Intro To Metabolic Pathways Flashcards
How do plants get their energy source
Through photosynthesis of co2 and water into glucose chemical energy
How is photosynthesis a anabolic reaction
It produces glucose from the reduction (gain of electrons and H) of co2 from water photolysis
Where do animals get their energy source
From diet
They can get polysaccharides such as starch in foods which are then broken down by amylases disaccharidases into glucose etc
What are humans called due to getting energy from chemical reactions eg glycolysis
Chemotrophs
What are the animals called which get energy from different sources such as food
Heterotrophs
What is the definition of metabolism
Bio chemicals modification of chemical compounds such as glucose
Catalysed by enzymes
What is a catabolic pathway and the properties it holds
It is the breakdown of molecules
It is energy generating (generates ATP)
It is oxidative - (it generates NADH)
What are the properties of an anabolic pathway
It is a build up reaction eg build of muscle from amino acids or production of hormones
Requires energy (generated by catabolic pathway)
It is reductive (it requires transfer of electrons to molecules) (USING NADPH)
Why is catabolic reactions called oxidative?
Because they generate NADH from NAD by oxidation of molecules such as glucose
Why do anabolic reactions need NADPH
Because they need the electrons from the NADPH to be transferred to the molecules
What 3 things is the energy generated from catabolic reactions used for
Active transport (eg of AA across membranes)
Mechanical work (muscle movement)
Heat
What is the problem with the energy source of humans being from food and what do we rectify that by
Because we need energy constantly but energy source is only available when we eat..
We need to store energy eg in form of starch or glycogen
What would happen if our energy source got too much and wasted substrate for anabolic reactions
Too much energy would be stored and cause obesity
Which type of pathway is exergonic (releases free energy) -DG
Catabolic pathway
What do endergonic reaction mean
Require energy to occur
What 3 ways do endergonic reactions take place
1- increasing temp
2- increasing substrate
3- link to favoured reactions (exergonic)
How does coupling of exergonic catabolic pathways and endergonic anabolic pathways occur
Using ATP generated from catabolic processes
ATP can be transported to unfavoured reactions such as muscle production and release energy by hydrolysis of ATP = transfer energy
Why is atp hydrolysis exergonic (releasing energy)
Phosphoanhydride bonds are very easily broken by h20 due to electrostatic repulsion and resonance stability = transfer energy to anabolic reactions
Which other 3 other than ATP are used for energy providing to anabolic reactions
GTP - for protein metabolism
CTP- for lipid synthesis
UTP- for carbohydrate metabolism - Eg glycogenesis
What is an acetyl group made of
C = O
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CH3
What is the bond called between an acetyl group and the b mercaptoethylamine on the acetyl coA
A thioester bond
What is acetyl from acetyl coA used for
The citric acid cycle to be oxidised further generating NADH and FADH
What is the thioester (thiol) bond between in acetyl coA
S - C
Why is thioester between the mercaptoethylamine and acetyl in acetyl coA exergonic(energetic)
Releases energy when hydrolysed
What 2 other thioesters are there apart from acetyl coA
Succinyl coA
Fatty acyl coA
Why is glucose into co2 and H20 exergonic (releases energy)
Because glucose is oxidative with the help of NAD picking up a H and electrons
To then reduce 02 in oxidative phosphorylation
Why does glucose energy need to be released step by step and how does it do this
Because if burned to release energy the release isn’t controlled
It does this by using NAD and FAD
What is the difference between NAD and NADP
NADP has an extra phosphate group added to hydroxyl on one sugar of NaD
Where is H added to on NAD in the oxidation of molecules such as oxygen
On the nicotinamide ring
How many Hydrogens are accepted by NAD and FAD
2 H and 2 E
What is a reductant
Something that donates its electrons to reduce another molecule (NADH)
What is an oxidant
Something that gains electrons by the oxidation of eg NADH into NAD
Why do electrons move from reductant to oxidant
Because reductants have low affinity for electrons as they lose them in order to reduce something else
What does NaD stand for
Nicotinamide adenosine dinuleotide
What does FAD stand for
Flavin adenosine dinucleotide
Where does 2 H and electrons get accepted in FAD when it is being reduced (oxidant)
On its isoalloxazinegrouo where 2 hydrogens are seperated
Name 5 ways pathways are controlled
1- negative feedback
2- feed forwaward
3- isoenzymes
4- compartmentalisation
5- multi enzyme complexes
6- reciprocal regulation
How does negative feedback work
When levels of the end product are high , this will allosterically inhibit the enzyme in the pathway to stop working
How does feedforward work to speed up pathway eg if something is toxic
More substrate is added of the reactant to then be converted quicker in pathway
What are isoenzymes are how does it give flexibility
Enzymes which catalyse the same reaction as enzyme in pathway
These respond differently to different things eg could be activated whilst other enzyme is inhibited
What are multi enzyme complexes for
Multiple AS so multiple enzymes working on different reactions can be inhibited altogether or activated all together
What is compartmentalisation
Keeping a reaction to eg one area of the mitochondria
How does reciprocal regulation work
When 1 pathway affects another
Eg if 1 path goes forward another will be repressed (antagonistic)
What is the differences between alkenes and alkynes
Alkenes have 1 or more c=c
Alkynes are also UNSATURATED BUT TRIPLE BONDED C C
