Chapter 25 Learning Objectives

Three uses of food by the body

Provides energy, building blocks for molecules, and storage for future use

Metabolism

Sum of all chemical reactions in the body

Anabolism

Builds larger molecules; requires energy (endergonic)

Catabolism

Breaks down molecules; releases energy (exergonic)

Endergonic reaction

Requires energy input

Exergonic reaction

Releases energy

ATP

Main energy molecule used by cells

Function of ATP

Couples energy-releasing and energy-requiring reactions

Oxidation

Loss of electrons (releases energy)

Reduction

Gain of electrons (stores energy)

Phosphorylation

Addition of phosphate to ADP to form ATP

Decarboxylation

Removal of CO2 from a molecule

NADH and FADH2

High-energy electron carriers used to make ATP

Three stages of cellular respiration

Glycolysis, Krebs cycle, Electron Transport Chain

Location of glycolysis

Cytosol

ATP produced in glycolysis

Net 2 ATP

Fate of pyruvic acid with oxygen

Converted to Acetyl CoA → enters Krebs cycle

Fate of pyruvic acid without oxygen

Converted to lactic acid

Location of Krebs cycle

Mitochondrial matrix

Reactions in Krebs cycle

Oxidation, decarboxylation, ATP and NADH/FADH2 production

Location of electron transport chain

Inner mitochondrial membrane (cristae)

Electron acceptors in ETC

Electron carrier proteins (cytochromes, CoQ, etc.)

Final electron acceptor

Oxygen

Byproduct of final electron acceptance

Water (H2O)

Overall cellular respiration equation

C6H12O6 + 6O2 → 6CO2 + 6H2O + 36-38 ATP

Glycogenesis

Formation of glycogen from glucose

Glycogenolysis

Breakdown of glycogen to glucose

Gluconeogenesis

Formation of glucose from non-carbohydrate sources

Lipoprotein

Molecule that transports lipids in blood

Chylomicrons

Transport dietary fats from intestines

VLDL

Transports lipids from liver to adipose tissue

LDL ("bad cholesterol")

Delivers cholesterol to cells; can form plaques

HDL ("good cholesterol")

Removes excess cholesterol to liver

Lipogenesis

Formation of lipids from glucose

Lipolysis

Breakdown of triglycerides into fatty acids and glycerol

Breakdown products of lipids

Fatty acids and glycerol

Protein breakdown products

Amino acids

Transport of amino acids into cells

Active transport

Functions of proteins

Enzymes, structure, hormones, transport

Essential amino acids

Cannot be made by body; must come from diet

Nonessential amino acids

Can be made by body

Factors affecting metabolic rate

Exercise, hormones, nervous system, temperature, age, food intake

Nutrients necessary for life

Water, carbohydrates, lipids, proteins, vitamins, minerals

Vitamins vs minerals

Vitamins are organic; minerals are inorganic

Calcium

Builds bones and teeth

Phosphorous

Bone formation and part of nucleic acids

Potassium

Needed for nerve impulses (action potentials)

Sulfur

Component of some amino acids and proteins

Sodium

Fluid balance and nerve impulses

Chloride

Acid-base balance

Magnesium

Cofactor for enzymes

Iron

Component of hemoglobin (oxygen transport)

Iodide

Required for thyroid hormone production

Manganese

Enzyme function

Copper

Iron metabolism and enzyme activity

Cobalt

Part of vitamin B12

Zinc

Enzyme function and immune support

Fluoride

Strengthens teeth

Selenium

Antioxidant

Chromium

Helps regulate blood glucose

Vitamin A

Vision (retina photopigments)

Vitamin D

Calcium absorption

Vitamin E

Antioxidant; protects cells

Vitamin K

Blood clotting

Vitamin C

Collagen formation and antioxidant

Vitamin B group

Energy metabolism and red blood cell production