Anatomy Ch 2

Matter, Atoms, Elements, and the Periodic Table

Matter has mass and occupies space

3 forms of matter:

• Solid (ex, bones)

• Liquid (ex, blood)

• Gas (ex, oxygen)

• Atom - The smaller particle displays chemical properties of an element.

• 92 Naturally occurring elements make up matter

  • organized in the periodic table of elements

Chemical Formulas: Molecular and Structural

Molecular Formula

• Indicates the number of types of atoms

  • ex: Carbonic Acid (H2CO3)

Structural Formula

• shows the number and kind of atoms

• shows the arrangement of atoms within the molecule

  • ex: O=C=O (carbon dioxide)

• Allows differentiation of isomers

  • Same number and type of elements, but arranged differently in spaces

Glucose vs Galactose vs Fructose

• Samww molecular formula

• 6 carbon, 12 hydrogen, 6 oxygen

• Atroms arranged differently

  • Isomers may have different chemical properties

    

Covalent Bonds

• Atoms share electrons

• Occurs when both atoms require electrons

• Formed commonly in the human body using

  • Hydrogen (H)

  • Oxygen (O)

  • Nitrogen (N)

  • Carbon (C)

Number of covalent bonds an atom can form:

• The simplest occurs between 2 hydrogen atoms

  • each sharing a single electron

• Oxygen needs two electrons to complete its outer shell

  • forms two covalent bonds

• Nitrogen forms three bonds

• Carbon forms four bonds

Single Covalent Bond

• One pair of electrons is shared

  • ex: between two oxygen atoms

Double Covalent Bond

• Two pairs of electrons are shared

  • ex: between two oxygen atoms

Triple Covalent Bond

• Three pairs of electrons are shared

  • ex: between two nitrogen atoms

Carbon needs four electrons to satisfy the octet rule

• can be obtained in several ways

  

Carbon Skeleton Formation;

Carbon

• Bonds in straight chains, branched chains, or rings

  • called the carbon skeleton

• Carbon is present where lines meet at an angle

• Additional atoms are hydrogen

Nonpolar, Polar, and Amphipathic Molecules

Amphipathic molecules

• larger molecules with both polar and nonpolar regions

  • ex: phospholipids

Molecular Structure and Properties of Water

Molecules are classified as:

• Organic Molecules - contain carbon and are/were part of a living organism.

• Inorganic Molecules - include all other molecules

  • ex: water, salts, acids, and bases

Water

• Composes 2/3 of human body weight

• Polar molecule

  • 1 oxygen atom bonded to two hydrogen atoms

  • oxygen atom has two partial negative charges

  • hydrogens have a single partial positive charge

• Can form 4 hydrogen bonds with adjacent molecules

  • central to water’s properties

Properties of Water

Phases of water depending on temperature:

• Gas (water vapor)

  • Substances with low molecular mass

• Liquid (water)

  • Almost all water in the body

  • liquid at room temp due to hydrogen bonding

• Solid (ice)

Functions of Liquid Water

• Treansports

  • Substances dissolved in water move easily through the body

• Lubricates

  • Decreases friction between body structures

• Cushions

  • absorbs the sudden force of body movement

• Excretes Wastes

  • Unwanted substances that dissolve in water are easily eliminated.

Water as the Universal Solvent

Water is the solvent of the body

Solutes are the substances that dissolve in water

Water is called the universal solvent because most substances dissolve in it

• chemical properties of a substance determine whether it will or won’t dissolve.

Substances that dissolve in water - polar molecules and ions

• Hydrophilic means “water-loving” on

• Water surrounds substances, forming a hydration shell

• Some substances dissolve but remain intact

  • ex: glucose and alcohol

  • Nonelectrolytes remain intact but don’t conduct current

• Some Substances dissolve and dissociate (separate)

  • NaCl dissociates into NA+ and Cl- ions

  • Acids and bases, like HCl

  • Electrolytes can conduct current

Substances that DON’T dissolve in water - Nonpolar molecules

• Hydrophobic means “water fearing”

• Hydrophobic exclusion - cohesive water molecules “force out” nonpolar molecules.

  • Excluded molecules interact via hydrophobic interactions

• Hydrophobic substances require carrier proteins to be transported within the blood

Substances that partially dissolve in water

Amphipathic molecules have polar and nonpolar regions

• The polar portion of the molecule dissolves in water

• nonpolar portion repelled by water

Phospholipid molecules are amphipathic

• Polar heads have contact with water

• nonpolar tails group together

• Results in bilayers of phospholipid molecules

  • ex: membranes of a cell.

  • Other amphipathic molecules form a Micelle.

