PLANTS
Chapters 9, 32
PHOTOSYNTHESIS:
Biological process that captures light energy and
transforms it into the chemical energy of organic
molecules, which are manufactured from CO2 and H2O
PHOTOSYNTHESIS EQUATION:
/enzyme
• *Very little glucose is
stored in plants
• Mostly find sucrose
• and starches in plants
3Co2 + 3 H20
C3H6O3 + 3 O2
CELLULAR RESPIRATION EQUATION:
+ enzyme
+ ATP
FYI…
• *Very little glucose is stored in plants;
Mostly find sucrose and starches in plants
Review…
Dehydration
Synthesis
Glycosidic
Linkages
?
Alpha/Beta Linkages?
Starch/cellulose?
?
“Flipped chimneys” *H-bonds
Ecology-Food Web/Trophic Connection
Major Photoautotrophs?
Plants, Algae/Phytoplankton, Cyanobacteria (~2.6bya)
“The Cycle of Life”
Stages of Photosynthesis
• STAGE 1: Capturing Light Energy (Light Reactions or Light
Dependent Reactions)…on the Thylakoid Membrane
• Energy is captured from sunlight (chloroplasts)
• Stage 2: Using Light Energy to make ATP and NADPH
• ATP = Major Energy Molecule
• NADPH = Energy Carrier
• Supplies energy needed to drive Stage 3
• Thylakoid Membrane
• Stage 3: Calvin Cycle
(‘Dark’ Reactions or Light Independent Reactions)
• The ATP and NADPH are used to power the manufacture of energy-rich
carbohydrates using CO2 from air…..Stroma of the chloroplast
Stage 2
• 3 Double–Membrane Organelles?
• Chloroplast, Mitochondria, Nucleus
Stage 3
*Double
Membrane:
Chloroplast
and
Thylakoid
STROMA
• The innermost membrane of the
chloroplast is called the thylakoid
membrane. (*double membrane)
• The thylakoid membrane is folded
upon itself forming many disks called
grana (singular = granum).
• The "cytoplasm" of the chloroplast is
called the stroma
Purpose: Convert solar energy to chemical energy
Properties of Light
p192
• Light: travels as packets of energy (wavelengths)
from?
• Sunlight: in as UV, out as IR
Optical = Visible, what is seen?
• Visible Light Absorb vs Reflect: Black? White?
Plants: Absorb (ROYBIV) vs reflect (G)
Chlorophyll - #1 Pigment-green, Carotenoids- yellow, orange, red
Chlorophyll Absorbance Spectrum
•
•
•
•
Pigments: light harvesting molecules on the thylakoid membranes
Each pigment absorbs a different type of light; plant utilizes a much wider range
In green plants, the primary photosynthetic pigments are Chlorophylls a & b.
*Carotenoids: Deciduous trees, Ripe fruit (Oranges, tomatoes, bananas)
Englemann’s
Experiment
1883
•
Aerobic
Bacteria- concentrate
near an O2 source
Alga
Control group?
Photosynthesis: Harvesting Light EnergyThe Thylakoid
Animation
(Notes)
Stroma: Outside Thylakoid
+ +
+
ADP + P1
4
+
+
1
+
3
5
+
+
NADPH + H
NADP+
2H+
1
2- (P700)
+
+
+
+
+
+
Inside the Thylakoid
+ + +
+
+
1. PSII, PSI
2. Reaction Centers: Chlorophyl a (Primary Pigment)
3. Proton Pump
4. ATP Synthase (Carrier Protein, enzyme)
5. Electron Carriers- Membrane Proteins
The Light Reactions
+
+
ADP + P1
+
+
+
+
NADPH + H
+
+
+
+ Chemiosmosis
1• Light energy absorbed by all pigments in PSII is funneled down to the reaction
center (P680- chlorophyll a); electrons so excited, the pair ‘jump ship’oxidation occurs as e -’s enter the ETC. “Bucket Brigade”
*H2O oxidation
2• e-’s power the proton pump- move protons from low (stroma) to high
concentration (thylakoid lumen); still enough energy to reach PSI > P700; gives
up its e-’s to an electron acceptor…..> stroma; attracted to p + NADPH formed.
3• Need -ATP synthase: ‘tunnel’ for protons to move from high>low (to stroma),
and as an enzyme for ADP > ATP ATP + NADPH “Energy on Hold” for Stage 3
Where does the Oxygen come from?
