Unit 1 AP Bio

what type of molecule is water

polar molecule - allows it to form hydrogen bonds - hydrogen bonds give properties that are essential to life on earth

why are water molecules attracted to each other

partial neg charge on oxygen atom is attracted to pos charge on a hydrogen atom in another water molecule

causes water molecules to be attracted to one another

cohesion

high surface tension - stick together

adhesion

stick to other things - climb up xylem in plants thru capillary action

why does water have high specific heat

waters ability to form hydrogen bonds - more energy required to seperate water molecules during phase changes - give water high specific heat + high heat of vaporization

ex: when person sweats - water in sweat on skin absorsbs heat from persons body as water evaporates - cooling effect on body temp

moderate climate - absorb + release energy = stabilizes climates in locations near large bodies of water

why does ice have low density

more space between molecules in solid state than liquid - hexagon crystal lattice holds molecuels apart

result - ice as a lower density than that of liquid water - floats

layer of ice can help protect organisms from temp extremes in atmosphere - survive winter

why is water good solvent

partially pos end + partially neg end (polarity) - act as a magnets surrounding + breaking apart ionic compounds - + other polar molecules

pH

higher pH = low H+

pH less than 7 - acidic

pH greater than 7 - basic

pH of 7 = neutral

buffers

crucial in maintaining constant pH levels in living cells

buffers can form acids/bases in response to changing pH levels in a cell

ex: carbonic acid-bicarbonate buffering system in blood plasma

DNA vs RNA

DNA - deoxyribose, A, T, C, G, double stranded, holds genetic info, usually found in nucleus

RNA - ribose, A, U, C, G - single stranted, transcribes + reguates expression of genetic info, found in nucleus/cytoplasm

pyrimidines vs purines

pyr - TUC - 1 bond

purines - AG - 2 bond

primary structure

amino acids joined by peptide bonds - resulting polypeptide chains have directionality + order of amino acids in chain determines primary structure

Secondary Structure

hydrogen bonds form between adjacent amino acids in poly chain

alpha helixes/beta pleated sheets

tertiary structure

3 dimensional folded shape

often determined by hydrophobic/hydrophilic interacrions between R groups in the polypeptide

most stable - hydrophilic R groups on surface (contact cytosol)

tertiary structures may also include disulfide bridges between sulfur atoms

quaternary structure

subunits joined together

what do nucleotides consist of

5 carbon sugar (deoxy or rivose), nitrogenous base (A, T, etc) and a phosphate groups

nucleotides have directionality - phosphate group always attached to 5 carbon in sugar + 3 carbon always has a hydroxyl group where new nucleotides can be added

proteins

C H O N S (no P)

polymers of amino acids

contain carboxylic acid group, hydrogen atom, side chain (R group) attached to a central carbon

R group unique - determines identity - nonpolar, polar, acidic, basic

lipids

CHOP

nonpolar (hydrophobic) - function in energy storage, cell membranes, insulation

building blocks is fatty acids

saturated fatty - max number of C-H bonds + solid at room temp + usually orginate in animals

unsaturated - at least one C=C double bond, liquid at room temp, orginate in plants

phospholipids - built from fatty acids + phosphate - fatty acids nonpolar + phosphater polar - phospholipids amphipathic - have hydropobic + hydrophilic regions

carbohydrates

CHO

polymers of sugar monomers

types of sugars used to made carbs + how linked determines structure + function

sugars may be joined in linear structures or brsanched chains

carbs used to store energy (starch) + structural functions (cellulose)

describe each NCHOPS

Carbon - backbone + versatile - can form single, double, triple bonds + linear, branched, ring-type structures - found in all types of macros

Oxygen - ususaly forms 2 bonds - all types of macros

Sulfur - 2 bonds - found in proteins

Nitrogen - 3 bonds - nucleic acids/proteins

phosphoprous - 3 bonds - nucleic acids/some lipids

hydrogen - single bonds - all types of macros

dehydration syn vs hydrolysis

remove water to link

add water to break

memb permeability

• small nonpolar can pass

• polar, ions, + larger molecules need embedded proteins because nonpolar tails repel them