!!! OCR A Level Biology: Respiration單詞卡 | Quizlet

Site of glycolysis

Cytosol

NAD

Nicotinamide adenine dinucleotide

Main steps in glycolysis

Phosphorylation lysis phosphorylation dehydrogenation formation of ATP

What happens in the first step of glycolysis (Phosphorylation)?

2 ATP molecules are hydrolysed to release two phosphates, both attached to a glucose molecule, forms hexose bisphosphate

What happens in the second step of glycolysis (Lysis)?

Phosphorylation destabilises the molecule, splits into two triose phosphate molecules

What happens in the third step of glycolysis (Phosphorylation)?

Inorganic phosphate group is added to a triose phosphate molecule to form two triose diphosphate molecules

What happens in the fourth step of glycolysis (Dehydrogenation and formation of ATP)?

Two triose bisphosphate molecules are oxidised by the removal of hydrogen atoms, forms two pyruvate molecules, NAD coenzymes accept the removed hydrogens and are reduced to form two reduced NAD molecules, 4 ATP molecules are produced using phosphates from the triose bisphosphate molecules

What is the kind of phosphorylation done in glycolysis?

Substrate level phosphorylation

What happens in the link reaction?

Pyruvate enters the mitochondrial matrix by active transport by carrier proteins, pyruvate is dehydrogenated and decarboxylated, hydrogen atoms given to NAD to form NADH, resulting two carbon acetyl group is bound to coenzyme A to form acetylcoenzyme A

Technical name for the removal of carbon dioxide and hydrogen from the pyruvate

Oxidative decarboxylation

Substrate level phosphorylation

When a phosphate group is transferred from one substrate to another

First step of the Krebs Cycle

Acetyl group combines with oxaloacetate to mak citrate

Second step of the Krebs Cycle

Citrate is decarboxylated and dehydrogenated, one molecule of reduced NAD and a 5 carbon compound is made

Equation for the formation of reduced NAD

NAD^+ + 2H^+ + 2e^- -> NADH + H^+

Third step of the Krebs Cycle

Alpha ketoglutarate is decarboxylated and dehydrogenated, one molecule of reduced NAD and a 4 carbon compound is made

Fourth step of the Krebs Cycle

4 carbon compound isomerised, one molecule of ATP made by substrate-level phosphorylation

Fifth step of the Krebs Cycle

4 carbon compound dehydrogenated, one molecule of FADH2 is made

Sixth step of the Krebs Cycle

4 carbon compound dehydrogenated, one molecule of NADH made, oxaloacetate regenerated

Products of the Krebs Cycle (Both cycles)

6 NADH, 2 FADH2, 2 ATP, 4CO2

Role of electron carriers in oxidative phosphorylation

To dissociate hydrogen into a proton and an electron, to pass electrons along the chain so energy is released

Role of oxygen in oxidative phosphorylation

Final electron acceptor, forms water

Equation for the formation of water in oxidative phosphorylation

O2 + 4H+ + 4e- -> 2H2O

Where does oxidative phosphorylation happen?

Inner mitochondrial membrane

Process of oxidative phosphorylation

NADH is oxidised and donates hydrogen to NADH dehydrogenase, hydrogen dissociates into a proton and an electron, electrons are passed along the electron carriers, releases energy, energy used to pump protons through the inner mitochondrial membrane, proton gradient forms, potential energy builds up, protons flow down gradient, allows ATP to form by ATP synthase

Oxidative phosphorylation

The production of ATP in the presence of oxygen

What is ATP made from in oxidative phosphorylation?

