Biochemical Pathways Photosynthesis and Cellular Respiration

Biochemical Pathways

Photosynthesis and

Cellular Respiration

AUTOTROPHS

○make their own food.

○ Ex: Phototrophs….Use light energy○ Ex: Chemotrophs…Use inorganic compounds

HETEROTROPHS

○Must eat org. mol. for energy (carbon source).

LightLight Form ofForm of energy energy

Other forms: Other forms: ○ thermal, electrical, kinetic, sound, chemicalthermal, electrical, kinetic, sound, chemical

Travels in waves Travels in waves (diff. wavelengths) (diff. wavelengths)

Wavelength (λ)

FM

TheElectromagneticSpectrum

Photosynthesis (Psyn):

Process: Process:

Light energy Light energy converts to converts to chemical energy (sugars) chemical energy (sugars)

Pigments used to capture light energy

Pigments

Chlorophyll a

Chlorophyll aC55H72O5N4Mg

Molecular wt. 893.5

Blue-Green

(Not on test)

Chlorophyll b

Chlorophyll bC55H70O6N4Mg

Molecular wt. 907.5

Yellow-Green

(Not on test)

Anthocyanin C15H11O+

Blue, red, pppp fruit, flowers fruit, flowers

(Not on test)

ß Carotene

C40H56

Mol. wt. 536.9 OrangeOrange, RedRed

(Not on test)

Xanthophyll

C40H56O2

Mol. Wt. 568 Yellow

(Not on test)

Chromatography

Splitting pigmentsapart

Evergreen plantspsyn. year round.

Deciduous plants affected by temp. and light changes;

leaves change color - drop.

Factors affecting the rate of psyn.TemperatureWater availabilityIntensity of lightCO2 availability

Vocabulary ChloroplastChloroplast-- plant cell organelle ; uses light energy

to make chemical energy thru psyn., has chlorophyll ChlorophyllChlorophyll-- pigment: captures light energy Stoma- opening under leaves; allows CO2 and O2 to

diffuse in/out of leaf. (stomata, pl.) ThylakoidsThylakoids-- saclike body in chloroplast;

made of photosynthetic membranes GranumGranum-- stack of thylakoids (grana, pl.) StromaStroma- fluid region outside thylakoid membranes in

chloroplast. NADPNADP++- - molecule that carries energy and hydrogen -

becomes NADPH ATPATP- chemical compound used to store energy

A closer look at leaves:

See this web page

PHOTOSYNTHESISPHOTOSYNTHESIS

Let’s draw this process…

6 CO2 + 6 H2O → C6H12O6 + 6 O2

light energylight energy

Carbon dioxide and water are used to make sugar, with oxygen as a byproduct.

Balanced equation

ChloroplastChloroplast Psyn. occurs here Inside:

Thylakoids = flattened membrane-bound sacks; has chlorophyllschlorophylls.

Grana- stacks of thylakoids.

Stroma= fluid matrix surrounding stacks.

Photosynthesis: two Photosynthesis: two stagesstages

Light Dependent Reaction (LDR)

Light Independent Reaction (LIR) or Calvin Cycle(used to be “dark Rx”)

Both occur in chloroplast

Photosynthesis: Light Dependent Rx light energy captured by chlorophyll H2O split – photolysis

O2 released

only takes place in light occurs in thylakoids makes NADPH & some ATP

nicotinamide adenine dinucleotide phosphate-oxidase

(Not on test)

Light Rx Process (site) (Light

reaction animation)(Not on test)

ATP Production during Aerobic Respiration involving the ETC and Chemiosmosis (Not on test)

Chemiosmosis

Photosynthesis: Light Independent Rx (Calvin Cycle) No light needed occurs in stroma fluid outside thylakoids NADPH & ATP powers cycle. CO2 is carbon source to make glucose

RESPIRATION: all organisms Converts sugars to other power molecules Stages:

1. Glycolysis

THEN:

2a. Aerobic Resp. of Mitochondrion (in eukaryotes)

OR:

2b. Anaerobic Resp. (Fermentation) (in pro/eu)

How do cells get energy from glucose?

GLYCOLYSISGLYCOLYSIS Splits glucose into 2 Splits glucose into 2 pyruvic acidspyruvic acids Takes place in the cytosolcytosol Doesn’t need oxygen (anaerobic) Very fast process

GLYCOLYSISGLYCOLYSIS Splits glucose into 2 Splits glucose into 2 pyruvic acidspyruvic acids Takes place in the cytosolcytosol Doesn’t need oxygen (anaerobic) Very fast process

C6H12O6 2 Pyruvic acids (3C ea.)

C6H12O6 2 Pyruvic acids (3C ea.)

2ATP2ATP

4 ADP4 ADP

2NAD+2NAD+

4ATP4ATP

2NADH2NADH

2ADP2ADP

CCCCCC

CCCCCC

Cellular Respiration

Step 1

Glycolysis Glycolysis (in cytosol, anaerobic)(in cytosol, anaerobic) Requires 2 ATP to start the Requires 2 ATP to start the

process process Net gain of 2 ATP and 2 NADH 2 pyruvic acids made

Cellular RespirationCellular Respiration

Step 2, 3 (in mitochondrion of eukaryotes)Step 2, 3 (in mitochondrion of eukaryotes) Kreb’s Cycle-Kreb’s Cycle-

In matrix fluid- breaks pyruvic acids into acetyl CoA In matrix fluid- breaks pyruvic acids into acetyl CoA and COand CO22 ( (2 ATP 2 ATP formed)formed)

Electron Transport chain-Electron Transport chain- In cristae membrane: In cristae membrane:

ATP synthaseATP synthase converts ADP to ATP ( converts ADP to ATP (32 ATP 32 ATP formed)formed)

CO2

O2

H2O

Total ATP YieldsTotal ATP Yields

Glycolysis 2 ATPGlycolysis 2 ATP Krebs Cycle 2 ATPKrebs Cycle 2 ATP Electron Transport 32 ATPElectron Transport 32 ATP

Total ATP from one glucose = Total ATP from one glucose = 36 molecules36 molecules..   CC66HH1212OO66 + + 66OO22 66COCO22 + + 66HH22O + O + 36ATP36ATP

This is the balanced equation for resp.This is the balanced equation for resp.

Respiration

schematic

Photosynthesis and Cellular Respiration form a continuous cycle : the products of one process are the

reactants for the other.

Photosynthesis

6CO2 + 6H2O lightlight C6H12O6 + 6O2

Cellular Respiration

C6H12O6 + 602 6 CO2 + 6 H2O + energy (ATP)

What’s the actual difference between the two (besides the order in which things appear)?

How Energy Cycles

If NO Oxygen present… Fermentation occurs (in cytosol)

Sustains glycolysisKeeps 2 ATPs forming from each glucoseTwo types:

○ Alcoholic ferm. (in prokaryotes, some eukaryotes)Some bacteria, yeast.

Byproducts: Ethyl alcohol and CO2

○ Lactic Acid ferm. (in YOU, and other eukaryotes)Muscle tissue

Byproduct: Lactic acid

How fermentation sustains glycolysisKeeps NADH cycle going