FINAL ALL CHAPTERS Flashcards
What is maltose composed of?
Two glucose molecules (α-1,4 glycosidic bond).
What is isomaltose composed of?
Two glucose molecules (α-1,6 glycosidic bond).
What is sucrose composed of?
Glucose and fructose (α-1,2 glycosidic bond).
What is lactose composed of?
Glucose and galactose
(β-1,4 glycosidic bond).
What causes lactose intolerance?
Deficiency in lactase, leading to improper digestion of lactose.
What symptoms arise from lactose intolerance?
Bloating, diarrhea, and gas due to fermentation in the colon.
How are peptide bonds counted in multiple polypeptides linked by disulfide bonds?
Each chain contributes n−1n−1 peptide bonds; disulfide bonds stabilize structure but are not peptide bonds.
What distinguishes essential amino acids from non-essential?
Essential must be obtained from diet; non-essential can be synthesized by the body.
Are most amino acids chiral or achiral?
Most are chiral, except glycine, which is achiral.
What happens to lactose when it is not digested?
It ferments in the colon, causing symptoms.
What is the formula for the number of peptide bonds in multiple polypeptides?
Each contributes n-1 n-1 peptide bonds.
What is an example of a metabolic property of amino acids?
Some act as precursor for neurotransmitters.
What distinguishes an essential amino acid?
It cannot be synthesized by the body and must be obtained from the diet.
What type of amine group do amino acids possess?
A primart amine group.
Which amino acid is achiral?
Glycine.
What is the role of disulfide bonds in proteins?
They stabilize the overall structure of multiple polypeptides.
Why is glycine considered unique among amino acids?
It is the only achiral amino acid.
How do amino acids function as neurotransmitter precursors?
They are converted into neurotransmitters, such as serotonin from tryptophan.
What dietary adjustments are often made by those with lactose intolerance?
Reduction or elimination of lactose-containing foods.
What are common gastrointestinal symptoms of lactose intolerance?
Bloating, diarrhea, gas, and abdominal pain.
What enzyme is responsible for breaking down lactose?
Lactase.
What are the basic components of an amino acid?
An amino group, carboxyl group, hydrogen atom, R group (side chain).
How is a peptide bond formed?
Condensation reaction between the carboxyl group of one amino acid and the amino group of another, releasing water.
What role do enzymes play in biochemical reactions?
They act as catalysts, lowering the activation energy and speeding up reactions.
What does enzyme specificity refer to?
The ability of an enzyme to selectively catalyze a particular reaction for specific substrates.
Why is pH important for enzyme function?
Enzymes have optimal pH ranges; deviations can denature the enzyme or affect its activity.
What are cofactors?
Non-protein molecules that assist enzymes in catalyzing reactions, often metal ions or organic molecules (coenzymes).
What is competitive inhibition?
When an inhibitor competes with the substrate for binding to the active site of the enzyme, increasing Km but not affecting Vmax.
What is non-competitive inhibition?
When an inhibitor binds to an enzyme regardless of whether the substrate is present, decreasing Vmax without affecting affecting Km.
What is the primary function of the TCA cycle?
To generate energy through the oxidation of acetyl-CoA and produce NADH and FADH2 for the ETC.
What is acetyl-CoA’s role in metabolism?
It serves as a key substrate in energy production and synthesis of fatty acids and ketone bodies.
What us a significant function of glutamine?
It serves as a nitrogen donor in the synthesis of nucleotides and amino acids.
What biochemical property determines the solubility of free fatty acids in water?
The degree of saturation (number of double bonds) and the length of the carbon chain.
How does saturation affect the solubility of fatty acids?
Saturated fatty acids are less soluble in water than unsaturated fatty acids.
What factors influence the melting point of unbranched fatty acids?
The length of the carbon chain and the degree of saturation.
How do longer chains and saturation affect the melting point?
Longer chains and higher saturation increase melting points, while unsaturation lowers them.
Are most fatty acids essential or non-essential?
Most fatty acids are non-essential; however, linoleic and alpha-linolenic acids are essential.
How are fatty acids classified as omega-3 or omega-6?
Based on the position of the first double bond from the methyl end (omega-3: third carbon; omega-6: sixth carbon)
What are the full names of three omega-3 fatty acids?
- Alpha-linolenic acid (ALA)
- Eicosapentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
What is a gene?
A segment of DNA that contains instructions for synthesizing proteins or RNA molecules; it is basic unit of heredity.
What type of bonds from between complementary nitrogen bases in DNA?
Hydrogen bonds.
How many hydrogen bonds form between adenine and thymine (A-T)?
2 hydrogen bonds.
How many hydrogen bonds form between cytosine and guanine (C-G)?
3 hydrogen bonds.
Why do phosphodiester bonds connect in a DNA molecule?
They connect the sugar and phosphate backbone, linking adjacent nucleotides.
Name the purine nitrogen bases.
