Module 5: Cell Signaling: 5 Signaling in Plants

Question 1

Plants coordinate their activities in response to changing conditions of: (3)

Answer 1

• light
• dark
• temperature

Question 2

The plant’s cycle of growth, flowering, and fruiting involves signaling among (what parts of the plant): (3)

Answer 2

• roots
• stems
• leaves

Question 3

Signaling in plants includes understanding how plant cells communicate with one another and respond to __.

Answer 3

light

Question 4

evolved independently in plants and animals.

Answer 4

• Multicellularity
• cell communication

Question 5

Plants and animals share the use of __, __, __, and __ for signaling.

Answer 5

• nitric oxide (NO)
• cyclic GMP
• Ca²⁺
• Rho family GTPases

Question 6

The genome of __ does not encode homologs of the nuclear receptor family, Ras, JAK, STAT, TGFβ, Notch, Wnt, or Hedgehog signaling pathways.

Answer 6

Arabidopsis thaliana

Question 7

The genome of Arabidopsis thaliana does not encode homologs of the __ (8) signaling pathways.

Answer 7

• nuclear receptor family
• Ras
• JAK
• STAT
• TGFβ
• Notch
• Wnt
• Hedgehog

Question 8

Plants do not use __ for signaling.

Answer 8

cyclic AMP

Question 9

• Cell-surface receptors in plants are __. (what type)
• They include transmembrane receptor __.
• These receptors have a __ and an __ . (what domains)

Answer 9

• enzyme-coupled
• serine/threonine kinases
• serine/threonine kinase cytoplasmic domain
• extracellular ligand-binding domain

Question 10

a type of cell-surface receptor in plants.

Answer 10

Leucine-rich repeat (LRR) receptor kinases

Question 11

There are __ (how many) LRR receptor kinases identified in Arabidopsis thaliana, including __, which is part of a cell-surface steroid hormone receptor.

Answer 11

• 175
• Bri1

Question 12

regulate the growth and differentiation of plants

Answer 12

Brassinosteroids

Question 13

The binding of __ to a Br1 cell-surface receptor kinase leads to the __ of specific transcription regulatory proteins.

Answer 13

• brassinosteroids
• degradation

Question 14

• __, also known as __ or __, help to coordinate plant development.
• These are small molecules produced by most plant cells and can diffuse readily through cell walls.
• can act locally or be transported to influence cells located further away.

Answer 14

• Plant hormones
• phytohormones
• plant growth regulators

Question 15

Major types of plant hormones include: (6)

Answer 15

• ethylene
• auxin
• cytokinin
• gibberellins
• abscisic acid
• brassinosteroids

Question 16

• a small gas molecule that plays several roles in plant physiology.
• promotes fruit ripening, leaf abscission, and plant senescence and acts as a stress signal in response to wounding, infection, and flooding.

Answer 16

ethylene

Question 17

Ethylene promotes __, __, and __.

Answer 17

• fruit ripening
• leaf abscission
• plant senescence

Question 18

Ethylene acts as a stress signal in response to __, __, and __.

Answer 18

• wounding
• infection
• flooding

Question 19

In plants, it is located in the endoplasmic reticulum and consists of dimeric, multipass transmembrane proteins.

Answer 19

Ethylene receptors

Question 20

In plants, it has a copper-containing ethylene binding domain that interacts with cytoplasmic regions.

Answer 20

CTR1

Question 21

Ethylene Signaling Pathway:
- __ stimulates the ubiquitylation and degradation of the nuclear transcription regulator __ in proteasomes.
- The binding of __ activates the receptors, altering their conformation, which prevents them from activating certain genes.
- Once released from degradation, __ can now activate the transcription of a large number of __.

Answer 21

• CTR1
• EIN3
• ethylene
• EIN3
• ethylene-responsive genes

Question 22

It promotes growth toward light, upward growth rather than branching out, and downward root growth.

Answer 22

Auxin

Question 23

Auxin is also known as

Answer 23

indole-3-acetic acid

Question 24

Auxin promotes growth toward __, __ growth, and __ root growth.

Answer 24

• light
• upward
• downward

Question 25

- It is involved in the initiation and positioning of various plant structures, aiding in flowering and fruiting. - It influences gene expression by controlling the degradation of transcription regulators.

Answer 25

Auxin

Question 26

stimulates the ubiquitylation and degradation of repressor proteins that block the transcription of auxin target genes in unstimulated cells.

Answer 26

Auxin

Question 27

Auxin stimulates the ubiquitylation and degradation of repressor proteins that block the transcription of __ in unstimulated cells.

Answer 27

auxin target genes

Question 28

Auxin has its transport system within plant cells. The transport system includes plasma-membrane-bound __ and __. (what proteins)

Answer 28

- influx transporter proteins - efflux transporter proteins

Question 29

In the transport system of auxin, it can be distributed asymmetrically in the plasma membrane, affecting auxin distribution within the plant.

Answer 29

efflux transporters

Question 30

- The localization of __ and the direction of __ are highly dynamic and regulated. - This regulation is achieved by controlling the traffic of __. - Auxin also inhibits __.

Answer 30

- auxin transporters - auxin flow - vesicles - root-cell elongation

Question 31

- Light-sensitive proteins are known as __. - These proteins have a covalently attached light-absorbing __, which changes shape in response to light, inducing a change in the protein's conformation.

Answer 31

- photoproteins - chromophore

Question 32

- involved in sensing red light (activates) and far-red light (inactivates). - can phosphorylate themselves and then phosphorylate one or more proteins in the cell. - They translocate into the nucleus and activate transcription regulators.

Answer 32

Phytochromes

Question 33

Phytochromes are involved in sensing __ light (activates) and __ light (inactivates). - can __ themselves and then __ one or more proteins in the cell. - They translocate into the __ and activate __.

Answer 33

- red - far-red - phosphorylate - phosphorylate - nucleus - transcription regulators

Question 34

detected by __ and __.

Answer 34

- phototropin - cryptochromes

Question 35

responsible for phototropism, the tendency of plants to grow toward light.

Answer 35

Phototropin

Question 36

flavoproteins that are sensitive to blue light.

Answer 36

Cryptochromes

Question 37

- These proteins are involved in the repair of ultraviolet-induced DNA damage. - also found in animals and play an important role in circadian clocks.

Answer 37

Cryptochromes