Exam 3 Flashcards
What is the main purpose of lipoproteins?
Transport lipids and cholesterol through the bloodstream
What are the four main types of lipoproteins?
Chylomicrons, VLDL, LDL, and HDL
What is the primary function of fatty acid catabolism?
Break down fatty acids to produce energy in the form of ATP
What is beta-oxidation?
The process of breaking down fatty acids into acetyl-CoA units
Where does fatty acid catabolism occur?
In the mitochondria of cells
What are ketone bodies?
Alternative energy source produced from fatty acids when glucose is limited
What triggers ketone body production?
Low glucose levels and high fatty acid breakdown
What is lipogenesis?
The process of creating fatty acids from acetyl-CoA
Where does fatty acid synthesis occur?
In the cytoplasm of cells
What is the rate-limiting enzyme in cholesterol synthesis?
HMG-CoA reductase
What regulates fatty acid synthesis?
Insulin levels and cellular energy status
How is cholesterol synthesis regulated?
Through feedback inhibition and hormonal control
What is the function of LDL?
Delivers cholesterol to peripheral tissues
What is the role of HDL?
Removes excess cholesterol from tissues and returns it to the liver
What are the three ways vertebrates utilize fat?
Dietary intake, mobilization from adipose tissue, and liver conversion of excess carbohydrates
What percentage of daily human energy requirements come from TAGs?
40% or more
What enzyme helps absorb fatty acids from diet?
Pancreatic lipase
Where is pancreatic lipase located?
Intestinal lumen
What is the function of lipoprotein lipase?
To absorb fatty acids from chylomicrons and VLDL
Where are lipoprotein lipases found?
Capillary walls
What is the purpose of hormone-sensitive lipase?
To break down cellular fat stores
Where is hormone-sensitive lipase found?
Intracellularly
What are bile salts derived from?
Cholesterol
What compounds help solve the problem of insoluble fat particles?
Bile salts
Where are bile salts produced?
In the liver
Where are bile salts stored?
In the gallbladder
What is the primary function of bile salts with TAGs?
They create mixed micelles
What are the four main components packaged with lipoproteins?
Triacylglycerols, cholesterol, cholesteryl esters, and specific proteins
What forms the exterior of lipoproteins?
Phospholipid head groups
What proteins coat the surface of lipoproteins?
Apolipoproteins
What are the five classes of lipoproteins in order of density?
Chylomicrons, VLDL, IDL, LDL, HDL
What does IDL stand for?
Intermediate-Density Lipoproteins
What does VLDL stand for?
Very Low-Density Lipoproteins
What does CM stand for in lipoprotein classification?
Chylomicrons
What does LDL stand for?
Low-Density Lipoproteins
What does HDL stand for?
High-Density Lipoproteins
What is the main function of the exogenous pathway?
Transport of dietary fat and cholesterol
What does the liver synthesize in the endogenous pathway?
TAGs and cholesterol
How are dietary lipids initially processed in the exogenous pathway?
They are packaged into chylomicrons
What lipoprotein packages liver-synthesized lipids?
VLDL
What are the three main products of β-oxidation?
Acetyl-CoA, FADH2, and NADH
What triggers the mobilization of stored TAGs?
Glucagon and epinephrine hormones
Where does fatty acid catabolism occur?
In the mitochondrial matrix through β-oxidation
What enzyme is responsible for releasing fatty acids from stored TAGs?
Hormone-sensitive lipase
How are fatty acids transported in the bloodstream?
By serum albumin
What are the four main ways fatty acid oxidation is regulated?
Cell energy state, hormonal regulation, malonyl-CoA regulation, and transcriptional regulation via PPAR receptors
Where does ketone body production exclusively take place?
In liver mitochondria
What are the five main functions of the liver in lipid metabolism?
Metabolizing dietary fatty acids, synthesizing fatty acids, synthesizing cholesterol, producing bile salts, and producing VLDLs/HDLs
Which lipoproteins does the liver produce?
VLDLs and HDLs
What molecule regulates fatty acid oxidation at the metabolic level?
Malonyl-CoA
What nuclear receptors are involved in transcriptional regulation of fatty acid oxidation?
PPAR receptors
What are bile salts used for?
To aid in the digestion and absorption of dietary fats
What key processes does ketogenesis provide energy for?
Brain, skeletal muscle, heart muscle, and kidney, especially during starvation
Where does fatty acid synthesis occur and in which tissues?
In the cytosol, primarily in liver and adipose tissue
What are the required components for fatty acid synthesis?
Acetyl-CoA, ATP, and NADPH
What are the three main functions of cholesterol?