2H2O
enzyme
‘Photolysis’: The light
splitting of water
4e- + 4p+ + O2
(1 molecule of Oxygen)
Two Possible Routes For Electron Flow in LR:
Cyclic vs Noncyclic Flow
*Notes, Text p200
Primary
Acceptor
(Reduction)
Primary
Acceptor
(Oxidation)
Cyclic vs Noncyclic
Noncyclic (Pictured above)
Cyclic
PSI and PSII (P680 & P700)
PSI only (P700)
Passes e- from H2O to NADP+
Electrons cycle through the system
Generates ATP (chemiosmosis), NADPH
and O2 (from H2O)
ATP (chemiosmosis)
Purpose of Cyclic: Possibly Back Up Plan? Efficiency? ‘Ancient ‘starter’ version?
THE CALVIN CYCLE: STEP 3
Light Independent
• ‘CYCLE’ RULES:
• Need an acceptor
molecule (RuBP- 5C
molecule the ‘welcoming
committee’) and it needs
to be replaced
RUBISCO
• And rubisco enzymecatalyzes the reaction-.
**Need 3 molecules of CO2
to make G3P
*On a global scale,
photosynthesis makes about
160 billion metric tons of
carbohydrate per year. No
other chemical process on
Earth is more productive or
is as important to life.
PGA- an acid
*Produced
Stage 2
*Produced
Stage 2
PGAL/G3P
(G3P)
Net Gain of 1
G3P(PGAL)
Text p203 Notes p6
Chemiosmosis in Mitochondria and Chloroplasts
PHOTOSYNTHESIS vs CELLULAR RESPIRATION
*SITE of PHOTOSYNTHESIS > Chloroplasts
*SITE of CELLULAR RESPIRATION > Mitochondria*
PHOTOSYNTHESIS
CELLULAR RESPIRATION
Endergonic- energy required to
reduce CO2
Exergonic- energy released from
oxidation of sugar
Light energy source > boosts energy
e’s as they move from H2O to sugar
e-s from sugar’s hydrogen atoms lose
energy as NAD+ transports them to
O2 > H2O
e-s transferred from H2O > CO2
reducing it to sugar
O2 “pulls” e-s down the ETC
NADPH receives e-s from ETC
NADH delivers e-s to ETC
*PHOTOSYNTHESIS is a REDOX REACTION
PHOTOSYNTHESIS
Photosynthesis 12.27
Light Reactions
Calvin Cycle Reactions
Occurs in thylakoid membrane
Occurs in stroma of chloroplast
Powered by light energy
Powered by energy from ATP
Chlorophyll absorbs light energy
in PSI and PSII
CO2 taken in from environment
H2O taken in from environment
Rubisco (Enzyme) catalyzes
reaction to incorporate CO2
Light energy splits H2O
H2O
2 H+ + 2 e- + ½ O2
(2p+)
CO2 + RuBP
CO2 Fixation
6-carbon sugar
Immediately
Oxygen is released into environment
3-C acid
3-C acid
Electrons (e-) enter ETS
(pump p+ inside thylakoid membrane)
ATP from L.R. provides energy
ETC powers (chemiosmosis
ATP)
(p+ diffuse along concentration gradient
through ATP synthetase enzyme complex in
thylakoid membrane: ADP + Pi
ATP)
H+ + e- + NADP
NADPH
NADPH provides H to form sugars
PGAL = 1st 3-C sugar
*PGAL: 1. replenishes RuBP
2. used to form lipids, proteins
3. Used to form glucose > sucrose > starches
Tissue Systems, Tissues and Cell Types
• DERMAL: Epidermis, Periderm ‘derm’
• Protection, Stomata Regulation
• VASCULAR: Xylem, Phloem
• Conduction, support, storage
• GROUND: Parenchyma,
Sclerenchyma, Collenchyma ‘chyma’
• photosynthesis (*Parenchyma)
• Support (Collenchyma, Sclerenchyma)
Text p703 Table 32-1
Anatomy of a Plant Leaf
• STOMAunderside of leaf
(aka stomate, stomata)
Mesohyll
• GUARD CELLS
• MESOPHYLL LAYER:
Photosynthetic cells
• VASCULAR TISSUE:
• XYLEM: Wider Diameter/Water up
• PHLOEM: tubes from leaves to the rest
of the plant
• XYLEM
• System of tubes and
transport cells that circulate
water and dissolved
minerals (up from roots)
• Support
• Dies after one year and then
develops new.