Adenine (A) and Guanine (G).
Name the pyrimidine nitrogen bases.
Cytosine (C), Thymine (T), Uracil (U in RNA).
What is a high anion gap associated with?
Accumulation of unmeasured anions (lactic acidosis, ketoacidosis).
What typically causes a normal anion gap?
Loss of bicarbonate (diarrhea, renal tubular acidosis).
What does the turnover number (k_cat) indicate about an enzyme?
The number of substrate molecules converted to product per enzyme molecule per unit time.
What happens to enzyme activity if temperature exceeds the optimal range?
Enzymes may denature, losing their functional shape and activity.
What is the enzyme-substrate complex?
The intermediate formed when an enzyme binds to its substrate, facilitating the reaction.
Name the two main types of enzyme inhibition.
Competitive inhibition and non-competitive inhibition.
What role do all allosteric sites play in enzyme regulation?
Allosteric sites allow molecules to bind, causing conformational changes that can enhance or inhibit enzyme activity.
What is a key difference between NADH and FADH2 in cellular respiration?
NADH produces more ATP per molecule than FADH2 when oxidized in the ETC.
How does insulin affect glucose metabolism?
Insulin promotes the uptake of glucose by cells and stimulates glycogen synthesis.
When is the lactic acid threshold?
It is the exercise intensity at which lactate starts to accumulate in the blood, indicating anaerobic metabolism.
What is the role of coenzymes in enzyme reactions?
Coenzymes assist enzymes by carrying chemical groups or electrons during reactions.
What is the main product of beta-oxidation?
Acetyl-CoA, which enters the TCA cycle for energy production.
How are glycolysis and the TCA cycle interconnected?
Pyruvate from glycolysis is converted to acetyl-CoA, which enters the TCA cycle.
What does the turnover number (k_cat) indicate?
It indicates the maximum number of substrate molecules an enzyme converts to product per unit time when fully saturated.
How is enzyme activity typically measured?
By monitoring the rate of product formation or substrate consumption over time.
What happens to enzyme activity at high temperatures?
Enzyme activity generally increases with temperature up to a certain point, after which it may denature and lose activity.
What are coenzymes?
Organic molecules that assist enzymes in catalyzing reactions, often derived from vitamins (e.g., NAD+, FAD).
What is a metabolic pathway?
A series of interconnected biochemical reactions that convert substrates into products through enzyme activity.
What does the Michaelis-Menten equation describe?
The relationship between reaction rate (v), maximum velocity (Vmax), substrate concentration ([S]), and Km.
How can you distinguish between competitive and non-competitive inhibition?
Competitive inhibition affects Km by increasing it, while non-competitive inhibition does not change Km but reduces Vmax.
How does lactic fermentation benefit muscles during exercise?
It allows for ATP production when oxygen is limited by regenerating NAD⁺ for glycolysis.
What is the primary use of ketone bodies in tissues?
They are converted back to acetyl-CoA for energy production, particularly in the brain and muscles.
What role does the heme group in hemoglobin play?
Each subunit contains a heme moiety that binds to iron (Fe²⁺), enabling oxygen transport.
What are the two primary functions of hemoglobin?
- Oxygen transporter (carries O₂ to tissues, CO₂ back to lungs).
- Buffer (maintains pH by binding protons and regulating CO₂ levels).
What does the oxygen dissociation curve measure?
The percentage of hemoglobin bound to oxygen (O₂ saturation).
What promotes O₂ release from hemoglobin in peripheral tissues?
Low partial pressure of O₂.
What factors produce the Bohr effect?
Increased CO₂, H⁺ concentration, and temperature enhance O₂ release.
What is the Rapoport-Luebering cycle?
A pathway that shunts 1,3-bisphosphoglycerate from glycolysis to generate 2,3-bisphosphoglycerate (2,3-BPG), lowering hemoglobin’s affinity for O₂.
What is the purpose of the HbA1c glycation test?
It measures average blood glucose levels over 2-3 months, useful for diagnosing and monitoring diabetes.
How does calcium function in muscle contraction?
It binds to troponin, causing a conformational change in tropomyosin that exposes myosin-binding sites on actin.
What is the role of ATP in muscle function?
Provides energy for muscle contraction and relaxation, crucial for cross-bridge cycling between actin and myosin.
What is rigor mortis?
Stiffening of muscles post-mortem due to ATP depletion, causing myosin heads to remain bound to actin.
What is the average lifespan of red blood cells?
Approximately 120 days; aged cells are removed by the spleen and liver.
Describe the metabolic degradation of heme to bilirubin.
Heme → Biliverdin → Bilirubin (unconjugated) → Conjugated bilirubin in the liver.
What is jaundice?
Accumulation of bilirubin in the blood leading to yellowing of skin and eyes.
What are the types of jaundice?
Pre-hepatic (hemolytic), hepatic (liver dysfunction), and post-hepatic (obstruction of bile flow).
