Module 5.7 Flashcards
What is respiration
Respiration is the process that occurs in living cells and releases the energy stored in organic molecules such as glucose .
What is the energy in respiration immediately used as ?
The energy is immediately used to synthesise molecules of ATP , from ADP , and inorganic phosphate (pI) .
What can ATP be hydrolysed to release ?
energy needed to drive biological processes . Microorganisms (both eukaryotic microbes such as yeast and prokaryotes such as bacteria ) , plants , animals and fungi and Protoctists all respire to obtain energy .
Why do living organisms need energy ?
Energy is the capacity to do work . The energy that is stored in complex organic molecules e.g. fats and carbohydrates , and proteins - is potential energy .
-It also is chemical energy , converted from light energy during the process of photosynthesis .
Why do living organisms need energy ? (2)
It is also chemical energy , converted from light energy during the process of photosynthesis ( topic 5.6.1) . When this energy is released , from organic molecules , via respiration , it can be used to make ATP to drive biological processes such as
what biological processes does ATP support
-active transport
-endocytosis
-exocytosis including secretion of large molecules from cells .
-synthesis of large molecules such as proteins
what biological processes does ATP support (2)
DNA replication
cell division
movement - movement of flagella or cilia or undulipodia and motor proteins .
-activation of chemicals .
what are anabolic reactions
they are metabolic reactions where large molecules are synthesises from smaller molecules .
what are catabolic reactions
metabolic reactions involving the hydrolysis of large molecules into smaller ones .
what do metabolic reactions and kinetic energy allow
allows them to move
e.g - diffuse down a concentration gradient from one place to another , they use their kinetic energy to do so .
check figure 1 for the energy transfer between and within living organisms .136
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learning tip about respiration and energy releases within it
respiration releases energy from respiratory substrates such as glucose but it does not create or make energy . however , some of the released energy can be used to make ATP .
What is ATP
ATP , is the standard intermediary between energy - releasing and energy consuming metabolic reactions in both eukaryotic and prokaryotic cells .
what does figure 2 show
figure 2 , shows the structure of an ATP molecule , it is a phosphorylated nucleotide . Each molecule of ATP , consist of adenosine which is the nitrogenous base adenine plus the carbon sugar ribose , and three phosphate groups .
What is the stability of ATP
ATP is relatively stable (it does not break down ADP and Pi) , when in solution in cells , but it is readily hydrolysed by enzyme catalysis . However , whilst in solution it can be easily be moved from place to place within a cell .
the role o f ATP synthase in the formation and breakdown in ATP
-The energy-releasing hydrolysis of ATP , is coupled with an energy-consuming metabolic reaction . ATP , is the immediate energy source for this metabolic reaction .
what happens when atp is hydrolysed
-When ATP is hydrolysed ADP and P , a small quantity of energy is released for use in the cells . Cells can therefore obtain energy , they need for a process in small manageable amounts that will not cause damage or be wasteful .
-ATP is referred to as the universal energy currency , as it occurs in all living cells , and is a source of energy that can be used in cells by a small amount .
what happens when some of the energy is released from the hydrolysis of ATP
The release of heat , both in respiration and during ATP hydrolysis , may appear to be inefficient and wasteful . Heat , however , helps keep living organisms ‘warm’ and enables their enzyme catalysed reactions to proceed at or near the optimum rate book1 2.4.4 .
What does figure 4 show on page 137
shows the chemical energy released from the hydrolysis of ATP .
What are cristae
they are highly folded mitochondrial membrane
what is the mitochondrial matrix
fluid filled inner part of mitochondira
RECAP on the shape of mitochondria
-Mitochondria may be rod-shaped thread - like or spherical , with diameters of 0.5-1.0 micrometres , and lengths of 2-5micrometers Occasionally up to 10 .
What is the membrane structure like for mitochondria .
What is key about the mitochondrial membrane
it is smooth , and the inner membrane is folded into cristae (singular crista ) , giving it a large surface area .
what is embedded in the inner membrane of mitochondria
embedded in the inner membrane are proteins that transport electrons , and protein channels associated with ATP , synthase enzyme that allow protons to diffuse through them .
what is between the inner and outer mitochondrial membranes of the envelope
it is the intermembrane space .
what is in the mitochondrial matrix
it is enclosed by inner membrane , is semi-rigid and gel-like . It contains mitochondrial ribosomes lopped mitochondrial DNA and enzymes for the link reaction and the krebs cycle .
What is the contents of the matrix (1)
-enzymes that catalyse the stages of these reactions .
-Molecules of the coenzyme NAD , and FAD .
Contents of matrix (2)
oxalacetate - the four carbon compound that accepts the acetyl group form the link reaction .
-Mitochondrial DNA - some of which codes for mitochondrial enzymes and other proteins .
contents of the matrix (3)
mitochondrial ribosomes structurally similar to prokaryotic ribosomes , where these proteins are assembled .
What is the outer membrane of the mitochondria consist of
the phospholipid composition of the outer membrane is similar to that of membranes around other organelles in eukaryotic cells .
