Chapter 2 The Chemical Level of Organization KEY

Chapter 2: The Chemical Level of Organization

KEY CONCEPT • All Matter is made up of atoms • Atoms join together to form chemicals with different characteristics • Chemical characteristics determine physiology at the molecular and cellular level

Atomic Particles • Proton: – positive, 1 mass unit • Neutron: – neutral, 1 mass unit • Electron: – negative, low mass

Isotopes • 2 or more elements with equal numbers of protons but different numbers of neutrons

Elements in the Human Body Table 2– 1

Molecules and Compounds • Molecules: – atoms joined by strong bonds • Compounds: – atoms joined by strong or weak bonds

States of Matter • Solid: – constant volume and shape • Liquid: – constant volume but change shape • Gas: – change volume and shape

Chemical reactions & Physiology? • Energy: – the power to do work • Work: – a change in mass or distance

Forms of Energy • Kinetic energy - energy of motion • Potential energy - stored energy • Chemical energy - potential energy stored in chemical bonds

KEY CONCEPT • When energy is exchanged, heat is produced, but cells cannot capture it or use it for work

Break Down, Build Up • Decomposition reaction (catabolism): AB A + B • Synthesis reaction (anabolism): A + B AB • Exchange reaction (reversible): AB A + B

KEY CONCEPT • Reversible reactions seek equilibrium, balancing opposing reaction rates • Add or remove reactants: – reaction rates adjust to reach a new equilibrium

How do enzymes control metabolism?

Activation Energy • Chemical reactions in cells cannot start without help • Activation energy gets a reaction started Figure 2– 7

How Enzymes Work Figure 2– 21

KEY CONCEPT • Most chemical reactions that sustain life cannot occur unless the right enzymes are present

Organic and Inorganic Molecules • Organic: – molecules based on carbon and hydrogen • Inorganic: – molecules not based on carbon and hydrogen

Why is water so important to life?

Properties of Water (1 of 2) • Solubility: – water’s ability to dissolve a solute to make a solution • Reactivity: – most body chemistry uses or occurs in water

Properties of Water (2 of 2) • High heat capacity: – water’s ability to absorb and retain heat • Lubrication: – to moisten and reduce friction

KEY CONCEPT • Most of our body weight is water • Water is the key structural and functional component of cells and their control mechanisms, the nucleic acids

Electrolytes • Inorganic ions conduct electricity in solution • Electrolyte imbalance seriously disturbs vital body functions – Fluid balance – Blood pressure – Muscular contractions

p. H • p. H: – the concentration of hydrogen ions (H+) in a solution • Neutral p. H: – a balance of H+ and OH— – pure water = 7. 0

Acids and Bases • Acid (acidic): p. H lower than 7. 0 – high H+ concentration, low OH— concentration • Base (basic): p. H higher than 7. 0 – low H+ concentration, high OH— concentration

p. H Scale • Has an inverse relationship with H+ concentration: – more H+ ions mean lower p. H, less H+ ions mean higher p. H Figure 2– 9

KEY CONCEPT • p. H of body fluids measures free H+ ions in solution • Excess H+ ions (low p. H): – damages cells and tissues, alters proteins – interferes with normal functions • Excess OH— ions (high p. H) also problem • Normal blood p. H – 7. 35 to 7. 45 • Incompatibile with life – 6. 8 to 7. 8

Acid and Alkaline • Acidosis: – excess H+ in body fluid (low p. H) – Loss of bicarbonate – Blood level < 7. 2 • Alkalosis: – excess OH— in body fluid (high p. H) – Blood level > 7. 5

Nucleic Acids • Large organic molecules, found in the nucleus, which store and process information at the molecular level • DNA and RNA

Deoxyribonucleic Acid (DNA) • Deoxyribonucleic Acid (DNA) – – Determines inherited characteristics Directs protein synthesis Controls enzyme production Controls metabolism • Ribonucleic Acid (RNA) – Codes intermediate steps in protein synthesis

KEY CONCEPT • DNA in the cell nucleus contains the information needed to construct all of the proteins in the body

Nucleotides • Building blocks of DNA • Have 3 molecular parts: – sugar (deoxyribose) – phosphate group – nitrogenous base (A, G, T, C)

DNA Bases Figure 2– 22 b, c

Complementary Bases • Complementary base pairs: – purines pair with pyrimidines: • DNA: – adenine (A) and thymine (T) – cytosine (C) and guanine (G) • RNA: – uracil (U) replaces thymine (T)

Nucleic Acids • Long chains of nucleotides form RNA and DNA • RNA and DNA Figure 2– 23

RNA and DNA • RNA: – Single strand • DNA: – Double helix – Joined at bases by hydrogen bonds

Forms of RNA • Messenger RNA (m. RNA) • Transfer RNA (t. RNA) • Ribosomal RNA (r. RNA)

ADP and ATP • Adenosine diphosphate (ADP): – 2 phosphate groups • di = 2 • Adenosine triphosphate (ATP): – 3 phosphate groups • tri = 3 – Energy for muscular contractions

KEY CONCEPT • Body recycles/renews all chemical components at intervals ranging from minutes to years • Metabolic turnover lets your body: – Grow – Change – Adapt

SUMMARY (1 of 2) • Atoms, molecules, and chemical bonds control cellular physiology • Metabolism and energy work within the cell • Importance of organic and inorganic nutrients and metabolites

SUMMARY (2 of 2) • Role of water and solubility in metabolism and cell structure • Chemistry of acids and bases, p. H and buffers • Structure and function of carbohydrates, lipids, proteins, and nucleic acids