AP Biology - Unit 1

Elements

Substances that cannot be broken down into simpler substances by chemical means

O, C, H, & N are?

• four elements used to build biological molecules

  • carbohydrates

  • Proteins

• Also used to form storage compounds and cells in organisms

trace elements

• required by organism only in very small quantities

• Iron (Fe), iodine (I), and copper (Cu)

Atoms

• The unit of life and are the building blocks of the physical world

Subatomic particles and charges

• protons - positively charged

• Neutrons - uncharged

• Electrons - negatively charged

Isotopes

• atoms of same element with same number of protons, but different number of neutrons in nucleus.

Isomers

• molecules with same chemical formula but different structures

Compound definition

• consists of two or more elements

Bonds in compound

• Held by chemical bonds

  • Ionic

  • Covalent

  • Hydrogen

ionic bond

formed between two atoms when one or more electrons are transferred from one atom to the other

Ions

Charged forms of atoms

Covalent bond

• formed when electrons shared between atoms

  • Non-polar - electrons shared equally

  • Polar - electrons shared unequally

Hydrogen bonds

• weak chemical bonds that form when a hydrogen atom is covalently bonded to another atom

Hydrogen bonds properties

• cohesion

• Adhesion

• Surface tension

• High heat capacity

• Expansion on freezing

Cohesion

• when water molecules stick together

Adhesion

• when water molecules stick to other substances

capillary action

• when adhesive and cohesive forces work together

• Accounts for ability of water to rise up roots, trunks, and branches of trees

Surface tension

• cohesion of water molecules (stick to each other)

• Surface of water has tension to it, allowing for contact atop surface w/o sinking

Acidic

• solution contains a lot of hydrogen ions (H+)

• If dissolved in water, will release a lot of hydrogen ions

Basic

• solution that contains a lot less hydrogen ions (H+)

• releases hydroxide ions (OH-) when added to water

pH scale

• measures acidity/alkalinity of a solution

• Numbered from 1 to 14

• Midpoint is 7, considered neutral pH

• Acidic, basic or neutral determined by concentration of hydrogen ions

• pH scale logarithmic, representing tenfold change in hydrogen ion concentration

  • -log [H+]

organic molecules

molecules with carbon

Inorganic molecules

don’t contain carbon

Carbon importance

• versatile atom

  • Ability to bind not only with other carbons but also with a number of other elements including nitrogen, oxygen, and hydrogen

polymers

• chains of building blocks (monomers) in macromolecules

monomers

• individual building blocks of a polymer

Dehydration synthesis

• endergonic, catabolic

• Polymer formed

• Water molecules is lost in reaction

Hydrolysis

• exergonic, anabolic

• Breaks down polymers into monomers by breaking covalent bond

• Produces a water molecule

Classes of organic compounds central to life on Earth

1. Carbohydrates

2. Proteins

3. Lipids

4. Nucleic acids

carbohydrates

• 1:2:1 ration of carbon, hydrogen, and oxygen

• Categorized as monosaccharides, disaccharides, or polysaccharides

  • Prefix = number of sugars in molecule

monosaccharide

• energy source for cells

• Most common: glucose and fructose

  • Formula: C6H12O6

Glucose

• C6H12O6

• Monosaccharide

• Important part of food we eat

• Product made by plants during photosynthesis

• Depicted as either “straight” or “rings”

  • Have OHs and Hs attached

fructose

• C6H12O6

• Monosaccharide

• Also found in plants

• Metabolized differently, in liver

• Depicted as either “straight” or “rings”

  • Has OHs and Hs attached

Disaccharides

• glycosidic linkage, a type of bond, joins two monosaccharides

• Glucose + glucose = maltose

• Broken by hydrolysis

Polysaccharides

• made of many repeated units of monosaccharides

• Branched/unbranched chains of monosaccharides

  • Starch

  • Cellulose

  • Glycogen

  • Cellulose

  • Chitin

Glycogen

• stores sugar in animals

Starch

• stores sugar in plants

cellulose

• Polymer of β-glucose and is a major part of cell walls in plants

• Provides structural support

Proteins

• important for structure, function, and regulation of tissues and organs

• Monomers - amino acids

  • Contain carbon, hydrogen, oxygen, and nitrogen

  • 20 of different ones

Chitin

• polymer of β-glucose

• Serves as structural molecule in walls of fungus and in exoskeletons of anthropods

Protein structure

• around central carbon

• Amino group (—NH2), carboxyl group (—COOH), hydrogen, and R-group

  • Different in R group (side chain)

side chain

Polarity determines whether an amino acid is more hydrophobic or more hydrophilic

Hydrophobic

• nonpolar and uncharged

Hydrophobic

Polar and uncharged

Polypeptides

• Polymer made of amino acids

  • Carboxyl group of one amino acid combines with amino group of another

• Connected by peptide bonds

dipeptide

• two amino acids bonded by a peptide bond

Primary structure

• linear sequence of the amino acids

Secondary structure

• when polypeptide beings to twist

• Forms either a coil (alpha helix) or zig-zag pattern (beta-pleated sheets)

tertiary structure

• when secondary structure reshapes polypeptide

• Amino acids far away in primary structure interacting with each other

Quaternary structure

• when different polypeptide chains interact with each other

Hemoglobin

• quaternary structure

• Molecule in blood that helps distribute oxygen to tissues in body

• When four seperate polypeptide chains interact

Lipids

• consist of carbon, hydrogen, hydrogen, oxygen

• Important due to non-polar structures

• Function as structural components of cell membranes

• Sources of insulation

• Signaling molecules

• Means of energy storage

triglyceride

• lipids located in the cells of fat tissues (adipocytes in adipose)

• Made of glycerol molecule/backbone with three fatty acid chains

  • Fatty acid chain covered in hydrogen

  • One end has a carboxyl group

Unsaturated fatty acid

• triglyceride

• Double bond in fatty acid chain

  • Less hydrogens

  • Prevents stacking/packing

saturated fatty acids

• triglyceride

• Saturated with hydrogens along fatty acid chains

Lipid saturation

• extent of saturation affects structure and function of lipid

• The more double bonds within lipid, the more unsaturated

Phospholipids

• two fatty acid “tails” and one negatively charged phosphate “head”

  • Head - hydrophilic (mixes well w water bc of negative charge)

  • Tails - hydrophobic (non-polar so doesn’t miss well with polar water)

  • Hydrophilic + hydrophobic = amphipathic

cholesterol

• four-ringed molecule

• Found in membranes

• Increases membrane fluidity, except at very high temps

• Important for making certain types of hormones and vitamin D

Nucleic acids

• contain carbon, hydrogen, oxygen, nitrogen, and phosphorus

• Made up of monomers called nucleotides

  • DNA: thymine, guanine, adenine, cytosine

  • RNA: uracil, guanine, adenine, cytosine

• DNA contains hereditary “blueprints of all life”

• RNA essential for protein synthesis