Chapter 4: ATP and energy release Higher Human Biology Unit 1: Cell Function and Inheritance...

Chapter 4: ATP and energy release

Higher Human Biology

Unit 1: Cell Function and Inheritance

19/04/23 1Mrs Smith: Ch4-ATP & Energy Release.

Lesson Aims

• To compare aerobic and anaerobic respiration

• To learn about structure and function of ATP

• To learn about the three stages of respiration


Previous Knowledge…

• What is the definition of Respiration?

• Difference between aerobic respiration and anaerobic respiration?

• How can you show that a living thing gives off energy when it is respiring?

• How can you prove that an organism releases CO2 during respiration?


Previous Knowledge…

aerobic respiration anaerobic respiration (plants) anaerobic respiration (animals)

Glucose + O2 CO2 + Water + energy

Glucose Lactic acid + energy

Glucose Ethanol + CO2 + energy

aerobic respiration

anaerobic respiration (animals)

anaerobic respiration (plants)

Remember that respiration occurs in EVERY LIVING THING


Metabolism

• Metabolism - all chemical reactions that occur in cells

• Catabolism – produces energy when bonds between atoms in our food are broken

• Anabolism – requires energy to make new bonds building up molecules


Aerobic Respiration

• Organisms break down organic materials through the process of aerobic cellular respiration.

• The goal of this process is to break down organic material and harness the released energy in the form of ATP, the universal currency of biological energy.


Anaerobic Respiration

• A few organisms can live without oxygen (anaerobically). These organisms are capable of metabolizing organic material, but their ATP yield is much lower than that found in aerobic respiration.


ATP

• ATP = Adenosine triphosphate

• ATP is a molecule that transports energy made during respiration and releases it for cellular processes (e.g. unzipping DNA, making enzymes…)

adenosine Pi Pi Pi


GEEKY SCIENCE JOKE

• Man goes into a bar,

• Barman says “What can I get you?”

• Man says “I’ll have a pint of Adenosine triphosphate”

• Barman says “Ahhhh that will be ATP”

• (80p.... Get it!!!! boom-chh)


Experiment the contraction of muscle fibre by ATP

A:ATP C:WaterB:Glucose MUSCLE FIBRE

In this experiment, the substance under investigation is adenosine triphosphate (ATP). This substance occurs in all living cells. The tissue used in this experiment is muscle. The contraction of the muscle is evidence that energy is being used. Ringer's solution is a solution of salts in water at about the same osmotic concentration as tissue fluid. 19/04/23 10Mrs Smith: Ch4-ATP & Energy

Release.

Analysing the results.

• When each of the slides has been exposed to its appropriate solution for at least five minutes, measure the lengths of the muscle filaments again, record this in your table and work out the amount of contraction and percentage contraction.

A (ATP) B (Water) C (Glucose)

1st length2nd lengthDecrease% contraction


Experiment Discussion1. Which of the three solutions caused the greatest percentage

contraction?

2. Glucose is generally considered to be the main source of energy for reactions such as muscle contraction (e.g. athletes may eat glucose tablets before strenuous effort). Discuss whether your results support this view.

3. The animal from which the muscle was obtained has probably been dead for many days. Does the fact that muscle fibres will still contract mean that the muscle is still alive?

4. Discuss whether the results of the experiment entitle you to say that ATP causes muscle contraction in living organisms.


ATP releases energy by breaking the 3rd chemical bond:

adenosine Pi PiPi

Energy released

adenosine Pi Pi Pi

Energy stored in this bond


This leaves us with an energy-less molecule called ADP (adenosine

diphosphate) and a spare phosphate

• These molecules are recycled as the chemical energy released during respiration remakes the third bond to make… ATP

adenosinePi Pi

Pi


The ATP EQUATION

• The process is therefore a reversible reaction:

ATP ADP + PiEnergy released

Energy required

When ATP is synthesised (made) we refer to it as phosphorylation (adding a phosphate).


Energy Transfer

Chemical energy from Respiration

ADP + Pi

ATP

Cellular reactions

e.g.Protein synthesisMuscle contractionActive transportNerve impulses


Respiration

3 stages:

• Glycolysis

• Kreb’s cycle

• Cytochrome system


OILRIG

• In a biochemical pathway, OXIDATION occurs when hydrogen is removed from a substrate. This releases energy.

• REDUCTION adds hydrogen and costs energy.

• Respiration is an oxidation reaction…

• Like all biochemical pathways, respiration is controlled by enzymes


CYTOPLASMCYTOPLASM

GLYCOLYSIS OCCURS HERE

MITOCHONDRIMITOCHONDRIONON

AEROBIC RESPIRATION OCCURS HERE

ATP TOTALATP TOTAL

GLYCOLYSIS = 2

CYTOCHROME SYSTEM = 36

TOTAL = 38

CYTOCHROME SYSTEM

36 ATP

ACETYL-CoA

2 ATP

GLUCOSEGLUCOSECC66HH1212OO66

PYRUVICPYRUVICACIDACID

KREBS CYCLE

O2

CO2

H2O

HYDROGEN


Glycolysis -1st stage

• Glycolysis is a part of both aerobic respiration and anaerobic respiration – this stage doesn’t require oxygen.

• Takes place in the cell cytoplasm• Here, a molecule of glucose (6C) is split into two

molecules of pyruvic acid (3C).

