Topic 1.2 Biological Molecules Flashcards
What is a glycosidic bond?
A bond formed between two monosaccharides (1,4 or 1,6).
Amylose
-One of the 2 polysaccharides that make up starch
-Long
-Unbranched
-Coiled structure (makes it compact)
(Starch- alpha helix structure, insoluble due to its structure).
Hydrophilic
-Having an affinity for water
-Capable of interacting with water through hydrogen bonding.
Hydrophobic
-Lacking an affinity for water
-Insoluble in water
-Repelling water
-Doesn’t form hydrogen bonds.
Is a lipid a polymer?
NO
-It is only 3 chains long, not repeated.
What do lipids contain?
-Carbon
-Hydrogen
-Oxygen
-Phosphorous (sometimes)
-Nitrogen (sometimes).
Cellulose properties
Occurs in: plants
Location: cell wall
Monomer: beta glucose
Glycosidic bond: 1-4
Shape of chains: very long and straight
Hydrogen bonds: extensive
Tensile strength: high
Function: structural and protective.
What is a condensation reaction?
A reaction that joins two monosaccharides (a molecule of water is produced).
What is a hydrolysis reaction?
A reaction that splits the disaccharide back into its monomer (using a molecule of water).
Glycerol structure
-Fats/lipids have a backbone of glycerol
-Fatty acids are hydrocarbon length
(structure ‘prop-1,2,3-anol : CH2OH CHOH CH2OH)
-Group: picture
Amylopectin
-One if the two polysaccharides that make up starch
-Long
-Branched; branches allow enzymes to break it down easily (by breaking glycosidic bonds) so glucose can be released quickly.
Glycogen properties
Occurs in: animals
Location: cytoplasm
Monomer: alpha glucose
Glycosidic bond:1-4 and 1-6
Shape of chains: coiled
Hydrogen bonds: limited
Tensile strength: low
Function: energy store.
Starch properties
Occurs in: plants
Location: chloroplasts, amyloplasts
Monomer: alpha glucose
Glycosidic bond: 1-4 and 1-6
Shape of change: coiled
Hydrogen bonds: limited number
Tensile strength: low
Function: energy store.
Cellulose
-Monomer is beta glucose
-Forms chains which run parallel with hydrogen bonds to form microfibrils
-Microfibrils are string
-Being fibrous cellulose is structurally important in plant cell walls.
Beta glucose structure
(Ballerina- ‘one arm up one arm down’)
trans isomer
Proteins equation
protein + water ⇌ amino acids
Ester bond
Bond between fatty acids and glycerol.
Condensation reaction for lipid
Glycerol + fatty acid –> lipid
(eliminating three H2O molecules).
Phospholipid
Phosphate group head (hydrophilic)
Fatty acid tail (hydrophobic)
Alpha glucose structure
(Acrobat- ‘moustache’)
cis isomer
(small and water soluble)
Test for triglycerides
Emulsion test
-water (shake) + ethanol (shake).
Functions of proteins and examples
-Channels eg. membrane proteins
-Hormones eg. insulin
-Transport eg. haemoglobin
-Protection eg. antibodies
-Structure eg. collagen, keratin
-Cell recognition eg. antigens
-Movement eg. actin, myosin
Amino acid structure
Peptide bond
A peptide bond is a bond between two amino acids, formed by a condensation reaction
Polyunsaturated
Molecules that contain more than one unsaturated carbon bond.
Peptide bond
A bonds between 2 polypeptides (amino acid).
Tertiary structure (3°)
-Protein folds tightly
-Held together by bonds between R groups (disulphide bonds, hydrogen bonds, ionic bonds).
Secondary structure (2°)
-Interactions between side chains cause chains to coil and twist
-Secondary structure is held together by hydrogen bonds
-Alpha helix and beta pleated sheets
Phospholipid structure
Amphipathic: glycerol backbone attached to 2 hydrophobic fatty acid tails (by ester bonds) and a hydrophilic polar phosphate head.
(Tails can splay outwards= waterproofing)
Primary structure (1°)
-Sequence/order of amino acids
-Link by peptide bonds in condensation reactions
-A polypeptide forms.
Quaternary structure (4°)
-Several folded units join together
-Held together by bonds including those that form between R groups and adjacent chains (disulphide bridges).
Glycerol/glycolipid structure
picture
Monosaccharides
Organic monomer that cannot be hydrolysed to a simpler sugar.
3 hexose monosaccharides: glucose, fructose, galactose
Structure of ribose
Pentose monosaccharide
Disaccharide examples
-Maltose: glucose + glucose
-Sucrose: glucose + fructose
-Lactose: glucose + galactose
(all have formula C12H22O11)
Polysaccharide definition
Polymer made from a repeating monosaccharide unit
-Starch
-Glycogen
-Cellulose
How do triglycerides form?
Condensation reaction between 1 molecule of glycerol and 3 fatty acids form ester bonds.
Saturated fatty acids
-Contain only single bonds
-Straight-chain molecules have many contact points
-Higher melting point= solid at room temperature
-Found in animal fats
Unsaturated fatty acids
-Contain C=C double bonds
-‘Kinked’ molecules have fewer contact points
-Lower melting points= liquid at room temperature
-Found in plant oils
Disulphide bridges in tertiary structure
Strong covalent S-S bond between molecules of the amino acid cysteine.
Ionic bonds in tertiary structure
Relatively strong bonds between charged R groups.
(pH changes causes these bonds to break due to interactions with OH- / H+ ions).
Hydrogen bonds in tertiary structure
Intermolecular force between H δ+ of O-H or N-H and lone pair on O or N of an adjacent molecule.
Numerous and easily broken.
Structure and function of globular proteins
-Spherical and compact
-Hydrophilic R groups face outwards and hydrophobic R groups face inwards= usually water-soluble.
-Involved I metabolic processes eg. enzymes
Structure and functions of fibrous proteins
-Can form long chains or fibres
-Sequences of amino acids repeat
-Insoluble in water
-Useful for structure and support eg. collagen.
Functions of collagen
Component of bones, cartilage, connective tissue, tendons.
Structure of collagen
-Stable alpha helix due to repeating sequence
-Forms fibres
-H bonds and staggered covalent bonds between fibres= high tensile strength.
Structure of a globular protein
- Has a tertiary structure and quaternary structure.
- Held by named bond.
- Hydrophilic on the outside of the molecule.
