Cell Respiration

• What are the roles of hydrogen and oxygen in the release of energy in cells? • How is energy distributed and used inside cells?

what is the full name of ATP?

what is the full name of ATP?

Adenosine Triphosphate

List 3 ways that make ATP suitable as an energy source

1.It cannot pass through cell membranes – each cell needs to make its own but doesn’t lose what it makes

2.It is hydrophilic – reactions can occur in the cytoplasm

3.It releases energy in small managable quantities by hydrolyzing ATP into ADP – useful for many processes in the cell

4.The third phosphate group is easily removed and re-attached.

List the three main uses for ATP and give examples for each

1. transport: protein pumps

2. movement: flagella and motor proteins

3. synthesis: DNA synthesis

Explain the importance of the hydrolysis of ATP and explain how it works

•ATP is hydrolyzed to ADP + Pi

-This releases energy that is used by enzymes to shift substrates to their transition state

-ATP is able to power cellular processes by transferring a phosphate group to another molecule

-Energy is released because a new lower energy bond is formed with a substrate or enzyme.

•It takes energy to make ATP from ADP + Pi

State the principle types of carbon compounds that can be used for producing ATP

glucose and fatty acids

Name other molecules that can be used to create ATP

fructose, sucrose, galactose, lactose

does aerobic reactions need O2 as an e- acceptor?

yes

does anearobic reactions need O2 as an e- acceptor?

no

input of aerobic reactions:

Carbohydrates, fats, oils, amino acids

input of anaerobic reactions:

only carbohydrates

waste from aerobic reactions:

CO2 and H2O

waste from anaerobic reactions:

CO2 and either lactic acid or ethanol

ATP yeild per glucose in aerobic reactions:

36-38 ATP

ATP yeild per glucose in anearobic reactions:

2 ATP

location of aerobic reactions:

glycolysis in cytoplasm but all other reactions in mitochondrion

location of anaerobic reactions:

all in cytoplasm

uses of aerobic respiration:

Water produced is used by the body

•A kangaroo rat doesn’t need to drink since aerobic respiration provides almost all the water it needs.

•Long lasting supply of ATP

uses of anearobic respiration:

When short rapid burst of ATP is needed

•Weight lifting, < 400-meter race, sprint finishes after long distance event, fight/flight

When O₂ runs out in respiring cells.

In environments where O₂ is limited – like waterlogged soils.

word equation of aerobic respiration:

Glucose + O₂ —> ATP + CO₂ + H₂0

word equation of anearobic respiration:

Glucose —> lactate + CO₂  (human)

Glucose —> Ethanol + CO₂ (yeast)

oxidation

Oxidation is a chemical reaction where a substance loses electrons, resulting in an increase in its oxidation state. It often involves the addition of oxygen or loss of hydrogen.

reduction

reduction refers to a reaction in which a substance gains electrons.

electron carrier definition

Electron carriers are substances that can accept and give up electrons as required

What is the electron carrier used in cell respiration?

-NAD⁺ (Nicotinamide Adenine Dinucleotide) or just NAD

NAD+ to NADH word equation

NAD⁺ + 2H —> NAD + H⁺ —> NADH + H⁺

what is NADH used for

NADH (or reduced NAD or NAD⁺⁾ is used in cellular respiration shuttle electrons to the electron transport chain

what does phosphorylation cause

Makes the whole molecule more unstable and likely to react or break down

steps of converting glucose into pyruvate (glycolysis)

1. phosphorylation

2. lysis

3. oxidation

4. ATP formation

lactic acid word equation

2 pyruvate + 2 NADH —> 2 lactate + 2 NAD+

steps of the link reaction

1. break down of complex molecules into their building blocks

2. conversion of building blocks to acetyle-CoA

3. metabolism of acetyle-CoA to CO2 and formation of ATP

what happens in the link reaction

Pyruvate will move from the Cytoplasm into the mitochondrial matrix by facilitated diffusion

steps of the Kreb’s Cycle

•Reduction of NAD+ (6x)

•Reduction of FAD (2x)

•Decarboxylation (4x)

products from the Kreb’s Cycle

• Products from the Krebs Cycle:

  • (2) ATP

  • (6) NADH

  • (2) FADH2

  • (4) Carbon dioxide (CO2)

what is the final step of aerobic respiration?

oxidative phosphorylation

what is oxidative phosphorylation

-Energy from the oxidation of glucose is used to phosphorylate ADP to produce ATP (hence oxidative phosphorylation

-Takes place in the cristae of the mitochondria

role of the electron transport chain

•The energy contained in glucose is gradually transferred into NAD⁺ or FAD through a series of oxidations or directly to the production of ATP.

gradient in electon transport chain

As the donated electrons move from carrier protein to carrier protein the released energy which H⁺ to be pumped from the matrix to the intermembrane space against a H⁺ concentration gradient

what is chemeosynthesis

-H⁺ moves across the inner membrane through ATP synthase, down the concentration gradient which releases energy

-This energy is used by ATP synthase to generate ATP from ADP + Pi

role of oxygen as terminal electron acceptor in aerobic cell resp

•Oxygen briefly becomes negative (O2^-) and combines with free floating H⁺ from the matrix to become water (H₂0)

-This helps maintain the H⁺ concentration gradient between the intermembrane space and the matrix.

products from electron transport chain

38 ATP and H2O

difference between lipids and carbs as respiratory substances

Simple sugars (glucose or fructose) of carbohydrates can be used directly in glycolysis and anaerobic respiration, while lipids have to be broken down into glycerol & fatty acids.

are carbohydrates used in glycolysis?

Yes. After glycolysis the pyruvate can be processed without O2.

are lipids used in glycolysis?

No. Not used in glycolysis so no suitable metabolite for use anaerobically.

is the hydrolysis of a carbohydrate required in order to be a respiratory substance?

yes if a starch or glycogen

is the hydrolysis of a lipid requried in order to be a respiratory substance?

yes in order to break down large fat molecules into glycerol and fatty acids

amount of energy produced per gram of carbohydrates

17 kilojoules/gram because most of the mass is oxygen and oxygen does not yeild energy

amount of energy produced per gram of lipids

27 kilojoules/gram because most of the mass is carbon and hydrogen which have high energy yeilds