Proteins Flashcards
What are the monomer units of proteins?
Amino acids
Proteins are what?
Macromolecules
What are proteins composed of?
Hydrogen carbon oxygen nitrogen and 2 amino acids also contain sulfur
How many known amino acids are there?
20
What kin of bond holds two amino acids together?
Peptide bond
How long are proteins usually?
100-300 amino acids long
What determines the function of proteins?
Their 3-D structure
What are several functions of proteins within the human body?
- Materials for building and maintaining cell membranes
- Form hormones
- Form enzymes
- Last source of energy for cellular respiration
- Form antibodies
- Acts as a gene regulators
Are all proteins soluble in water?
Yes
What is an optical isomer?
When substances have the same molecular and structural formula but are mirrored.
What are optical isomers referred to as and what are the different forms called?
Chiral and the different forms are called enantiomers
What was the first protein to be sequenced?
Insulin which has 2 peptide chains held together by 3 disulfide prodges of cysteine and had a total of 51 amino acids
What was the second protein to be sequenced?
Lysozyme which has on chain of 129 amino acids with 4 disulfide bridges. It’s found in tears and breaks down the polysaccharide walls of bacteria and prevents infection.
Explain primary structure.
Order of amino acids and location of disulfide bridges.
Explain secondary structure.
Hydrogen bonding can give more complex shapes. Such as an alpha helix, a beta pleated sheet or a random coil.
Explain what an alpha helix is.
Complete right handed turn every 3.6 amino acids around an alpha carbon. R-groups point out. Flexible and springy.
Explain beta pleated sheets
Polypeptide chains that run parallel to each other but run in opposite directions. There are hydrogen bonds that make it rigid and non stretchy.
Explain tertiary structure.
If a polypeptide is folded to make a compact molecule or a globular shape. Depends if molecule is hydrophobic or hydrophilic.
Explain myoglobin.
Has 153 amino acids with 8 alpha helix regions. At each segment there is a bend creating a globular structure.
What is a congucated protein?
A protein that contains a non protein heme group also known as a prosthetic group.
Explain quaternary structure
When there is more than one polypeptide chain that does not have covalent bonding or disulfide bridges.
What is a protein that has all 4 levels of structure called?
Oligomeric proteins.
What is each polypeptide chain in a protein called?
A protomer
Proteins with the same polypeptide chains are called what? Proteins with different polypeptide chains are called what?
Homo-oligomers and hetero-oligomers