• Net gain of 2 ATP• Hydrogen released is transferred to Cytochrome

system by NAD• If no oxygen present, pyruvic acid converted to

lactic acid


Glycolysis


Mitochondria Structure

19/04/23 22

Mitochondria

• Mitochondria are found in the cytoplasm of cells• The fluid-filled interior of the mitochondrion is

called the matrix• The cristae of the mitochondria is located on the

inner membrane• The folded inner membrane of the mitochondria

provides a large surface area• More active cells (e.g. muscle, sperm & nerve

cells) have many cristae in their many mitochondria as they require more ATP (energy)

Complete Torrance TYK questions 1-319/04/23 23

Kreb’s Cycle – Stage 2.

• Aerobic _ Only proceeds when oxygen is present.• Takes place in matrix of mitchondria• Also called TCA (Tricarboxylic Acid Cycle ) or Citric acid

cycle• Pyruvic acid (3C) diffuses into matrix and is broken

down into Acetyl CoA (2C)• Acetyl CoA binds with 4C molecule to give citric acid• Citric acid broken down into 4C molecule by series

of enzyme-controlled reactions• Produces CO2

• Hydrogen released is transferred to Cytochrome system by NAD


Kreb’s Cycle


• Throughout Glycolysis and the Kreb’s Cycle, the substrate is continually altered by the removal of carbon (in the form of CO2) and the removal of Hydrogen.

• What happens to the CO2?

• What happens to the Hydrogen?


Cytochrome System -3rd stage

Ever wondered what the heck happened to all that NAD NADH2…?•Also called electron transfer chain•Hydrogen passed along chain•The NAD carries the H to the Cristae of the Mitochondria.•The energy from the H electrons is the energy needed to synthesise ATP from ADP and Pi (remember? The 3rd bond etc.?)


• 36 ATP molecules are made from each molecule of glucose in the cytochrome system

• Once the Hydrogen has been passed through the system and lost the electrons, it joins with OXYGEN as its finale.

• The oxygen is therefore said to be the final hydrogen acceptor. This makes WATER!

Cytochrome System –Con’t


Cytochrome System – hydrogen chain.


The Big Picture..

19/04/2330Mrs Smith: Ch4-ATP & Energy

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Summary• One molecule of glucose gives a total yield

of 38 ATP– 2 from glycolysis– 36 from cytochrome system

• The Citric acid cycle turns twice for each molecule of glucose as there are 2 x PA (see page 7 of workbook)

• Glucose + O2 CO2 + H2O + 38 ATP• Respiration is carefully controlled by

various ENZYMES!19/04/23 31Mrs Smith: Ch4-ATP & Energy

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• If Oxygen is not present, then the biochemical process we have studied – aerobic respiration – cannot happen.

• Glucose (6C)

Pyruvic Acid (3C) Lactic Acid (3C)

2 ATP



• If Oxygen is not present, then the biochemical process we have studied cannot happen.

• Glucose (6C)

Pyruvic Acid (3C) Lactic Acid (3C)

2 ATP

O2 available

CAC19/04/2333

Mrs Smith: Ch4-ATP & Energy Release.

• “Oxygen debt” and “reversible”

• Only the 2 ATP from Glycolysis is made

• Therefore the net gain of anaerobic respiration is 2 ATP


Anaerobic Respiration (Plants)

• In plants and yeast anaerobic respiration takes a different and irreversible pathway.

• Glucose (6C)

Pyruvic Acid (3C) CO2 + Ethanol

2 ATP

How many carbons? Justify answer.


TASK!!! Essay Question

• An essay question is usually 10 marks in the exam you would have about 15 minutes to complete each essay.

• Give an account of Respiration under the following headings:

(i) Glycolysis (3)

(ii) Kreb’s Cycle (4)

(iii) Cytochrome system (3)


(i) Glycolysis Max 3

• 6C Glucose is broken down into 2 molecules of 3C Pyruvic Acid

• Hydrogen is released and picked up by NAD to become NADH2

• NADH2 goes to Cytochrome System (or cristae of mitochondria)

• Glycolysis makes 4 ATP but costs 2 ATP resulting in a net gain of 2 ATP

• Glycolysis takes place in the cytoplasm of the cell


(ii) Kreb’s Cycle Max 4

• 3C PA is converted in 2C Acetyl CoA• Acetyl CoA enters the matrix of the mitochondria• Acetyl CoA joins with 4C intermediate compound to form

6C Citric Acid• Citric Acid is changed into a 5C compound which is then

changed into a 4C compound• Each time a Carbon is removed, it is released as CO2

and eventually breathed out• Hydrogen is also released (oxidation) which combines

with NAD to make NADH2 (reduction)• NADH2 goes to Cytochrome System19/04/23 38Mrs Smith: Ch4-ATP & Energy

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(iii) Cytochrome System Max 3• Cytochrome System is located on the cristae of the

mitochondrion

• NADH2 is reduced/released Hydrogen

• As Hydrogen is passed along Cytochrome System, it loses electrons which released energy

• This energy is needed to regenerate ATP by phosphorylation/from ADP and Pi

• The Hydrogen then combines with Oxygen to form metabolic water

• The Cytochrome system makes 36 ATP19/04/23 39Mrs Smith: Ch4-ATP & Energy

Release.

Chapter 4: ATP and energy release Higher Human Biology Unit 1: Cell Function and Inheritance...

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