Midterm 3- Split pea Flashcards
Sensory response pathway of plants
1)Sensory cells perceive a stimulus and transduces the information to an internal signal
2)Cell-Cell Signal released by the sensory cells travels throughout the body
3)Target cells receive the signal and change activity in a way that produces an appropriate response.
Receptor proteins
Detect environmental signals and change shape transferring the signal into an internal signal usually with a hormone
Signal Molecules
Located within the cell and elicit a response when bound to a matching receptor
Two methods of signal transduction
1)Phosphorlaytion, change of ADP into ATP on an associated protein
2)Secondary messengers: Trigger production of release of inter cellular signals that amplify a signal
Different type of response to signals
1)Activate membrane transport
2)Change in electrical potential or Ph
3)Change in gene expression
Phototropisim
Directed movement of plants in response to blue light
Why do plants bend towards blue light?
Blue light triggers the opening of stoma allowing for photosynthesis to occur
Photoreceptors
Receptors that detect blue light and intitate the phototropic response
Coleoptile
Protective sheath that is found on the tip of the plant that promotes the movement of plants towards light
Fritz Went experiment
Use of Mica (horomone blocking) and Agar(Hormone tranducting) in between coleptile and plant, the agar would allow movement to occur where as the mica did not
Auxin
Hormone that signals for plant elongation on the side opposite to detected light, promotes fruit development, leaf and fruit falling, differentiate xylem and phloem as well as vascular cambium, and simulates root growth
Auxin receptors
1)ABP1=Extracellular response
2)T1R1=Intracellular response
Acid growth hypothesis
1)Auxin triggers H+ pumps lowering the Ph to 4.5
2)Lowered Ph triggers expanisins to cut H bonds between cellulose and other cell wall polymers loosening the cell wall
3)K+ wants to restore chemical gradient so moves into the cell and brings water with it, expanding the cell
Role of Red light and Far red light in plants
Red light acts as an on switch for germination and far red light acts as an off switch for germination
Phytochrome and their conformations
Absorbs both red and far red light
Pr: Has absorbed FR light and needs red light, no germination occurs
PFR: Has absored Red light and needs FR light to change back, germination occurs
Etiolation
When no blue light is present then the plant grows extremly long, narrow, thin, and pale to try and break to the light
De-etoliation
Once light levels are sufficient stem growth slows and now energy is invested in chloroplast and leaves
Photoperiodism
Plants internal clock that is controlled by the CO gene, in short day plants they only flower during short days and long day plants only flower in long days
Effect of red and far red on photoperiodism
Red light triggers a daylight response and far red light triggers a night response
Florigen
Flowering horomone
Flowering Locus
Gene that promotes flowering when activated, it triggers the apical meristem to activate and form a flower.
Heliotropism
Tendency for certain plants to track the movement of the sun throughout the day and then reset over the course of the night
Heliotropisim and plant development
1)Tethered stems that cannot response to light photosynthesis less
2)As plant growth slows so did sunlight tracking
3)Auxin is expressed alternating amounts due to gene expression
Gravitropisim
Movement of roots downward in response to gravity
Statolith hypothesis
Hypothesis that states that the movement of roots downward is due to amyloplasts filled with starch, the startch grannuales are heavy and move to the tip of the roots activating pressure receptors
Gravitropisim and Auxin
1)Auxin flows normally untill the root is tipped to one side
2)Gravity sensing cells redistribuste the auxin towards the bottom of the root
3)Change in auxin levels trigger growth on the top side and slow the growth on the bottom side leading to a downward bending of the root
Root vs shoot response of auxin
In shoots the auxin causes the plant to bend towards the light, in the shoot it cause the plant to bend away from gravity
Wind response of plants
