AP Bio Unit 1: Chemistry of Life

scientific method

A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions.

Null Hypothesis

the hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error.

alternative hypothesis

The hypothesis that states there is a difference between two or more sets of data.

positive control

Group expected to have a positive result, allowing the researcher to show that the experimental set up was capable of producing results.

negative control

Group with no response expected

experimental group

In an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable.

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied.

dependent variable

The outcome factor; the variable that may change in response to manipulations of the independent variable.

constants

Conditions/ factors that stay the same in the experiment

statistics

Collection of methods for planning experiments, obtaining data, organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions based on data.

descriptive statistics

numerical data used to measure and describe characteristics of groups. Includes measures of central tendency and measures of variation.

inferential statistics

numerical data that allow one to generalize- to infer from sample data the probability of something being true of a population

central tendencies

the mean, median, and mode of a data set. these represent the typical or common characteristics of a data set

mean

average

median

the middle score in a distribution; half the scores are above it and half are below it

mode

The value that occurs most frequently in a given data set.

variability

in a set of numbers, how widely dispersed the values are from each other and from the mean

range

the difference between the highest and lowest scores in a distribution

standard deviation

a computed measure of how much scores vary around the mean score

standard error

An estimate of the standard deviation of the sampling distribution of a statistic.

chi- square

Involves categorical variables. Looks at 2 distributions of categorical data to see if they differ from each other.

matter

Anything that has mass and takes up space

element

A substance that cannot be broken down into simpler substances

electronegativity

Ability of an atom to attract electrons in a bond.

atomic number

the number of protons in the nucleus of an atom

octet rule

atoms react by gaining or losing electrons so as to acquire the stable electron structure of a noble gas, usually eight valence electrons

chemical bonds

the attractive forces that hold atoms together

compound

A substance made up of atoms of two or more different elements joined by chemical bonds

covalent bonds

Bonds created by sharing electrons with other atoms.

nonpolar covalent bonds

electrons are shared equally

polar covalent bonds

unequal sharing of electrons

ionic bonds

Formed when one or more electrons are transferred from one atom to another

adhesion

An attraction between molecules of different substances

cohesion

Attraction between molecules of the same substance

capillary action

the attraction of the surface of a liquid to the surface of a solid

solvent

A liquid substance capable of dissolving other substances

solute

A substance that is dissolved in a solution.

pH

hydrogen ion concentration

buffer

A solution that minimizes changes in pH when acids or bases are added to the solution.

functional groups

the components of organic molecules that are most commonly involved in chemical reactions

organic chemistry

the study of compounds containing carbon

organic compounds

carbon-based molecules

hydrocarbons

organic molecules consisting of only carbon and hydrogen

macromolecule

large molecule formed by joining smaller organic molecules together

dehydration reaction (dehydration synthesis)

A putting together of components while removing water

hydrolysis

the chemical breakdown of a compound due to reaction with water.

polymer

molecules composed of many monomers; makes up macromolecules

monomer

small chemical unit that makes up a polymer

disaccharide

A double sugar, consisting of two monosaccharides joined by dehydration synthesis.

starch

Storage polysaccharide of plants.

cellulose

polysaccharide consisting of glucose monomers that reinforces plant-cell walls

monosaccharide

A single sugar molecule such as glucose or fructose, the simplest type of sugar.

polysaccharide

A polymer of thousands of simple sugars formed by dehydration synthesis.

glycogen

storage form of glucose in animals

glycosidic linkage

a covalent bond formed between 2 monosaccharides by a dehydration reaction

lipid

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen.

fat

A lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride.

fatty acid

hydrocarbon chain often bonded to glycerol in a lipid

phospholipid

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

antiparallel

subunits run in opposite directions

DNA

A complex double stranded molecule containing the genetic information that makes up the chromosomes.

RNA

A single-stranded nucleic acid that passes along genetic messages

nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

Nucleic acid

a complex organic substance present in living cells, especially DNA or RNA, whose molecules consist of many nucleotides linked in a long chain.

gene

A segment of DNA on a chromosome that codes for a specific trait

pyrimidine

a nitrogenous base that has a single-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; thymine, cytosine, or uracil

purine

a nitrogenous base that has a double-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; either adenine or guanine

primary structure

The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain.

secondary structure

The second level of protein structure; the regular local patterns of coils or folds of a polypeptide chain.

tertiary structure

Results from interactions between side chains.

quaternary structure

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits.

protein

A three dimensional polymer made of monomers of amino acids.

amino acid

monomer of protein