2.2 Cellular Respiration Flashcards
what is the word equation for aerobic respiration?
GO COW
glucose + oxygen –> carbon dioxide + water + energy
Purpose of aerobic respiration in cells?
to release energy from foods
Name the substance to which the energy released from the breakdown of glucose during aerobic respiration is transferred and describe how it is made?
ATP
Made from ADP + Pi
What are respiratory substrates?
Molecules which can be broken down to release energy in respiration
This energy released is used to fuel what cellular processes?
active transport muscle contraction protein synthesis DNA replication Carbon fixation
Respiration occurs in the three domains of life, what are these?
eukaryotes
bacteria (prokaryotes)
archaea
What is ATP? (5)
source of immediate energy
means of transferring energy
found in ALL cells
not an enzyme so its not affected by heat
composed of adenosine and three inorganic phosphate molecules to make adenosine triphosphate (ATP)
How does the formation of ADP + Pi occur from ATP?
The energy held in an ATP molecule is released when the bond attaching the terminal phosphate is broken by enzyme action which results in the formation of adenosine diphosphate (ADP) and inorganic phosphate (Pi)
What is needed to regenerate ATP from ADP + Pi?
energy
Why is ATP important?
because it acts as the link between catabolic energy releasing reactions and anabolic energy consuming reactions.
Example of catabolic energy releasing reactions?
respiration
Example of anabolic energy consuming reactions?
protein synthesis
CATCHPHRASE
why do you calculating a % change?
standardises the results allowing them to be compared
What enzyme does yeast contain?
dehydrogenase
what does enzyme dehydrogenase do?
removes hydrogen and high energy electrons from molecules during respiration
Loss of hydrogen can be detected how?
using resazurin dye which changes colour from blue to pink to colourless as hydrogen is lost from the respiration pathway and added to the dye.
CATCHPHRASE
purpose of a control
Tubes A and C are control tubes for a comparison to prove that the observed results are valid
What does resazurin act like in this experiment?
acts like a hydrogen acceptor/carrier
Why is there only a small amount of ATP present at one point in the body?
ATP is constantly being broken down and regenerated very little is stored in the body
Why is compartmentalisation of the inner membrane of a mitochondrion important in terms of metabolic pathways?
Compartmentalisation isolates and brings together specific metabolites within a metabolic pathway
What type of cell would you find mitochondria?
All eukaryotic cells
What are mitochondria?
known as powerhouses of the cell, they are the main site of ATP synthesis
What does a mitochondria consist of?
2 membranes; a smooth outer membrane and a folded inner membrane surrounding a central matrix
Where does the citric acid cycle take place?
mitochondria
Where is most ATP generated in?
in the electron transport chain which consists of proteins embedded in the inner membrane
What does the folding of the inner membrane of the membrane form and what does this do?
forms cristae increases the membranes surface area, so that more molecules of electron transport chain can fit
What is affected if there are more folds and each fold is longer?
ATP can be produced faster
What do active cells contain?
lots of large mitochondria with many long cristae e.g sperm
What is cell respiration?
the breakdown/ oxidation by the removal of hydrogen atoms of glucose molecules within a cell to release energy for the phosphorylation of ADP to ATP.
What are the three pathways in cell respiration?
Glycolysis which occurs in the cytoplasm
Citric Acid Cycle which occurs in the central matrix of the mitochondria
Electron Transport Chain which occurs in the cristae of the mitochondria.
Why is glucose called a carbohydrate?
Chemical formula is C6H1206 and it contains carbon, hydrogen and oxygen
What is glycolysis?
a metabolic pathway
Is it aerobic or an anaerobic phase?
no oxygen is required - anaerobic
During glycolysis what happens (brief)?
glucose is broken down into pyruvate, there is a net gain of 2ATP
What is the energy investment phase?
the phosphorylation of intermediates in glycolysis uses 2ATP and is the energy investment phase.
What is the phase followed by another phase?
followed by reactions that result in the direct regeneration of 4ATP for each glucose molecules and is the energy pay off phase resulting in the net gain of 2ATP
What is oxidation?
the removal of hydrogen with the release of energy
What kind of pathway is respiration?
an oxidation pathway
What happens during the energy pay-off phase?
dehydrogenase enzymes remove hydrogen ions (H+) which combine with the hydrogen carrier NAD to form NADH
what happens if oxygen is present?
