Biological Molecules Flashcards
What roles do ions have in biological systems?
Cell shape, involved in enzymic catalyst, chromosome shape, muscle contactions
What is the function of Ca2+
Nerve impulse, muscle contractions
What is the function of K+
Nerve impulse, stomal opening
What is the function of NH₄+
Production of nitrate by bacteria, nitrogen source, nitrogen waste component
What is the function of Na+
Nerve impulse, kidney function
What is the function of H+
Cataylsis of reactions, pH determination
What is the function of NO3-
Nitrogen supply to plants for amino acids, protein formation
What is the function of Cl-
Balance of other ions in cells
What is the function of OH-
Catalysis of reactions, pH determination
What is the function of HCO3-
Maintenance of blood pH
What is the function of PO4 3-
Cell membrane formation, nucleic acid formation, ATP formation, bone formation
What shape does water have and why?
Bent, non-linear shape because The oxygen molecules is slightly negative and the hydrogen molecules are slightly positive therefore the positive charges between the hydrogen molecules repel
What is the symbol for slightly?
δ Delta
What is meant by the term polar?
A polar molecule is a molecule that has both positive and negative charges
What is cohesion?
When the same molecules are attracted to each other due to its polarity
What effect does cohesion have on the melting and boiling point of molecules?
It increases as more energy is required to break the bonds between the molecules
What is a condensation reaction?
A reaction when monomers form to become larger units and a water molecule is formed from the forming of the hydroxyl group and the hydrogen ion
What is a hydrolysis reaction?
A reaction when water molecules are used to break up larger molecules into smaller ones
What is the general formula of a carbohydrate?
(CH2O)n (n = between 3-8)
What is the name of a carbohydrate with 3 carbons in the backbone?
Trisose
What is the name of a carbohydrate with 5 carbons in the backbone?
Pentose
What is the name of a carbohydrate with 6 carbons in the backbone?
Hexose
What is an Aldehyde group
H-C=O
What is the formula of glucose?
(CH2O)6
What is the difference between alpha and beta glucose?
The placement of the hydroxyl group, isomerism
What are some properties of glucose?
Small, soluble, strong due to bonds, easily bonds to each other for storage
What are some of the differences between amylose and amylopectin?
Amylose is unbranched and coiled whereas amylopectin is branched.
What are some similarities between amylose and amylopectin?
Both have alpha glucose as a monomer
What is the difference between amylopectin and glycogen?
Amylopectin is a part of starch and is glucose storage in plants but glycogen is glucose storage in animal and fungal cells
What is a reducing sugar?
A monosaccharide or disaccharide have a Ketone or Aldehyde group with ‘free’ electrons
What is a non-reducing sugar?
A sugar that cannot donate electrons
What is the test for reducing sugars?
Benedict’s reagent with sample in warm water
What is a positive result for Benedict’s test?
Solution goes brick red
Why does the colour change in a Benedict’s test?
Because electrons are donated to the Cu2+ in solution, which forms red Copper Oxide
What is a negative result for Benedict’s test?
Solution remains blue
What is the test for non-reducing sugars?
Add hydrochloric acid, heat in water bath, allow to cool, neutralise with sodium hydrogen bicarbonate, then repeat Benedict’s test
What is the test for starch?
Iodine
What is a glycosidic bond?
A type of covalent bond that bonds a carbohydrate to another group (which may or may not be another carbohydrate)
What is the enzyme that digests starch?
Salivary and pancreatic amylase
What is the enzyme that digests glycogen?
Beta cells in pancreatic islets secrete glucagon which activates enzymes that digest glycogen
What is the enzyme that digests cellulose?
Cellulase
Give an example of a reducing sugar
Glucose, fructose
Give an example of a non-reducing sugar
Sucrose
Name the three main lipid types
Triglycerides, phospholipids and cholesterole
What are the subunits of triglycerides?
3 Fatty acids and glycerol
How are triglycerides formed?
Condensation reactions, 3 water molecules released in esterification
What is the triglyceride structure?
Hydrophilic base with 3 hydrophobic tails
What are unsaturated fats?
Liquid fats with double bonds between carbon atoms
What are saturated fats?
Solid fats with no double bonds between the carbon atoms
What is the variable in amino acids?
The R group
What are the subunits of phospholipids?
