Chapter 25: Metabolism And Nutrition Flashcards
Metabolism
Refers to all of the chemical reactions that occur in the body.
2 types: catabolism and anabolism.
Produce nonvolatile acids
Catabolism
Or decomposition
Chemical reactions that break down complex organic molecules into similar ones.
These reactions are exergonic: produce more energy than they consume, releasing the chemical energy stored in organic molecules.
Anabolism
Or synthesis
Chemical reaction that combine simple molecules and monomers to form the complex structural and function components.
Example: formation of peptide bonds between amino acids.
Are endergonic reaction: consume more energy than they produce.
ATP-Adenosine Triphosphate
Molecule that participates most often in energy exchanges in living cells.
Couples energy relabeling catabolic reactions to energy requiring anabolic reactions.
Contains 3 prostate groups
Greatest amount of emergency stored in ATP is in the 3rd phosphate group
Provides energy for formation of peptide bonds between amino acids to form a peptide
Coupling of Catabolism and Anabolism by ATP
ATP couples catabolic (decomposition) reactions with anabolic (synthesis) reactions.
Catabolic (Energy released) is used to drive anabolic reactions.
Energy from complex molecules in catabolic reactions to combine ADP and a phosphate group to resynthesize ATP.
ADP+P+ energy=ATP
40% of energy released in catabolism is for cellular functions. The rest (60%) is converted to heat to maintain body temp.
Oxidation
Also known as: dehydrogenation
Is the removal of electrons from an atom or molecule.
Results is a decrease in potential energy of the atom or molecule.
Reaction is: exergonic
Dehydrogenation Reactions
Most biological oxidation reactions involve the loss of hydrogen atoms.
Reduction
Opposite of oxidation.
Is an addition of electrons to a molecule.
Results in an increase in the potential energy of the molecule.
Nicotinamide Adenine Dinucleotide (NAD)
A coenzyme that is commonly used by animal cells to carry hydrogen atoms.
Derivation of the B vitamin niacin.
Flavin Adenine Dinucleotide (FAD)
Coenzyme commonly used by animal cells to carry hydrogen atoms.
Derivative of vitamin b2 or riboflavin
Oxidation-Reducation
Or redox reactions
Are always coupled. Each time one substance is oxidized another is simultaneously reduced.
Phosphorylation
Addition of a phosphate group to a molecule to increase its energy potential.
Forms: substrate, oxidative, photo
Organism use 3 Mechanism of Phosphorylation to Generate ATP
- Substrate level phosphorylation: generate ATP by transferring a high energy phosphate group from a substrate directly to ADP. Occurs in cytosol.
- Oxidative phosphorylation: removes electrons from organic compounds and passed them through a series of electron acceptors called electron transport chain to molecules of O2. Occurs in mitochondrial membrane.
- Photophosphorylation: occurs only in chlorophyll-contained plant cells or in certain bacteria that contain other light absorbing pigments.
Glucose
Bodies prefers source for synthesizing ATP.
Complete oxidation includes: water, CO2, ATP, O2
ATP Production: Glucose
Body cells that require immediate energy, glucose is oxidized to produce ATP.
Amino Acid Synthesis: Glucose
Excessive amino acids are converted into glucose
Cells throughout the body can use glucose to form several amino acids which can be incorporated into proteins.
Glycogen Synthesis: Glucose
Hepatocytes and muslce fibers can perform glycogensis. Storage of glycogen: 125 g in liver, 375 g in skeletal muscles.
Triglyceride Synthesis: Glucose
When glycogen storage ares are filled up, hepatocytes can transform the glucose to glycerol and fatty acids by lipogenesis.
Triglycerides are deposited in adipose tissue.
Glucose Movement into Cells
Occurs by facilitated diffusion
A high level of insulin in the body increase the insertion of one type of GluT called GluT4 into plasma membranes of most body cells there by increasing the rate of facilitated diffusion of glucose into cells.
Glycolysis
Chemical reactions spilt 6 carbon molecules of glucose into 2 3-carbon molecules of pyruvic acid.
Key Regulator for Rate: phosphofrutokinase
Thyroid hormone promotes this process
Occurs in: cytosol
Does not require O2 so it can occur under aerobic or anaerobic conditions.
ATP: 2 from substrate level phosphorylation
Pyruvic Acid
Produced by glycolysis.
Used in metabolic crossroads
Its fate depends on the availability of O2.
