phase transition?The phosphorylate the tumour supressor Rb, which relieves the inhibition of transcription fcator EF2. EF2 can then cause expression of cyclin E, which interacts with CDK2.
- 39Where is the second checkpoint located?At the end of G2 phase, triggering the start of M phase
- 40When does the mitotic spindle check point occur?The point in metaphase where all the chromosomes should be aligned at the mitotic plate and be under bipolar tension.
- 41How does the mitotic spindle checkpoint work?The tension created by the bipolar attachment is what is sensed, which initiates the anaphase entry
- 42How do tumours occur?The loss or damage of tumour suppressor genes or the activation of proto-oncogenes
- 43What effect do mitotic inhibitors have?Affect microtubules in metaphase of the cell cycle
- 44What are mitotic inhibitors used for?They are used to treat tumours but the also kill other rapidly dividing cells such as hair.
- 45What are telomeres?Caps on the end of chromosomes.
- 46What happens to telomeres in replication?They decrease in length every time
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- Biology- Semester 1 (Tutorial 3- Cell cycle and Mitosis) Karteikarten am Tutorial 3- Cell Cycle and Mitosis , erstellt von emma_moran am 01/01/2014.
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