L30 Fat Metabolism Flashcards
Fat is stored in…
White adipose tissue
Fat is stored as…
Triglycerides
Fat cells are known as…
Adipocytes
Adipocytes contain an expandable…
Fat reservoir
Other than energy storage, fats are also used in the body as (3)…
Thermal insulation
Electrical insulation
Cell structural support
Cholesterol…
a) cannot be recycled by the liver, must be metabolised by the body
b) cannot be metabolised or recycled
c) cannot be metabolised by the body, except the kidney
d) cannot be metabolised by the body, must be recycled by the liver
d) cannot be metabolised by the body, must be recycled by the liver
Fat is a very efficient energy source. A 70kg person has on average enough fat to supply energy for…
2 months
Most naturally occurring triglycerides are…
Cis (with H on the same side of C=C double bond)
Saturated triglycerides shape
Linear
Unsaturated fats shape
Kinked
Fat metabolism has 3 stages…
- Lipolysis
- Activation of fatty acids
- Oxidation of fatty acids
Step 1 of fat metabolism, lipolysis, is mediated by…
Hormones
Lipolysis occurs under conditions of..,.
Starvation, stress or exercise
Lipase breaks which bonds in triglycerides?
Ester bonds
Lipase catalyses the conversion of triglycerides into…
Glycerol and fatty acids
Glycerol from lipolysis moves to the…
Liver
Glycerol is processed in the liver and converted to G-3-P, which can be used in…
Gluconeogenesis or citric acid cycle (if converted to pyruvate)
In fatty acid activation, fatty acids from lipolysis enter the…
Cytoplasm
Step 2 of fat metabolism is…
Fatty acid activation
Fatty acid is activated by addition of…
CoA
Forming Acyl CoA
Energy for fatty acid activation comes from…
Hydrolysis of ATP to AMP + PPi
The acyl group is needed inside the mitochondria, however acyl CoA cannot cross the membrane, thus it is added to…
Carnitine, forming acyl carnitine
Step 3 of fat metabolism is…
Beta oxidation
Hydrogen is removed from the beta carbon
Beta oxidation occurs over 4 steps…
- Oxidation I (FAD)
- Hydration
- Oxidation II (NAD+)
- Cleavage (acylation)
Products of beta oxidation are…
8 acetyl CoA
7 FADH2
7 NADH and H+
High energy yield compared to glucose. For example C16 (Palmitic acid) yields …
108 ATP
versus 32 for glucose
In the absence of glucose, glycolysis is…
Switched off
In the absence of glucose, citric acid cycle intermediates…
Enter gluconeogenesis to maintain blood glucose homeostasis
In ketone metabolism, acetyl CoA is converted to…
Ketone bodies in the liver
Lipogenesis occurs during…
High energy conditions
Lots of glucose, high acetyl CoA, high citrate
The lipogenesis pathway is increased by (2)…
High citrate and insulin
Lipogenesis pathway is decreased by (4)…
High AMP, glucagon, Adrenalin or palmitoyl
The decrease in lipogenesis caused by high palmitoyl is an example of…
Negative feedback
Glycerol is recycled in the liver to produce…
Glucose (gluconeogenesis)
Energy is released from fatty acids by…
Beta oxidation
Beta oxidation can be summarised as (4)…
Oxidation, hydration, oxidation, cleavage
Lipogenesis is the opposite of…
Lipolysis
They key enzyme controlling fatty acid synthesis is…
Acetyl CoA carboxylase
Insulin is a major regulator of lipogenesis in…
Type 2 diabetes
Ketone bodies are generated from fatty acid metabolism under which 2 conditions?
Prolonged starvation (or lack of glucose)
Type 1 diabetes
In type 1 diabetes, excessive ketone bodies in the blood can decrease pH dangerously resulting in…
Ketoacidosis
