Proteins & DNA Flashcards
What are proteins in terms of their monomer?
A sequence of amino acids linked by peptide bonds
Describe the primary structure of proteins.
A sequence of amino acids
Describe the secondary structure of proteins
This is where the polypeptide chain interacts with itself, causing folding. Both caused by hydrogen bonding
- Alpha helix
- Beta pleated sheet
Describe the tertiary structure of proteins
Final shape of a single polypeptide chain (further folding). Bonds form due to interactions between R groups
What bonds can form in the tertiary structure of proteins
- Hydrogen bonds
- Ionic bonds
- Disulfide bridges
- Hydrophobic and Hydrophilic interactions
What are the main features of disulfide bridges?
- S – S bonds
- Occur in tertiary and quarternary structures
- Oxidation of cystine residues
- Harder to break than hydrogen bonds
- Weaker than covalent bonds
Describe the quarternary structure of proteins
Involves more than one polypeptide chain. E.g. haemoglobin
Describe the hydrolysis of proteins
Addition of water to break apart the molecule into its monomers, amino acids.
What method is used to separate and identify amino acids?
Thin layer chromatography
What developing agents can be used when carrying out thin layer chromatography?
- Ninhyrdin
- Ultraviolet light
How do you calculate Rf values in order to determine different amino acids?
Distance traveled by spot / Distance traveled by solvent
Describe the link formed between two amino acids in a dipeptide?
amino acid-C–CO—NH–C-amino acid
- Where CO is C=O
What is an enzyme?
A protein that acts as a biological catalyst
What are breaker enzymes?
Enzymes that break down molecules to smaller pieces (eg polymers to monomers)
What are builder enzymes?
Enzymes that join molecules together to form bigger molecules
Describe the enzyme model of action.
The substrate binds to the active site of the enzyme as they are complementary to each other. The enzyme that breaks the substrate down into smaller pieces.
What is a competitive inhibitor?
Binds to the active site, preventing the substrate from binding to it
What is a non-competitive inhibitor?
Binds to the enzyme itself, changing the shape by distorting bonds, so the active site is no longer complementary to the substrate
Describe the structure of a DNA nucleotide
Deoxyribose sugar attached to a phosphate group and a nitrogenous base
What are the 4 nitrogenous bases and which are complementary to each other?
- Adenine and thymine
- Guanine and cytosine
What is the technical name for the backbone of DNA, as a result of many nucleotides joining together?
Sugar-phosphate backbone
What bonds form between base pairs?
Hydrogen bonds
How many bonds form between each base pair?
- AT forms 2
- GC forms 3
Describe the structure of DNA
Double helix
