Test 3 (ch. 8, 9, 10)

Photoautotrophs

organisms that are able to use light to manufacture their own food

Heterotrophs

rely on the sugars produced by photosynthetic organism for their energy needs

chemoautotrophs

make sugars using energy from inorganic chemical compounds

Stomata

small openings on the underside of leaves where carbon dioxide enters and oxygen leaves

Guard Cells

found on either side of the stoma, and regulate the opening and losing

thylakoid

disc-shaped structures that fill the chloroplasts

chlorophyll

pigments that absorbs light and is found in thylakoid membranes

Carotenoid

larger group of pigments

Granum

stack of thylakoids

Stroma

lipid-filled space surrounding the granum

Photosynthetically Active Radiation

wavelength range of light that plants absorb (700 nm - 400 nm)

Absorption Spectrum

spectrum of wavelengths of photosynthetically active radiation a pigment absorbs

Photoact

light energy excites an electron from the chlorophyll a pair, and the electron passed to the primary electron acceptor

Photosystem

multiprotein complex

Photorespiration

light-independent photosynthetic pathway of plants (plants doing cellular respiration)

Organisms that can Photosynthesize

• plants

• algae

• cyanobacteria

Chemoautotrophy use What for Energy

inorganic chemical compound

Elements Required for Photosynthesis

• sunlight

• carbon dioxide

• water

Products of Photosynthesis

• oxygen

• GA3P

GA3P

glyceraldehyde-3-phosphate

GA3P makes What

2 make 1 glucose

Place in Leaves where Photosynthesis Happens

mesophyll

How are CO2 and O2 exchanged through the leaf

small opening called stomata

Place where Photosynthesis take Place in Eukaryotes

Chloroplast

Structure of Chloroplast

• double membrane (inner and outer)

• filled with thylakoids that contain chlorophyll (absorb light)

Classes of Pigments that Absorb Light in Plants

• chlorophylls

• carotenoids

Light-Dependent Reactions

use light energy

Light-Independent Reactions

uses chemical energy

Light-Dependent Reaction (Location)

thylakoid membrane

Light-Independent Reaction (Location)

stroma (liquid-filled space surrounding granum)

Products of Light-Dependent Reaction

• ATP

• NADPH

Form Sun Emits Solar Energy

electromagnetic radiation

Solar Radiation Categorized

wavelength

Longer Wavelengths Potential Energy

less energy carried (radio, microwave, inferred)

Short, Tight Wavelengths Potential Energy

carry most energy (ultraviolet, x-ray, gamma)

Wavelength Range Plant Pigments can Absorb

700 nm-400 nm

Types of Chlorophyll pigments in Plants

• chlorophyll a

• chlorophyll b

Role of Carotenoid

dispersal of excess energy absorbed by plants tissues & used to attract seed dispersers

Absorption Spectrum Related to Green Pigments of Plants

plants can absorb all the colors except green which it reflects which is why we see plants as green

Parts of a Photosystem

• light-harvesting complex

• reaction center (middle)

Light-Harvesting Complex

300-400 chlorophyll molecules (and other pigments) bound to antenna proteins

Reaction Center

a specialized pair of chlorophyll a molecules capable of being oxidized (giving up e-)

Location of Light-Harvesting Complex & Reaction Center

thylakoid membrane

Proteins that House the Chlorophyll Pigments

antenna proteins

Energy Transferred by the Chlorophyll Molecules

photon pushes chlorophyll into excited state which transfers it from chlorophyll molecules to chlorophyll molecule

Energy Once Passed to Chlorophyll a molecule

electron from chlorophyll a is passed to the primary electron acceptor

Primary Electron Acceptor in Plants

pheophytin

What Happens During a Photoact

light energy is converted into an excited electron (chemical energy)

