AP bio unit 1

gene

unit of heredity

genome

all of an organism’s genetic information

cells

simplest self-reproducing unit that can exist independently

species

species

group of interbreeding organisms that can produce offspring

energetics

the study of energy and how it’s distributed through biological, chemical, or physical processes

dna

the carrier of genetic info for all organisms

biological system

system made up of both biotic and abiotic entities that interact

emergent property

property of a system that the individual parts do not have on their own (eg nest construction is possible if there’s many ants), EMERGES from interactions in a system

scientific inquiry

about the natural world. exploration → investigation → communication

controlled experiment

researcher sets up at least two groups to be tested; the conditions and setup of the groups are identical but the researcher introduces a single change to one group

percent change

(final-initial)/initial * 100

standard error of the mean

s / sqrt(n)

standard deviation

molecules

chemicals made up of two or more atoms

organic molecules

biological molecules that contain carbon

the three subatomic particles

proton (nucleus), neutron (nucleus), electron (electron shells/energy levels)

atomic number

the number of protons

isotopes

atoms of same element but different number of neutrons

ions

electrically charged atoms (cations are positive and anions are negative)

valence electrons

electrons on the outermost energy level

group/family

elements in the same column in the periodic table. column number is also the number of electrons

four most common elements

carbon, hydrogen, oxygen, nitrogen (also phosphorous)

covalent bond

when a pair of electrons are shared between two atoms. double bonds are if there’s two pairs shared. (typically nonmetal + nonmetal)

polar covalent bonds

electrons are not shared equally

electronegativity

atom’s ability to attract electrons (increases left to right, bottom to top on periodic table). in the example of h2o, since oxygen has higher EN and electrons are negative, it gains a partial negative charge

why are electrons shared unequally?

difference in EN

ionic bonds

two ions with opposite electrical charges bonded together (instead of sharing, the difference in EN was so high that one atom stole an electron from the other) (typically metal + nonmetal like NaCl)

why does NaCl dissolve?

the negatively charged ends of water molecules (o) are attracted to the positive sodium, and the positively charged ends of water molecules (h) are attracted to the negative chloride

chemical reaction

process by which atoms or molecules are transformed into different molecules. the things that’re changed are reactants and the molecules formed are the products. their bonding partners are changed.

why carbon so good??

• of its six electrons, four r in outermost shell allowing it to form a lot of bonds

• carbon can make compounds in many diff shapes (CH4 is a tetrahedron)

• carbon atoms can link with other carbons to form chains or rings

four classes of organic molecules

proteins, nucleic acids, lipids, and carbohydrates

polymers/monomers

• polymers are long chains made up of smaller repeating subunits called monomers.

• most of the organic molecules are polymers.

what do proteins do and what are they made up of?

• speed up chemical reactions, deliver messages, and provide structural support for the cell.

• they’re made of amino acids in peptide bonds.

• all amino acids have nitrogen.

what do nucleic acids do and what are they made up of?

• nucleic acids encode and transmit genetic information (DNA, RNA) and are polymers made up of nucleotides.

• they are informational molecules.

• all nucleic acids have nitrogen.

what’s another name for carbohydrates, what are they made of, and what do they do?

• sugars.

• they are polymers made up of monosaccharides.

• they store energy.

what’s different about lipids and what do they do?

• they’re hydrophobic, meaning nonpolar and don’t dissolve in water, while the other three are hydrophilic.

• they’re also not polymers because they don’t consist of repeating subunits.

• they make up the cell membrane, store energy and act as messengers.

hydrogen bond

a polar bond where a slightly pos hydrogen atom bonds with a more electronegative atom. they are weaker than covalent bonds.

cohesion

water molecules sticking to each other

adhesion

water molecules sticking to other things

surface tension

consequence of cohesion, strong bond on surface because surface molecules don’t have molecules surrounding them on every side

structures of ice, water and steam

• ice: open crystalline lattices from each water molecule bonded to four others

• water: water molecules move around and are closer together; bonds break and form (more dense than ice)

• steam: water molecules move around even more rapidly, keeping them far apart and preventing most bonds

specific heat

• the amount of energy required to change the temperature of a substance

• motion increases as temp increases

why’s water more resistant to temp changes?

a lot of the energy heat provides goes into breaking hydrogen bonds so it takes longer for the temp to make any changes