Exam 2

Glucose requirements for the body

-Central Nervous System and Red Blood Cells rely on glucose as an energy source

- Avg human body needs 160g of glucose a day

-120g of glucose is used to feed the brain

-20g of glucose is in our body fluids

-190g of glucose is stored in glycogen stores

NADH

High electron carrier

Kinase enzymes

Move phosphate groups

Phase 1

6 carbon ring glucose uses net 2 ATP to breakdown the glucose and converting one 6c glucose into two glyceraldehyde-3-phosphate (3c).

Phase 2

• Occurs in duplicate, so now 4 ATP are generated instead of 2 ATP.

• 2 NADH and 2 H+, their levels are limited within the cell. NAD+ is regenerated in the mitochondria during oxidative phosporylations.

• Generates 2 pyruvate: Starting material for citric acid cycle.

• Substrate-level phosporylation

Substrate level Phosphorylation

Smaller amount of ATP being formed in glycolysis and citric acid cycle.

Acetyl COA

High energy molecule

Oxidative Phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain.

Chemoimosis for mitochondria

From food to ATP

Chemoismosis for chloroplasts

Light energy to chemical energy of ATP

Mitochondria proton gradient

Mitochondrial matrix- lo[H+]

inter membrane - hi[H+]

Chlorplast proton gradient

stroma - lo[H+]

Thylakoid - hi[H+]

Calvin cycle

• Anabolic

• CO2 input and leaves as G3P

• Uses ATP and the reducing power of NADPH to convert CO2 to the sugar G3P

• Needs to be ran 3 times

• Occurs in stroma

3 Phases of Calvin Cycle

1. Carbon fixation

2. Reduction

3. Regeneration of the CO2 acceptor

Phase 1: Carbon fixation

• Forms a 6C molecule by combining CO2 and RuBP

• Catalyzed by rubisco

• 6C splits into two 3-phosphoglycerate

Phase 2: Reduction

• Requires energy of ATP and NADPH

• Reduced to triose phosphate

Phase 3: Regeneration of CO2 acceptor

• requires more ATP (3 additional)

• Rearrangement of 5 remaining molecules of triose phosphate to regenerate RuBP

G3P

3C carbohydrate

What happens wen stomata are closed?

CO2 levels are reduced and O2 levels accumulate

Photorespiration

-Rubisco takes O2 waste product and produces a two carbon compound

• Consumes ATP and O2 and releases CO2 without producing ATP or sugar

Difference between Citric acid cycle and Calvin cycle

CAC: Generates ATP

Calvin cycle: Uses ATP

Difference between ATP in photosynthesis and mitochondria

• Photosynthesis just generates ATP for the Calvin cycle

• Mitochondria generates ATP for the whole cell

Light reactions

• Carried out by molecules in the thylakoid membranes

• Convert light energy to chemical energy of ATP and NADPH

• Split H20 and release O2

Photosynthesis

Process of converting solar energy into chemical energy

Autotrophs

“Self feeders” , they get energy and carbon from non-living sources

• use CO2 to make organic molecules

• They are producers

Photoautotrophs

Use sunlight energy to make organic molecules , plants are photoauthotrophs

Heterotrophs

Obtain energy and carbon from the organic material derived from other organisms

What part of the plan conducts photosynthesis?

Chloroplast

Enzymes are grouped into what biological membrane?

The thylakoid membrane

What is a hi e- carrier for photosynthesis?

NADPH

Calvin cycle

Building phase

Chloroplasts

The sit of photosynthesis in plants

Whats the major location of photosynthesis?

• Leaves

• CO2 enters and O2 exits the leaf through microscopic pores called the stomata

Where are chloroplasts found on leaves?

Mainly in cells of the mesophyll which is the interior tissue of the leaf.

How many chloroplasts are per mesophyll cell?

30-40 chloroplasts per mesophyll cell

Stroma

• Dense fluid held within inner membrane

• Chloroplasts are composed of a double membrane surrounded by stroma

Thylakoids

• Sacs in a third membrane system

• Some form stacks called grana

Where does the green color of leaves come from?

• Chlorophyll

• A pigment that resides in the thylakoid membranes

Redox process in photo.

H20 is oxidized and CO2 is reduced

Light reactions

• Phase 1

• Occurs in thylakoid membrane

Calvin cycle

• Phase 2

• Occurs in stroma

Photophosphorylation

ATP is generated in a chloroplast

Carbon Fixation

Process where CO2 is initially incorporated into an organic molecule

Electromagnetic radiation

Light is a form of electromagnetic energy

Wavelength

The distance between crests of electromagnetic waves

What is photosynthesis powered by?

Visible light

Photons

• Particle that can travel through a wave.

• they have a fixed quantity of energy

Fluorescence

The afterglow of electrons releasing photons when falling down to the ground state.

Excitation of chlorophyll by light

When pigments absorb light, and electron is elevated from a ground state to an unstable excited state.

Light harvesting complexes

Pigment molecules that transfer energy of photons to the reaction center

Reaction center complex

• An association of protons holding a special pair of chlorophyll a molecules and a primary electron acceptor

• chlorophyll a transfers a excited electron to the primary electron acceptor

Photo system II

• functions first, founded second

• is best at absorbing a wavelengh of nm

• absorption of light energy by PSII allows electrons pulled from water to enter the photosynthetic ETC.