-It contains proteins some of which form channels or carriers that allow the passage of molecules such as pyruvate into the mitochondrio .
inner membrane mitochondria
the lipid composition of the inner membrane differs from that of the outer membrane . This lipid bilayer is less permeable to small ions such as hydrogen ions than is the outer membrane .
what do the folds in the cristae of the mitochondria enable
the folds cristae in the inner membrane gives a large surface area for the electron carriers and ATP synthase enzymes embedded in them .
what are the electron carriers used for
the electron carriers are protein complexes arranged in electron transport chains . Electron transport chains are involved in the final stage of aerobic respiration , oxidative phosphorylation.
check figure 3 of the electron transport chain
it summarises events that takes place along the electron transport chain .
what is the use for ATP synthase enzymes
ATP synthase enzymes are large and protrude from the inner membrane into the matrix . Protons can also pass through them .
LEARNING TIP OF THE MITOCHONDRIA
The outer layer of the mitochondrion should always be described as an envelope because it consists of two membranes .
each electron transport chain (1)
each electron carrier protein contains a cofactor a non protein haem group that contains an iron ion .
each electron transport chain (2)
what can the iron ion do
the iron ion can accept and donate electrons becasue it can become reduced (Fe2+) by gaining an electron and then become oxidised (Fe3+) , when donating the electron to the next electron carrier . Electron carrier . ELectron carrier proteins are OXIDO REDUCTASE ENZYMES .
each electron transport chain (3)
The electron carriers also have a coenzyme that , using energy released from the electrons pump protons from the matrix to the intermembrane space.
each electron transport chain (4) what happens when protons accumulate in the intermembrane
protons accumulate in the intermembrane space and a proton gradient forms across the membrane .
each electron transport chain (5)
What does the proton gradient can produce a flow of protons through the channels in the ATP synthase enzymes to make ATP . You will learn more about this 5.7.5 (already learnt abt synthesis of ATP by phosphorylation 5.6.3)
meaning of glycolysis
glycolysis is the first stage of respiration a 10 stage metabolic pathway that converts glucose to pyruvate .
where does glycolysis occur
it occurs in the cytoplasm of all living organisms that respire including prokaryotes .
how long is the sequence for glycolysis
it involves a sequence of 10 reactions , each catalysed by a different enzyme some with the help of the coenzyme NAD .
What is the pathway outline for glycolysis (1)
- Phosphorylation of glucose to hexose bisphosphate .
What is the pathway outline for glycolysis (2)
splitting each hexose bisphosphate molecule into two triose phosphate molecules .
What is the pathway outline for glycolysis (3)
oxidation of triose phosphate to pyruvate .
revise figure 1 on 5.7.2
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What is NAD
what does it oxidise .
it is a non-protein molecule that helps dehydrogenase enzymes to carry out oxidation reactions .
-Nad oxidise substrate molecules during glycolysis in the link reaction and the krebs cycle .
where is Nad synthesised
NAD , is synthesised in living cells from nicotinamide , (vitamin B3) the five carbon sugar ribose , the nucleotide base adenine and two phosphoryl groups (F2) REPRESENTS ITS MOLECULAR STRUCTURE .
how many hydrogen toms can the nicotinamide accept .
two hydrogen atoms becoming reduced NAD /
What is the function of reduced NAD
reduced NAD , carries the protons and electrons to the cristae of the mitochondria , and delivers them to be used in oxidative phosphorylation for the generation of ADP from Pi .
What happens when reduced NAD gives up the protons and electrons that it accepted during one of the first three stages of respiration .
It becomes oxidised and can be reused to oxidise more substrate in the process becoming reduced again .
1st stage of glycolysis - phosphorylation - explain process . (1)
Glucose is a hexose sugar , which means it contains six carbon atoms . Its molecules are stable and needed to be activated before they can be split into three carbon compounds . One molecule of ATP is hydrolysed and the released phosphoryl group is added to glucose to make hexose monophosphate .
1st stage of glycolysis - phosphorylation - explain process . (2)
Another molecule of ATP is hydrolysed and the phosphoryl group added tot he hexose phosphate , to form a molecule of hexose bisphosphate . This sugar has one phosphate group at carbon atom number one and another at caron atom six .
What happens to the energy from the hydrolysed ATP .
The energy from the hydrolysed ATP molecules activates the hexose sugar , and prevents it from being transported out of the cell .
How does hexose bisphosphate split
each molecule of hexose bisphosphate is split into two three carbon molecules , triose phosphate , each with a phosphate group attached .
stage one of oxidation of triose phosphate to pyruvate (1)
(This process is anaerobic but it involves oxidation as it involves the removal of hydrogen atoms from substrate molecules .
dehydorgenase enzymes aided by the coenzyme NAD , remove hydrogen from triose phosphate .
stage one of oxidation of triose phosphate to pyruvate (2)
the two molecules of NAD , accept , the hydrogen atoms (proton and electrons ) and become reduced .
stage one of oxidation of triose phosphate to pyruvate (3)
at this stage , of glycolysis of two molecules NAD are reduced for every molecule of glucose undergoing this process . Also at this stage , four molecules of ATP are made for every triose phosphate molecules undergoing oxidation .
What are the products of glycolysis (1)
for each molecule of glucose , at the end of glycolysis there are ;
-two molecules of ATP , four have been made but two were used to kick start the process so the net gain is two molecules of ATP .
What are the products of glycolysis (2)
-Two molecules of reduced NAD
-Two molecules of pyruvate
What are the first two stages of respiration
1.glycolysis
2.the link reaction