Phosphate group and 2 fatty acids
Phospholipids are surfactants. What does this mean?
Surfactants are molecules that lower surface tension
What do phospholipids make up?
Cell membranes- phospholipid bilayer
What are the differences between phospholipids and triglycerides?
Triglycerides have 3 fatty acids tails, phospholipids have 2 fatty acid tails
Triglycerides do not have a phosphate group base
What is the structure of cholesterol?
4 steroid rings with a hydrocarbon tail, thin
Why is cholesterol both hydrophobic and hydrophillic?
Because the hydroxyl group is attracted to water but the steroid rings and hydrocarbon tail repel from water
What is cholesterol insoluble in?
Human blood
How does the structure of cholesterol help the structure of animal cell membranes?
The small, thin structure allows cholesterol to fit inbetween the phospholipid bilayer and maintain the temperature of fluids inside the cell by changing the fluidity of the cell membrane
State and describe the tests for lipids
Emulsion test: add ethanol and water to sample, shake solution and observe
What is a positive result for a lipids test?
The solution will go cloudy
What is used in a quantitative sugars test?
A colourimeter
What are proteins?
A molecule containing 2 or more polypeptides joined together
What are polypeptides?
A polypeptide is 2 or more amino acids joined together by peptide bonds
What are the components of an amino acid?
An amine group, hydrogen, a central carbon, an R group variable, a carboxyl group, covalent bonds
What are the four structures of proteins?
Primary, secondary, tertiary and quaternary
What is the primary structure of proteins?
Simple chain of amino acids, only has peptide bonds, no R-group interactions
What is the secondary structure of proteins?
Alpha helix or beta-pleated sheet, only has hydrogen and peptide bonds, no R-group interactions, 3D
What is the tertiary structure of proteins?
Long chain, ionic, disulfide, hydrogen and peptide bonds, hydrophilic and hydrophobic interactions, R-group interactions, may have prosthetic groups, 3D
What is the quaternary structure of proteins?
Multiple protein subunits (jumbled mess), maybe alpha and beta chains, ionic, disulfide, hydrogen and peptide bonds, hydrophilic and hydrophobic interactions, 3D
What are the different types of proteins?
Globular, conjugated and fibrous
Name the features of globular proteins
Tertiary shape, compact, water-soluble, spherical
What are some functions of globular proteins?
Immunity, muscle contraction, chemical reactions
Name an example of a globular protein
Insulin
How do the properties of globular proteins affect insulin’s function?
Transported via blood so needs to be soluble, needs to fit onto cell receptors so needs to be a specific shape
Name the features of conjugated proteins
Globular with a non-amino acid component
What are prosthetic groups?
Non-amino acid component (R-group)
What are proteins called if they don’t have prosthetic groups?
Simple proteins
What are some possible prosthetic groups of conjugated proteins?
Lipids (lipoproteins), carbohydrates (glycoproteins), metal ions, molecules
Name two examples of conjugated proteins
Haemoglobin, catalase
How are the properties of haemoglobin affected by its prosthetic group?
Iron II, quaternary protein with 2 alpha and 2 beta subunits, iron II bonds reversibly with oxygen so good for transport
How are the properties of catalase affected by its prosthetic group?
An enzyme, quaternary, prosthetic group of iron II, breaks down hydrogen peroxide which is useful because it is damaging to cells (a common byproduct of metabolic processes)
Name the features of fibrous proteins
Primary structure, long, strong, repetitive, limited and usually small R-groups, insoluble, organised, simple, NOT COMPLEX OR 3D!!!
Name three examples of fibrous proteins
Keratin, elastin and collagen
Name some features of keratin
Group of fibrous proteins present in hair, skin and nails, contains lots of cysteine which results in lots of disulfide bonds which makes keratin strong, inflexible and insoluble
What does the flexibility of fibrous proteins depend on?
The angle of the disulfide bonds
Name some features of elastin
Makes up elastic fibres in walls of blood vessels and alveoli in the lungs, give structure and flexibility so can expand if needed, quaternary protein made of TROPOELASTIN
What is tropoelastin?
Subunit of elastin that is able to stretch and recoil without breaking, has alternate hydrophobic and lysine-rich areas
Name some features of collagen
Connection tissue found in skin, tendons, ligaments and the nervous system, made of three polypeptides wound together into a triple helix (strong rope-like structure)
