Lectures 6-10 Flashcards
When is substrate level phosphorylation important?
When we need energy rapidly, without oxygen
Is the electron transport chain an aerobic or anaerobic process?
Aerobic
What sort of phosphorylation is glycolysis?
Substrate level phosphorylation
When a larger amount of ATP is generated, what sort of phosphorylation is it?
Oxidative phosphorylation
What is essentially the process of oxidative phosphorylation?
The process of using high energy electron carriers (NADH and FADH2) to generate ATP
What happens to glycolysis during any situation where you need energy instantaneously and rapidly and large amounts of it?
It is all guns blazing
What does glycolysis generate a lot of?
Pyruvate
Energy production via the ETC relies on what?
Redox reactions
Where does the ETC occur?
Occurs in the inner mitochondrial membrane
The cristae (folds) (Check this) of the mitochondria
Each molecule of NADH generated in the TCA cycle can generate how many ATP molecules?
3 ATP molecules
Each molecule of FADH2 can generate how many ATP molecules?
2 ATP molecules
How many ATP molecules can we derive in total from 1 complete oxidation of the TCA cycle?
3xNADH = 9ATP
1xFADH = 2ATP
1xATP
Total = 12ATP
How is the ETC regulated?
Largely dependent on the energy status of the cell
So it’s all about the amount of ADP and ATP, high ADP encourages energy production but large amounts of ATP means there is sufficient energy in the cell so energy production is not necessary
Slide 19, lecture 6
Why is the ETC not a major pathway for energy production during short duration, HI exercise?
Too slow
Why is the ETC very important for energy production in prolonged, endurance exercise?
Glycolysis and PCr would start to fail
The ETC is also very important in high intensity, intermittent sports, why?
Resynthesis of PCr and glycolysis fails
Look in PE exercise book
For diagrams of ATP/PC system, glycolytic system and the aerobic system
Can we metabolise fructose in the muscle?
No - the enzymes and transport proteins are not available
What is one of the ways that the body can use ketone bodies?
A process called gluconeogenesis
What is gluconeogenesis?
Essentially the reverse of glycolysis
Where does gluconeogenesis take place?
The liver
What substrates can the liver convert to glucose?
Amino acids (glutamine and alanine)
Lactate
Glycerol
When is lactate formed?
In glycolysis from the oxidation of pyruvate (which is oxidised to produce Acetyl CoA for the TCA cycle)
The reaction where lactate is formed in glycolysis from the oxidation of pyruvate is catalysed by which enzyme?
Lactate dehydrogenase (LDH)
What is lactate needed for?
It acts as a ‘safety net’ to be re-concerted back to pyruvate for glucose if aerobic oxidation is not possible
When is lots of lactate produced?
When glycolysis is full guns blazing
Only the liver can use glucose to make glycogen but what can muscles convert into glycogen?
Glucose-6-phosphate
How many irreversible reactions need to be overcome in gluconeogenesis?
3
When is gluconeogenesis activated?
When glucose is not consumed, a prime time for this is during sleep
When is gluconeogenesis activated during periods of exercise?
After 40-45 minutes of steady state exercise
How can you inhibit gluconeogenesis?
Consume a sports drink
What does glucagon do?
Causes the liver to convert stored glycogen into glucose
Questions
Slide 18, lecture 7
What happens to our ability to use gluconeogenesis with training?
It improves
What can the pentose phosphate pathway be used for?
To oxidise glucose
The pentose phosphate pathway can be used to oxidise glucose - how much ATP is generated?
None
The pentose phosphate pathway can be used to oxidise glucose - what is generated instead of ATP?
NADPH
The pentose phosphate pathway can be used to oxidise glucose - what are the end products of this pathway?
Pentose and phosphate
The pentose phosphate pathway can be used to oxidise glucose - where can it occur?
In several tissues - the most important being the cytosol of the liver and adipose
The pentose phosphate pathway can be used to oxidise glucose - what type of reaction is it? What is this reaction essential for?
It is an anabolic reaction essential for building things up
What is glutathione?
An important antioxidant
What increases free radical production?
The ETC and aerobic exercise
What molecule upregulates the pentose phosphate pathway?
NADP+
What is NADPH used for? And what do we use NADP+ for?
NADPH is used up by building new fatty acids or glutathione - we use NADP+ to get more NADPH
What you really need to know slide
Lecture 7, slide 28
What are biological enzymes made of?
Protein
What are proteins made of?
Made of individual “building block” units called amino acids (AAs) that are linked together by peptide bonds
What is a chain of amino acids (AAs) called?
A peptide
Long peptides are called what?
Proteins
The order of amino acids (AAs) allows for what?
Different proteins to have different functions
How many different amino acids does the body use?
20
What is an essential amino acid?