Cell membrane incorporation, steroid hormone precursor, and bile acid precursor
What is the rate-determining enzyme in cholesterol synthesis?
HMG-CoA Reductase
What factors regulate cholesterol synthesis?
Insulin, glucagon, and intracellular cholesterol levels
What is hypercholesterolemia?
High blood cholesterol levels
How do statins treat high cholesterol?
They reduce endogenous cholesterol synthesis and increase LDL receptors
Where does protein digestion begin?
In the stomach and continues in the intestines
What do salivary enzymes break down?
Starch to glucose
What do gastric and pancreatic proteases break down?
Proteins into peptides and amino acids
What do lipases release?
Fatty acids from triacylglycerol
How are glucose and amino acids absorbed?
Through intestinal cell transporters
Where do water-soluble substances go after absorption?
Enter portal vein to liver
What is the activated form of trypsinogen?
Trypsin
What is the activated form of chymotrypsinogen?
Chymotrypsin
What are procarboxypeptidases A and B converted to?
Carboxypeptidases A and B
What type of molecules are responsible for transporting nutrients in intestinal cells?
Transporters
What is the main function of digestive proteases?
Breaking down proteins into smaller peptides and amino acids
What are zymogens?
Inactive precursor forms of enzymes that must be activated
Name the three main types of macromolecule digestive enzymes
Proteases, lipases, and amylases
What is the primary site of nutrient absorption?
Small intestine
Primary functions of protein turnover
- Energy production during metabolic needs 2. Elimination of abnormal proteins 3. Cellular metabolism regulation
What are the two main protein degradation mechanisms?
- Lysosomal Degradation (CMA) 2. Proteasome Degradation
Where is Lysosomal Degradation most important?
In liver and kidney during starvation
What sequence do proteins need for CMA targeting?
KFERQ sequences
What percentage of cytosolic proteins contain KFERQ sequences?
Approximately 30%
What protein controls Lysosomal Degradation?
LAMP2A
What are the three main functions of LAMP2A?
- Recognizes KFERQ proteins 2. Forms multimeric complexes 3. Transports proteins into lysosome
What molecule tags proteins in Proteasome Degradation?
Ubiquitin
What type of process is Proteasome Degradation?
ATP-dependent
What specific modification is required for Proteasome Degradation?
Polyubiquitination
E1 Activating Enzyme Function
Links ubiquitin to start protein degradation process
E2 Conjugating Enzyme Role
Receives ubiquitin from E1 and carries it forward
E3 Ligase Purpose
Transfers ubiquitin to specific protein targets for degradation
Name 4 conditions linked to protein degradation:
Alzheimer’s, Parkinson’s, Huntington’s, ALS
Step 1 of Nitrogen Removal
Transamination converting amino acids to L-Glutamate
Step 2 of Nitrogen Removal
Oxidative deamination of glutamate
Fish Nitrogen Excretion
Eliminates nitrogen waste as ammonia
Birds and Reptiles Waste…
Excretes nitrogen waste as uric acid
Terrestrial Vertebrates…
Removes nitrogen waste through urea
Urea Cycle Location
Liver
Primary Function of Ubiquitination
Tags proteins for degradation
Protein Degradation Impact
Associated with various neurological disorders and disease progression
Nitrogen Removal Purpose
Eliminates excess nitrogen from amino acid breakdown
Organism Adaptation
Different species evolved various nitrogen excretion methods based on environment
What happens to Glucogenic amino acids during metabolism?
They can be converted to glucose
What is the end product of ketogenic amino acids?
They form acetyl-CoA or ketone bodies
What type of genetic condition is PKU?
Autosomal recessive
What are the two main complications of PKU?
Intellectual disability and metabolic complications
What is the primary treatment approach for PKU?
Dietary control
What is the genetic basis of Transcarbamylase Deficiency?
X-chromosome mutation
What are the main symptoms of Transcarbamylase Deficiency?
Lethargy, vomiting, breathing problems, and potential brain damage if untreated
What are the three main sources of carbon skeletons in amino acid biosynthesis?
Glycolysis intermediates, citric acid cycle, and pentose phosphate pathway
What are the primary sources of amino groups in amino acid biosynthesis?
Glutamate and Glutamine
How many nonessential amino acids exist?
11 types that the body can synthesize
How many essential amino acids exist?
9 types that must be obtained from diet
What is the role of glutamate and glutamine in amino acid synthesis?
They serve as donors of amino groups for the formation of other amino acids
what arelipoproteins?
specific proteins which can transport the fat between organs
