Metabolism 4 Flashcards
Lipid transport
- ____, ____, _____ transported as lipoproteins
- Mainly in the ___ from site where you absorb fa like ____ to the___ where a lot of fa syn and storage and to ____ tissue
- __ ___ ___ transported by serum ____
- In the blood
Lipid transport
Phospholipids, Triacylglycerols (TAGs), cholesterol transported as lipoproteins
Mainly in the blood from site where you absorb fa like intestines to the liver where a lot of fa syn and storage and to adipose tissue
Free fatty acids transported by serum albumin
In the blood
Digestion of Fats in Foods
- ___ ____ cleave __ ___ off TAG’s at carbon _ & carbon _ in the ___ of the ___.
- Other____ remove carbon_ fa
- Fatty acids move through ____ _____ cells and combines with ____to form new ____’s
- Delivered as ____ through ___ system and____ to___ tissue
- Combine with lipoproteins to form chylomicrons
- ____ (enzymes that breakdown TAGs) are activated on the __ ___ and they hydrolyze ___ to___ __ and ____, which are___ by the cells.
- Finally___for ___
Digestion of Fats in Foods
Pancreatic lipases cleave fatty acids off TAG’s at carbon 1 & carbon 3 in the lumen of the intestine.
Other esterases remove carbon 2 fa
Fatty acids move through intestinal epithelial cells and combines with glycerol to form new TAG’s
Delivered as chylomicrons through lymphatic system and bloodstream to peripheral tissue
Combine with lipoproteins to form chylomicrons
Lipases (enzymes that breakdown TAGs) are activated on the cell surfaces and they hydrolyze TAGs to fatty acids and glycerol, which are taken by the cells.
Finally oxidized for energy
Lipoproteins
Defined by ___/___ratio
Higher protein/lipid ratio ____ the density) ___>___>___>___>____
H – High, I-Intermediate, L – Low and VL – Very Low Density Lipids
- LDL, IDL and VLDL
- Transport ____ and ____ from the ___ to the ___
- Chylomicrons
- ___ density
- Transport ___ lipids from ____ to ___ cells
- HDL
- Transports ___ from the ___ to the ___
- ___ ‘HDL/LDL’ besT
Lipoproteins
Defined by protein/lipid ratio
Higher protein/lipid ratio higher the densityHDL>LDL>IDL>VLDL>chylomicrons
H – High, I-Intermediate, L – Low and VL – Very Low Density Lipids
LDL, IDL and VLDL
Transport cholesterol and triglycerides from the liver to the tissues.
Chylomicrons
Lowest density
Transport dietary lipids from intestine to target cells
HDL
Transports cholesterol from the tissues to the liver
High ‘HDL/LDL’ best
Lipoproteins
Lipoprotein particle structure
- Core ___ ___ (_____ and ___ ___)
- Outer shell of more___ ___ and___ (__-___)
2 functions
- ___ ____ lipids
- Contain __-___ signals
Lipoproteins
Lipoprotein particle structure
Core hydrophobic lipids (triacylglyerols and cholesterol esters)
Outer shell of more amphipathic lipids and proteins (apo-lipoproteins)
2 functions
Solubilize hydrophobic lipids
Contain cell-targeting signals
VLDL
- VLDLs are synthesized in the ____
- Transported in the___
- At cell surfaces, ____ in VLDLs are acted on by ___ releasing___ ___
- __ ___ are taken up by the tissues.
- VLDL remnants remain in the ___ are converted to ___ and subsequently into ___
- When fa are taken up by tissues
- IDL are converted to LDL in the blood by ___ _____
- Add cholesterol and Add fa onto cholesterol
VLDL
VLDLs are synthesized in the liver
Transported in the blood
At cell surfaces, triacylglycerols in VLDLs are acted on by lipases releasing fatty acids
Fatty acids are taken up by the tissues.
VLDL remnants remain in the blood are converted to IDLs and subsequently into LDLs.
When fa are taken up by tissues
IDL are converted to LDL in the blood by cholesterol esterification.
Add cholesterol and Add fa onto cholesterol
LDL Particle
- Major carrier of_____
- ~1500 esterified molecules of cholesterol
- Mainly composed of ____-__
- ____ molecule
- Recognized by ___ on the___
- It will dock onto the liver. Particle will be taken up by the liver and components will be recycled
- Function: Transportation of___ to ___ ___
- Regulates __ __ ___of ___ in___ ___
LDL Particle
Major carrier of cholesterol
~1500 esterified molecules of cholesterol
Mainly composed of Apoprotein-B
Signal molecule
Recognized by receptor on the liver
It will dock onto the liver. Particle will be taken up by the liver and components will be recycled
Function: Transportation of cholesterol to peripheral tissues
Regulates de novo synthesis of cholesterol in peripheral tissue
HDL Particle
- __ __ released cholesterol from ___
- ___ cells,___turnover
- Cholesterol ___ by _______
- Cholesterol Transferred from HDL to ___ or ____or returned to liver as ___
HDL Particle
Pick up released cholesterol from plasma
Dying cells, membrane turnover
Cholesterol esterified by acyltransferase
Cholesterol Transferred from HDL to VLDL or LDL or returned to liver as HDL
Cholesterol metabolism
- Cholesterol in LDL particles containing apoprotein B
- ___ ____recognizes _______ _
- LDL particle ____ (receptor mediated endocytosis)
- Cholesterol___, LDL receptor ____
- Primary source of ___ for cells other than ___ is the ____
- Particle is broken down. Get release of cholesterol and fa. Will be stored in ___
- Receptor dependent mediated endocytosis process
Cholesterol metabolism
Cholesterol in LDL particles containing apoprotein B
LDL receptor recognizes apo-protein B.
