2.2 biological molecules Flashcards
1
Q
difference between alpha and beta glucose
A
- alpha has H attached to C1 above the ring while beta has it below
2
Q
bonding in alpha glucose
A
- glycosidic bonding
- condensation reaction : releases water
- 1-4 bond
- breaking: hydrolysis: using water
3
Q
starch
A
- amylose : alpha glucose molecules bonded with 1-4 glycosidic bonds form a spiral
- amylopectin : AND some 1.6 bondings : branching increases hydrolysis for quick energy : more end for enzyme attachment
4
Q
glycogen
A
- more 1-6 links, more branched structure
- less dense and more soluble than starch: indicates higher metabolic requirements for animals
- no osmotic effect, unreactive , compact
5
Q
cellulose
A
- main component of plant cell walls
- long straight chains of beta glucose by beta 1-4 glycosidic bonds: every second molecule is turned upside down
- does not coil
- chains line up and form microfibrils by parallel H bonds
- structure provides strength
6
Q
lipids
A
- insoluble in water
- acid + alcohol = ester
act as… - insulators from heat loss
- metabolic source of water
- E stores
-structural components - mechanical protection
- electrical insulation
- waterproofing, buoyancy
- precursors of many cell constituents
- higher energy value than carbs
7
Q
triglyceride
A
- one glycerol + 3 fatty acids joined with ester bonds
- fatty acid: carboxylic acid head, HC tail, double bond bends chain: unsaturated
- glycerol: 3 OH groups
- condensation reaction
8
Q
phospholipids
A
- one fatty acid is replaced with a phosphate group
- hydrophilic, polar head / hydrophobic fatty acid, non polar tail
- phospholipids form spontaneous bilayer and are therefore essential components of cells and organelles
- also components of lung surfaces
9
Q
cholesterol
A
- forms the basis of steroid (oestrogen/testosterone)
- hydrophilic (polar) and a hydrophobic (non polar) part: contributes to membrane bilayer
- precursor for bile salts and sex hormones
10
Q
proteins
A
- amino acids have same general structure: amino group and carboxylic acid group, different R group
- form peptide bonds by condensation and split by hydrolysis (ribosomes)
structure:
1. primary structure: sequence of amino acids: 100s long
2. secondary structures: alpha helix, beta pleated sheet, held in place by hydrogen bonds, regular order
3. tertiary structure: folding and coiling held by 4 types of bonds: H bonds, disulfide bonds, ionic bonds, hydrophobic interactions
4. quaternary structure: more than one polypeptide chains bonding together, + heme prosthetic group: part of protein not made of amino acids, other groups bonded to polypeptide
11
Q
globular proteins
A
- curl up into a spherical shape so that their non-polar hydrophobic R groups point into centre and polar remain outside: soluble in water
- mostly metabolic roles like enzymes
haemoglobin: - made up of 4 polypeptide chains, known as globin: 2 alpha and 2 beta globins
- each heme group contain an iron: bind to an O2 molecules: 1 haemoglobin can carry 8 O atoms
- interactions between hydrophobic R groups inside is important in holding it in its correct three dimensional shape
- hydrophobic important in maintaining solubility: Sickle Cell Anaemia
12
Q
fibrous proteins
A
- form long strands, not soluble
- structural roles
collagen: - skin, tendons, cartilage, bones, teeth, blood vessels
- 3 polypeptide chain, each a helix wound around each other: triple helix
- strands held together by covalent and H bonds
- every 3rd amino acid is glycine: smallest: allows strands to lie close and form a tight coil
- each complete collagen forms cross links with those running parallel, forming fibrils: bundle of fibrils: fibres
- ends are staggered to prevent weak spot running through
- flexible + tensile strength
13
Q
denature
A
- when protein shape is broken
- due to T and pH change
- irreversible, breaking tertiary bonds
- fibrous loses strength, globular becomes inactive/insoluble
14
Q
H bonds and polarity
A
- polarity: unequal sharing of electrons within a molecule, one atom has higher electronegativity (tendency to attract bonding par of e) , molecule has a slightly +ve and -ve area
- H bonds form between water molecules as H+ attracted to O-
- adjacent molecules become attracted to each other, collective make strong. stable bonding
15
Q
water as a universal solvent
A
- dissolves most small molecules with a charge
- allows transport in plants and animals
- big non polar molecules do not dissolve
- sugar dissolved due to OH bonds
