Topic 2 - Biological molecules Flashcards
What type of bonding is present between the oxygen and hydrogens in a water molecule
Covalent bonding
Why is a water molecules considered polar
the oxygen nucleus pulls the shared electrons away from the hydrogen nuclei. Giving the oxygen nuclei a δ- charge, and the hydrogen nuclei a δ+ charge.
The polarity of water causes attraction between water molecules. What is the force of attraction between water molecules
Hydrogen bonds from the H to the lone pair of O
Why is liquid medium a useful property of water
Provides habitats for aquatic organisms, medium for chemical reactions & used for transport
Why is important metabolite a useful property of water
Used in hydrolysis & condensation reactions
Why is high specific heat capacity a useful property of water
Keeps aquatic & cellular environments stable
Why is high latent heat of vaporisation a useful property of water
Evaporation has a cooling effect on organisms
Why is cohesion of molecules a useful property of water
Water is drawn up the xylem
Why is surface tension a useful property of water
Allows pond-skaters to walk on the surface
Why is good solvent and transport medium a useful property of water
Dissolves ionic and polar molecules, allowing them to easily be transported
Why is good reaction medium a useful property of water
The cytoplasm in cells is an aqueous solution where many chemical reactions happen
Why is incompressible a useful property of water
Can prevent plants from wilting & act as a hydrostatic skeleton for invertebrates
What are monomers
Monomers are individual molecules that make up a polymer.
What are polymers
Polymers are long chains that are composed of many individual monomers that have been bonded together in a repeating pattern.
What is a condensation reaction
When two molecules combine to form a more complex molecule with the removal of water
What is a hydrolysis reaction
When larger molecules are broken down into smaller molecules with the addition of water
What are the simplest carbohydrates (and name the 3)
Monosaccharides are the simplest carbohydrates, consisting of only one sugar molecule
Glucose, Fructose & Galactose
What are pentose sugars
Pentose sugars = ribose sugars
Found in many important biological molecules such as ribonucleic acid (RNA), ATP, NAD
What type of sugar is glucose
Hexose
How many isomers does Glucose have
2
Draw alpha glucose
O-C-C-C-C-CH2OH
OH: down, down, up, down
Draw beta glucose
O-C-C-C-C-CH2OH
OH: up, down, up, down
What are disaccharides and what kind of bond is there
Disaccharides are sugars that are composed of two monosaccharides joined together in a condensation reaction, forming a glycosidic bond.
What monosaccharides are maltose made up of
2 x alpha glucose
What monosaccharides are sucrose made up of
alpha glucose and fructose
What monosaccharides are lactose made up of
beta glucose and galactose
What is the main polysaccharide energy store in plants and what is it composed of
amylopectin (starch) is the main polysaccharide energy store in plants, is composed of α-glucose.
What is the difference between amylose and amylopectin
Amylose is a straight chain polymer of glucose units vs amylopectin is a branched chain polymer of glucose units
What is the polysaccharide energy store in animals called and what is it composed of
glycogen is the main polysaccharide energy store in animals, is composed of α-glucose.
What is the structural component of plant cell walls and what is it composed of
Cellulose is a structural component of plant cell walls, composed of long unbranched chains of b-glucose.
What is a saturated fatty acid
there are no C=C bonds and the molecule has as many hydrogen atoms as possible.
What is an unsaturated fatty acid
there is at least one C=C bond, therefore the molecule contains fewer hydrogen atoms than is maximally possible.
How is a triglyceride molecule formed
A triglyceride molecule is formed by joining one molecule of glycerol to three fatty acids through three condensation reactions, forming ester bonds.
What key roles do triglycerides have
Triglycerides have key roles in respiration and energy storage
Why so triglycerides have key roles in respiration and energy store
due to its insolubility and high carbon to hydrogen ratio
How is a phospholipid formed
Phospholipids replace one of the fatty acid chains in triglycerides with a phosphate molecule.
What property enables phospholipids to form phospholipid bilayers
Hydrophobic tails and hydrophilic heads
What is the monomer unit in proteins
Amino acids
What do the 20 naturally occurring amino acids differ by
R groups
Draw an amino acid (structural formula)
NH2 (amino group) to a C (bonded to an H and R group) and then bonded to a carboxyl group
How are dipeptides formed
Dipeptides are formed when two amino acids are joined together by a condensation reaction, forming a peptide bond.
