Lecture 10 --energy nutrition: metabolism of CHO & Fats Flashcards
Carbohydrates (‘describe the molecules from which we derive energy’)
Formula: CH2O
Only MONOSACCHARIDES are absorbed
Proteins (‘describe the molecules from which we derive energy’)
Chains of amino acids joined by peptide bonds
Fats (‘describe the molecules from which we derive energy’)
Formula: CH3–(CH2)n–COOH
We mostly consume Triglycerides
Can be SATURATED or UNSATURATED
How much energy is in carbohydrates?
4 kcal/g
What are SATURATED FATS?
Have only linear, single bonds
What are UNSATURATED FATS?
have CIS DOUBLE BONDS (which give them ‘kinky chains’)
What form of Fatty Acid is easiest to metabolise? Why?
Saturated FA are easier to metabolise
Unsaturated FA have CIS DOUBLE BONDS which gives them ‘kinky chains’ that are hard to metabolise
What is the purpose of enzymes in Unsaturated FA metabolism?
To convert the CIS double bonds to TRANS double bonds
What are the enzymes involved in unsaturated FA metabolism?
(1) Enoyl CoA isomerase
(2) 2,4 Dienoyl CoA reductase
(‘Outline hepatic processing’) What are the 3 processes involved in hepatic processing?
(1) Glycogenesis
(2) Glycogenolysis
(3) Gluconeogenesis
What is GLYCOGENESIS
Conversion of glucose –> glycogen for storage
What is GLYCOGENOLYSIS
Breakdown of glycogen to glucose-6-phosphate
What is GLUCONEOGENESIS
Synthesis of glucose from Fats and Amino Acids (Alanine & Lactate)
What are the main Amino Acids used in gluconeogenesis?
Alanine
Lactate
What % of the liver = glycogen?
7-10% of weight of liver = glycogen
What are the processes:
Glycogen –PROCESS?–> glucose-1-P
Glucose-1P–PROCESS?–>Glycogen?
Pyruvate–PROCESS?—>Glucose-6-P?
(1) Glycogenolysis
(2) Glycogenesis
(3) Gluconeogenesis
What enzyme enables glycogen to be converted back to glucose in the liver?
Glucose-6-Phosphatase
How are fats metabolised?
(1) Emulsified with bile salts
(2) Incorporated into BILE SALT MICELLES
(3) Packaged into CHYLOMICRONS in enteric cells
(4) LIPOLYSIS: lyses lipids, cleaving the FAs from the glycerol backbone
Outline the process of GLYCOLYSIS
> ANAEROBIC process
In a nutshell: GLUCOSE LYSIS (6 carbons),
> Consumes: -1 glucose, -2 ATP
Produces: +4 ATP, +2 NADH, +2 pyruvate
NET +2ATP, +2NADH, +2 pyruvate (3 carbons each)
Outline the process of the CITRIC ACID CYCLE
> AEROBIC PROCESS
Pyruvate (3C) –> Acetyl CoA (2C) =>Citrate ==FED INTO==> CITRIC ACID CYCLE
Produces: 10 NADH (per glucose)
The 2 carbons from Acetyl CoA are released throughout the CAC and used to drive the oxidation of NADH & FADH
What is the use of the 2 carbons from acetyl CoA in the citric Acid Cycle?
They are used released and used to drive the oxidation of NADH & FADH
Outline the process of OXIDATIVE PHOSPHORYLATION (electron transport chain)
> AEROBIC PROCESS
(1) NADH–reduced–> NAD+ & H+
(2) Pump H+ across the mitochondrial membrane –> inter membrane space
(3) = High [proton] = protons travel down [gradient] across inner mitochondrial membrane through ATP SYNTHASE
(4) The energy derived from protons travelling down their [gradient] is used to phosphorylate ADP–>ATP
What role do NADH & FADH produced in glycolysis & the citric acid cycle play in the production of ATP?
In the electron transport chain (ETC) NADH is REDUCED and used to drive oxidative phosphorylation of ADP–> ATP
How many ATP are produced per NADH in the ETC?
3 ATP
