BIO 141 ch 12 - cell cycle

1. asexual reproduction

   1. the cell can duplicate/reproduce using its own DNA - no outside help

2. growth and development

   1. the cell transfers / copies DNA to the new cell and growth begins

3. tissue renewal

   1. the new cell grows and reproduces tissue

explain three functions of cell division

somatic

• nonreproductive

• 2 sets of chromosomes

gametes

• reproductive [sperm and egg]

• have half as many chromosomes as somatic cells

Explain the difference between gametes and somatic cells.

1. miotic phase

   1. mitosis - division of genetic material in the nucleus

   2. cytokinesis - division of the cytoplasm

2. Interphase

   1. G1 phase

      1. metabolic activity and growth

         1. this is the normal life of a cell

   2. S phase

      1. DNA synthesis - now chromosomes are duplicated

   3. G2 phase

      1. preparation for cell division

list the phases of the cell cycle and describe the sequence of events that occurs during each phase

1. prophase

   1. two centrosomes migrate to opposite ends of the cell - the continue to migrate during prometaphase

2. prometaphase

3. metaphase

   1. the centrosomes are at opposite ends of the cell

4. anaphase

5. telophase

List the phases of mitosis and describe the events characteristic of each phase. Recognize the phases of mitosis from diagrams and micrograph

from the centrosomes at either side of the cell an aster which is short microtubules extended out reaching the sister chromatids

each sister chromatid has a kinetochore which is a structure of proteins associated with specific sections of chromosomal DNA at each centromere

• the microtubules are able to shorten by depolymerizing at their kinetochore ends [ shorten so they bring the sister chromosome to the centrosome ]

Describe the spindle apparatus, including centrosomes, kinetochore microtubules, non-kinetochore microtubules, asters, and centrioles (in animal cells)

1. chromosome replication begins

2. one copy of the origin is now at each end of the cell

3. replication finishes

4. two daughter cells result

in animal cells it is thought that mitosis evolved from binary fission

• in certain unicellular eukaryotes they exhibit types of cell division that seem intermediate between binary fission and mitosis

Describe the process of binary fission in bacteria and how this process may have evolved in eukaryotic mitosis

cyclins and cdks are regulatory proteins involved in cell cycle control

the activity of cdk rises and falls with changes in concentrations of cyclin

cdk must attach to cyclin to be active

MPF is a cyclin-Cdk complex that triggers a cells passage past the G2 checkpoint into the M phase

cdk enzyme is always there but its not always active. as it goes into S phase it starts to accumulate cyclin, then at G2 then you have enough cyclin to bind and becomes MPF and go through mitosis

once mitosis ends, the cyclin gets degraded

Describe the roles of checkpoints, cyclin, Cdk, and MPF in the cell cycle control system

internal

• one example is that cells will not begin anaphase until all chromosomes are properly attached to their spindle at the metaphase plate

external

• can be both chemical and physical influences on cell division

  • growth factor can be released by some cells to stimulate other cells to divide

Describe the internal and external factors that influence the cell cycle control system

cancer cells break the rules of typical density dependent inhibition

• typically crowded cells will stop dividing

also most cells need anchorage dependence to divide - meaning they have to be attached to a substrate

cancer cells need neither of these types of regulation for division

• they go through increased rates of cell division

• they pile up and break the density dependent rule

• they can grow even when growth factor isnt there

Explain how the abnormal cell division of cancerous cells differs from normal cell division. Explain the involvement of receptors. What are the rules that cancer cells appear to break while normal cells follow them.