Biological Molecules Flashcards
Test for lipid
- dissolve in ethanol and add water
- milky while emulsion should form
Name of bond between glycerol and fatty acid
Ester
Adaptations of starch
- insoluble so does affect water potential of cell
- helical structure so can be compacted
- large molecule so cannot cross cell-surface membrane
- branched so MANY ENDS for enzymes to hydrolyse quickly for energy release
Adaptations of cellulose
- long straight chains of beta glucose
- successive glucose units are rotated 180 degrees relative to each other
- many hydrogen bonds
- provide strength to cell wall
- form microfibrils which run parallel
- with hydrogen cross linkages
Test for reducing sugars
- Benedict’s solution goes from blue to brick-red
- heated with reducing sugars
Test for non reducing sugars
- heat with Benedict’s reagent + solution remains blue
- heat with dilute hydrochloric acid
- neutralise using sodium hydrogen carbonate as slightly alkaline conditions are required
- heat with Benedict’s reagent + observe colour change from blue to brick-red
Lipid uses
- energy storage
- thermal insulation
- waterproofing
Triglyceride
1 glycerol + 3 fatty acids (carboxyl group and R-group i.e. hydrocarbon chain)
Test for proteins
- biuret test
- add NaOH and CuSO4
- changes colour from pale blue to purple
Adaptations of glycogen
Same as starch
- less dense and more soluble than starch to fulfil higher metabolic requirement of animals (e.g. run from predators)
- glycosidic bonds are easily broken so rapid release of glucose
Why is HCl added in test for non reducing sugars
- hydrolyses non reducing sugar
- into its constituent monosaccharides
- positive Benedict’s test
Prosthetic groups
Inorganic group forming part of quaternary structure of conjugated protein e.g. haemoglobin has iron containing haem groups
Nucleotide components
Nitrogenous base
Phosphate group
Pentose sugar
ATP structure
Phosphorylated macromolecule
- adenine
- ribose
- three phosphate groups
How does ATP release energy
Bonds between phosphate groups are unstable and have a low activation energy so are easily broken to release the potential energy stored in the bond
ATPase
Catalyses hydrolysis of ATP into ADP and Pi (inorganic phosphate)
ATP Synthase
Catalyses condensation reaction between ADP and Pi for reform ADP
Compare the structure of starch and cellulose
similarities
- polymers of glucose monomer
- insoluble
- contain glycosidic bonds
differences
- alpha vs beta glucose
- helical vs long, straight chains
- monomers same way up vs alternate
Name processes in which ATP in produced
- photosynthesis
- aerobic respiration
- anaerobic respiration
Role of ATP
- active transport
- cell division (contraction of spindle fibres)
- synthesis of DNA, proteins etc.
- muscle contraction
- nerve impulses (resting potential)
- phosphorylation
Suggest why cells are always producing ATP
- immediate energy source so is unstable
- cannot be stored since it is constantly broken down
Suggest why ATP is better than glucose
- involves a single reaction to release energy immediately
- releases a small amount of energy so is more manageable / less wasted
- cannot pass out of cell so cells always have supply
Suggest why it is important ATP releases energy in small, manageable amounts
- avoids wastage
- overheating
Equation to show how energy is released from ATP
ATP + H2O -> ADP + Pi
Why serial dilution
- without serial dilution you would need to measure very small volumes
- which is difficult to do accurately
Give examples of nucleotides
- ATP
- DNA
- RNA
Condensation
- reaction which joins two molecules together with the formation of a chemical bond
- involves elimination of water molecule
Hydrolysis
- reaction which breaks a chemical bond between two molecules
- involves use of water molecule
State which monosaccharides the following disaccharides are made of:
- maltose
- sucrose
- lactose
maltose - glucose x2
sucrose - glucose + fructose
lactose - glucose + galactose
(glycosidic bond formed between them)
Explain how the structure of triglycerides are related to their function
- good source of energy due to long hydrocarbon chains which have many energy-containing C-H bonds
- poor conductors of heat so acts as thermal insulators
- large/uncharged hence insoluble in water so can be stored without affecting water potential of cells
Explain how the structure of phospholipids are related to their function
- hydrophilic head due to negatively charged phosphate group so face outwards
- hydrophobic tail due to non-polar hydrocarbon chain so face inwards
- form a bilayer in cell membranes
Give examples of inorganic ions
- iron
- hydrogen
- sodium (potassium)
- phosphate
- nitrate
Explain the biological importance of iron
- Fe3+ attached to haem groups in haemoglobin of red blood cells
- each Fe3+ binds to one oxygen molecule when partial pressure for oxygen is high at lungs
- rapid saturation of oxygen to make oxyhaemoglobin
- unloads oxygen when partial pressure is low at muscles
- oxygen necessary for aerobic respiration which produces more ATP than anaerobic
Explain the biological importance of sodium/potassium ions
- sodium potassium pump maintains resting potential
- influx of sodium ions allows for passage of action potential
- hyperpolarisation due to excess potassium ions results in refractory period so action potential is unidirectional and discrete
- sodium-potassium pump creates concentration gradient for sodium so it co-transports glucose/amino acids into epithelial cells from lumen of ileum
Explain the biological importance of nitrate ions
- nitrogen-fixing bacteria in root nodules convert atmospheric nitrogen into nitrogen-containing compounds
- nitrifying bacteria in soil convert ammonium to nitrite then nitrate in two stage oxidation process
- nitrate taken up by roots in active transport and lower water potential in root hair cells so water enters by osmosis
- nitrates used for amino acids, DNA/RNA and ATP
Explain the biological importance of phosphate ions
- phosphate requires for production of DNA/RNA
- oxidative phosphorylation to produce ATP from ATP synthase
- substrate level phosphorylation of glucose during glycolysis to produce triose phosphate from more reactive phosphorylated glucose
- phospholipid bilayer for cell-surface membrane which is selectively permeable
Explain the biological importance of hydrogen ions
- concentration of hydrogen ions affects pH which controls enzyme action since it interferes with ionic bonding of R groups of amino acids
- enzymes have conformational change of active site based on pH so can catalyse multiple reactions under different conditions
- hydrogen ions and electrons reduce NADP in LDR
- NADPH reduces glycerate-3-phosphate in Calvin cycle to TP
- creates electrochemical gradient during oxidative phosphorylation so moves through ATP synthase resulting in a change in shape so it catalyses ATP production
Explain the biological importance of water
- reactive (metabolite) for hydrolysis and condensation reactions plus raw product in photosynthesis
- cohesion-tension theory in xylem and surface tension for skaters
- high latent heat for cooling with little water loss
- high specific heat capacity so acts as a buffer against sudden temperature changes/ maintain homeostasis
- UNIVERSAL solvent for reactions occur faster in solution /removal of waster products
- ice has lower density so floats and insulates aquatic organisms during winter
Difference between alpha and beta glucose
position of H and OH group on carbon 1 inverted for beta
