General Questions - long detailed response Flashcards
(18 cards)
What are the main functions of Carbs in the body
Source of Energy (ATP)
Short term energy storage (Glycogen)
Supportive structures (mainly in plants)
Stool bulk and frequency (cellulose)
Cell signaling, recognition and immunity (glycolipids, glycoproteins)
Synthesizing other substances (proteins, lipids, nucleic acids)
What are the 3 major groups of carbs and their characteristics
- Monosaccharides
- simplest unit (single sugar)
- Eg glucose, fructose, galactose
- Named by carbon count (trios, tetrose, pentose, hexose, heptose) - Disaccharides
- 2 monos joined by glycosidic bond
- Eg Sucrose (fructose + Glucose), Lactose (Galactose + Glucose, Maltose (Glucose + Glucose) - Poly
- Many mono units
EG. Starch, Gyycogen, Cellulose
Describe the process of Carb digestion
- Mouth
- Saliva, Moistens food
- Salivary amylase breaks down starch
- Physical breakdown by teeth and tongue - Pancreas
- Produces pancreatic amylase
Breaks down glycogen and starch - SI
- Microvilli enzymes break down Poly and disaccharides
-Alpha-dextrinase, maltase, sucrase, lactase
-Mono absorbtion occurs here - LI
-processes indigestible fibre (cellulose)
- Forms feces
What are the main classifications of lipids
- Saponification
- Saponifiable (can form soap): triglycerides, phospholipids,
-Non-saponifiable: cholesterol, bile acides, steroid hormones - By function
-energy storage (triglycerides,)
- Membrane lipids (phospholipids, sphingoglycolipids, cholesterol)
-Messenger lipids (steroid hormones, eicosanoids)
-Emulsification lipids (bile acids)
-Protective coating lipids (biological waxes)
What are the different types of fatty acids and their charecteristics
- By chain Length
- short chain (4-6 carbons) gut microbe fermentation products
- Medium chain (8-10 carbons) coconut milk
- Long chain (12-26 carbons) most common, found in various foods - By Saturation
- Saturated - only single bonds
- Monosaturated - one double bond
- Polyunsaturated - multiple double bonds
What is cholesterol and it’s function
- Most abundant steroid in body
Functions: - Regulates cell membrane fluidity
- Increases nerve transmission speed
- Precursor for other molecules
Found in: - All cell membranes
- 10% of brain tissue
-All body fluids
Transported by:
LDL (to tissue)
HDL (back to LV)
What are the 4 stages of Biochemical energy production
- Digestion
- Acetyl group formation
-Occurs in cytosol/mitochondria
-Oxidises small molecules
-Produces NADH, FADH2, Acetyl units - Citric Acid Cycle/Krebs cycle:
-Ocurs in Mitochondria
- Produces C02, ATP, NADH, FADH2 - Electron transport chain and Oxidative Phosphorylation:
- Produces APT
-Uses hydrogen gradient
What are the 3 types of enzyme inhibition
Types of Enzyme inhibition
1. Reversible competitive
- Temporarily binds active site
- Decreases activity
2. Reversible non-competitive
- binds to non active site
- prevents activity
3. Irreversible
- Permanently blocks active site
- Requires new enzyme creation
Explain how glycolysis is regulated through feedback inhibition. What are the 3 key regulatory steps?
Regulated through 3 irreversible steps
Step 1. (Hexokinase): Inhibited by glucose-6-phosphate buildup through competitive inhibition
2. Step 3 (Phosphofructonkinase) Inhibited by high ATP or citrate concentrations
3. Step 10 (Pyruvate kinase): inhibited by ATP and Acetyl CoA through non competitive inhibition at allosteric sites
How do muscle cells and LV cells differ in their handling of glucose-6-phospate? Why is this important?
Muscle cells can only use G6P for energy production (lack enzyme to convert to glucose
LV cells can convert G6P back to glucose and release it into blood stream
Important because it allows LV to regulate blood glucose levels, ensures muscles use stored energy efficiently and maintains glucose homeostasis
Describe the differences between glycogenesis and gluconeogenesis
Glycogenesis
- converts glucose to glycogen for storage
-Activated by high glucose 6 phosphate levels
-Stimulated by insulin
-Occurs mainly in LV and muscle tissue
Gluconeogenesis:
- Produces glucose from non carb sources
-Occurs during fasting
-Uses substances like pyruvate, lactate, glycerol, amino acids
-Primarily occurs in LV and KD
What are the key differences between glycerophospholipids and sphingophospholipids
Glycerophosphlipds:
-Use glycerol as platform molecule
-Contain 2 fatty acids
-Found in all cell membranes
Shingophospholipids:
-Use sphingosine as platform
- Contain one fatty acid
-Especially abundant in myelin shealths
-Part of sphingosine forms part of hydrophobic tail
Explain how bile acids assist in lipid digestion and absorbtion
- Emulsification function
- Break large fat droplets into smaller ones
- Increase surface area for enzyme action - Micelle formation:
- Form mixed micells with fatty acids and monoglycerides
- Enable transport through aqueous intestinal environment - Absorbtion enhancement:
Allow fat-soluble moecules to be absorbed by intestinal cells - Recycling
- Most bile acids are reabsorbed in ileum
- Return to LV via enterohepatic circulation
What is the difference between intrinsic and extrinsic regulation of metabolic pathways
Intrinsic:
- Direct response o substrate/product levels
-Eg high ATP inhibiting its own production pathway
-No external signalling molecules needed
-Immediate response to cellular conditions
\
Extrinsic:
- Response to signals from other cells
-Uses hormones or other signalling molecules
-Involves secondary messengers
-Eg insulin signalling glucose uptake
How do coenzymes differ from cofactors in metabolic reactions?
Coenzymes:
- Organic molecules
- Made from dietary nutrients
-Eg FAD, NAD+, Coenzyme A
-Often involved in electron transfer
-May be modified during reaction
Cofactors
- Usually simple ions
- Required in trace amounts
- Eg Zinc, Magnesium
- Often help stabilize enzyme structure
- Not modified during reaction
Compare and contrast 3 possible fates of pyruvate after glycolysis
- Aerobic (Acetyl CoA)
- requires oxygen
- Occurs in mito matrix
- Enters CAC
- Most efficient energy yield - Anaerobic (Lactate)
- No oxygen required
- Occurs in cytosol
- Common in muscle cells
- Temporary solution
- Can cause muscle fatigue - Anaerobic (Ethanol)
- No o2 required
- Occurs in certain microorganisms
- Produces Co2
- Used in fermentation process
Explain why the electron transport chain is called a chain and how it relates to ATP production
- Series of protein complexes in inner mito membrane
- Electrons passed from one complex to next like links in a chain
- Each transfer releases energy
- Energy used to pump H+ ions across membrane
- Creates proton gradient
- Gradient powers ATP synthase
- Final electron acceptor is oxygen
- Produces most ATP of all metabolic processes
How does cholesterol synthesis differ from fatty acid synthesis
Cholesterol synthesis:
- Occurs in cytosol
- Uses acetyl-CoA units
- Forms ring structures
-Regulated by HMG-CoA reductase
-End product inhibits own synthesis
Fatty acid synthesis
- occurs in cytosol
-Uses malonly-CoA
-forms linear chains
-regulated by acetyl-CoA carboxylase
-product inhibition less direct
