BIO EXAM: 3rd Set

Can chloroplasts produce ATP w proton (w/o light)?

Yes!

What is Jagendorf’s proof?

ATP made in dark (1966)

Isotope-

hot molecule- different neutron

What is the smallest ion

A PROTON

Characteristics of pH 4.0

• Acidic

• Has tons of protons

• Put in thylakoid space

Characteristics of pH 8.0

• Basic

What is the differences between the two pH’s

10^4 → 10,000 fold

What makes the isolated chloroplasts produce ATP

At a pH of 4.0 you add ADP + Pi(radioactive) = pH of 8 → ATP

What is this section?

Calvin → Light independent reaction

Where is this located?

The grana

Where is this located?

Stroma lamella

What is rubisco

Most abundant enzyme in nature(all plants must have RUBISCO to capture CO2)

What is the Calvin cycle?

Building sugar from air

Rubisco(the enzyme) is:

Ribulose-1,5-bisphosphate carboxylase/oxygenase

How much CO2 does rubisco fix

3-10 CO2 per second(slow reaction rate)

• Usually enzymes make thousands so plants make HUGE amounts of it

• Half the soluble protein in a lead

Rubisco is the most

abundant protein on Earth

What is the order of the Calvin Cycle?

Carbon Fixation→ Reduction → Regeneration of RuBP

Is this true? In the Calvin Cycle the last material becomes the initial

True!

Glucose=

6 carbon molecules

NADPH provides

Electron

Reduction produces….

2 molecules of Glyceraldehyde 3-Phosphate(3C) (G3P)

Calvin cycle needs

NADPH and ATPoM

Most important molecule?

Every phase of the Calvin cycle has 3C(3 carbons) except?

Regeneration of RuBP

Matter Cycles

CO2 and Organic molecules

Energy flows

Sunlight → Chemical energy(ATP) → Heat

Why does life use cycles?

Catalytic economy, continuous processing, hub function, and control and stability

Catalytic economy

Regenerated intermediates ( ex: RuBP) act like catalysts

Continuous processing

Steady streams of substrates(ex: acetyl coA) requires an acceptor that is constantly resupplied= keeps running

Hub function:

Intermediates serve as metabolic crossroads, providing essential precursors for biosynthesis

Control & Stability

Linking steps into a loop allows centralized regulation → controlling a few key enzymes fine-tunes the entire pathway

Photorespiration

Is bad! It just uses energy with out producing glucose

Hot dry days =

Problem for plants

Oxygen is what to plants

Toxic! Rubisco cannot always tell the difference between CO2 and O2 → Rubisco picks up too much O2

What is a stomata?

a tiny pore or opening found on the surface of plant leaves

Stomata

What is this?

C3 pathway→ Normal!

What is this showing?

C4 pathway

Examples of C4 carboxylase

Corn + sugar cain are C4 plants!

C3

C4

CO2 → Phosphoenolpyruvate + Oxaloacetate → Malate → Inside the bundle-sheath cell, malate releases a CO2CO2​ molecule, converting back into pyruvate → remaining pyruvate is transported back to the mesophyll cell.

• This image illustrates C4 photosynthesis, a specialized carbon fixation pathway used by certain plants (like corn,sugarcane, and grasses) to minimize photorespiration in hot, dry conditions

• CO2 → Phosphoenolpyruvate + Oxaloacetate → Malate → Inside the bundle-sheath cell, malate releases a CO2CO2​ molecule, converting back into pyruvate → remaining pyruvate is transported back to the mesophyll cell.

Why cycles matter in biology?

Repetition (same event happens again) + Cycle (the last step regenerates the first)

EX: Citric acid cycle(Krebs) and Calvin cycle

What is the toxin?

phosphoglycolate (PG)

What is happening in the net carbon loss

• Rubisco takes O2 instead of CO2

• Uses energy + losing CO2

• Reducing photosynthesis rate

Understand this!