Biochemistry 4230 - Exam 3 - thinGS tO knOW
01 - Lipid Structures
- Never Had Slide Deck For This Topic
02 - Fatty Acid Oxidation
Fatty Acid Oxidation
Free Fatty Acid Activation with CoA
- Fatty acid activation takes the initial fatty acid in the cytosol and adds a CoA to yield acyl-CoA on the inner membrane.
Oxidation Occurs in Mitochondrial Matrix
Which Molecules Can Diffuse and Which Cannot:
Can Diffuse:
- Nonpolar Molecules: , , hydrocarbons with less than 10 carbons
Cannot Diffuse:
- Polar molecules
- Ions
Free Fatty Acid Transport
- The acyl chain is then passed to a carnitine to become acyl-carnitine
- Acyl-carnitine can enter the mitochondrial matrix where the acyl group is then committed to undergo complete oxidation via beta-oxidation and the citric acid cycle.
Steps in Beta Oxidation
Steps:
- Dehydrogenation / Oxidation
- Hydration
- Dehydrogenation / Oxidation
- Thiolytic Cleavage
Products:
- acetyl-CoA
- NADH
- FADH2
Similarities to Citric Acid Cycle:
- Both Operate in Mitochondria
- Both have Dehydrogenation , Hydration , then Dehydration Steps
Saturated vs Unsaturated
Melting Point ( Lowest to Highest )
- Unsaturated < Cis Bonds < Trans Bonds < Saturated
Odd-Number Chain
- Odd number fatty acid chains produce a propionyl-CoA
- propionyl-CoA gets converted into succinyl-CoA
- succinyl-CoA is then converted into oxaloacetate
- oxaloacetate is a substrate in gluconeogenesis
Energy Generation for All Possible Combinations
- Fatty Acid's no matter what provide more energy per carbon than sugars
03 - Lipid Synthesis
Why Fatty acid synthesis?
- Because carbohydrate storage is limited by size and quantity.
- Excess carbohydrates in the diet are converted to pyruvate and eventually acetyl-CoA
Acetyl-CoA transport
- Molecular Carrier is Acyl Carrier Protein (ACP)
- Citrate ( mitochondria to cytosol )
Molecules involved
- NADP
- Precursors = Acetyl CoA and Malonyl CoA
- Products = Fatty Acid Chains
How NADPH is generated
- generated by reducing the beta carbonyl carbon on the fatty acid chain
Differences between Fatty acid oxidation and synthesis
- See Multiple Charts
How is Malonyl-CoA formed and why is it necessary?
- Acetyl-CoA + Acetyl-CoA Carboxylase = Malonyl-CoA
- Necessary for both Fatty Acid Synthesis and Fatty Acid Oxidation
What is a Phosphopantetheine moiety and how are fatty acids attached?
- Acyl Carrier = Protein bound phosphantethiene
How many cycles to make palmitate
7
Quantities of reactants and products used/generated
FA Elongation
- process inside the endoplasmic reticulum (ER) that adds 2 carbons from malonyl CoA to growing Fatty Acyl CoA
Desaturation
- Adding double bonds in specific locations to make non-essential fatty acids
Essential fatty acids
- Cannot be synthesized in human body
- Can't make double bonds past carbon 9
Regulation of ACC and pyruvate dehydrogenase
Acetyl-CoA Carboxylase (ACC) is Regulated By:
- allosteric ( citrate and long-chain fatty acids )
- covalent modification mechanisms
Pyruvate Dehydrogenase is Regulated By:
- Insulin promotes dephosphorylation (activation)
04 - Cholestrol Formation
- Never Had Slide Deck For This Topic
05 - Lipid Transport
General statistics about heart disease
- Black men and women are more at risk than white
- Older individuals are more at risk
- Males are more at risk within their race
- two top leading causes of death in 2018 and 2019 the US were heart disease and cancer
Atherosclerosis
Define it
hardening of the arteries over the course of several decades
- often leads to heart attack , stroke, or other peripheral vascular disease
Role of macrophages and how they got there
- In the intima the monocyte will acquire characteristics of a macrophage with scavenger receptors which help to engulf nonspecific molecules and debris; including fat and lipoproteins
Foam cells
- engorged macrophages with lipids
Fatty streak
- accumulation of foam cells that appear on arterial wall indicating early atherosclerosis
Fibrous cap
- Over time additional lipid will pool forcing the cell to make thin fibrous caps between the lipid pool and the remaining lumen (hollow part of the vessel)
Possible result of thrombosis
Why cholesterol is such a concern
If no tissues require cholesterol the LDL will continue to circulate, eventually depositing the excess fat on the arterial walls
- leads to Atherosclerosis
Medical diagnosis of LDL and HDL
- LDL: high cholesterol lipoprotein responsible for transporting cholesterol to peripheral tissues
- HDL: removes excess cholesterol for is removal from the body
LDL receptor complications and results
- If no tissues require cholesterol the LDL will continue to circulate, eventually depositing the excess fat on the arterial walls
Hyperlipoproteinemia
General characteristics
- Inability to break down lipids or fats in your body; specifically cholesterol and triglycerides.
- Many of the types are genetically inherited either as dominant or recessive traits, while other simply “run in families”
Symptoms
- Many people with this condition experience no symptoms, and only become aware of it when they develop a heart condition
- Others experience lipid deposits or xanthomas on the skin
06 - Membrane Stucture and Function
Properties and functions of membranes
- Acts as a barrier
- Selectively permissible
- A fluid mosaic
- Concentration gradients / isolation
General membrane constituents and their organization
Fluid mosaic model and fluidity
Differential content of proteins in membranes
Similarities and differences between membrane protein types
Differences between transmembrane, lipid-linked, and peripheral proteins
Transmembrane / Integral / Intrinsic
- Highly associated with the membrane and are typically very difficult to dissociate from the membrane
Lipid- Linked / Anchored
- Covalently modified with a lipid
Peripheral / Extrinsic
- •Loosely associated with the membrane and easily dissociate from it