Define oxidants.
Substances that can oxidize other molecules, often producing free radicals.
Define antioxidants.
Molecules that neutralize free radicals and prevent oxidative damage.
What is oxidative stress?
An imbalance between oxidants and antioxidants, leading to cellular damage.
Name some reactive oxygen species (ROS).
Superoxide (O₂⁻), hydrogen peroxide (H₂O₂), hydroxyl radical (*OH), nitric oxide (NO).
What enzyme converts superoxide radicals into hydrogen peroxide?
Superoxide dismutase (SOD).
What are some enzymatic antioxidants?
Superoxide dismutase (SOD), glutathione peroxidase, glutathione reductase.
What are some non-enzymatic antioxidants?
Vitamins (e.g., C, E), minerals (e.g., selenium, zinc).
What are the biochemical components of glutathione?
Cysteine, glutamine, and glycine.
What is the function of glutathione in the body?
Acts as a major antioxidant, reducing oxidative stress.
What does glutathione reductase do?
Converts GSSG back to reduced glutathione (GSH) using NADPH.
What is the biochemical importance of the pentose phosphate pathway?
Generates NADPH for reductive biosynthesis and ribose-5-phosphate for nucleotide synthesis.
What is favism?
A genetic condition where consumption of fava beans leads to hemolytic anemia due to glucose-6-phosphate dehydrogenase (G6PD) deficiency, causing oxidative stress in red blood cells.
What hormone promotes glucose uptake and storage in the fed state?
Insulin; it also stimulates lipogenesis and enhances protein synthesis.
What are the effects of insulin on lipids in the fed state?
Increases fatty acid synthesis and storage in adipose tissue; promotes storage of triglycerides.
What hormone is prominent in the fasting state?
Glucagon; it increases mobilization of fatty acids and promotes gluconeogenesis.
How does glucagon affect lipid metabolism?
Enhances lipolysis (breakdown of fats) and increases ketogenesis for energy supply.
List biochemical signs of metabolic syndrome.
Elevated blood glucose, dyslipidemia (high triglycerides, low HDL), hypertension, central obesity.
What are the pathophysiological manifestations of metabolic syndrome?
Increased risk of cardiovascular diseases, development of type 2 diabetes, chronic inflammation, and endothelial dysfunction.
What is the role of acetyl CoA in fatty acid biosynthesis?
It serves as a precursor for the synthesis of fatty acids.
What is the biochemical role of malonyl CoA in fatty acid biosynthesis?
It acts as a building block and provides carbon units for fatty acid synthesis.
How does biotin function in the biosynthesis of fatty acids?
It acts as a coenzyme for acetyl CoA carboxylase, essential for converting acetyl CoA to malonyl CoA.
Describe the initial step in vitamin D biosynthesis in the skin.
UVB radiation converts 7-dehydrocholesterol to previtamin D3.
What occurs to previtamin D3 in the liver?
It is converted to 25-hydroxyvitamin D (calcidiol).
What is the final activation step of vitamin D in the kidney?
Conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D (calcitriol).
How does vitamin D affect calcium absorption?
It increases intestinal absorption of calcium by enhancing expression of calcium-binding proteins.
What are the structural differences between vitamin D3 and D2?
Vitamin D3 (cholecalciferol) is produced in the skin; D2 (ergocalciferol) is derived from yeast and fungi and is less potent.
What are the five types of lipoproteins?
Chylomicrons, VLDL, LDL, HDL, IDL.
What does potency refer to in terms of vitamin D?
Potency indicates how effectively a vitamin raises serum levels of 25-hydroxyvitamin D; D3 is generally more potent than D2.
How is the relationship between volume and density characterized in lipoproteins?
Larger lipoproteins (e.g., chylomicrons) are less dense; smaller lipoproteins (e.g., HDL) are more dense.
What is the difference between exogenous and endogenous pathways of lipoproteins?
Exogenous: Transport dietary lipids from intestines to tissues (chylomicrons). Endogenous: Transport synthesized lipids from liver to tissues (VLDL, LDL).
What is the role of Apo-B48?
It is crucial for intestinal lipid transport and is present in chylomicrons.
What role does Apo-CII play in lipid metabolism?
It activates lipoprotein lipase, facilitating the hydrolysis of triglycerides.
What is the function of Apo-B100?
It is important for lipid metabolism and receptor binding, found in VLDL and LDL.
What does Apo-A1 do?
It activates lecithin-cholesterol acyltransferase (LCAT) and is a major protein in HDL.
What is the reverse transport of cholesterol?
The process by which HDL collects excess cholesterol from tissues and transports it back to the liver.
Why do LDL particles have a longer circulation time than other lipoproteins?
Due to their size and affinity for receptors, allowing prolonged delivery of cholesterol.
Why is HDL referred to as “good cholesterol”?
It reduces the risk of atherosclerosis by transporting excess cholesterol for excretion or recycling.