• Rings of a tree
VASCULAR SYSTEMS
*Not Circulation
• PHLOEM
• System of tubes that
transports sugars and other
molecules created by the
plant from photosynthesis
• Always alive
• The dripping sap from a
tree usually phloem
PHOTORESPIRATION
• The process that reduces the efficiency of
photosynthesis in C3 plants during hot spells in summer;
requires O2 and produces CO2 and H2O- does NOT
produce ATP
Evolutionary? (When high CO2 and low O2); GMO’s?
• When stomates open, CO2 enters; is available to chloroplasts
• When stomates close to conserve water, CO2 exchange is shut off
• Chloroplasts still photosynthesizing, leading up to a buildup of O2.
• Rubisco enzyme binds to O2 (like it does to CO2) -stops the food
making.
• Plants go into a dormant-like state.
C3
• Anatomically the
same (both have
Mesophyll cells to
store CO2
• Physiologically
different- CAM
• Most Plants
plants keep their
• Stomata open during the
stomates
CLOSED
day.
• during
Photorespirationthe day, slows
sugar at
production
open
night.
(Rubisco grabs O2 not
• Not
CO2)as efficient, but
• CAM
More plants
efficientcan
in cool/
moist/low
survive
inlight
harsh
conditions than
C4 or
conditions
(Desert)
CAM (less machinery,
less energy required)
(Add to Notes P-13)
C4
• Corn, Sugarcane, Crabgrass
• Stomata open during the
day.
• Special enzyme for fast
uptake of CO2
• Faster photosynthesis than
C3 because CO2 then
delivered direct to Rubiscostops photorespiration
• Can close stomata sooner/
Fast CO2 uptake
CAM
• Cacti, Orchids, pineapples
• Stomata open at night- less
transpiration.
• Stores CO2 taken in at night
as an acid, breaks it down to
CO2 as needed.
• “CAM-idle” –Dry spell- close
stomata night and day- O2
used for respiration, CO2 for
photosynthesis
• Recover quicker from dry
spells than plants that go
dormant
ROOT
FUNCTIONS
1. Anchorage
2. H2O and Mineral
Absorption
3. Food Storage
4. Tap Roots vs
Fibrous Roots
Chapter 35
p748
“TACT”
Transpiration
Adhesion
Cohesion
Tension
TENSION COHESION MODEL
1.1.
• Water vapor transpires from the
surface of leaf mesophyll cells to
the drier atmosphere through
stomata.
• This produces a tension that
pulls water out of the leaf xylem
toward the mesophyll cells
2.
• Cohesive forces (water
molecules- H bonds)allow
columns of water to be pulled
up through the xylem
Text p741, Figure 34-11 Lab Question #6,7
3.
• This in turn pulls water up root
xylem, forming continuous
column of water from root
xylem to stem xylem to leaf
xylem. The upward pull of
water causes soil water to
diffuse into root.
Water
Potential
and
Transpiration
Translocation in phloem
The pressure
flow hypothesis
In Phloem. Solutes move
from sources to sinks
• At source cell (leaf), sucrose is
actively moved into phloem sieve
tubes (*requires ATP)- reducing
their water potential….
• Water diffuses in from xylem,
raising the osmotic pressure in
the sieve tubes, increases turgor
pressure
• At sink cell (root), sucrose is
actively and passively unloaded
into the sink cell (*requires ATP)
• Water diffuses back into the
xylem
Text p743, Lab question #4-5
Factors Affecting Rate of Photosynthesis:
• Light intensity
increases, the rate of
photosynthesis
increases.
• At high light
intensities the rate
becomes constant,
even with further
increases in light
intensity there are no
increases in the rate.
• The plant is unable to
harvest the light at
these high intensities;
chlorophyll system
can be damaged by
very intense light
levels.
• Why different rates?
(Which is C3, C4?)
Light Intensity:
C3 shade plant vs C3 sun plant vs C4?
Factors Affecting Rate of Photosynthesis:
• TEMPERATURE:
• (a) Increasing rate of
photosynthesis as the kinetic
energy of reactants increases.
• (b) Maximum rate of reaction of
photosynthesis at the 'optimal'
temperature.
• (c) Decrease in rate of
photosynthesis as the enzymes
become unstable and denature.
Factors Affecting Rate of Photosynthesis: CO2
*Very much like the effect
of a substrate on the rate
of a reaction.
(a) O2 is used up- no
photosynthesis; only
respiring.
(b) Concentration of the
CO2 (substrate) increases,
rate of reaction increases.
(c) The atmospheric levels
of CO2 and the associated
rate photosynthesis.
(d) Maximum rate of photosynthesis.
