Gastrointestinal System Flashcards
What does the first law of thermodynamics state?
Energy can be neither created nor destroyed, only transferred
What does the body need energy for?
Contraction Accumulating molecules across concentration gradients waste disposal heat building and repairing
What is Gibbs free energy (-delta G)?
The difference in energy between the substrates and the product
If the product has more energy than the substrates, G is positive
Describe Gibbs in terms of positive and negative metabolism.
Negative G would be exergonic (giving off energy, i.e. breaking down ATP)
Positive G would be endergonic (i.e. if you want to MAKE ATP you need energy)
Is food breakdown exergonic or endergonic?
Exergonic, you are releasing energy
What does ATP consist of?
5-carbon ribose sugar
Adenine
3 phosphate groups
What type of chemical reaction occurs to release energy from ATP?
Hydrolysis removes the phosphate
How much ATP is typically turned over in a day for 1 person?
80kg
What processes give rise to Acetyl Co-enzyme A for glucose, fatty acids, and amino acids?
Glucose- glycolysis
Fatty Acids- beta-oxidation
Amino Acids- transamination, oxidative deamination,
What are the phases of Krebs?
Decarboxylation- Acetyl Co-A is condensed with oxaloacetate to form citrate, which is then decarboxylated into succinyl Co-A
Reduction- succinyl co-a aids in reducing NAD and FAD and will eventually form oxaloacetate
How many NADH and FADH2 molecules are reduced in one cycle of Krebs?
3 NADH
1 FADH2
They are then fed into the ETC
What is the purpose of the Electron Transport Chain?
To pump protons (H+) across the inner mitochondrial membrane, into the inter membrane space
How many electrons and protons are donated to the electron transport chain by NADH and FADH2?
NADH can donate 2 electrons, and 1 proton to ETC
FADH2 donates 1 electron and 1 proton
How do electrons move from 1 radox centre to the next?
Using either Quinone or Cytochrome C proteins
What happens to the electrons when they are passed to radox centre 4?
Donated to molecular oxygen to produce water
This is why oxygen is essential
How much ATP is created for each Acetyl Co-A enzyme entering TCA?
NADH yields 2.5 ATP
FADH yields 1.5
(3x2.5)+(1x1.5)= Total is therefore 10 ATP
What happens during glycolysis, and where does it occur?
In cytosol of cells
6 Carbon Glucose converted into 2, 3 carbon pyruvates
First stage- glucose converted into fructose 1,6-bisphosphate using 2 ATP
2nd Stage- 2 NADH and 4 ATP are produced while creating 2 pyruvates
What happens to pyruvate as it enters the mitochondria?
Acetyl dehydrogenase converts pyruvate into acetyl co-a by removing a carbon
This also produces NADH
How does the body store glucose, and what organ aids in this storage?
Glycogen formed by Liver
What enzyme is responsible for the breakdown of fats?
Triglycerides are broken down by lipase into fatty acids, which are then moved into the body
How are fatty acids carried throughout the body?
Albumin (most prolific plasma protein)
Where does beta oxidation of fatty acids occur?
Mitochondrial matrix
What reactions occur to allow fatty acid transport into the mitochondria?
1- Acyl CoA synthase adds acyl CoA to fatty acid, creating Fatty Acyl CoA which can move across outer mito membrane
2- CoA is removed in intermembrane space, and carnitine is added, creating fatty acyl carnitine which can then move across inner mito membrane
3- Once in matrix, carnitine is replaced by acyl to create fatty acyl coa, which can be metabolized.
How much energy do you yield in beta-oxidation of fatty acyl coa?
For every beta-oxidation, you get: 1 Acetyl CoA 1 NADH 1 FADH Acetyl CoA can then feed into Krebs (3 NADH, 1 FADH2)
What happens in the stages of protein breakdown?
Transamination- removal of amino acid R group, and adding it onto a keto acid (typically alpha-ketoglutamate), forming an oxaloacetate/pyruvic acid (alpha-ketoacid) and a glutamate.
Alpha-ketoacid can then be utilized in ketogenic reaction (forming fatty aids, or acetyl coa), or glucogenic reaction (forming glucose, or pyruvates) which can be fed into krebs.
Deamination- glutamate is oxidized using nadp, to form alpha-ketoglutarate (process releases ammonia) . Alpha-ketoglutarate will undergo further processes to yield oxaloacetate/glutamate which can be fed into krebs
All these reactions are reversible
What does it mean for an amino acid to be ketogenic of glucogenic?
It can form a fatty acid (leucine or lysine) or a glucose molecule after transamination and deamination
How can you calculate energy requirements for a person?
Basal Energy Expenditure
a.k.a. basal metabolic rate
What structures form a triglyceride and how does it different from a phospholipid?
Glycerol backbone with 3 fatty acids
Phospholipid has glycerol, 2 fatty acids, and a phosphate group that has been modified with an alcohol
What are monosaccharides?
Glucose
Fructose
Galactose
How are disaccharides formed? Name 3 common ones as well as their monomers
Monosaccharides joined by glyosidic bond
Common; Sucrose (glucose + fructose), maltose (glucose + glucose), Lactose (glucose + galactose)
What are 2 common polysaccharides and how are they formed?
Starch, formed from amylose (alpha 1,4 glyosidic bonds) and amylopectin (alpha 1,4 glycosidic bonds with some alpha 1,6 glycosidic bonds)
Fibre- beta 1,4 links, cannot be digested
What is amylase and where is it produced?
Production: parotid, sublingual, and submandibular salivary glands as well as in the pancreas
Begins break down of carbohydrates, while moistening food
What is lingual lipase and where is it produced?
Production: parotid, sublingual, and submandibular salivary glands
Begins break down of lipids, while moistening food
What is the role of chief cells and where are they found?
Secrete pepsinogen (inactive ) for protein breakdown, which is converted to active pepsin form by acid Found below base of gastric mucosal pit
What is the role of parietal cells and where are they found?
Secrete hydrochloric acid which denatures proteins and activates pepsinogen (by opening and cleaving it)
Found in the neck of the gastric pit