LDL particle endocytosed (receptor mediated endocytosis)
Cholesterol released, LDL receptor recycled
Primary source of cholesterol for cells other than liver is the intestine.
Particle is broken down. Get release of cholesterol and fa. Will be stored in liver.
Receptor dependent mediated endocytosis process
Regulation of receptor mediated endocytosis
- Receptor subject to ___ ____
- When [cholesterol] high in cells, LDL-Receptor synthesis __ ___
- Blocks additional cholesterol uptake
- Don’t want to accumulate more cholesterol in the liver
- ___ ____ by controlling rate of ____ synthesis
- Blocks additional cholesterol uptake
Regulation of receptor mediated endocytosis
Receptor subject to feedback regulation
When [cholesterol] high in cells, LDL-Receptor synthesis shut offBlocks additional cholesterol uptake
Don’t want to accumulate more cholesterol in the liver
Gene regulation by controlling rate of mRNA synthesis
LDL Receptor Defects
Deficiency or dysfunction of LDL receptors leads to familial ______
Gene on chromosome 19
Dominantly inherited condition
Results in ____ LDL cholesterol levels in the___, premature _____ of coronary arteries
___types of mutations
LDL receptor is not produced
Mutation in terminal region;
Unable to bind LDL
Mutation in C-terminal region;
Prevents complex from undergoing endocytosis
LDL Receptor Defects
Deficiency or dysfunction of LDL receptors leads to familial hypercholesterolemia
Gene on chromosome 19
Dominantly inherited condition
Results in elevated LDL cholesterol levels in the blood, premature arteriosclerosis of coronary arteries
3 types of mutations
LDL receptor is not produced
Mutation in terminal region;
Unable to bind LDL
Mutation in C-terminal region;
Prevents complex from undergoing endocytosis
Additional defects in cholesterol metabolism
_____ B-100
Genetic defect prevents ____ by receptor
Result is____ serum cholesterol
Tangier Disease
Lack of ATP-binding cassette protein, which ___ cholesterol out of cell
Cholesterol buildup in ___ & other organs
Additional defects in cholesterol metabolism
Apoprotein B-100
Genetic defect prevents recognition by receptor
Result is elevated serum cholesterol
Tangier Disease
Lack of ATP-binding cassette protein, which exports cholesterol out of cell
Cholesterol buildup in tonsils & other organs
Summary
Lipoproteins defined by ____ ratio
Cholesterol taken into cell via __ __ ___
___ ___critical to cholesterol regulation
Summary
Lipoproteins defined by protein/lipid ratio
Cholesterol taken into cell via receptor mediated endocytosis
LDL receptor critical to cholesterol regulation
Summary of amino acid metabolism
Dietary proteins are broken down by digestive enzymes to amino acid.
These amino acid are transported in the bloodstream to various tissues.
Amino acids are used for ___ ___ or they could be ___, since amino acids ___ be ___
During degradation, the _____ is removed and incorporated into ___ for excretion in terrestrial vertebrates.
The remaining carbon skeleton can used as ___ for____ intermediates, ___ generation, __ __ and ___ ___ formation.
Summary of amino acid metabolism
Dietary proteins are broken down by digestive enzymes to amino acid.
These amino acid are transported in the bloodstream to various tissues.
Amino acids are used for protein synthesis or they could be degraded, since amino acids CANNOT be stored.
During degradation, the α-amino group is removed and incorporated into urea for excretion in terrestrial vertebrates.
The remaining carbon skeleton can used as precursors for citric acid cycle intermediates, glucose generation, fatty acid and ketone body formation.
Removal of the alpha-amino group (transamination)
To enter metabolic pathways for energy generation, ___ must first be ____ and disposed.
Occurs in 2 Steps
1.Transfer of ______ to ____ to form ____. The resulting ____ can be used to generate ____ in some tissues.
2____ is ___ly ____ed to form____ using ___(___ is generated)
Removal of the alpha-amino group (transamination)
To enter metabolic pathways for energy generation, Nitrogen must first be removed and disposed.
Occurs in 2 Steps
- Transfer of α-amino group to α-ketoglutarate to form glutamate. The resulting α-ketoacid can be used to generate energy in some tissues.
- Glutamate is oxidatively deaminated to form ammonia (NH4) using NAD+ (NADH is generated)
Transaminases (aminotransferases)
Enzymes that transfer _____from an ____ to form an ____
Contains the coenzyme ____ ____
Enzymes are found in ___ and ____
Aspartate transaminase
Aspartate + ____ —> ____ + ____
Alanine transaminase
Alanine + _____ –>___+ ___
Each aa has a corresponding transaminase
Transaminases (aminotransferases)
Enzymes that transfer α -amino group from an amino acid to form an α -keto acid
Contains the coenzyme Pyridoxal Phosphate
Enzymes are found in cytoplasm and mitochondria
Aspartate transaminase
Aspartate + α -ketoglutarate ßàoxaloacetate + glutamate
Alanine transaminase
Alanine + α -ketoglutarateßàpyruvate + glutamate
Each aa has a corresponding transaminase