Catabolic pathways

What are catabolic pathways

release energy by breaking down complex molecules into simpler compounds

Aerobic Respiration

oxygen is consumed as a reactant along with organic fuel

Anaerobic Respiration

Organic fuel is broken down without oxygen

Fermentation

Partial breakdown of organic fuel (sugars) without oxygen

Cellular respiration

• Can be aerobic and anaerobic respiration

• in aerobic respiration, the electrons stored in the fuel source bonds are ultimately transferred to oxygen

• Some of the energy converted is used to make ATP, but the rest is lost as heat

• it is exergonic

• the cell controls the use of energy over multiple steps in the catabolic pathway

What do catabolic pathways depend on?

They depend on the transferring of electrons during chemical reactions

What is redox

the transfer of electrons from one molecule to another. always coupled

What is oxidation?

the loss of electrons. (becomes more positive)

What is reduction?

the gain of electrons( becomes more negative)

What is the reducing agent?

the molecule that gives up electrons and becomes oxidised

What is the oxidising agent?

the molecule that recieves more electrons and becomes reduced

What is nicotinamide adenine dinucleotide (NAD⁺)?

an electron transporter (shuttle)

What is the function of NAD+

• Facilitates the electron transfer over multiple steps in the breakdown of glucose

• it is a coenzyme and oxidising agent

• it can cycle between an oxidised (NAD+) and reduced (NADH) form

What happens if the transfer of electrons was uncontrolled?

there would be one big release of energy, with lots of heat loss

The electron transport chain

• small releases of energy at each step, which can be used to make more ATP

• electrons get removed from glucose and are transferred to the electron transport chain via NADH

• the bonds that hold the electrons in the ETC are increasingly unequal for each step. note that the change in free energy is the same.

What are the two ways ATP is made?

1. substrate-level phosphorylation

2. Oxidative phosphorylation

Why is cellular respiration also called aerobic respiration

because the electrons from glucose are ultimately transferred to O2 to form H2O.

in prokaryotes, glycolysis and the citric acid cycle occur in the cytosol, and oxidative phosphorylation occurs in the plasma membrane

What does glycosis mean?

sugar splitting

How many carbons is glucose (6 carbon sugar) split into?

3-Carbon sugar