free response exam 3 biol 211

Name two different ways neighboring cells can communicate with each other?

through gap junctions of facilitated diffusion of molecules that trigger cellular responses

Ci.e nitric oxide).

(Paracrine 8 gap junction)

Indicate for each step (write a Y for yes in the appropriate boxes) if it occurs in meiosis I or meiosis I and indicate which of the three steps is responsible for reducing the sets of chromosomes from two to one during meiosis.

crossing over - Y meiosis 1

separation of homologous chromosomes - Y meiosis 1 and reduces chromosome set 2n to 1n

separation of sister chromatids - Y meiosis 2

separation of homologous chromosomes - Y meiosis 1 and reduces chromosome set 2n to 1n

separation of sister chromatids - Y meiosis 2

Draw a diagram of a cell cycle, label each stage.

What is the role of IP3 as a second messenger molecule? Which other second messenger does it activate? How do you think it contributes to the amplification of the signal in the transduction pathway it is involved

1P3 relays the signal from the activated receptor and amplifies it through phosphorylation, triggering a cellular response.

Signal transduction cascades amplify hormonal signals. How does a kinase in a phosphorylation cascade contribute to signal amplification?

Kinase contributes to signal amplification in a phosphorylation cascade by activating move kinase proteins than before in the cascade, yielding a greater signal

explain the difference between oncogene and tumor supressor gene

oncogenes do not regulate cell cycle (cause cancer)

tumor suppressor genes do the opposite

tumor suppressor genes do the opposite

explain how the activity of the MPF factor in cell cycle is regulated

MPF is regulated by the levels of cyclin. Cyclin builds up during the cell cycle and activates MPF, which triggers the cell to enter mitosis. When cyclin breaks down, MPF becomes inactive.

why do x linked recessive disorders more commonly affect males than females

Males only have one X chromosome, so if they inherit an X-linked recessive disorder, they will have it. Females have two X chromosomes, so they usually need two copies of the recessive allele to be affected

define allele

a different version of a gene

how is a homologous chromosome diff from a sister chromatid

Homologous chromosomes - pair of chromosomes, one from each parent, that have the same genes but may have different alleles.

Sister chromatids: Two identical copies of the same chromosome joined together at the centromere

Sister chromatids: Two identical copies of the same chromosome joined together at the centromere