Biochemistry flashcards - Grade 12 Biology

intramolecular bonds

intramolecular bonds

1. covalent bonds - 2 non metals sharing e- equally

2. ionic bonds - 1 atom loses e- and the other gains the e-

3. polar covalent bonds - sharing of e- less equally

type of intramolecular bond is distinguished by difference in electronegativity (∆EN):

covalent = ∆EN < 0.4 → share equally

ionic = ∆EN > 1.7 → atom w greater EN takes e- from atom w lesser EN, both become charged

polar covalent = ∆EN = 0.5-1.7

polar covalent bonds

• one atom has a stronger hold on shared e-

• one end of molecule gets slightly + charged, one end gets slightly - charged

δ- = stronger EN end gets - charge

δ+ = weaker EN end gets + charge

influences attraction & biological interaction

water is polar, has polar covalent bonds

e- spend more time near the O than the H, difference in charge btwn poles of the molecules

δ- = O

δ+ = H

due to its polarity, it forms H bonds w itself → a lot of H bonds = a lot of strength

water forms bonds through

• H bonding w itself

• cohesion: water molecules are attracted to other water molecules

• adhesion: water is a polar molecule and thus attracts other polar molecules

intermolecular forces

1. London dispersion forces: v weak attraction btwn all molecules, even non polar ones. increase w molecule size

2. dipole dipole attraction: attractive force btwn 2 polar molecules

3. H bonding: special kind of dipole dipole attraction btwn 2 polar molecules w H bonded to N, O, F

carbon, the backbone of nearly every bio molecule except for water

• organic compound = compound containing C-H bonds and maybe other elements too such as N, O, etc.

  • often found in organisms

• C-H is non polar bond → hydrocarbons are non polar but polarity can be achieved by adding other atoms called functional groups

functional groups (FG)

molecules interact w eo at specific regions of their molecules and classifies molecule types

after a rxn btwn 2 molecules’ functional groups, a linkage will be formed

alcohols

• FG: -OH ~ hydroxyl

• simplest = CH3OH

aldehydes

• end group of fg -CO ~ carbonyl

• simplest = HCOH

ketones

• middle fg -CO ; middle carbon

• simplest = CH3COCH3

organic acids

• fg: -COOH ~ carboxyl; end group

• simplest = HCOOH

amine

• fg: -NH2 ~ amino

• simplest = CH3NH2

phosphate group

• fg: -PO4 ~ phosphate ; no official classification

hydrolysis rxns

rupture, use of water to rupture/break down, catabolic, splits a larger molecule apart ~ water required and used up

dehydration synthesis rxns

condenses smaller particles into larger ones. anabolic and builds up molecules ~ water is released as a product

ether linkages

• glycosidic link btw sugars when it occurs btwn sugar molecules

• btwn 2 hydroxyl groups

• used in carbohydrates

• pattern COC

ester linkages

• btw hydroxyl and carboxyl

• used in triglycerides

• pattern OCO

phosphate ester linkages

• btwn hydroxyl (1st) and phosphate (2nd)

• used in phospholipids and nucleic acid - instructs DNA and RNA

• pattern OPO

peptide linkages

• btwn carboxyl (1st) and amino (2nd)

• links amino acids together

• pattern OCNH

carbohydrates

• made of C, H, O - ratio 1:2:1

• formula - (CH2O)n where n is # of carbons

• short term energy source, building blocks, cell surface markers

• 3 kinds - monosaccharides, disaccharides, polysaccharides

monosaccharides

• chain of carbons w hydroxyl groups attached

• contain carbonyl groups

• have diff #s of carbons - commonly 3, 5, 6 carbon sugars

• isomers = compounds with same empirical formula but diff configurations

  • glucose, galactose, fructose are isomers - C6H12O6

glucose

galactose

fructose

disaccharides

• 2 simple sugars attached by ether/glycosidic linkage, dehydration synthesis rxn - 2 OH linked together

maltose

glucose + glucose → maltose + water

• linkage btw c1 on glucose 1 and c4 on glucose 2

• a 1-4 glycosidic linkage

lactose

b galactose + glucose → lactose + water

• glucose can be a or b

• linkage btw c1 on galactose 1 and c4 on glucose 2

• b 1-4 glycosidic linkage

sucrose

glucose + fructose → sucrose + water

• flip fructose so hydroxyl on the side for bonding

• linkage btw c1 on glucose 1 and c2 on fructose 2

• 1-2 glycosidic linkage (either a or b depending on the glucose)

polysaccharides

• large molecules - same linkage used to make a strand, several hundred-thousand monosaccharides bonded w glycosidic linkages

• straight chain = a 1-4 glycosidic linkages or brained chains = a 1-6 glycosidic linkages

• energy storage and structural support

• all a or all b linkages

starch

• plant energy storage

• straight chains - amylose

• branched chains - amylopectin

• stored in leaves and roots

glycogen

• animal energy storage

• many side branches

• made in liver, muscle, fat cells

cellulose

• plant structural support

• in cell walls

• H bonds btw chains from fibres, strong

• straight chain of b glucose units - b 1-4 linkages

chitin

• animal structural support and fungi as well

• polymer of straight chain b-N-acetylglucosamine

• 2nd most abundant organic material

• no branches

lipids

• mostly C and H, with few O

• hydrophobic - repel water

• few polar O-H bonds & more non polar C-H bonds

• long term nrg storage, membranes, dissolving fat soluble vitamins ADEK

• fats, phospholipids, sterols, waxes

nucleic acid

• molecules that are polymers made of nucleotides

• 3 components - pentose sugar, phosphate group, nitrogenous base

proteins

• structural support, storage, transport, signalling, cell response, movement, defence, catalysis of rxns

• amino acids make these up

• side chains determine function

• 4 levels of folding:

  • 1º - N → C terminus

  • order determines folding

  • 2º - coils and folds ; stabilized by H bonds btw amino and carboxyl groups

  • a helixes and b pleated sheets

  • 3º - super coiling involving side groups

  • 4º - many polypeptide chains come together

enzymes

• bio catalysts - assist in chemical rxns

• distort substrate chemical bonds

• sometimes need cofactors

cell membrane and transport

• fluid mosaic model

• phospholipids = main molecule

• membrane fluidity

• proteins - integral and peripheral