Rebecca DavenportBIOL 140611/14/16Ch 12 blueprint1. Cell cyclea.b. Key roles of cell division:1. Cell division- Replicates entire DNA for daughter cells, the two sets of DNA separate into two daughter cells.ii. Unicellular organisms: reproduces the entire organism iii. Multicellular eukaryotes depend on cell division for1. Development from a fertilized cell2. Growth & Development3. Repairiv. Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division.c. Cell division results in genetically identical daughter cells:i. Mitosis- copy and paste mechanism, so cell division as a form of asexual reproduction, create daughter cells that are genetically identical to parents, called Clones.ii. Cell division results in daughter cells with identical genetic information1. Chromosomes- what DNA molecules in a cell are packaged into.2. Chromatin- are what chromosomes consist of, which condenses during cell division.3.iii. Somatic cells (nonreproductive cells)- have two sets of chromosomes1. Undergo mitosisiv. Gametes (reproductive cells: sperm and eggs)- have half as many chromosomes as somatic cells1. Undergo meiosis v.d. Distribution of chromosomes during eukaryotic cell division:i. They will take their genome (just need one copy of genome), duplicate it, move it to opposite ends of cell so when cell divides in half, each daughter has a copy.ii. When we have just one copy of genome we call them Chromosomes, when we have replicated chromosomes we call them sister chromatins; these are identical, we need them so each daughter cell will have one.e. Mitotic spindle:i. Mitotic spindle: a structure of microtubules (MT) that controls chromosome movement during mitosis; form in the centrosomeii. Spindle includes: centrosomes, spindle microtubules, and asters.iii.f. Phases of the cell cycle:i. Interphase- cell growth & copying of chromosomes, happens before mitotic phase.1. G1 phase (“first gap”)- growth, making proteins to do it’s job.2. S phase (“synthesis”)- replicate DNA.3. G2 phase (“second gap”)- continued growth to prepare for cell division.i.ii. Chromosomes not chromatin^^^iii. Microtubules originate from centrosomes.4. Cell grows during all 3 subphases; chromosomes are duplicated only during the S phase ii. Mitotic (M) phase (cell division)1. Mitosis- the division of the genetic material in the nucleus. i. Happens after interphase. ii. Asexual reproduction. iii. Only has one round of reproduction.iv. Somatic cells.v. Daughter cells will be identical to parents called clones.1. Diploid cell will produce Diploid2. Haploid cell produces haploid2. Prophase- form mitotic spindle moves DNA to opposite ends of cell forming sister chromatins.i. Prometaphase (will be prophase on exam)- nuclear envelope fragments so we can gain access to sister chromatins. 1. Kinetochore microtubules- attached to sister chromatins.2. Non-kinetochore microtubules (Polar)- do not attach to sister chromatins.3.3. Metaphase- all sister chromatins are attached to spindles, lined upneat in the middle called the metaphase plate. i. Sister chromatins are attached via cohesions proteins.ii.4. Anaphase- cohesions are split, chromatins are pulled towards opposite sides of cell, the cell is also elongating.i.5. Telophase- spindle breaks down and nuclear envelope is reformed, DNA uncondenses (spaghetti form).i.6.2. Cytokinesis, the division of the cytoplasm. Happens after mitosis.1. In animal cells- it occurs by a process known as cleavage, forming a cleavage furrow.2. In plant cells-a cell plate forms.3.g. Binary fission in Bacteria:i.h. Control system:i. The cell cycle appears to be driven by specific chemical signals present in the cytoplasmii. The sequential events of the cell cycle are directed by a distinct cell cycle controlsystem, which is similar to a clockiii. The cell cycle control system is regulated by both internal and external controlsiv. The clock has specific checkpoints where the cell cycle stops until a go-ahead signal is received (G1, G2, and M phases)v. Cancer cells manage to escape the usual controls on the cell cycle vi.i. Cell cycle clock:i. Two types of regulatory proteins are involved in cell cycle control: cyclins and cyclin-dependent kinases (Cdks)1. They check status internally of cell.2.ii. The activity of a Cdk rises and falls with changes in concentration of its cyclin partner.iii. MPF (maturation-promoting factor) is a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phaseiv. Stop and go signs: internal and external signals at the checkpoints1. Many signals registered at checkpoints come from cellular surveillance mechanisms within the cell2. Checkpoints also register signals from outside the cell3. Three important checkpoints are those in G1, G2, and M phases!!4. For many cells, the G1 checkpoint (restriction checkpoint) seems to be the most important!!!5. If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the S, G2, and M phases and divide6. If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a non-dividing state called the G0 phasev. Loss of cell cycle controls in cancer cells:1. Cancer cells do not respond normally to the body’s control mechanisms2. Cancer cells may not need growth factors to grow and divide3. They may make their own growth factor4. They may convey a growth factor’s signal without the presence of the growth factor5. They may have an abnormal cell cycle control system6. A normal cell is converted to a cancerous cell by a process called transformation7. Cancer cells that are not eliminated by the immune system form tumors,masses of abnormal cells within otherwise normal tissue8. If abnormal cells remain only at the original site, the lump is called a benign tumor9. Malignant tumors invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form additional
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