Plants produce shorter and stiffer stems in response to proteins produced when wind is detected by the plant
Thigmotropism
Movement in response to touch, tendrils will contact and object and grow towards it (pos) or roots will contact and object and move away from it (neg)
Thigmotropism and Venus fly trap triggering
1) At rest
2)Depolarization from opening of Ca2+ channels
3)Activation of K+ channels to slow depolarization
4)Peak depolarization dominated by K+
5)Initial re polarization due to K+ now moving out of the cell
6)Final repolarization and hyper polarization
7)Further hyper polarization to prevent consecutive firing
Diffrence in plant vs animal action potentials
Plants: Ca2+ and K+ signals, -120mv resting potential, H+ repolarization, slow speed and long cool down
Animal:Na+ and K+ signal, -70mv resting potential, Na+ and K+ repolarization, high speed and fast cool down
Cytokinens
Made in the root meristem and move up the plant, regulate growth by binding receptors that modify the cell cycle
Cell cycle phases
G1 GAP1
S Synthesis
G2 GAP2
M Mitosis
CDC25
Triggers mitosis from the G2 phase via dephosphorlation by CDK
CYCD3
Triggers G1->Sphase via phosphorlation with CDK
ABA
Inhibits growth and seed germination when conditions are unoptimal
Gibberellions
Simulate plant growth and are involved incoverting the endosperm of seeds into sugar
Requirements to trigger plant germination
1)H20
2)O2
3)Warm temperature
4)Damage or tampering of the seed coat
5)Small seeds will need red light
Process of germination triggered by gibberllions
1)Seed absorbs water
2)Gibberellons diffuse to the aleurone layer
3)Amylase is released and breaks down endosperm
4)Sugar is made available for growth
ABA stoma closing
1)ABA reaches gaurd cells inhibiting H+ ATPases
2)Cl- channels open and anions leave
3)K+ follows
4)Water leaves the cell and the guard cells are flaccid and stomata closing
Blue light stoma opening
1)Blue light stimulates photoreceptors allowing H+ to move out fo the cell
2)Cl- and K+ move into cell with water
3)Swollen guard cells
Brassinosteroids
Regulate the growth and plant body size, control cell division and root and shoot growth.
Brassinosteroid receptors
BRI1-Outer plant receptor
BRL- promotes phosphorylation inside of the cell
Ethylene
A gas hormone Involved in fruit ripening, leaf abscission and flower senescence. It converts starch into sugar, breaks down cell walls and chlorophyll
Cellulose microfibrils
Fibres inside of the stomata preventing it from expanding forcing it into the bean shape that is associated with stomata opening.
Four types of Mechanical defence
1)Bark
2)Waxy cuticle
3)Spikes,prickles, and thorns
4)Trichomes
Difference between spines, prickles, and thorns
Spines are modified leaves, Thorns are modified stems to prevent large herbivores, and prickles are modified epidermis that prevents smaller animals from predating on them
Gladular Trichome
Elongated shape that secret compounds like resin or formic acid and histones
Non gladular trichomes
Short and stiff trichomes that can be used to slow down insect movement and prevent proboscis insertion into the plant
Gorgons dewstick adaptation
Has trichomes that secret a sticky resin to attract and trap insects
Peppermint adaptation and Human use
Methol and Menthone repel bugs, humans use it for flavor
Lemon adaptation and Human use
Citrol slows down insect respiration and inhibits their movements and reaction time, humans use it for flavor and as insect repellent
Pine tree adaptation and Human use
Pinene repels insects, humans use it as a solvent and feul
Tanins and Human use
Derived from chloroplasts and inhibits herbivores digestion by binding to digestive proteins. Humans use it as a dye, leather tanning, preserving iron etc.
Pyrethroid and Human use
Found in crysanthmums, prevents the closing of sodium channels in insects, humans use it to treat parasites, pesticide, and mosquito control
Opium, caffeine, nicotine and Human use
Caffine->Nervous system protein disruption
Opium and Nicotine->Blocks firing of action potentials
Humans: Stimulants and pain killers
Stinging nettles adaptation
Injection of formic acid and histones using trichomes that act as hypodermic needles
Inducible plant defences
Defences that only activate when a threat is present