What is a polypeptide
A polypeptide is a polymer made of many amino acids joined together by peptide bonds.
How many polypeptide chains are in proteins
A protein may contain one or more polypeptide chains
Definition of a primary protein and bond type
The specific sequence of amino acids in a polypeptide chain
Peptide bonds
Definition of a secondary protein and bond type
The curling or folding of the polypeptide chain into α-helices and β-pleated sheets due to the formation of hydrogen bonds
Hydrogen bonds
Definition of a tertiary protein and bond type
The overall specific 3-D shape of a protein, which is determined by interactions between R groups and the properties of R groups
Hydrogen bonds, ionic bonds and disulphide bridges
Definition of a quaternary protein and bond type
The specific 3-D shape of a protein that is determined by the multiple polypeptide chains and/or prosthetic groups bonded together
Hydrogen bonds, ionic bonds and disulphide bridges
What are inorganic ions
Inorganic ions are atoms or molecules with an electric charge, containing no carbon.
What are cations
Positively charged ions
What are anions
Negatively charged ions
Where do inorganic ions occur in solution
Inorganic ions occur in solution in the cytoplasm and body fluids of organisms, some in high concentrations and others in very low concentrations
Role of hydrogen ions
Hydrogen ions determine the pH of bodily fluids. The higher the concentration, the lower the pH
Role of sodium ions
Sodium ions are used in the co-transport of glucose and amino acids across cell membranes and transmission of nervous impulses
Role of phosphate ions
Phosphate ions are essential components of DNA, RNA, nucleotides & ATP
Role of calcium ions
Calcium ions regulate protein channels, impulse transmission and harden body parts like teeth.
Role of potassium ions
Potassium ions play a role in muscle contraction, nervous transmission. active transport and maintaining turgidity in plant cells.
Role of ammonium ions and nitrate ions
Ammonium ions and Nitrate ions are part of the nitrogen cycle and a source of nitrogen for biological molecules
Role of hydrogen carbonate ions
Hydrogencarbonate ions are formed when carbon dioxide dissolves in blood. They are important in the transport of carbon dioxide in the blood and the regulation of blood pH
How do you test for reducing sugars and state the results
Benedict’s reagent -> heat
Blue to Red/orange ppt
Reagent test strip
Compare with calibration card
How do you test for non reducing sugars and state the results
Hydrochloric acid -> heat
Sodium hydrogen carbonate
Benedict’s reagent -> heat
Red/orange ppt
How do you test for starch and state the results
Iodine in potassium iodide solution
Yellow to blue/black
How do you test for proteins and state the results
sodium hydroxide
Copper (II) sulphate
Blue to purple
How do you test for lipids and state the results
Ethanol
Water -> shake
Cloudy white
What is a globular protein
a protein with a spherical shape that is soluble in water; they typically have metabolic roles
What are the important properties of globular proteins
They are roughly spherical in shape, with hydrophobic R groups on the inside and hydrophilic R groups on the outside. They are therefore soluble in water
They have very specific shapes; this allows them to carry out very specific functions
Give three examples of globular proteins and state their bonds types and roles
Haemoglobin is a conjugated globular protein, made of 4 polypeptide chains and 4 haem prosthetic groups which contain Fe2+.
Insulin is composed of two polypeptide chains, joined together by disulphide links. The specificity of the shape allows binding to cell membrane receptors.
Pepsin has hydrogen bonds, disulphide link and few basic R groups to keep it functional in low pH stomach acid.
State three properties of fibrous proteins
They contain long polypeptide chains with repeating sequences of amino acids
The amino acids have non-polar R groups, so the proteins are insoluble in water
The polypeptide chains are able to form fibres which make the proteins stronger
Give three examples of fibrous proteins as well as their bond type and their use
Collagen is used to make bones, tendons and are found in artery walls to help resist the high pressure
Keratin contains high amounts of cysteine, resulting in disulphide links forming between the two polypeptide chains, which makes the molecule very hard and strong. It is found in fingernails, hooves and horns.
Elastin has the ability to stretch and recoil. Elastin is stretchy due to coiling of the elastin molecules and cross-links that keep the molecules together. It is found in the lungs, bladder and blood vessel walls.
