ap biology | chemistry of life

covalent bond

chemical bond between two atoms that shares electrons

electronegativity

an atom’s ability to attract electrons

oxygen has _____ electronegativity than hydrogen

higher

which end of a water molecule has a partial negative charge?

oxygen

which end of a water molecule has a partial positive charge?

hydrogen

why is water polar?

oxygen is more electronegative than hydrogen

what bond is formed between oxygen and hydrogen atoms on a water molecule?

polar covalent bond

cohesion

water’s tendency to stick together

(hydrogen bonds formed between two of the same molecule)

adhesion

water’s tendency to stick to other polar molecules

(hydrogen bonds formed between two different molecules)

hydrogen bond

a bond formed between a polar hydrogen and a polar oxygen atom and separate molecules

high specific heat

water can absorb + release large amounts of thermal energy before changing chemical states

ice is ___ dense than water

less

why does ice float?

ice is less dense than water

pH

“power of hydrogen”
pH = -log[H+]

what is the pH of water?

7 (neutral)

buffers

form acids + bases in response to pH changes

crucial to keeping relatively constant pH

water has high solvency for

polar molecules + ionic compounds

capillary action

water’s ability to flow up narrow spaces without assistance of gravity

ex ; water flowing up a straw, water flowing up a stem

four main classes of organic compounds / macromolecules

carbohydrates

lipids

proteins

nucleic acids

most common elements in organisms

NCHOPS

nitrogen, carbon, hydrogen, oxygen, phosphorus, sulfur

carbon is the _____ of organic molecules

backbone

carbon, oxygen, hydrogen is found in

all types of macromolecules

carbon has ___ valence electrons, which allows it to create a large variation of bonds

four

sulfur is typically found in

proteins

nitrogen is found in

nucleic acids + proteins

phosphorus is found in

nucleic acids + some lipids

macromolecules are formed by

monomers

the structure + function of a macromolecule is determined by

the types of monomers and how the monomers are linked

dehydration synthesis

when monomers formed a covalent bond and water is formed as a byproduct

(hydrogen + oxygen pulled out to form water)

hydrolysis

when macromolecules are broken down by adding water

(hydrogen + oxygen later recombine as water)

carbohydrates

polymers of sugar monomers

stores energy + structural functions

linear or branched structures

lipids

nonpolar macromolecules

triglycerides, phospholipids, steroids

made of fatty acids

saturated fatty acids

maximum number of c-h single bonds

solid at room temperature

straight structure

unsaturated fatty acids

contains at least on c=c double bond

liquid at room temperature

bent structure

a lipid’s function depends on

saturation level

phospholipid

built from glycerol molecule, phosphate group, and two fatty acids

amphipathic ; shares both hydrophobic (fatty acid) and hydrophilic (phosphate group)

steroids

relatively flat, nonpolar molecules

many steroids are formed by modifying cholesterol molecules

nucleic acids are polymers of

nucleotides

proteins are polymers of

amino acids

amino acids contain

an amino group, a carboxylic acid group, a hydrogen atom, and a r-group

what part of an amino acid determine its identity?

r-group

protein functions

enzyme catalysis

maintaining cell structures

cell signaling

cell recognition

etc.

the order of amino acids in the polypeptide chain determines the ____ structure of a protein

primary

primary structure (protein)

polypeptide chain

secondary structure (protein)

when hydrogen bonds (may) form between adjacent amino acids

alpha helix + beta sheet

tertiary structure (protein)

often determined by the hydrophobic/hydrophilic interactions between r-groups and polypeptide

hydrophilic r-groups on the surface of the protein ; hydrophobic r-groups on the interior of the protein

three dimensional shape

quaternary structure (protein)

multiple subunits

amino acids are joined by

peptide bonds

chaperonins

special proteins that help fold a polypeptide into its three-dimensional structure

nucleics acids are polymers of

nucleotides

two types of nucleic acids

DNA + RNA

nucleic acids structure

five carbon sugar (deoxyribose or ribose)

nitrogenous base (adenine, thymine, cytosine, guanine, uracil)

phosphate group

phosphate group is always attached to the 5’ carbon

3’ carbon has a hydroxyl group

DNA is ____ stranded

double

RNA is ____ stranded

single

(but can form three-dimensional structures when folded)

DNA function

holds genetic information

RNA function

transcribes and regulates the expression of genetic information

DNA is located

in the nucleus

RNA is located

in the nucleus + cytoplasm

DNA bases

adenine, thymine, cytosine, guanine

RNA bases

adenine, uracil, cytosine, guanine

DNA five-carbon sugar

deoxyribose (one less oxygen than ribose)

RNA five-carbon sugar

ribose

DNA strands are anti____

parallel

pyridimines

single ringed

thymine, uracil, cytosine

purines

double-ring structure

adenine, guanine

thymine bonds with

adenine

forms two hydrogen bonds

guanine bonds with

cytosine

forms three hydrogen bonds

when the amount of H+ ions increases

the pH decreases

(becomes more acidic)