(e) There is a range of values for different plants reaching their
saturation level with carbon dioxide. Once the saturation level has
been reached- no further increase in the rate of photosynthesis
Text p581…
PLANT KINGDOM
Vascular
Non-Vascular*
•
•
•
•
“Bryophytes”
No Conducting Tissue
Stay Small in Size
Ex- Moss, liverworts
Seedless*
• “Tracheophytes”
• Conducting Tissue
• Xylem (H2O up)
• Phloem (food ‘down’)
• Enables Larger Size
• Ex: Most Plants
Seed Producers
• Produce Spores
• Ex- Ferns
Angiosperms
Gymnosperms
ALL PLANTS:
1. Eukaryotic
2. Autotrophic
3. Multicellular
4. Chloroplasts
5. Cell Walls
Cellulose
• Non Flowering “cone-bearing”
• “Naked” Seeds (no fruit covering)
• Ex- Most Conifers (Evergreenspines/spruce /fir/hemlock/cedar)
form/function?
• Produce Flowers
• Seeds (In Fruits)
• Most Abundant
Monocots
Dicots
Parts of a Flower
ANGIOSPERMS
STAMEN
CARPEL
(PISTIL)
(+ stigma, style)
“Perfect Flower” = Having
both male and female parts
POLLINATION
The transfer of pollen from an anther
(male) to a stigmas (female) of a flower
of the SAME species
It is important to remember that the transfer of pollen
from the male to the female precedes fertilization
SELF POLLINATION
CROSS POLLINATION
• Pollination involving the
same flower, flowers on
the same plant, or two
genetically identical
plants
• A reproductive process
in which the pollen from
one plant is transferred
to the stigma of another
plant (*Same species)
Pollen lands everywhere….what stops fertilization errors??
PREZYGOTIC BARRIERS? Gametic Recognition
POLLINATORS?
Plant Defenses
Adaptions to improve
Survival & Reproduction:
Mechanical, Chemical
*Cuticle- keep water in, pathogens out; close the stomata! Spines! Thorns!
*Polymers to reduce digestibility; Odor!
*Essential oils- attract predatory insects to kill plant-feeding insects
a) Pathogen-associated
molecular patterns (PAMP)triggers immunity
b-c) Pathogens suppress the immune signaling,
while some plants have proteins that resist the
suppressor, resulting in an immune response
Damage Control – cell death signals
• UPON INFECTION,
SALICYLIC ACID FORMS A
CONCENTRATION GRADIENT
WITH HIGHER LEVELS AT THE
INFECTION SITE AND LOWER
LEVELS OUTWARD- INFECTED
CELLS DIE, DISTANT CELLS
SURVIVE.
Salicylic Acid
• AUXIN Hormone- Plant Tipson the ‘dark side’ stimulate
the uneven growth
• Plant Growth in Response to
light/no light
• PLANTS RESPOND TO CHANGES IN DAY LENGTH
• *Seasonal flowers
• Plants use pigments to respond to environmental
conditions- day length.
Plant Hormones
PLANT
FERTILIZATION
OF
FLOWERING
PLANTS
THE MEGASPORE
• ALTERNATION OF GENERATIONS: Dominant
independent sporophyte generation;
microscopic gametophyte and nutritionally
dependent on the sporophyte
• DOUBLE FERTILIZATION: Two separate
nuclear fusions; unique to flowering plants
• HETEROSPOROUS: Two types of spores
MEGASPORES: Egg
MICROSPORES: Sperm
MEGASPOROCYTE: Each young ovule
contains a megaspore mother cell
produces 4 haploid megaspores
(meiosis); one develops into a mature
gametophyte- an embryo sac- 7 cellssix with one nuclei, one central cell
with two nuclei (polar nuclei).
TEXT p610, Fig p612
meiosis
7 cells6- one nuclei
1 with 2
Pollen tube leads to
one egg; all but 2
disintegrate
Double Fertilization .50
Seed Structure
SEEDS: Ovules
DICOTS
EMBRYO:
Epicotyl/plumule: 1st leaves
Hypocotyl: Stem
Radical: Root
ENDOSPERM: Food source
MONOCOT
FRUITS: Mature, ripened
ovaries
Two Pathways for
solutes and water:
SYMPLAST: A continuum consisting
of the cytoplasm of many plant
cells, connected from one cell to
the next by plasmodesmata
(cytoplasmic channels)
Text p752
APOPLAST: A
continuum of the
interconnected,
porous plant cell
walls, along which
water moves freely.
(around the cell
walls)
CASPARIAN STRIP:
Text p751 Fig 35-4; Lab Packet
Endodermal
waterproof barrier
“the mortar”