MBS 217 Lecture 11 Flashcards
Define nutrient
a substance in food that promotes normal growth, maintenance, and repair
Major nutrients
Carbohydrates, lipids, and proteins
Food equals energy
ATP
Energy can be derived from
Protein
Carbohydrates
Fats
Types of carbs
Starch (complex carbohydrates) in grains and vegetables
Sugars in fruits, sugarcane, sugar beets, honey and milk
Insoluble fiber: cellulose in vegetables; provides roughage
Soluble fiber: pectin in apples and citrus fruits; reduces blood cholesterol levels
Glucose is the fuel used by cells to make
ATP
What relies on glucose
Neurons and red blood cells (RBCs) rely almost entirely upon glucose
Excess glucose is converted to
glycogen or fat and stored
Triglycerides
Saturated fats in meat, dairy foods, and tropical oils
Unsaturated fats in seeds, nuts, olive oil, and most vegetable oils
Essential fatty acids
Linoleic and linolenic acid, found in most vegetable oils
Must be ingested
Essential uses of lipids in the body
Help absorb fat-soluble vitamins
Major fuel of hepatocytes and skeletal muscle
Phospholipids are essential in myelin sheaths and all cell membranes
Functions of fatty deposits (adipose tissue)
Protective cushions around body organs
Insulating layer beneath the skin
Concentrated source of energy
Regulatory functions of prostaglandins
Smooth muscle contraction
Inflammation
Control of blood pressure
Functions of cholesterol
Stabilizes membranes
Precursor of bile salts and steroid hormones
Structural materials:
keratin, collagen, elastin, muscle proteins
Use of amino acids in the body
All-or-none rule
Adequacy of caloric intake
Nitrogen balance
Hormonal controls
All-or-none rule
All amino acids needed must be present for protein synthesis to occur
Adequacy of caloric intake
Protein will be used as fuel if there is insufficient carbohydrate or fat available
Nitrogen balance
State where the rate of protein synthesis equals the rate of breakdown and loss
Positive if synthesis exceeds breakdown (normal in children and tissue repair)
Negative if breakdown exceeds synthesis (e.g., stress, burns, infection, or injury)
Hormonal controls
Anabolic hormones (GH, sex hormones) accelerate protein synthesis
What do Vitamins function as
coenzymes
Which vitamins have been made in the body?
Vitamins D, some B, and K are synthesized in the body
Two types of vitamins based on solubility
Water-soluble vitamins
Fat-soluble vitamins
Water-soluble vitamins
B complex and C are absorbed with water
B12 absorption requires intrinsic factor
Not stored in the body
Fat-soluble vitamins
A, D, E, and K are absorbed with lipid digestion products
Stored in the body, except for vitamin K
Vitamins A, C, and E act as antioxidants
Prevent oxidative damage
Seven required minerals
Calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium
How to prevent toxic overload
Uptake and excretion must be balanced
What do minerals do
Work with nutrients to ensure proper body functioning
Define metabolism
Metabolism refers to all chemical reactions in an organism
Biochemical reactions inside cells involving nutrients
Cellular Metabolism
Includes all chemical reactions within cells
Provides energy to maintain homeostasis and perform essential functions
Essential Functions of metabolism
Metabolic turnover:
Periodic replacement of cell’s organic components
Growth and cell division
Special processes, such as secretion, contraction, and the propagation of action potentials
Two types of metabolic reactions
Anabolism: synthesis of large molecules from small ones (Building up)
Catabolism: hydrolysis of complex structures to simpler ones (Breaking down)
Cellular respiration
catabolism of food fuels and capture of energy to form ATP in cells
phosphorylation
Enzymes shift high-energy phosphate groups of ATP to other molecules
Why are phosphorylated molecules activated
to perform cellular functions
Stages of Metabolism
Digestion, absorption and transport to tissues
Cellular processing (in cytoplasm)
Synthesis of lipids, proteins, and glycogen, or
Catabolism (glycolysis) into intermediates
Oxidative (mitochondrial) breakdown of intermediates into CO2, water, and ATP
Oxidation
gain of oxygen
lose electrons and energy
Reduced substances
gain electrons and energy
Coenzymes
NAD+ - reduced to NADH
FAD - reduced to FADH2
ATP Synthesis
Substrate-level phosphorylation
Oxidative phosphorylation
Substrate-level phosphorylation
phosphate groups directly transferred from phosphorylated substrates (high energy intermediates) to ADP (adenosine diphosphate) to synthesise ATP
glycolysis occurs in
Krebs cycle occurs in
(in cytoplasm)
Mitochondria
Oxidative Phosphorylation
Production of ATP from the oxidized NADH and FADH2
Made up of two components: electron transport chain and chemiosmosis
Chemiosmotic process
Couples the movement of substances across a membrane to chemical reactions
Carried out by electron transport proteins
Nutrient energy is used to create H+ gradient across mitochondrial membrane
H+ flows through ATP synthase
Energy is captured and attaches phosphate groups to ADP
Glucose is catabolized in three pathways
Glycolysis
Krebs cycle
Electron transport chain and oxidative phosphorylation