Photosystem I

• Functions second, founded first

• Best at absorbing wavelength of 700 nm

• A second input of light energy by PSI produces electron donor molecules capable of reducing NADP+

Obligate anaerobes

Use only fermentation or anaerobic respiration and cannot survive in the presence of O2.

• May use S2 for Electron transport chain

• O2 is toxic

Facultative anaerobes

Yeast and many bacteria, can use CR in the presence of O2, or fermentation when O2 is absent.

• Microorganisms, single-cell organisms

Beta oxidation

Breaks down fatty acids into two-carbon fragments, yielding acetyl CoA

Oxidize fat

A gram of oxidized fat produces more than twice as much ATP as an oxidized gram of carbohydrate

What is the preferred substrate for all cells?

Glucose

Oxidative Phosphorylation

End of electron transport chain.

Fermentation

Generate NAD+ for use in glycolysis. Different types depending on the cell.

• lactic fermentation

• Ethanol fermentation

Lactic Acid Fermentation

Occurs for muscle cells. Human muscles.

• Pyruvate is converted directly to lactate without producing CO2

  • NADH is regenerated to NAD+

Alcohol fermentation

Occurs for Yeast cells. Used in baking, brewing and winemaking.

• Pyruvate is converted to ethanol in two steps.

  1. CO2 is released from pyruvate, forming acetaldehyde

  2. Acetaldehyde is reduced by NADH to ethanol.

     • NADH is then oxidized regenerating NAD+

Lactic Acid equation

Glucose + 2ADP + 2Pi = 2 Lactic acid + 2ATP + 2H2O

How much ATP does fermentation produce?

Net 2 ATP per glucose molecule

Glycogen

A large, branched chain of glucose molecules attached to central protein.

What accounts for the most energy extracted from glucose?

NADH and FADH2 because they donate electrons to the electron transport chain.

Chemiosmosis

• Is an energy coupling mechanism that takes the energy in a H+ gradient to drive cellular work.

• Moving protons from HI concentration to Low concentration.

ATP synthase

Uses exergonic flow of H+ to drive the phosphorylation of ATP

• generates energy by moving H+ molecules down their concentration gradient into the mitochondrial matrix.

H+ gradient

• Known as proton- motive force

• Drives ATP synthase

• Can only move across the inner membrane through protein complexes called ATP synthase.

Energy flow in CR

Glucose - NADH - electron transport chain - proton motive force - ATP

How much energy in glucose is transformed ATP?

About 34% of the energy in a glucose molecule is transferred to ATP, making about 32 ATP per molecule.

Citric acid cycle

Takes place in mitochondrial matrix

How do energy levels change in the electron transport chain?

Energy levels lower as they move dow the electron transport chain.

What causes most of the ATP to be produced during CR?

Oxidative phosphorylation

When does the electron transport chain get used?

During the last stage of CR, creating an electrochemical gradient that leads to the creation of ATP by oxidative phosphorylation.

What if there is no O2?

The electron transport chain will stop operating and oxidative phosphorylation will cease.

Cells will then generate ATP using either anaerobic respiration or fermentation.

Fermentation

Allows continuous production of ATP by the substrate-level phosphorylation of glycolysis.

Cooperativity

The binding of one substance molecule to the active site of one subunit locks all the other subunit into the active shape.

-Amplifies the response of enzymes to substrates

Allosteric Regulation

-Allosteric activator stabilizes active form

-Activator molecule stabilizes the active shape

Feedback Inhibition

Prevents a cell from wasting chemical resources by synthesizing more product than is needed.

• Bonds to a non-competitive site

Cellular respiration

Carb/glucose - waste - energy (heat lost)

Aerobic respiration

Requires O2

Anaerobic

Happens in the absence of O2

Photosynthesis

CO2+H20+Energy - Carbs+O2

• Plants take CO2 out of the air, use light energy and carbs to the mitochondria to generate ATP.

Breakdown of Organic molecules

Exergonic, energy releasing, harness energy

OIL

Oxidation

Is

Lost

RIG

Reduction

Is

Gained

Glycolysis

Breaks down glucose into two molecules of pyruvate in the cystosol.

• With or without O2

• Occurs in the cytoplasm

Pyruvate Oxidation and Citric acid cycle

Completes the break down of glucose in the mitochondrial matrix.

• takes place in mitochondria

Oxidative Phosphorylation

Accounts for most of the ATP synthesis by cellular respiration.

• 90% of ATP is generated

Dehydrogenases Enzymes

Facilitates the transfer of two electrons and one hydrogen ion to NAD+

NAD+ is an coenzyme

Bioluminescence

Organisms converting energy to light (firefly)

Metabolic Pathways

Beings with molecule, ends with product.

Metabolism

The totality of an organisms chemical reactions.

Enzyme

Increase rate of reaction in metabolic pathways.

Catabloic pathways

Release energy by breaking down complex molecules into simpler compounds. (negative delta G)

Cellular respiration

Glucose is broken down into carbon dioxide and water.

Anabolic pathways

Called biosynthetic pathways, consume energy to build complex molecules from simpler ones. (Positive delta G) ATP input.

Energy

The capacity to cause change- perform work. Work is the movement of matter.

Kinetic energy

Energy associated with motion