An amino acid that must be consumed in the diet - the body cannot make them on its own
How many amino acids are essential amino acids? (Must be consumed in the diet)
9 out of the 20 amino acids
What is a non-essential amino acid?
One that the body doesn’t have to consume and can make
How many amino acids are non essential amino acids?
11 out of the 20 amino acids
Complete proteins contain what? (In terms of amino acids)
Complete proteins contain all 9 essential amino acids
What are some key essential amino acids we need to know?
Isoleucine
Leucine
Valine
Examples of complete protein sources?
Chicken
Beef
Milk
Eggs
Examples of incomplete proteins
Nuts, seeds, vegetable proteins
What is the structure of an amino acid?
Central carbon atom linked to:
Amino group (positive) Carboxylic acid group (negative) Hydrogen Distinctive side chain (R) Makes each amino acid different
Lecture 8, slide 10 for diagram
Examples of branches chain amino acids
Leucine
Isoleucine
Valine
Unlike other amino acids, most branches chain amino acid metabolism occurs where?
In skeletal muscle
Why does BCAA metabolism occur in skeletal muscle and not the liver?
Liver lacks the first 2 enzymes in the pathways that break down BCAAs
Where does amino acid metabolism occur?
Liver
Why is Leucine unique among amino acids?
It’s ability to stimulate synthesis of new muscle proteins
Different protease enzymes present in the gut break the protein into what?
It’s amino acids
After release into the blood stream from the small intestine what happens to amino acids?
They are metabolised primarily in the liver and skeletal muscle
Do we store proteins?
No
What is transanimation?
The process by which other amino acids are formed?
What does trans animation enable?
All amino acids required for life to be formed
What does trans animation involve?
Transferring an amino group (NH3) to a keto acid (an amino acid without its amino group) to form a new amino acid
What enzymes catalyse transamination?
Transaminases and aminotranferases
Are the reactions during transamination reversible or irreversible?
These reactions are reversible
Keto acids develop seven products
Slide 22, lecture 8
What does the glucose alanine cycle do?
Converts alanine into glucose for energy
What is oxidative deamination?
When the amino group is taken from the newly formed amino acid
What happens to any amino acids that the body does not use?
They are removed via the urea cycle in the liver
Degrading amino acids leads to an accumulation of which highly toxic product?
Ammonia
In a normal day how much urea would an individual approximately excrete?
35-55g of urea
What you really need to know slide
Slide 31, lecture 8
What do proteins do each day?
Form new muscle cells
Form synthetic pathways
Form plasma proteins, immune cells and haemoglobin
Form new enzymes in the gut and digestive system
What does protein turnover involve?
Protein synthesis (formation of new proteins) Protein degradation (breakdown of proteins into amino acids)
Approximately how much protein do we lose per day?
35-100g
The half life of different proteins varies, some are very fast (minutes), such as…
Enzymes in the liver
The half life of proteins varies, some are slow (days/weeks), such as…
Mitochondrial proteins
Myofibrillar proetins
How can cardio-respiratory training and resistance training impact skeletal muscles?
They can upregulate proteins - leading to hypertrophy, this is part of the reason that we become fitter and stronger
What is muscular hypertrophy?
An increase in muscle size
For growth, muscle protein synthesis must exceed what?
Muscle breakdown
What do we want to do in transcription?
We want to copy the information encoded in a gene and duplicate it to make a new protein
In transcription the copy forms a messenger called what?
Ribonucleic acid (mRNA)
Where does transcription take place?
In the nucleus of a cell
In transcription (recap what transcription is) what does RNA polymerase II transcribe?
The info in the gene to form mRNA
What is translation?
After transcription, the mRNA can now be taken from the nucleus to form the new protein (translation)
Where is the mRNA taken after translation?
To ‘protein factories’ called ribosomes
What is translation dependent upon?
It is dependent on the ‘genetic code’ of the mRNA, in other words what amino acids they are going to form
Recap slide 14-19, lecture 9
Translation/codon stuff
How many possible codons are there?
64
What happens to mRNA after an exercise bout?
There will be an acute increase in mRNA
What are the two main pathways for protein degradation?
Lysosomal pathway and the ubiquitin pathway
What are the ubiquitin and lysosomal pathways used for?
To rid the body of damaged or abnormal proteins
Proteins can be tagged for degradation by the addition of a chemical marker called what?
Ubiquitin
Where are ubiquitin-tagged proteins taken to? And what happens there?
The proteasome, or “recycling centre”
There they are broken down into their component parts
What you really need to know slide
Slide 24, lecture 9
What are simple lipids?
Fatty acids - building blocks
What are compound lipids?
Triacyglycerols - energy stores (triglycerides)
and
phosphoacylglycerols - membranes (phospholipids)
What are derived lipids?
Steroids - e.g. cholesterol
What are fatty acids composed of?