In Photosystem II, Where Does the Electron Come From

splitting water

In Photosystem I, Where Does the Electron Come From

electron transport chain

Where Does High Energy Electron GO After Photosystem II

primary electron chain

Waste Products of Photosystem II

oxygen

Energy Derived from Electron Transport Chain Use

pump hydrogen ions from the stroma into the thylakoid lumen

Where is Chemiosmotic Gradient Happen in Chloroplast

lumen of thylakoid

How is Hydrogen Ion Harnessed

hydrogen ions passively diffuse through ATP synthase

Hydrogen Ion Use

attach 3rd phosphate group to ADP making ATP

Purpose of Photosystem I

turn NADP to NADPH

Product of Photosystem I

NADPH

ATP and NADPH Used for During Photosynthesis

build carbohydrates for long term energy storage (glucose)

Carbon Comes from What to Build Carbohydrates

CO2

Stages of the Calvin Cycle

• fixation

• reduction

• regeneration

Fixation

• CO2 fixed from inorganic to organic moleucle

• RuBisCo catalyzs a reaction between CO2 and RuBP

RuBisCo

ribulose bisphosphate carboxylase/oxygenase

RuBP

ribose bisphosphate

Reduction

ATP and NADPH used to reduce 3-PGA into G3P

Regeneration

• some G3P enter cell cytoplasm help formation of other compounds

• other G3P used to regenerate RuBP using ATP

Enzyme Most C3 Plants Use for Carbon Fixation

RuBisCo

High-Energy 5 Carbon Molecule Carbon is Fixed to

RuBP

Molecule Formed by Reduction of 3-PGA

G3P (glyceraldehyde 3-phosphate)

Fate of G3P

• some used for formation of other compounds in plant

• others used to regenerate RuBP

Name of Undesirable “Alternate” Pathway in Light-Independent Reaction

photorespiration

Enzyme that Causes the Problem of Photorespiration

RuBisCo incorporates oxygen into RuBPinstead of carbon (causing a release of CO2)

Conditions Where Photorespiration Occur

excessive water loss/oxygen build up (stomata closed preventing oxygen from coming in and carbon dioxide from leaving)

Detrimentally of Photorespiration in Plants

causes plants to oxidize carbon without making ATP (wasteful process)

Enzyme C4 Plants Use Instead of RuBisCo

PEP carboxylase

Benefits of PEP Carboxylase

higher affinity for CO2 than RuBisCo & doesn’t have oxidase alternate activity

C4 Plants use of Spatial Separation to Overcome Photorespiration

reduce expose of RuBisCo to oxygen by turning carbon dioxide into malate

Cost Associated with C4-Types Photosynthesis

every 1 glucose molecule = 12 molecules of ATP

CAM Plants Avoid Photorespiration How

stomata open at night (lower temp.) and take in CO2 then close stomata during day

Intermediary Compound that Store Fixed CO2 until Daytime

malic acid (malate)

Enzyme CAM Plants Use to Fix Carbon

PEP Carboxylase

Calvin Cycle in CAM Plants

mesophyll cells

Ligand

a molecule that binds another specific molecule, delivering a signal in the process

Target Cell

cells that are affected by chemical signals

Neurotransmitter

carry chemical signals (messages) from one neuron (nerve cell) to the next target cell

Hormone

chemical that carries messages through the blood to the organs, skin, muscles, and other tissues

Gap Junction

small watery channels between cells

Plasmodesmata

Narrow thread of cytoplasm that passes through the cell walls of plants cell and allows communication between them

Intracellular Mediator

communication within a cell

Signal Transduction

conversion of an extracellular signal into a intracellular signal

Signaling Cascade

chain of events that conveys the signal throughout the cell

Why Do Cells Need to Communicate

to respond to external stimuli and each other

Categories of Chemical Signaling

• Paracrine

• Endocrine

• Autocrine

• Direct

Difference Between Chemical Signaling Categories

distance the signal travels to reach the target cell

Paracrine

• locally between cells that are in close proximity (close by but not next to)

• quick response

• short lived

Endocrine

• signal in one part of body but affects other body regions further away (far away)

• slower response

• long lasting

Autocrine

• To itself

• quick response

• longer lasting

Direct

• Cells that are in direct contact with each other (neighbors)

• quick response

• short lived

Paracrine (Example)

neurotransmitters (signals between nerves)

Endocrine (Example)

thyroid gland