Phytochrome and Photomorphogenesis Flashcards Preview

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Flashcards in Phytochrome and Photomorphogenesis Deck (58):
1

is as protein pigment that absorbs red and far-red light most strongly, and also blue light

phytochrome

2

each subunit of phytochrome consists of a light absorbing pigment molecule called

chromophore

3

each subunit of phytochrome consists of a polypeptide chain

apoprotein

4

T/F: Phytochrome is a soluble, light-regulated protein kinase, which first auto phosphorylates and then activates other proteins

true

5

In dark-grown or -- plants, phytochrome is present in a red light-absorbing form Pr

etiolated

6

Pr is converted by -- to a far-red light absorbing form, Pfr

red light

7

switching of forms between Pr and Pfr

photoreversibility

8

Pr = red light

650-680 nm

9

Pfr = far red light

710-740 nm

10

Which form is physiologically active?

Pfr

11

-- red:far red ratio → germination. Lets wild seeds respond when they arrive in a forest gap or clearing

high

12

Low red:far red ratio → -- in sun plants

elongation

13

“Etiolation” response involves allocating strongly to --, to escape the shade

long, thin stems

14

-- plants show etiolation response more strongly

Sun-adapted

15

phytochrome regulates - leaf movements (open day, close night)

nyctinastic

16

in legumes nyctinastic movements are caused by rhythmic -- changes in flexor and extensor motor cells int eh pulvinus at the base of the petiole

turgor

17

because red:far red ratio is low under canopies, plants can sense --

green shade

18

domestic plants lose etiolation response so they can be grown in -- without etiolating

high densities

19

floral meristems distinguished from vegetative meristems by their

larger size

20

transition from vegetative to reproductive dev is marked by an increase in -- in central zone of shoot apical meristem

frequency of cell divisions

21

when reproductive dev is initiated, vegetative meristem is transformed into the -- which bears cauline leaves and flowers

primary inflorescence meristem

22

axillary buds of cauline leaves dev into --

secondary inflorescence meristem

23

inflorescence meristem has -- growth

indeterminate

24

flowers have -- growth

determinate

25

floral meristems initiate four organ types in concentric rings called

whorls

26

initiation of -- consumes all of the meristematic cells in the apical dome

carpels

27

specifies sepals

A

28

specifies petals

A + B

29

specifies stamens

B + C

30

specifies carpels

C

31

loss of A

carpels replace sepals, stamen replace petals

32

loss of B

sepals replace petals, carpels replace stamen

33

loss of C

petals replace stamen, new flower replace carpel

34

-- may flower within a few weeks after germinating

annual plants

35

perennial plants (forest trees) take up to -- to flower

20+ years

36

-- and -- is an internal factor controlling the switch to reproductive dev

size or age

37

internal cues

autonomous regulation

38

environmental cues

obligate response

39

promoted by environment but flower w/o

facultative response

40

in many populations of a given species, flowering is -- favoring cross-breeding and allowing seeds to be produced in favorable environments

synchronized

41

gradual change from juvenile to adult accompanied by changes in -- like leaf morphology and phyllotaxy, thorniness

vegetative characteristics

42

shoot dev can be described as a series of independently regulated, overlapping programs which modulate the expression of a common set of processes

combinatorial model

43

dev phase change tends to occur first at the -- of the shoot

base

44

in rapidly flowering herbaceous species juvenile phase is very short

few days

45

once meristem has switched to the adult phase, only adult vegetative structures are produced, culminating in --

floral evocation

46

reversion of adult shoots to juvenile phase

rejuvenation

47

-- cause phase change

gibberellins

48

once adult phase has been attained it is relatively stable and tends to be maintained during vegetative propagation or --

grafting

49

two stages of floral evocation

competence and determination

50

a but is competent if it is able to -- when given the appropriate signal which leads to determination

flower

51

vegetative shoot that is not determined is grafted onto a flowering stock it will

continue in vegetative phase until it achieves determination

52

vegetative shoot that is determined is grafted onto a flowering stock

flower immediately

53

organisms can sense and respond to tome of day by showing -- attuned to light/dark cycles

circadian rhythms

54

internal pacemaker exists such that the cycles can continue in the absence of external cues, in continuous light or darkness

endogenous oscillator

55

three parameters of circadian rhythms

period, phase, amplitude

56

recognizable features, peaks, troughs

phase

57

time between comparable points in cycle, peaks

period

58

in constant light or dark rhythms become

free-running