A hydrocarbon tail and a carboxyl group head
Slide 4, lecture 10 for diagram
Fatty acids can vary in length from 1-30 carbons, how long are short chain fatty acids (SCFA)?
Less than 8 carbons
Fatty acids can vary in length from 1-30 carbons, how long are medium chain fatty acids (MCFA)?
8-14 carbons
Fatty acids can vary in length from 1-30 carbons, how long are long chain fatty acids (LCFA)?
More than 14 carbons
Where are short chain fatty acids often found?
Milk fat
Where are medium chain fatty acids often found?
Milk fat and coconut
Where are long chain fatty acids found?
LCFA are the most common in our diet, they are either saturated or unsaturated
So saturated fatty acids have any double carbon bonds?
No
What is the molecule of saturated fatty acids like? What does this mean?
Molecule is straight and tightly packed - hence why high saturated fat foods are solid at room temperatures
Examples of saturated fatty acids
Cheese
Butter
Red meat
Do unsaturated fatty acids have any carbon double bonds?
Yes, at least one carbon double bond
What is the molecule of unsaturated fatty acids like? What does this mean?
It is less tightly packed, meaning it is a liquid at room temperature
What is an unsaturated fatty acid with one double carbon bond called?
A mono-unsaturated fatty acid (MUFA)
What is an unsaturated fatty acid with more than one double carbon bond called?
Poly-unsaturated fatty acid (PUFA)
Examples of unsaturated fatty acids
Avocado
Salmon
Olive oil
How are lipids stored?
Stored as triacylglycerides or triglycerides in adipose tissue and muscle
What happens when fatty acids are broken from their glycerol back bone?
They can be used by the liver and muscle to produce energy
Why are lipids surrounded by a carrier protein?
Because they are hydrophobic and the protein helps transport lipids around the body to different tissues
When can lipids be metabolised?
After a meal containing fat (not immediately however)
Where can lipids be broken down from?
Adipose tissues (large stores)
When is lipid metabolism the major metabolic pathway?
At rest and when hungry
What hormone activates lipid metabolism at rest?
Glucagon
What is the main hormone that activated lipid metabolism during exercise?
Adrenaline
Slide 15
Lecture 10
What is lipolysis?
The breakdown of a triglyceride into one glycerol and three free fatty acid molecules
In lipolysis, each fatty acid is broken down by a different hormone
Adipose triglyceride lipase (ATGL)
Hormone sensitive lipase (HSL)
Monoacylglycerol lipase (MGL)
Lipolysis is regulated by several hormones, such as…? What do these stimulate?
Glucagon
Epinephrine
Stimulate lipase enzymes to split the TAGs into glycerol and free fatty acids
Albumin is transported to the cell cytosol by 3 different transporter proteins, what are they?
Fatty acid binding protein
Fatty acid transport protein
Fatty acid translocase (CD36)
How can the number of transport proteins be increased?
By aerobic exercise and/or a high fat diet
Once transported to tissues, fatty acids can be used to generate energy via a process called what?
Beta-oxidation
What is the process of beta-oxidation?
Chemically, beta-oxidation is a process whereby the carbon chains of fatty acids are removed, therefore, shortening the molecule
What is the aim of beta-oxidation?
Derive Acetyl CoA for use in the TCA cycle
Where does beta-oxidation occur? And what does it require?
Occurs in the mitochondrial matrix and required oxygen
Why is the energy yield from lipids greater than carbohydrates?
Because they contain more carbons
However, because lipids have more carbons what does this mean about the rate of fat metabolism?
More carbons enquires more oxygen to become oxidised for energy; hence, fat metabolism is slower
Despite fat metabolism being slower, what is an advantage of fat metabolism?
More ATP can be produced
Why is Malonyl CoA decreased during exercise?
To allow for beta-oxidation to occur
When does Malonyl CoA increase?
When there is an abundance of Acetyl CoA in the cytoplasm - inhibiting beta-oxidation
What is Acetyl CoA availability dependent on?
Carbohydrate availability in the cell
Are there any differences in the metabolism of saturated and unsaturated fatty acids?
Yes, two different enzymes are used to produce Acetyl CoA (not really important)
Saturated fatty acids are oxidised more quickly than unsaturated fatty acids
Recap
Slide 28, lecture 10
There is a decrease in fat oxidation in HIE due to several changes
Inadequate blood flow in adipose tissue inhibiting blood FFA delivery to the muscles
Lactate build up inhibits oxidation
What you really need to know slide
Slide 36, lecture 10
What is substrate level phosphorylation?
Generating ATP from glycolysis / TCA cycle
What is oxidative phosphorylation?
The process of using high energy electron carriers (NADH and FADH2) to generate ATP
How many H+ ions are needed to create 1 ATP?
Approx. 3
