Week 5 LS2

Who identified the first growth factors?

Allan Lipton and Nancy Kohler through experiments with blood. It was found that platelets are responsible for blood clotting. So they tried purifying cells with purified platelet proteins. This led to the development of PDGF(platelet derived growth factors)

The CORRECT sequence of steps in the eukaryotic cell cycle is:

G1-->S phase-->G2---> mitosis--->cytokinesis

Which major checkpoint delays the cell cycle when DNA replication is incomplete?

G2

Cells must decide if they should follow through with the cell cycle. They ask themselves if..

Is the cell big enough? Is there room? Growth factors? Is the DNA replicated?

Four events must occur for cell division

Reproductive signal: to initiate cell division Replication: of DNA Segregation: distribution of the DNA into two cells Cytokinesis: separation of the two cells

The amount of _____ is fairly constant throughout the cell cycle, but the amount of _____ varies.

cyclin-CDK complexes are fairly constant.. they are just sometimes inactive The amount of DNA varies

p53

is an example of a tumor oppresor

The CORRECT sequence of steps in the M phase of the cell cycle is:

prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis

A skin cell in G2 of interphase has _____ as much DNA as it had in G1

twice

The S cyclin-CDK complex

controls the cell cycle during S and G2 phase, triggers DNA synthesis during S phase, prevents a second round of DNA synthesis

Which of the following is NOT true about gametes?

True: They have half as many chromosomes as a somatic cell in of the same individual, they are called egg and sperm cells in animals, they are made during meiotic division, they fuse to form a new organism during fertilization NOT TRUE: they are genetically identically to other gametes during meiotic division

In which phase of mitosis do spindle microtubules shorten?

anaphase