Biochemistry 2.1-2.4 Flashcards
What is the difference between covalent and ionic bonds?
- covalent share electrons (stable)
- ionic bonds easier to separate
- dissociation
- electrons move
Why is water bipolar?
- oxygen negative
- hydrogen positive
- polarity
What are hydrogen bonds?
- intermolecular force
- dipole-dipole force
- strongest
- between water molecules
- or bases of DNA
What are properties of water?
- cohesion
- water holds it shape (H-bonds)
- surface tension
- water “membrane” withstands pressure from air
- adhesion
- water reacts with polar substances (also solid)
- capillary action
- water hold together and sticks to glass
- forces pull water upwards
- thermal
- water holds heat
- high boiling point (H-bonds)
- solvent
- for polar and ionic substances
- hydration shells
Why is water more dense than ice?
- in liquid state molecules are densely packed
- in ice water molecules are arranged in crystal lattice
- more space between them
- highest density at 4ºC
- normally substances in liquid state have more space
- hexagonal structure maximises the amount of hydrogen bonds between molecules
- water reservoirs freeze at the top
- organisms live underneath
- isolates water from further freezing
Boiling point of water vs methane
- hydrogen bonds are stronger and don’t allow for movement
- b.p. of water higher
- more energy to break H bonds
What is specific heat capacity and heat of vaporisation?
- specific heat capacity
- energy needed to raise temp of 1g by 1ºC
- conductivity regulates temperature of living things
- heat of vaporisation
- energy needed for 1g to change from liquid to gas
- no dehydration
Water as a coolant
- water evaporation needs a lot of energy
- sweat cools down body
Why are biological membranes wet?
- alveoli, villi and capillaries
- substances dissolve quickly
- prevent collapsing
Benefits of living in water?
- high density of water
- swimming and floating
- ice on top, underneath not frozen
- swimming and floating
- transparent
- photosynthesis
Why is carbon necessary for living things?
> 4 covalent bonds
complex molecules
gives and receives e-
How are polymers formed?
- few molecules combined
- large molecule
- releasing small ones
- ex.: water - dehydration reaction
What is hydrolysis?
- hydrolysis → opposite of dehydration
- polymer split into monomers + H2O
Anabolism vs catabolism
- anabolism
- formation of molecules from monomers
- catabolism
- breakdown of complex molecules into monomers
How are carbohydrates, proteins and triglycerides synthesised?
- carbohydrate
- monosaccharides → disaccharides → polysaccharides
- proteins
- amino acids → dipeptides → polypeptides
- triglycerides
- 3 fatty acids + glycerol → triglyceride
Examples of saccharides
- sucrose → glucose + fructose
- maltose → glucose + glucose
- lactose → glucose + galactose
How are peptide bonds created?
- condensation reaction
- carboxyl group connects to amino group
- water is released
What are properties of glucose, fructose, sucrose and lactose?
- glucose
- producing ATP
- transported in blood
- fructose
- fruit sugar
- energy source
- sucrose
- table sugar
- transported in plants (plant sap)
- lactose
- milk sugar
- energy for infants
- digested by lactase
What are bonds between 2 monosaccharides
- glycosidic bonds
What are functions of carbohydrates?
- energy source
- energy storage
- starch - plants
- glycogen - animals
- structure
- cellulose
- cell membranes
- glycoproteins
- proteins + sugar = antigens
What are the properties of glycogen and starch?
- glycogen
- stores energy in muscles and liver
- mobilised when blood glucose level drops
- lots of branches and 2 glycosidic bonds
- starch
- stored in plants
- starch has less glycosidic bonds and therefore less branches (or none)
What is amylose and amylopectin?
- building blocks of starch
- amylose = single strand
- amylopectin = branched
- plant growth
What are the properties of cellulose?
- multiple B-glucose molecules
- plant cell walls
- put at 180º to previous → stable structure (wall)
- digested by cellulase
- humans can’t digest → fibre (pushes faeces out)
What is the difference between unsaturated and saturated fats?
- saturated = single bonds only
- unsaturated = double and single bonds
- bent
What is the difference between cis and trans fats?
- unsaturated fats → double bonds
- difficult to rotate 2H+ mol.
- on the same side → cis → bent
- on opposite sides → trans
What are phospholipids?
- fats with phosphate group
- hydrophobic tails and hydrophilic heads → form plasma membrane
Why are fats good energy storage?
- don’t affect osmosis of cell
- long-term energy storage
- harder to break down
- more energy per unit of fat than sugar
- thermal isolation and shock absorber
What are LDL and HDL?
- LDL = low density lipoprotein (“bad cholesterol”)
- more dense in cholesterol than proteins
- used when fat deficiency
- HDL = high density lipoprotein
- carries excess cholesterol to liver
How does cholesterol accumulate in blood vessels?
- LDL sticks to wall of vessels
- endothelium destroyed
- monocytes detect, macrophages destroy build-up
- die from overeating
- cholesterol builds up → cloth
- fibrous cap covers the clot
- calcium hardens
- plaque (mountain) restricts blood flow
How is insulin synthesised?
- preproinsulin (polypeptide) → proinsulin
- chain C released → insulin created
What are the levels of protein structure?
- primary (chain)
- secondary (α helix or β sheets)
- hydrogen bonds
- tertiary (3D)
- hydrophobic bonding (not an actual bond)
- disulphide bridges
- salt bridges (ions)
- quaternary (more than one chain)
What is the function of rubisco?
- enzyme (catalyst) for light-independent phase of photosynthesis
- RuBP + CO2
What is the function of insulin?
- animal hormone
- secreted in β cells of pancreas
- lower blood glucose level
- triggers uptake by cells
What is the function of immunoglobulins?
- immunoglobulins = antibodies
- destroy foreign cells
- recognise antigens
- produced by lymphocytes
- different structures
What is the function of rhodopsin?
- light-sensitive protein
- produced by rods (photoreceptors in retina)
- B&W vision
What is the function of collagen?
- building structure (connective tissue)
- elastic
What is the function of spider silk?
- resistant to pulling apart
- used by spiders to make webs
What is proteome?
- complete set of proteins expressed by an organism
