Unit 7.1-7.2 Enegy in living systems, ATP, & glycolysis

What happens when energy is transferred from one compound to another? And WHY is this important?

Shift of e from one compound to another removes potential energy from the 1st compound and increases potential energy of 2nd compound

This is important because it allows for incremental shifts in energy

What is a redox reaction

Oxidation: Strips an e from an atom in a compound

Reduction: The addition of this e to another compound

What is the reducing agent vs the oxidizing agent

RA: Molecule that donates an e

OA: Molecules that accept and e

LEO the lion says GER

Molecules that lose an electron are oxidized, molecules that gain an electron are reduced

What is an electron carrier?

Molecules that bind & carry high-energy e between compounds in biochem pathway

• can occur in an oxidized state or a reduced state

• Very important in cellular respiration & photosynthesis

• EX: NAD+ → NADH (NAD+ is oxidized), FAD+ → FADH

Explain how electrons are involved in the transfer of energy within a cell

• e help capture energy released by cellular respiration

• help absorb energy in a controlled stepwise process

• Physically transfer e from the atom to the compound → e carriers bind & carry these e

What is ATP

Adenosine Triphosphate = “energy currency” of the cell

• adenosine is a nucleoside consisting of a nitrogenous base adenine & sugar, ribose

• The bonds that link the phosphate group are high energy bonds

Is ATP unstable or stable

It is highly unstable

What makes ATP a good source of energy for cells

• a cell cannot store significant amount of free energy or the heat in the cell would increase

• ATP can fill any energy need in a cell, similar to a rechargeable battery

What is the heart of ATP?

AMP (adenosine monophosphate)

What is chemiosmosis

In mitochondria, a process of ATP production in cellular metabolism, generates 90% of ATP made during glucose catabolism also used in light rxns of photosynthesis to harness sun energy

What is oxidative phosphorylation

Process of ATP using chemiosis

How is ATP generated?

By an endergonic rxn where ADP undergoes phosphorylation

Where does energy required for generation of ATP come from (other than chemiosis)

1. Coupled exergonic rxn: Coupling is when exergonic and endergonic rxns are paired, endergonic rxns are pushed by coupling to exergonic rxns

What is glycolysis?

Occurs in cytoplasm outside of mitochondria

• first step in breakdown of glucose to extract for cellular metabolism

• need 2 ATP, then release 2 NADH+ & 4 ATP net gain: 2 ATP per 1 glucose molecule & 2 pyruvate molecules

Anaerobic = Does not require oxygen

What occurs in part 1 of glycolysis?

Breaking of glucose requiring energy (2 ATP)

• we phosphorylate glucose to make it more reactive & break it into two 3C molecules

What occurs in the third step of glycolysis?

Phosphofructose molecule, a major inhibitory step, will the process move on? A 2nd ATP molecule donates increases energy to phosphorylate to fructose-6-phosphate

What happens in part 2 of glycolysis?

Part 2: Extracting energy & preparing molecules to become pyruvate

For each of 3C molecules

>1 NADH & 2 ATP are formed

>1 pyruvate is formed

> some water is produced

Summarize glycolysis

>Inputs?

>Outputs?

>If there is too high of an ATP concentration

Inputs: glucose, 2 ATP, 2 NAD+ and ATP used ‘prime’ glucose, make it more reactive

Outputs: 2 pyruvate, 4 ATP (net gain of 2), 2 NADH

If there is too high of an [ATP] it inhibits phosphofructokinase b/c cell does not need glucose to make more ATP, can make a different molecule

What do the first five steps of glycolysis do?

They convert one six-carbon glucose into two three-carbon glyceraldehyde 3-phosphate molecules (G3P)

In glycolysis how is the conversion of one glucose into G3P completed?

With one molecule of ATP (consumed in step one and three) both of these reactions are catalyze by kinase enzymes and are irreversible

How many times do all of the reactions in the second half of glycolysis occur and why?

Two times because the original glucose molecule is broken down into two G3P molecules

During what steps is ATP produced? Are these steps reversible

Two ATPS are produced one at step 7 and one at 10, step 7 is reversible while 10 is not

What can the NADH created in the second half of glycolysis be used for?

It can be used by other cellular processes such as cellular respiration to produce even more ATP for the cell