Energy and respiration Flashcards
Glucose Equation
glucose + oxygen → carbon dioxide + water (+ energy)
C6H1206 + 6 O2 → 6 CO2 + 6 H20 (+ 2870kJ)
Removal of one phosphate group from ATP releases approximately 30.5 kJ mol -1 of energy, forming ADP
Removal of a second phosphate group from ADP also releases approximately 30.5 kJ mol-1 of energy, forming AMP
Removal of the third and final phosphate group from AMP releases 14.2 kJ mol-1 of energy, forming adenosine
Difference between Autotrophs and heterotrophs
Autotrophs are organisms that are able to synthesise their own usable carbon compounds from carbon dioxide in the atmosphere through photosynthesis
Heterotrophs don’t have this ability; they require a supply of pre-made usable carbon compounds which they get from their food
Why is ATP a ood energy currency
ATP is a small,
soluble molecule
that provides a short-term store of chemical energy that cells can use to do work
It is vital in linking energy-requiring and energy-yielding reactions
ATP is described as a universal energy currency
The hydrolysis of ATP can be carried out quickly and easily wherever energy is required within the cell by the action of just one enzyme, ATPase
A useful (not too small, not too large)
quantity of energy is released from the hydrolysis of one ATP molecule - this is beneficial as it reduces waste but also gives the cell control over what processes occur
ATP is relatively stable at cellular pH levels
Which macromolecule has the highest energy value?
Lipids (39.4 kJ g-1)
Energy values of macromolecules: Lipids > Proteins > Carbohydrates.
What is the energy value of proteins?
17.0 kJ g-1
Proteins have a lower energy value compared to lipids.
What is the energy value of carbohydrates?
15.8 kJ g-1
Carbohydrates have the lowest energy value among the three macromolecules.
What role do hydrogen atoms play during respiration?
They become available from broken down substrate molecules
Hydrogen atoms are vital for ATP production.
What are the hydrogen carrier molecules involved in respiration?
NAD and FAD
These molecules become reduced by picking up hydrogen atoms.
What happens to reduced NAD and FAD during respiration?
They release hydrogen atoms which split into protons and electrons
This process occurs at the inner mitochondrial membrane.
What is formed when protons are pumped across the inner mitochondrial membrane?
A proton / chemiosmotic gradient
This gradient is crucial for ATP production.
How is ATP produced during respiration?
Through chemiosmosis
Protons flow back into the mitochondrial matrix via ATP synthase.
What happens to protons after they flow back into the mitochondrial matrix?
They are oxidised to form water
This is part of the process of cellular respiration.
What is the relationship between hydrogen content and ATP formation?
Higher hydrogen content results in a greater proton gradient
This allows for the formation of more ATP via chemiosmosis.
What are fatty acids in lipids made up of?
Long hydrocarbon chains with a high proportion of hydrogen atoms
The structure contributes to their high energy value.
Fill in the blank: A molecule with a higher hydrogen content will result in a greater _______ across the mitochondrial membrane.
proton gradient
This gradient is essential for ATP synthesis.
Glycolysis
takes place in the cytoplasm of the cell
Phosphorylation: glucose (6C) is phosphorylated by 2 ATP to form fructose bisphosphate (6C)
Glucose + 2ATP → Fructose bisphosphate
Lysis: fructose bisphosphate (6C) splits into two molecules of triose phosphate (3C)
Fructose bisphosphate → 2 Triose phosphate
Oxidation: hydrogen is removed from each molecule of triose phosphate and transferred to coenzyme NAD to form 2 reduced NAD (sometimes called NADH)
4H + 2NAD → 2NADH + 2H+
Dephosphorylation: phosphates are transferred from the intermediate substrate molecules to form 4 ATP through substrate-linked phosphorylation
4Pi + 4ADP → 4ATP
Pyruvate is produced: the end product of glycolysis which can be used in the next stage of respiration
2 triose phosphate → 2 pyruvate
results in the production of
2 pyruvate (3C) molecules
Net gain 2 ATP
2 reduced NAD
Substrate linked reaction
using energy provided directly by another chemical reaction.
chemiosmosis
a process that takes place across the inner membranes of the mitochondria using energy released by the movement of hydrogen ions down the conc gradient
The link reaction
takes place in the matrix of the mitochondrion
The link reaction is so-called because it links glycolysis to the Krebs cycle
The steps are:
1. Decarboxylation and dehydrogenation of pyruvate by enzymes to produce an acetyl group, CH3C(O)-
- Combination with coenzyme A to form acetyl CoA
It produces:
Acetyl CoA
Carbon dioxide (CO2)
Reduced NAD (NADH)
pyruvate + NAD + CoA → acetyl CoA + carbon dioxide + reduced NAD
role of coenzyme A
Role of coenzyme A
A coenzyme is a molecule that helps an enzyme carry out its function but is not used in the reaction itself
Coenzyme A consists of a nucleoside (ribose and adenine) and a vitamin
In the link reaction, CoA binds to the remainder of the pyruvate molecule (acetyl group 2C) to form acetyl CoA
It then supplies the acetyl group to the Krebs cycle where it is used to continue aerobic respiration
This is the stage that brings part of the carbohydrate (or lipid/amino acid) into the further stages of respiration and links the initial stage of respiration in the cytoplasm to the later stages in the mitochondria
pyruvate + NAD + CoA → acetyl CoA + carbon dioxide + reduced NAD
krebs cycle
Acetyl group and oxaloacetate combine to form citrate
(2CoA)
decarboxylation and dehydration
(2CO2 and 2NADR)
decarboxylation and dehydration
(2CO2 and 2NADR)
SLR
(2ADP +P1—>2ATP)
Dehydration/ oxidation
(2FAD—> 2FADR)
Dehydration/ oxidation
(2NAD—> 2NADR)
net loss
4CO2
6 NADR
2FADR
2ATP
Oxidative phosphorylation and chemiosmosis
keypoints
movement of protons
proton gradient through the ATP synthase to generate ATP
When ATP synthase rotates, it accepts ADP+P1 joins them together, releases ATP
Powered by H+ by diffusing from higher to lower down the conc. gradient
ATP is produced in the membrane of mitochondria
Mitochondria
Inner membrane space
(Must have high proton conc.)
Matrix (Must have a lower proton conc.)
outer mitochondrial membrane
(allowing only specific molecules to enter)
cristae (Where ATP synthase is present)
ATP synthase
(Imbedded in the inner mitochondrion membrane and can be multitude)
Main source of production of ATP
chemiosmosis:
through ATP synthase
inner mitochondrial layer
h+ diffuses below the conc. gradient and powers the ETC
