Metabolism Flashcards
L13 L14 L15 L16 L17 L18 L19
What are aldoses and ketoses?
Aldoses: Monosaccharides which are aldehydes
Ketoses: Monosaccharides which are ketoses
How do pyranoses form?
When monosaccharides are in solution, carbon sugars form ring structures spontaneously. Outside of solution, they’re straight chains.
What is the orientation of the Alpha and Beta glucose -OH groups?
Alpha- DDUD
Beta- UDUD
‘Alpha isnt capital so is a DDUD. Beta is capital so makes me go UDUD’
What are epimers?
An epimer is a stereoisomer where the penultimate carbon of the straight sugar chain has a different position of the -OH group.
There are D-isomers and L-isomers
What are anomers?
An anomer is a stereoisomer where the first carbon of a cyclical monosaccharide has different positions for the -OH group.
There are alpha and beta isomers.
What is a pyranose?
Collective term for polysaccharides with a ring formation with and oxygen in the ring and 5 carbons.
Definition of metabolism.
‘The totality of chemical reactions and physical change that occur in living organisms, comprising of anabolism and catabolism.’
What is catabolism?
What is anabolism?
Catabolism: Metabolic breakdown of complex substances into smaller products. Generates ATP and NADH
Anabolism: Energy requiring part of metabolism where simpler substances are transformed into more complex ions. Uses ATP and other triphosphate nucleotides.
What is stepwise breakdown and why is it used?
Instead of the entire sugar combusting at once, smaller combustions take place.
It ensures that not all energy from sugar is used and lost immediately. Energy at each step is stored in activated carrier molecules.
https://slideplayer.com/slide/8259822/25/images/14/Harnessing+Energy+-+Stepwise+Breakdown+of+Carbohydrates.jpg
Why is ATP hydrolysis favourable?
There is electrostatic repulsion betweem the phosphate groups which is revealed when Pi is removed from ATP. Additionally there is +ve entropy.
How much energy is released when ATP is hydrolysed to ADP?
How much energy is released when ATP is hydrolysed to AMP?
-31 to -50 kJ/mol
Doubled when ATP is hydrolysed to AMP
What do NAD and FAD stand for?
Nicotinamide adenine dinucleotide
Flavin adenine dinucleotide
What is a futile cycle?
When there are reversible reactions which cause product to be reverted back to reactant.
Pyruvate structure
https://pubchem.ncbi.nlm.nih.gov/image/imgsrv.fcgi?cid=107735&t=l
Lactate structure
https://pubchem.ncbi.nlm.nih.gov/image/imgsrv.fcgi?cid=91435&t=l
What are thioester bonds?
Thioester bond: R-CO-S-R’
Why is glycogen a better fuel source than glucose?
Glycogen is low in osmolarity but glucose is osmotically active because there are more molecules.
What enzyme is used for glycogen synthesis and breakdown?
Synthesis: Glycogen synthase
Breakdown: Glycogen phosphorylase
How is glycogen synthesised?
4 Steps
Glucose + ATP –(Glucokinase/hexokinase)–> Glucose 6-phosphate + ADP
Glucose 6-phosphate <=(Phosphoglucomutase)=> Glucose 1-phosphate
Glucose 1-phosphate + UTP –(UDP glucose pyrophosphorylase)–> UDP glucose + PPi
UDP glucose + glycogen [n glucose] –(Glycogen synthase)–> glycogen [n+1 glucose] + UDP
How is glycogen broken down?
Chemical reactions
Glycogen [n glucose] + phosphate group –(glycogen phosphorylase)–> Glucose 1-phosphate + glycogen [n-1 glucose]
Glucose 1-phosphate –(Phosphoglucomutase)–> Glucose 6-phosphate
Glucose 6-phosphate + H2O–(Glucose 6-phosphatase)–> Glucose + phosphate group
What is the net yield of ATP from glycolysis?
2 ATP
How is glycogen metabolism regulated?
Hormones binds cell surface receptor and activates internal signalling pathway.
Internal signalling activates a protein kinase.
Glycogen synthase is inhibited by phosphate group.
Glycogen phosphorylase is activated by phosphate group.
What is feedback inhibition?
When the product of a reaction inhibits the enzyme responsible for the reaction.
What does phosphofructokinase do? How is it inhibited?
Catalyses Fructose 6-phosphate to Fructose 1,6-biphosphate
ATP inhibits the enzyme
Where in the cell does the ‘link reaction’ occur?
The matrix of the mitochondria
TCA cycle
https://www.researchgate.net/profile/Justine_Couper/publication/28800358/figure/fig3/AS:798422542086144@1567370176387/5-The-Krebs-Cycle-Tricarboxylic-Acid-Cycle-TCA-Cycle-Metabolic-pathways-for.png
Which reactions of the TCA cycle are irreversible?
What are the enzymes?
Why?
Step 1 (citrate synthase) Step 3 (isocitrate dehydrogenase) Step 4 (α-ketoglutarate)
Don’t know about step 1, but step 3 and 4 produce CO2 which means theres +ve entropy
How is the TCA cycle is regulated?
Feedback inhibition of key enzymes (citrate synthase)(isocitrate dehydrogenase) (alpha-ketoglutarate)
What is anaplerosis?
Anaplerosis is the replenishing TCA cycle intermediates that have been extracted for biosynthesis.
How are ‘new’ molecules for the TCA cycle made?
Pyruvate –(pyruvate carboxylase)–> oxaloacetate
Pyruvate <==(Malic acid)==> Malate (malic acid only used for backwards reaction)
NAD+ and NADH structure
https://i.pinimg.com/originals/e2/a3/6c/e2a36c116cd8c2450d11e28229b4061a.jpg
NADP+ structure
https://www.researchgate.net/profile/Rui_Huang11/publication/307613193/figure/download/fig3/AS:402989975130118@1473091705321/Chemical-structures-of-NADP-and-NAD-Structures-of-NADP-and-NAD-were-shown-and-the.png
FAD structure
https://www.researchgate.net/profile/Sergio_De_Nicola/publication/51873284/figure/fig1/AS:213801812140036@1427985732028/Structural-formula-of-flavin-adenine-dinucleotide-FAD.png
Where does oxidative phosphorylation take place?
The inner mitochondrial membrane
What are the components of the ETC?
Flavin cofactors and Coenzyme Q (Hydrogen acceptors)
Iron Sulfur proteins and cytochrome proteins (Electron acceptors)
Structure of CoQ?
https://www.researchgate.net/profile/Srinivasan_Shanmugam/publication/247916115/figure/fig1/AS:298359173730304@1448145778093/Chemical-structure-of-coenzyme-Q10.png
What is the function of Iron-Sulfur proteins?
Proteins within protein complexes in the ETC that contain Fe-S clusters. They’re capable of redox reactions so they transport electrons along the ETC.
What is the function of cytochrome proteins?
Cytochromes are proteins containing haem groups as a cofactors, that perform electron transfer reactions and catalysis by reduction or oxidation of their haem iron.
What is the arrangement of the proteins in the ETC?
Flavin -> CoQ -> cyt b -> cyt c -> cyt a
What is ubiquinone?
Otherwise known as Coenzmye Q.
It is the intermediate molecules between protein complex I and III
What is gluconeogenesis?
Making glucose in catabolic reaction from non-carbohydrate precursors. Most amino acids are capable of gluconeogenesis.