Study Guide

Difference between autotrophs and heterotrophs

Auto - self-sustaining, creates organic molecules from inorganic

hetero - needs to feed on other organisms for energy, depends on autotrophs for food and oxygen

Fossil Fuels

Represents stores of energy from sun

Were once alive, accumulating energy and creating complex molecules

Not fully decomposed

Chloroplasts came from..

Evolved from photosynthetic bacteria

Chloroplasts

In leaves

green from chlorophyll

Cells of mesophyll

Photosynthesis

Converts solar energy to chemical energy

Describe structure of chloroplasts

Stacks of thylakoids → granum

in Thylakoid space → stroma

Has outermembrane and innermembrane

Stomata

open and close to reduce water loss, where CO2 enters and O2 exits

How do Chloroplasts Split Water

Split H2O into hydrogen and oxygen and incorporates electrons of H into sugar molecules

Releases Oxygen as byproduct

How is photosynthesis a redox process

Reverses direction of electron flow

H2O is oxidized and Co2 is Reduced

Light Reactions

Splits water

Releases O2

Reduce NADP+ to NADPH

Generates ATP from ADP by photophosphorylation

Calvin Cycle (basic)

Forms sugar from CO2 using ATP and NADPH

Carbon Fixation

CO2 into organic molecules

Visible light

380nm to 700nm

Describe photosynthesis

Light and H2O enter, light reactions use NADP+ and ADP + P and produce O2, ATP, and NADPH

ATP, NADPH, and CO2 are then used in the Calvin Cycle to produce sugar

Thylakoids

Transfers light energy into ATP and NADPH

What does wavelength determine

Type of electromagnetic energy

Electromagnetic spectrum

entire range of electromagnetic energy

Photons

Wave and discrete particles

Engelman’s Experiment

took bacteria that needed O2 to grow and exposed to different wavelengths of light

Areas recieving wavelengths favorable to do photosynthesis

IMPORANT → what wavelengths of light do algae need to grow (every but green)

They do not use green light, which is why they reflect it

Absorption spectrum of chlorophyll a

violet-blue and red

Action spectrum

Relative effectiveness driving a process

Chlorophyll a

main photosynthetic pigment

Accessory pigments

Chlorophyll b - broaden spectrum

Carotenoids - absorb excessive light

Photosystem

reaction-center complex surrounded by light-harvesting complexes

Primary electron acceptor

reaction center that accepts excited electrons - is reduced

Difference between photosystem I and II

I - Functions 2nd, electrons “fall” dow electron transport chain, H2O splits to gain electrons, uses P700 to lose electron to electron acceptor, transfers electron to NADP+ → NADPH to then Calvin Cycle

II - Functions 1st, light comes in and absorbed by P600 to then gain electron and send to primary receptor

Linear Electron Flow

• Photon hits a pigment and its energy is passed among pigment molecules until it excites P680

• Excited electron from P680nis transferred to primary electron acceptor

• H₂O is split by enzymes → electrons transfer from H+ atomms to P680+ → P680

• Oxygen is released as by product

• Electrons “fall” down electron transport chain from PS II to I

• Drives proton gradient across thylakoid membrane

• Diffusion of H+ ions across membrane drives ATP synthesis

Linear electron flow importance

Involved both photosystems and produces ATP and NADPH using light energy

Photosystem 1

Transferred light energy excited P700 which loses an electron to an electron acceptor, P700+ accepts the electron

Each electron “falls” down electron transport chain from primary electron acceptor to protein

Electrons then transferred to NADP+ and reduce it NADPH

NADPH provides electrons for Calvin Cycle

Cyclic Electron Flow

only uses PS I and produces ATP, no NADPH or O2

Chemiosmosis in Chloroplast vs Mitochondria

Both generate ATP

Mitochondria transfer chemical energy from food

Chloroplasts transform light energy into chemical energy (ATP)

How do plants lose water in a drought

Throught stromata to take in CO2 bc it opens/closes

Opening stomata is necessary for photosynthesis

Cytochrome Complex

Full Calvin Cycle

3 Carbon Enter

Combines with Rubisco → intermediate

6 ATP come in and break down into 6 ADP

6 NADPH come in and break down into 6 NAP+ and 6 P

Reduced into G3P

3 ATP break down into 3 ADP

CO₂ is regenerated and accepted by RuBP

1 G3P is the product every 3 cycles to fix 3 molecules of CO2

3 phases of Calvin Cycle

Carbon Fixation

Reduction

Regeneration of CO2 acceptor

When G3P is a sugar it is eqivalent to

18 ATP

12 NADPH

Photorespiration

evolutionary because Rubisco first evolved when the atmosphere had less O2 and more CO2

• Limits damaging products of light reactions that build up in the absence of the Calvin Cycle

C3 Plant

Fixate CO2 via rubisco to form 3-Carbon compound

85%

Why do plants want to waste energy?

Stomata close

PS I → produces ATP → heat

Burned via photorespiration

What do plants do if it doesn’t have enough water?

Cyclic flow → uses only photosystem 1 to not use O2 to not use H2O

C4 Plant

5%

Minimize cost of photorespiration by incorporating CO2 into 4-Carbon compounds in mesophyll cells

Requires PEP Carboxylase

PEP Carboxylase

Fixes CO2 even when CO2 concentrations are low

C4 Pathway

CO2 comes in and is fixed by PEP Carboxylase

Becomes 4-Carbon Compound

Turns into pyruvate

ATP comes in to become ADP and turns the 4C into a 3C

Pyruvate can the separate CO2 which is used in Calvin cycle to produce sugar

and is released to vascular tissue

Cost of being a C4 Plant

Uses extra ATP to close stomata

Importance of Greenhouse gases

Effects are unpredictable

CAM plants

Open stomata at night to incorporate CO2 as organic acid

Stomata close during the day and CO2 is released from organic acids and used in Calvin Cycle

Difference between spatial separation and temporal separation of steps

Spatial - Carbon fixation is in mesophyll Cell

CO2 is released into Calvin Cycle in Bundle-sheath cell

Temporal - Carbon fixation is at nighttime

CO2 is released into Calvin Cycle during the day

cellular messaging

via chemical signals

Evolution of cell signaling

Pathway similarities suggest signaling molecules evolved in prokaryotes and were modified later in eukaryotes

Signal transduction pathway

steps by which a signal on a cell’s surface is converted into a specific cellular response

What do signal transduction pathways do

convert signals into cellular responses

Example of cell signaling

Yeast of a and Alpha using secreted factors to locate each other and then combine to mate

Local vs long distance signaling