Chapter 12- Energy and Respiration Flashcards
State 3 uses of energy in cells
- moving substances across membranes via A.T
- Movement such as contracting muscles or moving organelles in cells
- Anabolic reactions
- Maintanence of a constant body temperature
what is an ATP molecule made up of
- adenine base
- ribose sugar
- 3 phosphate groups
What makes ATP the perfect energy currency
- The hydrolysis of a molecule of ATP can be done quickly and easily
- Releases a good amount of energy which is enough but not wasted
- ATP is a stable molecule
What are 2 ways to synthesise ATP
- Substrate-linked reactions
- chemiosmosis
Define substrate- linked reactions
- The transfer of phosphate group from a substrate molecule to ADP to produce ATP by energy directly from a chemical reaction
What is Aerobic respiration
This is the breakdown of organic molecules in a series of stages to release chemical potential energy with the use of oxygen
what are the 4 stages that glucose can be broken down into
- Glycolysis
- Linked reactions
- Krebs cycle
- Oxidative phosphorylation
Define Glycolysis and where does it take place
- This is the breakdown of glucose and takes place in the cytoplasm
summarise the series of steps for glycolysis
- 1 Glucose is phosphorylated by ATP
- 2 Raises the energy level and forms fructose biphosphate by the splitting of glucose (uses ATP)
- 3 Breaks down to 2 triose phosphate (releases 2 ATP)
- This is then dehydrogenated and the H+ is transferred to NAD
- 4 two reduced NAD formed from each triose phosphate
- 5 two pyruvate molecules are produced (3C) (Releases 2ATP)
Descibe how ATP is used to break down glucose in the first step of glycolysis
- Two ATP molecules are used in this stage
- One ATP molecule is used to create glucose phosphate which later forms fructose phosphate
- The second ATP molecule is used further to form Fructose 1,6 biphosphate
Oxidation VS Reduction
Oxidation: addition of O2 and removal of H
Reduction : addition of H and removal of O2
Describe the substrate linked phosphorylation in glycolysis
- a phosphate group is directly transferred from a substrate which is a phosphorylated molecule from the intermediates
Describe the linked reaction in steps
- Pyruvate enters the mitochondrial matrix with Active trannsport
- Enzymes then remove both CO2 (decarboxylation) and H (dehydrogenation)
- the remaining molecule combines Co enzyme A (CoA)
- finally forms Acetyl CoA
Describe the components of CoA
- a ribose sugar
- adenine base
- a vitamin
Summarise the Krebs cycle in steps
- 1 Acetyl CoA (2C) combines with oxaloacetate (4C) to form citrate (6C)
- 2 Citrate is further decarboxylated twice and dehydrogenated 4x making carbon combine with O2 to form CO2 as a waste and H is carried with NAD and FAD to form reduced NAD & FAD
- 3 Oxaloacetate is again formed to begin the cycle
How many molecules of:
CO2
NAD
FAD
ATP
are produced during the Krebs cycle for 1 pyruvate molecule
- 2 CO2
- 3 reduced NAD
- 1 reduced FAD
- 1 ATP
Where does oxidative phosphorylation occur?
The inner mitochondrial
membrane
Describe the steps of oxidative phosphorylation
- Reduced NAD and FAD are passed to the electron transport chain(ETC)
- Hydrogen is then released from the reduced NAD/FAD and splits into electron and proton (H+)
- The energy released from the movement of the electrons across the ETC pushes the H+ to the inter membrane space
- Because of an accumulation of H+ at the space, they diffuse back through ATP synthase down their gradient
- Oxygen accepts the electron and proton to form water while ATP is being produced
what are the functions of NAD in the cytoplasm of a cell
- Acts as a hydrogen carrier
- acts as a coenzyme
- used in glycolysis
Make 2 similarities between the structure of ATP and NAD
1- Both have ribose sugars
2 - both have adenine base
differences between NAD and ATP
- ATP has 1 ribose while NAD has 2
- NAD has nicotinamide base
- ATP has 3 phosphates while NAD has 2
what is anaerobic respiration
Is a type of cellular respiration that occurs in the absence of oxygen
Describe anaerobic respiration in alcoholic fermentation
- Pyruvate is decarboxylated into ethanal (acetylaldehyde)
- ethanal takes hydrogen from the reduced NAD to form ethanol and NAD is formed
What was the name of the enzyme that reduced ethanal to ethanol
Ethanol dehydrogenase
Describe anaerobic respiration in Lactic fermentation
- Pyruvate is reduced to lactate by the enzyme lactate dehydrogenase
- In this pathway, reduced NAD transfers its hydrogens to pyruvate to form lactate
- Pyruvate is the hydrogen acceptor
- The final product lactate can be further metabolised
What are the differences between Lactic and alcoholic fermentation
yeast- Irreversible reaction
Lactic - Reversible reaction
Yeast- One step
Lactic- 2 steps
Yeast- Releases CO2
Lactic- No CO2
Describe mitochondrion’ structure with relation to its function
1 - inner membrane is folded to provide a large surface area where ATP synthase, carrier proteins are.
2 - Mitochondrial matrix contains enzymes and acts as the site of link reaction and Krebs cycle
3 - The outer membrane has protein carriers for pyruvate and reduced NAD
4 - Inter membrane space has low pH due to high conc of protons from the ETC which creates a proton gradient resulting to synthesis of ATP
5 - The inner membrane is impermeable however the outer membrane is permeable so as to allow products of glycolysis to enter.
Why do Lipids have a higher energy value than carbs
This is due to the higher number of C-H bonds which yield more reduced NAD so more ATP per gram
What is the Respiratory quotient
This shows the substrate used in respiration whether anaerobic respirations is occurring
The RQ formula:
Volume of CO2 given out in unit time / Volume of O2 takin in in unit time
