Lecture 17: Signaling Pathways

a _____ is an external input that initiates a plant response

signal

what is a signal?

an external input that initiates a plant response

the physical component that biochemically responds to the signal is called the ________

receptor

once the receptor senses the signal, it ________ it and ______ it

transduces, amplifies

receptors transduce and amplify signals by modifying molecules called _________

second messengers

________ are molecules that receptors use to transduce and amplify signals

second messengers

hormones are a type of ______ signal

chemical

a _______ is a sequence of processes where an external signal interacts with a receptor, causing a change in a second messenger

signal transduction pathway

whats the 4-step order of a signal transduction pathway?

signal, receptor, signal transduction, response

amplification of a signal can happen via ________ or release of ________

phosphorylation, second messengers

what are the 2 things that can be used to amplify a signal?

phosphorylation, second messengers

give 2 examples of second messengers

Ca2+, ROS

what are the 3 things that could happen to a signal?

be amplified, not be amplified, signal attenuation

process where after a response has been created, feedback mechanisms slow down and reset sensor

signal attenuation

Name the 5 ways that plants can sense their environment

physical, biophysical, biomechanical, metabolic, epigenetic

give an example of a physical way a plant can sense their environment

cell contraction

give an example of a biophysical way a plant can sense their environment

heat stress denaturation

give an example of a metabolic way a plant can sense their environment

ROS accumulation

give an example of a biochemical way a plant can sense its environment

Ca2+ channel proteins

give an example of an epigenetic way a plant can sense its environment

heat altering chromatin structure

receptors are typically made of _____, and usually associated with ______

proteins, pigments

______ modify proteins and lipids by adding a phosphate

kinases

______ are stretch receptors that adjust cell volume and size

mechanoreceptors

toxic byproducts made when plants are stressed

ROS

ROS function like a ______ signal

chemical

when ____ is present, organalles and plasma membranes break down, causing ______

ROS, cell death

ROS are created in a ______ feedback loop

positive

______ can detoxify ROS by taking some of their ______

antioxidants, electrons

give 3 examples of antioxidants

vitamins A, C, E

plants produce antioxidants using ______ or ______

NADPH, NADH

unlike ROS, Ca2+ can directly influence ______

transcription

what are the 4 kinds of signal transduction?

ROS, Ca2+, hormones, transcriptional regulation

when stress on one part of a plant induces changes to the rest of the plant

systemic acquired acclimation

systemic acquired acclimation happens via a self-propagating wave of ______

ROS

WHen a plant is dry, it triggers ____ to accumulate, causing a loss of ______

ABA, tugur pressure

when a plant has heat stress, the _____ become uncoupled, which disrupts ____ flow

photosystems, electron

when a plant has too much salinity, ____ stress causes ___ to accumulate in the cell

osmotic, ions

when a plant is flooded, it reduces _____ levels

oxygen

are hormones a type of secondary signal, or second messengers?

secondary signal

______ hormones influence cells that are far

endocrine

_______ hormones influence cells that are close

paracrine_

_________ hormones influence the same cell it was made in

autocrine

what are 2 things that can cause hormones to be made

environmental input, programmed development

_______ are for being inside the cell, and are fast amplifiers

second messengers

________ are new signals sent out, and includes hormones

secondary signals

ABA in water stressed plants is an example of a secondary signal or a second messenger?

secondary signal

explain how environments can cause stress responses

can disrupt homeostasis, trigger signal transduction pathways, can change gene expression, can cause cell death

ROS and Ca2+ channels are an example of a _______

positive feedback loop

how are ROS and Ca2+ channels intertwined?

ROS opens Ca2+ channels, they activate kinases, kinases make more ROS

Explain how ABA induces stomatal closure.

during drought, ABA accumulates in guard cells, they bind to receptors, makes more ROS, makes more Ca2+, causes ions to leave, causes water to leave, stomata closes