Watee: A neutral Solvent

Water spontaneously dissociates to form ions

• The bond between oxygen and hydrogen breaks apart spontaneously

  • 1/10,000,000 ions per liter

  • OH group hydroxide ion (OH-)

• A hydrogen ion is transferred to a second water molecule

  • Hydronium ion (H3O+)

• An equal number of positive hydrogen ions and negative hydroxyl ions are produced

  • water remains neutral - H₂O + H₂O → H₃O⁺ + OH⁻

    • simplifies to: H₂O → H⁺ + OH^–

Acids and Bases

Base accepts H+ when added to a solution

• proton acceptor

• deceased concentration of free H+

• more absorpt_ion of H+ with stronger bases

  • ex: ammonia and bleach

• Less absorption of H+ with weaker bases

  • ex: bicarbonate in blood and secretions released into the small intestine

• Substance B ( a base in water) + H+ —→B—- H

pH, Neutralization, and the Action of Buffers

pH is a measure of H⁺

• relative amount of H⁺

• Range between 0 and 14

The pH of plain water is 7

• water dissociated to produce 1/10,000,000 of H⁺ and OH^- ions per liter

• equal to 1 times 10^-7 or to 0.0000001

pH and H⁺ concentration are inversely related

• Inverse of the log for a given H⁺ concentration

• As H⁺ concentration increases, pH decreases

• As H⁺ concentration decreases, pH increases

Interpreting the pH scale

Solutions with equal concentrations of H⁺ and OH⁻

• Are neutral

• Has a pH of 7

Solutions with greater H⁺ than OH⁻

• Are acidic

• Have a pH < 7

Solutions with greater OH⁻ than H⁺

• They are basic (alkaline)

• Have a pH > 7

Moving from one increment to the next is a 10-fold change

• ex: a pH of 6 has 10 times greater concentration of H⁺ than pure water

Neutralization

• When an acidic or basic solution returns to neutral (pH 7)

• Acids are neutralized by adding a base

  • ex: medications to neutralize stomach acid must contain a base

• Bases neutralized by adding acid

Buffers

• Help prevent pH changes if excess acid or base is added

• Act to accept H⁺ from excess acid or donate H⁺ to neutralize base

  • carbonic acid (weak acid) and bicarbonate (weak base) buffer blood pH

  • Both help maintain blood pH in a critical range (7.35 to 7.45)

Lipids

• diverse group of fatty, water-insoluble molecules

• function as stored energy, cellular membrane components, and hormones.

  Four primary classes:

  • Triglycerides

  • phospholipids

  • eicosaniods

Triglycerides are used for long-term energy storage

Formed from glycerol and 3 fatty acids

• Fatty acids vary in length and number of double bonds

  • Saturated - lack double bonds

  • Unsaturated - one double bond

  • Polyunsaturated - two or more double bonds

• Adipose tissue stores triglycerides

  • Lipogenesis - formation of triglycerides when there’s excess nutrients

  • Lipolysis - breakdown of triglycerides when nutrients are needed

Fatty Acids: Saturated, unsaturated, and trans fats

Most animal fats are Saturated

• Most are solid at room temperature

Most vegetable fats are unsaturated

• Most are liquid at room temperature

• generally healthier

• can be converted to saturated fats through hydrogenation

Partial hydrogenation may lead to Trans Fats

• increase the risk of a heart attack and stroke

Carbs

Carbohydrates

• An- H and an -OH are usually attached to every carbon

• The general chemical formula is (CH₂O)^_n

  • n = number of carbon atoms

Monosaccharides

• Simple sugar monomers

Disaccharides

• formed from two monosaccharides

Polysaccharides

• formed from many monosaccharides

Glucose

• 6 carbon carb

• Most common monosaccharides

• primary source of energy to cells

• Concentration must be carefully maintained

Glycogen

• Liver and skeletal muscle store excess glucose and then bind glucose monomers together (glycogenesis)The liverr hydrolyzes glycogen into glucose as needed (glycogenolysis)

• The liver can also form glucose from non-carbohydrate sources (gluconeogenesis)

Nucleic Acids

• Store and transfer genetic information

• two classes of nucleic acid

  • Deoxyribonucelic acid (DNA)

  • Ribonuecleic Acid (RNA)

    • both are polymers composed of nucleotide monomers

    • Monomers are linked covalently through phosphodiester bonds.

Deoxyribonucleic acid (DNA)

• Double-stranded nucleic acid

• Located in chromosomes in nucleus and in mitochondria

• Deoxyribose sugar, phosphate, and one of four nitrogenous bases

  • Adenine, guanine, cystosine, thymine

  • No uracil

• Double strands held together by hydrogen bonds

  • Form between complementary bases

    • Thymine paired with adenine

    • Guanine paired with cytosine

Ribonucleic acid (RNA)

• Single-stranded nucleic acid

• Located in nucleus and in cytoplasm of cell

• Ribose sugar, phosphate, and one of four nitrogenous bases

  • Adenine

  • Guanine

  • Cystosine

  • Uracil

  • No thymine

Adenosine triphosphate (ATP)

• A nucleotide is composed of a nitrogenous base adenine, a ribose sugar, and three phosphate groups

• Central molecule in the transfer of chemical energy within cell

• Covalent bonds between the last two phosphate groups are unique,
  energy rich

• Release energy when broken, Important nucleotide-containing molecules

• Nicotinamide adenine dinucleotide

• Flavin adenine dinucleotide

• Both participate in production of ATP

Proteins

Protein functions include

• Synthesis and digestion (actions of enzymes)

• Structural support. ex: cytoskeleton proteins

• Body movement. ex: actin and myosin of muscle

• Transport in blood; ex: hemoglobin carries O₂

• Membrane transport via carrier proteins

• Protection, ex: antibodies