Topic 2: Molecular Biology Flashcards
State one role in living organisms for each of the following: sulfur, calcium, phosphorus and iron. [4]
Sulfur - Amino acids
Calcium - Bone/Teeth
Phosphorus - DNA/RNA
Iron - hemoglobin (blood transport)
Outline the role of condensation and hydrolysis in the relationship between fatty acids, glycerol and triglycerides. [6]
- Hydrolysis: when large molecules are broken down into smaller ones
- Addition of water
- Fatty acids produced by hydrolysis of fats
- Breaking of ester bonds
- Condensation: when small molecules are joined to form a larger molecule
- Fatty acids linked to glycerol
- Up to three fatty acids
- Formation of ester bonds
Explain the relationship between the properties of water and its uses in living organisms as a coolant, a medium for metabolic reactions and a transport medium. [8]
- polar molecule
- oxygen partial negative charge, hydrogen partial positive charge
- hydrogen bonds form between adjacent water molecules
- water remains liquid over wide range of temp
- moderate temp fluctuation
- high latent heat of vaporization
- allows sweating to cool organisms
- polarity makes it a good universal solvent
- blood transport solutes in water
- cohesive properties allow transpiration stream
State the role of four named minerals needed by living organisms. [4]
- sulfur: amino acids
- calcium: bone/teeth
- iron: hemoglobin
- phosphorus: DNA/RNA
- potassium: sodium-potassium pumps
- magnesium: part of chlorophyll molecule
Outline the role of condensation and hydrolysis in metabolic reactions involving carbohydrates. [4]
- hydrolysis: breaking down of large molecules into smaller ones with the addition of water
- disaccharides break down to form monosaccharides
- condensation: building up of large molecules from small ones with the release of water
- two monosaccharides join to form one disaccharide
Metabolic reactions are catalysed by enzymes. Explain how enzymes catalyse reactions and how a change in pH could affect this. [8]
- enzymes speed up rate of reaction
- active site specific to substrate
- forms enzyme-substrate complex
- lock and key model
- works best at optimal pH
- increase/decrease from optimal pH decreases activity
- changes structure/active site
- changes 3d structure of protein
- substrate cannot fit into active site
- enzymes becomes denatured
- loss of biological properties
Outline the thermal, cohesive and solvent properties of water. [5]
- high specific heat capacity
- large amount of heat causes small change in temp
- high latent heat of vaporization
- large amount of heat energy required to vaporize water
- hydrogen bonds make water cohesive
- high surface tension
- polar molecule
- good solvent
State one disaccharide and the two monomers from which it can be synthesized. [2]
- Sucrose (Fructose, glucose)
- Galactose (Glucose, lactose)
- Maltose (Glucose, glucose)
Define metabolism. [1]
all the enzyme-catalyzed reactions in a cell
Discuss the roles of the enzymes secreted by the pancreas during digestion. [3]
- amylase breaks down starch to maltose
- lipase breaks down lipids into glycerol and fatty acids
- proteases break down proteins into amino acids
Compare and contrast cis-fatty acids and trans-fatty acids. [2]
- both unsaturated fatty acids (C=C double bond)
cis-fatty
- two H atoms on the same side
- healthier
- lower melting point
trans-fatty
- two H atoms on different sides
- less healthy
- higher melting point
Distinguish between the thermal properties of water and methane. [2]
water
- higher boiling point
- higher melting point
- higher specific heat capacity
- higher latent heat of vaporization
Explain the reasons for the unique thermal properties of water. [2]
- polar molecule
- partial negative charges on oxygen, partial positive charges on hydrogen
- strong hydrogen bonds form between molecules
- require high amount of energy to break
Outline what type of sugar lactose is and its function. [2]
- disaccharide
- made from monosaccharides glucose and galactose
- provide energy for young mammals
Explain the production of lactose-free milk. [3]
- run milk with lactose through immobilized beads of lactase
- lactase breaks down lactose into glucose and galactose
- lactose-free milk is sweeter
- suitable for people who are lactose-intolerant
List the general functions of non-membrane proteins. [4]
- contraction/movement
- acts as catalysts
- structural support
- transport
- immunity
- hormones
- DNA packing
Define anabolism and catabolism. [2]
Anabolism
- synthesis of complex molecules from simpler molecules (condensation reaction produces water)
Catabolism
- breakdown of complex molecules into simpler molecules (hydrolysis reaction splits water)
Outline the types of lipids. [3]
Triglycerides
- three fatty acids and one glycerol linked by ester bonds (condensation)
Phospholipids
- two fatty acids linked to glycerol linked by ester bonds (condensation)
Steroids
- four fused rings e.g. progesterone, estrogen, testosterone
BMI Equation
BMI = Mass in kg / (height in meters)^2
Outline six examples of proteins and their functions. [6]
- Rubisco - an enzyme that catalyzes photosynthesis reaction that fixes CO2 from the atmosphere
- Insulin - hormone that lowers blood glucose conc
- Immunoglobulins - antibodies that bind to antigens on pathogens
- Rhodopsin - pigment that makes rod cells
- Collagen - structural protein to prevent skin tearing/give tensile strength
- Spider silk - structural protein used to make webs for catching prey
Outline how three properties of water enhance its use by living organisms. [6]
- cohesive properties help in transpiration pull
- high surface tensions allow organisms to stride across the surface
- high latent heat of vaporization, good coolant
- high specific heat capacity, maintain environmental temperatures
- low density, ice forms insulation of lakes allowing life below
- transparency for vision in animals
- solvent properties, medium for metabolic reactions
- solvent properties allow the transport of soluble molecules
Respiration and other processes in cells involve enzymes. Explain the factors that can affect enzymes. [8]
- collisions between enzyme active site and substrate
- temperature rise, enzyme activity increases
- more frequent collisions
- fastest rate at optimum temperature
- high temperatures above optimum denatures enzyme
- optimum pH
- increase/decrease from optimum pH decreases activity
- extreme pH alters 3D protein structure
- increasing substrate concentration increases rate
- increases chance of collision
- until plateau
- when all active sites occupied
Explain the solvent properties of water using an example. [3]
- water is a polar molecule
- substances that dissolve in water are hydrophilic
- water forms hydrogen bonds with polar substances
- H side of water attracted to negative ions/vice versa
- e.g. glucose dissolves because it is polar
Describe the structure of proteins, including features common to all proteins and features that vary. [7]
- one of more polypeptides
- polypeptide is a chain of amino acids
- amino acids linked by peptide bonds
- twenty different amino acids
- primary structure is the sequence and order of amino acids
- any sequence can be linked together → many possible polypeptides
- secondary structure is the formation of alpha helices and beta pleated sheets
- stabilized by hydrogen bonding
- tertiary structure is the further folding of the polypeptide
- stabilized by interactions between R groups
- two main classes: fibrous or globular
- 3D structure determined by amino acid sequence
- quarternary structure if two or more polypeptides are linked to form a protein
Explain the role of proteins in the movement of substances across membranes. [5]
- protein pumps for active transport
- movement of particles against conc. gradient
- requires ATP
- protein channels for facilitated diffusion
- particles diffuse along conc. graident
- allows hydrophilic/polar particles to diffuse across
- aquaporins for movement of water by osmosis
- more aquaporins, more membrane permeability to water
- proteins are integral/embeddeded in phospholipid bilayer
