1. Unit 2 Chemical Constituents of Cells and Metabolism
Anatomy and Physiology

2. 2.3 Chemical Constituents of Cells
Organic compounds contain both hydrogen and carbon.
All other compounds are considered inorganic.
Water
Most abundant compound in living things and 2/3 of the weight of adults.
An important solvent - most metabolic reactions occur in water.
Important in transporting materials in the body - a major component of blood.
Carries waste materials and can absorb and transport heat.

3. 2.3 Chemical Constituents of Cells
Oxygen
Needed to release energy from nutrients and is used to drive the cell's metabolism.
Carbon Dioxide
Released as a waste product during energy-releasing metabolic reactions.
Inorganic Salts
Provide necessary ions - sodium, chloride, potassium, calcium, magnesium, phosphate, carbonate, bicarbonate, and sulfate.
Electrolytes play important roles in many of the body's metabolic processes.

4. 2.3 Chemical Constituents of Cells
Organic Substances:
Carbohydrates
Provide energy for cellular activities - composed of carbon, hydrogen, and oxygen.
Made from monosaccharides (simple sugars-glucose); disaccharides (two monosaccharides joined together-sucrose); and polysaccharides (complex sugars) e.g. starch - built of many sugars .
Humans synthesize the polysaccharide glycogen.

6. 2.3 Chemical Constituents of Cells
Lipids: function-protection, insulation and storage
Organic substances that are insoluble in water and include fats, phospholipids, and steroids.
Fats supply energy for cellular function, and are built from glycerol and three fatty acids. Fats have a smaller proportion of oxygen atoms than carbohydrates.
Fatty acids with hydrogen at every position along the carbon chain are saturated; those with one or more double bonds are called unsaturated fats.
A lean person has 18-25% of their body mass of fat
Triglycerides- don’t dissolve in bloodstream and any excess carbs, proteins, fats and oils is deposited in adipose tissue

7. 2.3 Chemical Constituents of Cells
Phospholipids: Contain glycerol, two fatty acids, and a phosphate group – for cell structure.
Steroids: Complex ring structures, and include cholesterol, which is used to synthesize the sex hormones.

9. 2.3 Chemical Constituents of Cells
Proteins:
Have a great variety of functions in the body--as structural materials, energy sources, hormones, receptors on cell membranes, antibodies, and enzymes to catalyze metabolic reactions (enzymes).
Contain C, O, H, and nitrogen atoms; some also contain sulfur.
Building blocks are the amino acids, each of which has a carboxyl group, an amino group and a side chain called the R group.

10. 2.3 Chemical Constituents of Cells
Proteins have complex shapes held together by hydrogen bonds.
Protein shapes, which determine how proteins function, can be altered (denatured) by pH, temperature, radiation, or chemicals.

12. 2.3 Chemical Constituents of Cells
Nucleic Acids:
Form genes and take part in protein synthesis.
Contain carbon, hydrogen, oxygen, nitrogen, and phosphorus - bound into building blocks called nucleotides.
Two major types: DNA (with deoxyribose) and RNA (with ribose).
RNA (ribonucleic acid) functions in protein synthesis; DNA (deoxyribonucleic acid) stores the molecular code in genes.

13. DNA vs. RNA DNA RNA Doulbe Helix Sugar is Deoxyribose
Stores Genetic Info
Nitrogenous Bases
Thymine
Adenine
Guanine
Cytosine
RNA
Single Strand
3 kinds of RNA
mRNA, rRNA, tRNA
Sugar is Ribose
Makes proteins
Nitrogenous Bases
Uracil
Adenine
Guanine
Cytosine

15. 4.2 Metabolic Reactions Introduction
Metabolic reactions are of two types:
Anabolic reactions - Larger molecules are constructed from smaller ones, requires energy
Catabolic reactions - Larger molecules are broken down, releases energy.
The reactions of metabolism are often reversible.

16. 4.3 Control of Metabolic Processes
Enzymes control the rates of all the metabolic reactions of the cell.
Enzyme Action
Complex proteins that lower the activation energy of a reaction so it may begin and proceed more rapidly. Enzymes are called catalysts.
Work in small quantities and are recycled by the cell.
Each is specific, acting on only one kind of substrate.
Active sites on the enzyme combine with the substrate and a reaction occurs.
The speed of enzymatic reactions depends on the number of enzyme and substrate molecules available.

17. 4.3 Control of Metabolic Processes
Factors That Alter Enzymes
Enzymes (proteins) can be denatured by heat, pH extremes, chemicals, electricity, radiation, and by other causes.

18. 4.4 Energy for Metabolic Reactions
Energy is the capacity to do work.
Common forms of energy include heat, light, sound, electrical energy, mechanical energy, and chemical energy.
Release of Chemical Energy - Cellular Respiration
Often occurs through the oxidation of glucose.
Burning glucose requires energy to begin the process.
The end-products of these reactions are heat as well as stored energy.
This stored energy is called ATP which has a chain of three phosphates.

20. 4.4 Energy for Metabolic Reactions
ATP Molecules
Up to 38 molecules of ATP are produced for each molecule of glucose oxidized.
ATP molecules contain three phosphates in a chain.

21. 4.4 Energy for Metabolic Reactions
Energy is stored in the last phosphate bond.
Energy is stored while converting ADP to ATP; when energy is released, ATP becomes ADP, ready to be regenerated into ATP.

22. 4.4 Energy for Metabolic Reactions
Anaerobic Respiration
The first part of cellular respiration is the splitting of 6-C glucose that occurs through a series of enzyme-catalyzed steps called glycolysis.
The result is two 3-C molecules of pyruvate.
Glycolysis occurs in the cytosol and does not require oxygen (is anaerobic).
Energy from ATP is used to start the process but there is a net gain of energy as a result.

23. 4.4 Energy for Metabolic Reactions
Aerobic Respiration
Oxygen is needed for aerobic respiration, which occurs within the mitochondria.
There is a much greater gain of ATP molecules from aerobic respiration.
The final products of glucose oxidation are carbon dioxide, water, and energy.

25. 4.5 Metabolic Pathways
The enzymes controlling either an anabolic or catabolic sequence of reactions must act in a specific order.
A sequence of enzyme-controlled reactions is called a metabolic pathway.

26. 4.5 Metabolic Pathways Regulation of Metabolic Pathways
Determined by a regulatory enzyme responsible for one of its steps.
A rate-limiting enzyme is the first step in a series.