AP Bio Unit 1

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Polarity of Water

Unequal sharing of electrons between oxygen and hydrogen, making oxygen slightly negative and hydrogens slightly positive

Hydrogen Bonding

Weak bonds formed between the slightly positive hydrogen of one water molecule and the slightly negative oxygen of another

cohesion

water molecules sticking to other water molecules due to hydrogen bonding

adhesion

water molecules sticking to other water molecules due to hydrogen bonding

surface tension

a measure of how difficult it is to stretch or break the surface of a liquid, related to the cohesion of water molecules

High Heat Capacity

water’s ability to resist temperature changes because a large amount of heat energy is required to break hydrogen bonds

High Heat of Vaporization

the amount of energy required to convert liquid water into gas (steam), which helps organisms cool down via sweating

density of phases of water

ice is less dense than liquid water because hydrogen bonds hold molecules farther apart

versatile solvent

water’s polarity allows it to dissolve ionic compounds and polar molecules easily

Covalent bond

a chemical bond formed by the sharing of electron pairs between atoms (nonpolar or polar)

Ionic bond

a chemical bond formed through electrostatic attraction between oppositely charged ions

hydrophobic

water-fearing; nonpolar molecules that do not mix well with water

hydrophilic

water-loving; polar or charged molecules that interact well with water

dehydration synthesis

a reaction that joins monomers together by removing a molecule of water

hydrolysis

a reaction that breaks down polymers into monomers by adding a molecule of water

Hydroxyl

(-OH), polar, found in alcohols

Carbonyl

(>C=O). ketones, aldehydes

Carboxyl

(-COOH), acts as an acid, donates H+

Amino

(-NH2), acts as base. accepts H+

Sufhydryl

(-SH), helps stabilize protein structure through disulfide bridges

Phosphate

(-OPO 2- 3), contributes negative charges, important in nucleic acids and energy transfer

Methyl

(-CH3), affects gene expression and nonpolar interactions

Monomers

small, basic molecular units that serve as building blocks for polymers

polymers

long molecules consisting of many similar or identical building blocks linked by covalent bonds

Carbohydrates

Carbon, Hydrogen, Oxygen (CHO)

Carbohydrate Monomer

monosaccharides (ex. glucose, fructose)

Disaccharides

two monosaccharides join by a glycosidic linkage via dehydration synthesis (ex. sucrose, lactose)

polysaccharides

Starch: energy storage in plants
cellulose: structural component of plant cell walls (tough fibers)

Lipid

Carbon, hydrogen, oxygen (CHO)

Lipid characteristics

diverse hydrophobic molecules; not true polymers

triglycerides

composed of one glycerol molecule and three fatty acids joined by ester linkages

saturated fats

fatty acid chains with no double bonds between carbon atoms; solid at room temperature

unsaturated fats

composed of fatty acid chains with one or more double bonds; liquid at room temperature

phospholipids

composed of glycerol, two fatty acids (hydrophobic tails), and a phosphate group (hydrophilic head); major component of cell membranes

Steroids

lipids characterized by a carbon skeleton consisting of four fused rings (ex. cholesterol)

Protein

Carbon, Hydrogen, Oxygen, Nitrogen

Protein Monomer

Amino acids (feature an amino group, carboxyl group. and a variable R-group side chain)

Peptide Bonds

Covalent bonds linking amino acids together into dipeptides or polypeptides, running from the N-terminus (amino end) to the C-terminus (Carboxyl end)

Primary

Sequence of amino acids linked by peptide bonds

Secondary

Coils and folds (alpha-helix and beta-pleated sheet) stabilized by hydrogen bonds along the backbone

Tertiary

Three-dimensional folding due to interactions between R-groups (hydrogen bonds, ionic bonds, hydrophobic interactions, disulfide bridges)

Quartenary

Association of multiple polypeptide chains into a functional protein macromolecule

Nucleic Acids

Carbon, Hydrogen, oxygen, nitrogen, phosphorus (CHONP)

Nucleic Acid Monomer

Nucleotides (composed of a pentose sugar, a phosphate group, and a nitrogenous base)

Nucleosides

a nucleotide without the phosphate group (sugar+base)

Phosphodiester Linkages

Covalent bonds that join nucleotides together to form the sugar-phosphate backbone, running in a 5’ to 3’ direction

Purines

Adenine(A), Guanine (G), double ring structure

Pyrimidines

Cystine (C), Thymine (T), Uracil (U), single ring structure

Sugars

Ribose (in RNA) vs. Deoxyribose (in DNA, lacks one oxygen atom)

Base Pairing

held together by hydrogen bonds (A pairs with T/U; G pairs with C)

Independent Variable

The variable that is intentionally manipulated or changed by the experimenter

Dependent variable

the variable that is measured'; it changes in response to the independent variable

constants

factors that are kept the same throughout all experimental groups to ensure a fair test

controls

standard of comparison, used to check for validity in an experiment

SEM (Standard Error of the Mean)

a statistic used to measure how far the sample mean of the data is likely to be from the true population mean; often displayed as error bars on graphs

Isomers

molecules that share the same molecular formula (same number and types of atoms) but have different structural arrangements. giving them unique chemical properties

Isotopes

Alternative forms of the same element that have the same number of protons but a different number of neutrons, resulting in the different atomic masses

radioactive tracers

radioactive isotopes used by scientists as “labels” or markers in biological research to track the path of chemicals and metabolic processes through living organisms

Identification of molecules based on structure

the ability to look at a chemical blueprint (such as recognizing carbon rings, nitrogenous bases, or specific functional groups) to determine whether a molecule is a carbohydrate, lipid, protein, or nucleic acid

pH/H+ Ion concentration

a logarithmic measure of the acidity or basicity of a solution, determined by the concentration of hydrogen ions (H+) present (pH = -log(H+)

Component of Cytoplasm

water acts as the primary fluid component, serving as a versatile solvent where cellular solutes dissolve and metabolic reactions occur