4/14 lecture

Question 1

Summary of “how biology happens” (4 parts)`

Answer 1

organisms and cells respond to signals by changing gene expression; regulatory proteins alter transcription; enzymes are proteins that make or break things; or turn enzymes, transport proteins, or receptors on/ off

Question 2

signal transduction (5 steps)

Answer 2

environmental or developmental signal; receptor; signal transduction pathway; signal transmission; response

Question 3

How does phytochrome change gene expression?

Answer 3

Pfr causes the degradation of the phytochrome interactinf factors (PIFs) in the nucleus

Question 4

what is a repressor?

Answer 4

protein that prevents gene transcription

Question 5

What is an activator?

Answer 5

protein that activates gene transcription

Question 6

what does Pfr express?

Answer 6

Pfr allows “light genes” to be expressed and prevents “dark genes” from being expressed)

Question 7

what is Abcesic acid?

Answer 7

ABA!; hormone that represses germination, causes stomatal closure and senescence

Question 8

What is gibberellic acid?

Answer 8

GA!; hormone that encourages germination and stem elongation

Question 9

How does Pfr effect GA?

Answer 9

it increases GA biosynthesis

Question 10

what is the shade avoidance response?

Answer 10

tall, spindly growth of a plant in response to shade