Biological Molecules

Flashcards about biological molecules

What is a monomer?

Simple, basic, molecular unit from which larger molecules/polymers are made from. E.g monosaccharides, amino acids, nucleotides.

What is a polymer?

Large, complex molecule made up of repeating monomers joined together. E.g starch, glycogen, cellulose, polypeptide (protein), DNA, RNA.

What happens in a condensation reaction?

Joins two monomers together, forms a chemical bond, eliminating a water molecule.

What happens in a hydrolysis reaction?

Separates two monomers, breaks a chemical bond, requires the addition of a water molecule.

What are the functions of carbohydrates?

Energy, storage, strength

What are monosaccharides?

Simplest sugars, monomers from which larger carbohydrates are made.

What monosaccharides make up maltose?

Glucose + glucose

What monosaccharides make up sucrose?

Glucose + fructose

What monosaccharides make up lactose?

Glucose + galactose

What is the function of starch?

Found in many parts of a plant in the form of small grains and is an important component of food.

What is the function of glycogen?

Main storage of energy in animals, stored in muscle and liver cells.

What is the function of cellulose?

Provides structural strength in the cell walls of plants.

What are reducing sugars?

Can donate electrons, Glucose, fructose, galactose, maltose, lactose

What are non-reducing sugars?

Cannot donate electrons, Sucrose

What happens during a positive result for the iodine test?

Add iodine in potassium-iodide solution to the sample. Orange → blue/black

What is the structure of triglycerides?

1 molecule of glycerol attached to 3 fatty acids. Non-polar, hydrophobic.

What is the structure of phospholipids?

1 glycerol, 1 phosphatase group 2 fatty acid tails. Amphipathic - both hydrophobic and hydrophilic regions.

What happens during a positive result for the lipids test?

Add ethanol to the sample. Then add water. Shake. White/milky emulsion

What are the components of an amino acid?

NH2= amine group, COOH = carboxyl group, R = variable group

How do amino acids form dipeptides and polypeptides?

Condensation reaction between OH on carboxyl group and H on amine group, releasing a water molecule and forming a peptide bond.

What is the primary structure of proteins?

Sequence of amino acids in a polypeptide chain.

What is the secondary structure of proteins?

Hydrogen bonds form between amino acids close together which causes the polypeptide chain to be coiled into an alpha helix or folded into a beta pleated sheet.

What is the tertiary structure of proteins?

Further conformational change of the secondary structure, coiled or folded further, leads to additional bonds forming between the R groups (side chains).

What is the quaternary structure of proteins?

The way polypeptide chains are assembled. Stabilised with hydrogen bonds, ionic bonds and disulfide bridges.

What is the relationship between protein structure and function?

The sequence of amino acids is determined by the genetic code. This effects the primary structure. The primary structure determines how the polypeptide is coiled or folded in the secondary structure. It also determines where bonds form. This affects the whole shape of the protein. Shape of a protein determines its function. So altering the primary structure affects the tertiary structure shape which affects the function.

What are globular proteins?

Soluble, R group folded in molecule

What are fibrous proteins?

Insoluble, R group exposed

What are enzymes?

Biological catalysts

What happens during a positive protein test?

Add biuret reagent, if protein is present color will change from blue to purple.

What is the role of enzymes?

Biological catalysts that speed up the rate of a chemical reaction.

How do enzymes speed up reactions?

Providing an alternate pathway for the reaction with lower energy and binding reactants at active site and positioning them correctly.

What is the lock and key model?

Active site fixed shape, substrate is complementary to active site, binds to it, forms enzyme-substrate complex. Enzyme catalyses reaction to form products (synthesis or split).

What is the induced fit model?

Active site of enzyme is not completely complementary to substrate, substrate binds and distorts hydrogen bonds holding enzyme in shape, active site changes shape to complete fit. Enzyme catalyses reaction and releases products

What causes enzyme specificity?

Only catalyse one reaction as only one substrate is complementary to the active site.

What factors affect enzyme activity?

Temperature, pH, enzyme concentration, substrate concentration, competitive inhibitors, non-competitive inhibitors

How do non-competitive inhibitors function?

They bind away from active site in allosteric site which causes a permanent conformational change in the active site.

What is the function of DNA?

Stores genetic information and is hereditary material responsible for passing genetic material from cell to cell from generation to generation.

What is the function of RNA?

Transfer genetic info from DNA to ribosomes to make proteins (translation)

What is the structure of a nucleotide?

Phosphate group, pentose sugar - deoxyribose or ribose, nitrogenous base -A,T,C,G,U

What is the structure of DNA?

Double helix structure, 2 separate polynucleotide strands wound round each other. Held by hydrogen bonds between bases, pentose sugar in nucleotides - deoxyribose. Nitrogenous bases - adenine, thymine, cytosine, guanine

What is the structure of RNA?

Single polynucleotide strand, shorter chain, pentose sugar in nucleotides - ribose sugar, nitrogenous bases - adenine, uracil, cytosine, guanine

What are the differences in the DNA and RNA comparison feature?

Shape, Length, Pentose sugar, Bases

What is the role of DNA Helicase?

Breaks hydrogen bonds to separate the polynucleotide strands.

What is the role of DNA Polymerase?

Join together adjacent nucleotides

What is the role of DNA Primase?

Catalyze the synthesis of short RNA molecules used as primers for DNA polymerases.

What is the role of DNA Ligase?

Joins DNA fragments together

What is the importance of the semi-conservative replication of DNA?

Ensures genetic continuity between generations of cells.

What is the conservative model of DNA replication?

original DNA molecule remained intact and that a separate daughter DNA copy was built up from new molecules of deoxyribose, phosphate and organic bases.

What is the semi-conservative model of DNA replication?

Original DNA molecule split into two separate strands, each of which then replicated its mirror image (i.e. the missing half).

Why do animals and plants need energy?

Active transport, DNA replication, Cell division, Protein synthesis

What are the properties of ATP?

Small, soluble molecule so It can be easily transported around the cell and it can be broken down easily to release energy instantly.

Why cant a cell get energy directly from glucose

Stores or releases only a small, manageable amount of energy at a time meaning no energy is wasted as heat

What is a hydrolysis reaction?

Requires a molecule of water to break a bond

What is a condensation reaction?

Releases a molecule of water as a new bond is formed

What is a solvent?

A substance capable of dissolving another substance.

What is latent heat?

The heat energy that’s needed to change a substance from one state to another, e.g. from a liquid to a gas.

What is specific heat?

The energy needed to raise the temperature of 1kg of a substance by 1 °C.

What is cohesion?

The attraction between molecules of the same type (e.g. two water molecules).

What are inorganic ions?

Is one which doesn’t contain carbon

What is the function of the inorganic ions: iron, phosphate, hydrogen and sodium

Haemoglobin carries oxygen, phosphate is needed for phosphorylation, hydrogen is needed for pH and sodium is needed for co-transport