ADP and Pi

Chemiosmosis

The diffusion of protons down a concentration gradient through a partially permeable membrane

Role of the electron transport chain in chemiosmosis

The protons are actively pumped into the intermembrane space using energy released from the transport of electrons down the chain

Role of proton gradients in chemiosmosis

Protons diffuse down the proton gradients through ATP synthase in the inner mitochondrial membrane

Role of ATP synthase in chemiosmosis

Protons diffuse down the proton gradient through ATP synthase which releases the energy required to synthesise ATP

Similarity between oxidative phosphorylation and photophosphorylation

Both use ATP synthase and chemiosmosis

Fermentation

Breakdown of complex organic compounds into simpler inorganic compounds without the use of oxygen or the involvement of an electron transport chain

Type of fermentation that occurs in mammals

Lactate fermentation

Process of lactate fermentation

Pyruvate acts as an hydrogen acceptor which oxidises the NADH, catalysed by lactate dehydrogenase, pyruvate converted to lactate, NAD regenerated, used to keep glycolysis going so small amount of ATP made

What is the reason for the oxygen debt that follow exercise?

Conversion of lactic acid to glucose requires oxygen

Why can't lactate fermentation continue indefinitely?

Reduced quantity of ATP wouldn't be enough to maintain vital processes, accumulation of lactic acid would decrease pH which would denature proteins

Type of fermentation that yeast does

Alcoholic fermentation

Process of alcoholic fermentation

Pyruvate converted into ethanal, catalysed by pyruvate decarboxylase, ethanal can oxidise NADH, ethanal becomes ethanol, NAD can be used to continue glycolysis

Benefits of being able to respire anaerobically

Anaerobic respiration is fast, failsafe for emergency situations, allows some organisms to survive in low-oxygen environments

Why does anaerobic respiration produce a much lower yield of ATP than aerobic respiration?

Organic compounds aren't completely broken down, small quantity of ATP is synthesised by substrate-level phosphorylation alone

How to investigate respiration rates in yeast

Yeast suspension and glucose solution sealed in a flask to ensure anaerobic conditions, carbon dioxide released, pushes coloured liquid along capillary tube, distance moved and diameter of tube can find volume of gas produced

How to use data logging to investigate respiration rates in yeast

Yeast suspension and glucose solution in a flask, covered with layer of liquid paraffin, carbon dioxide sensor in flask, links to software

Explanation for RQ value of proteins

Have to be hydrolysed and amino acids have to be deaminated which requires ATP

Explanation for RQ value of lipids

Lipids have a lot of carbon-hydrogen bonds, require a lot of oxygen to break all the bonds, relatively little carbon dioxide is released

Equation for respiratory quotient

RQ = CO2 produced/ O2 consumed

Explanation for RQ value of carbohydrates

6 molecules of O2 are used to produce 6 molecules of CO2

How to do investigations into the effect of factors on the rate of respiration

Use a respirometer

How a respirometer is set up and used

Equal masses of controls and respiring things used, potassium hydroxide used as a carbon dioxide scrubber, volume of oxygen absorbed can be measured using the distance that the coloured fluid moves down the graduated tube

Role of the outer mitochondrial membrane

To separate the contents of the mitochondrion from the rest of the cell in compartmentalisation

Role of the inner mitochondrial membrane

To be the site of oxidative phosphorylation with electron transport chains and ATP synthase

Role of the cristae

Projections of inner membrane which increase surface area available for oxidative phosphorylation

Where does the Krebs Cycle occur?

Mitochondrial matrix

Number of ATP molecules produced by aerobic respiration

38

Obligate anaerobes

Can't survive in the presence of oxygen

Facultative anaerobes

Can switch between aerobic and anaerobic respiration

Obligate aerobes

Can only survive in the presence of oxygen

What happens to lactic acid?

Transported by the liver

How is glycerol used as a respiratory substrate?

Converted to pyruvate, produce acetyl group, enters link reaction

Coenzymes involved in cellular respiration

NAD, FAD, coenzyme A, ATP

Why may ATP be considered a coenzyme?

Links reactions, energy released as a result of actions of one enzyme is used by another enzyme

Differences between use of NADH and FADH2 in oxidative phosphorylation

FAD electrons released further along the chain, lead to the production of less ATP

Why is the net yield of ATP less than the theoretical maximum?

Some ATP used to transport pyruvate into the mitochondrial matrix, some energy released in ETC lost as heat