If O2 is scare: pyruvic acid is reduced via anaerobic pathway by the addition of 2 hydrogen atoms to form lactic acid.
2 pyruvic acid+ 2 NADH+2H= a lactic acid + 2 NAD.
Coenzyme A (CoA)
Derived from pathothenic acid a B vitamin.
Enzyme required in oxidation of glucose.
Used in cellular respiration.
The Krebs Cycle
Oxidation of acetylcholine CoA to produce CO2, ATP, NADH + H and FADH2
Most abundant product: reduced coenzymes
ATP production: 1
Reactions: 8
Reaction occurs in matrix of mitochondria.
Once pyruvic acid has undergone decarboxylation and remaining acetyl group has attached to CoA, resulting compound acetyl CoA enters this cycle.
Reduction reactions and decarboxylation reactions that release co2.
Oxidation-reduction reactions transfer chemical energy in form of electrons, 2 coenzymes, NAD and FAD.
Electron Transport Chain
Is a series of electron carries, integral membrane proteins in the inner mitochondrial membrane.
Membrane fold into Cristal that increase surface area accommodating thousands of copies of the transport chain in each mitochondria.
Each carrier in chain is reduced, picks of electrons and oxidized as it gives up electrons.
Electrons passing through chain, exergonic reactions releases energy used to form ATP.
ATP production: 26-28
Chemiosmosis
Produces ATP is when hydrogen ions diffuse back into the mitochondria matrix.
An accumulation of large amount of H between inner and outer mitochondria membranes occurs.
Glycogen
ATP combines with molecules of glucose.
Polysaccharide that is only form of carbohydrate in the body.
Glycogenesis
Synthesis of glycogen when body does not immediately need ATP.
Occurs when stimulation of insulin from pancreatic beta cells stimulates hepatocytes and skeletal muscle cells to carry this reaction out.
Body can store about 500g of glycogen, 75% in skeletal muscle fibers, 25% in liver cells.
Glycogenolysis
Is catabolic.
Stimulated by: epinephrine
Happens when body needs ATP.
The process of splitting glycogen into its glucose subunits.
Glycogen stored in liver is broken down into glucose and released into the blood to be transported to cells where is its catabolized by cellular respiration.
Gluconeogenesis
Process by which glucose is formed from noncarbohydrates sources.
The glycerol part of triglycerides, lactic acid and certain amino acids are converted in the liver to glucose.
Stimulates by cortisol.
Lipids
Are non polar, hydrophobic molecules.
(Ie) triglycerides
To be transported in watery blood they first must be made more water soluble by combining with proteins produced by the liver and intestines.
Lipoproteins
Lipid and proteins combination that is formed to make lipids transportable in watery blood.
Spherical particles with an outer shells of proteins, phosolipids and cholesterol molecules,
Outer shell is known as: apoprotiens (apo).
Chylomicrons
Transport dietary lipids to adipose tissue for storage.
Form in mucosal epi cells of small intestine.
Contains:
1-2% proteins
85% triglycerides
7% phosolipids
6-7% cholesterol
Small amount of fat soluble vitamins
Very Low Density Lipoproteins (VLDLs)
Form in hepatocytes
Contain mainly endogenous lipids.
50% of triglycerides
Transport triglycerides synthesized in hepatocytes to adipocytes for storage.
Low Density Lipoproteins (LDL)
Carry about 75 % of total cholesterol in blood.
5% triglycerides
Deliver it to cells throughout body for use in repair of cell membranes and synthesis of steroid hormones and bile salts.
Contain single protein: apo B100.
High Density Lipoproteins (HDL)
Removes excess cholesterol from body cells and the blood.
Transport it to the liver for elimination.
5-10% triglycerides
The Fate of Lipids
Lipids can be oxidized to produce ATP.
If body does not need lipids (triglycerides) they are stored in adipose tissue in body and liver.
2 Essential Fatty Acids the Body cannot Synthesize
Linoleum acid
Linolenic Acid
Triglyceride Storage
Major functions of adipose tissue: to remove triglycerides from chylomicrons nad VLDLS and stores them until they are needed for ATP production in other parts of the body.
Triglycerides stored in adipose tissues constitutes 98% of all bodies energy.
Lipolysis
Catalyzed by enzymes called lipase.
Fasting increase this process.
Process is carried out by hepatocytes and adipose tissue
Triglycerides must split into glycerol and fatty acids for muscle, liver, adipose tissue to oxidize the fatty acids derived from triglycerides to produce ATP.