NAD carries hydrogen to the electron transport chain
Why is ATP production during glycolysis referred to as a net gain?
2 ATP are used in the energy investment phase and 4ATP are produced in the energy pay off phase
What is phosphorylation?
an enzyme controlled process in which a phosphate group is added to a molecule
Where does phosphorylation occur?
Occurs in the formation of ADP and Pi
Also occurs when phosphate and energy are transferred from ATP to the molecules of a reactant in a metabolic pathway making them more reactive
When will a step in a pathway proceed?
proceed only if a reactant becomes phosphorylated and energised
during glycolysis what is phosphorylated?
phosphorylation of intermediates occur during the energy investment phase
State the meaning of fermentation?
respiration without oxygen
State the location of fermentation in cells?
cytoplasm
when does anaerobic respiration take place?
in the absence of oxygen
How many ATP molecules are released by glycolysis in anaerobic respiration?
2 ATP molecules
What is pyruvate converted to in plant and yeast cells?
ethanol and carbon dioxide
What is pyruvate converted to in animal cells?
lactate
Why is anaerobic respiration described as being irreversible?
Pyruvate is broken down to ethanol and carbon dioxide is lost to the atmosphere
Why is anaerobic respiration in animals described as being reversible and what is it called?
Lactate is converted back to pyruvic acid when oxygen becomes available. This is called repaying the oxygen debt.
Name the hydrogen carrier in glycolysis?
NAD
Where does the Citric Acid Cycle (CAC) take place?
central matrix of mitochondria
What is pyruvate (3C) from GLYCOLYSIS converted to?
converted to an Acetyl group (2C) which combines with coenzyme A to form Acetyl Coenzyme A (Acetyl CoA) which enters the CAC.
What does dehydrogenase do?
removes hydrogen ions which combine with NAD to form NADH
What is released?
Carbon dioxide (3C –> 2C)
What does Acetyl CoA (2C) combine with?
oxaloactetate (4C) to form citrate (6C)
What is the result of several enzyme controlled steps that occur after?
the regeneration of oxaloacetate
What is released?
Carbon dioxide
What is regenerated?
ATP from ADP + Pi
When more hydrogen is released what does it combine with?
with NAD to form NADH and a second coenzyme FAD to form FADH2
What is the optimum function of respiratory enzymes such as dehydrogenase and optimum production of ATP?
human body temp 37 degrees
Why will the CAC go round twice for each glucose molecule?
there are two pyruvate molecules at the end of glycolysis
Describe the role of dehydrogenase in glycolysis and CAC?
oxidises and removes hydrogen ions from metabolites which are carried by NAD and FAD to the electron transport chain
Why is the inner mitochondrial membrane highly folded?
to increase the surface area over which the reactions of the electron transport chain can occur maintaining a high reaction rate.
Where does the Electron Transport Chain (ETC) take place?
on the cristae (inner folded membrane) of the mitochondrion
Explain the process?
chain of protein carrier molecules accept high energy electrons from the hydrogen carriers NADH and FADH2
High energy electrons flow along the chain of protein carrier molecules
Energy released from this flow of electrons is used to pump hydrogen ions across the inner membrane of the mitochondria from the matrix side to the space between the membranes
The return flow of H ions back to the matrix rotates part of a membrane protein called ATP synthase which synthesises ATP to form ADP + Pi
When the low energy H ions and electrons reach the end of the protein carrier chain they combine with oxygen which is the final hydrogen acceptor to form water.
How will the H+ ions move back into the matrix?
diffusion
What will they require?
channel proteins/ pores
Why do we need to breathe in every 5 seconds?
to provide oxygen as the final hydrogen acceptor in the ETC
What does cyanide do?
Inhibits the enzyme in the ETC which stops the flow of electrons
what happens to the rest of the energy in anaerobic respiration?
glucose isnt completely broken down to release all the energy therefore the energy is held in the bonds of lactate in mammals and ethanol in plants/yeast
