Metabolic pathways Flashcards
They are 3
What are the main purposes of metabolism ?
- The conversion of the energy in food to energy available to run cellular processes
- The conversion of food to building blocks for the synthesis of molecules
- Elimination of metabolic wastes
What are chemical reactions of metabolism organised in ?
Metabolic Pathways
What is a metabolic pathway ?
- A sequenece of chemical reactions that begins with a particular molecule —-> of another molecule (s)
- These reactions are enzyme catalyzed
How can we control a metabolic pathway ?
- By the presence or absence of a particular
- The rate of enzyme activity controls the rate of a pathway
What do enzymes do?
- Orientates the rectants into the correct positions for the reaction to take place.
- The binding of a substrate also lowers the activation energy of the reaction.
They are 2
What classes is metabolism divided in ?
- Catabolism
- Anabolism
They are 2
What classes is metabolism divided in ?
- Catabolism
- Anabolism
What is an anabolic metabolism ?
- Requires energy (endergonic)
- Synthesis of nucleic acids, carbodydrates, lipids aand proteins
What is a catabolic metabolism?
- Common in all organisms showing evolution
- Releases energy (exergonic)
- Breakdown of nucleic acids, carbohydrates, lipids, proteins into small metabolites
What does ATP stand for and what is it ?
- Adenosine triphosphate
- It’s the energy currency of the cell (primary energy carrying molecule in the cell)
What is the structure of ATP ?
- Phosphate groups
- Adenine
- Ribose
What is the source of the ATP bonds ?
- High energy containing bonds
- Energy is releaseb when the ebonds are broken
does the forward reaction release or require energy ?
it releases energy
does the backwards reaction release or require energy ?
it requires energy
What are the 3 stages in which energy is extracted fom food?
- Glycolysis
- TCA (Krebs) cycle
- Electron Transport Chain
What is glycolysis ?
The lysis of glucose
Where does glycolysis occur ?
Cytoplasm
Can gycolysis operate withou oxygen/anaerobic condition ?
yes
What happens to pyruvate when oxygen is available?
pyruvate entres the mitochondria to undergo oxidative metabolism where TCA occurs
What are glucose tranporters ?
A group of memebrane proteins (5 different types - GLUT transporters that facilitate the transport of glucose across the plasma memebrane - facilitated transport
When is glucose tranport reversible ?
- if cellular level of glucose exceeds the plasma level then glucose will leak out of the cell
- This reaction is catalysed by the enzyme hexokinase
What does phosphorylation do?
it traps glucose in the cell
How much ATP is used up per glucose ?
2 ATPs consumed
What does NAD stand for ?
Nicotinamode adenine dinucleotide
What is NAD?
cofactor or activated carrier
What does NAD+ do ?
NAD+ accepts electrons from other molecules and becomes reduced by NADH
What does NADH do ?
it donates electron
What will be the consequence of limiting the amount of NAD in the cytoplasm ?
When oxygen is available NAD is regenerated from NADH in the mitochondria
How much ATP does glycolysis consume and produce ?
And what is the net gain ?
2 ATP consumed
4 ATP produced
Net gain is 2 ATP
What is the equation for the first phase of glycolysis ?
- glucose + 2 ATP —–> 2 glyceraldehyde 3 phospphate + 2 ADP
What is the equation for the first phase of glycolysis ?
- glucose + 2 ATP —–> 2 glyceraldehyde 3 phospphate + 2 ADP
What is the equation for the 2nd phase of glycolysis ?
glyceraldehyde 3 phospahte + (NAD+) + ADP+ Pi —-> 3-phosphoglycerate + NADH+ (H+) + ATP 2x
3-phosphoglycerate + ADP ——> pyruvate + ATP x2
What is the overall equation of glycolysis ?
glucose + (2NAD+) + 2ADP + 2Pi ——> 2 pyruvate + 2NADH + (2H+) + ATP x2
What is the overall equation of glycolysis ?
glucose + (2NAD+) + 2ADP + 2Pi ——> 2 pyruvate + 2NADH + (2H+) + ATP x2
What does the mitochindria do when the oxygen regenerates?
NAD from NADH
How does glycolysis work in the absence of oxygen ?
- due to lack of oxygen mitochondrial oxidative metabolism is unable to regenerate all NAD required for glycolysis
- Pyruvate is reduced to lactate NADH –> NAD
Glycolysis converts __a__ molecule of __b__ into __c__molecules of __d___
a) 1
b) glucose
c) 2
d) pyruvate
How do cells regenerate NAD from NADH in the absence of oxygen ?
- By reducing pyruvate to lactate
What enzyme is NADH regenerated by ?
- NADH is generated by the enzyme glyceraldehyde 3 phospahte dehydrogenase
What enzyme catalyses the 1st step in glycolysis ?
Hexokinase
