proteins Flashcards
describe the general structure of amino acid?
*Include the general formula
an amine group on the left, a carboxylic acid group on the right and a carbon with hydrogen and an R in the middle
NH2-CHR-COOH
what does the R- side chain do?
provides the amino acid with their specific property
what type of bonds do protein have?
a peptide bond C-N
Describe the formation and breakage of a peptide bond
formation
: by condensation, a hydroxyl group from the carboxylic acid is removed including a hydrogen from the amine group to a di-peptide and a water molecule
breakage
: by hydrolysis, water molecule is added to reform the amino acid
what is the simplest amino acid including its formula
glycine
NH2-CH2-COOH
What are the 4 protein structures formed?
1- primary structure
2- secondary structure
3- tertiary structure
4- quaternary structure
describe the primary structure
the sequence of amino acid to form a poly peptide chain
how many types of amino acids are found?
20 types
what 2 types of shapes are found in the secondary structure?
1- alpha-helix
2- beta-sheet
describe the alpha-helix
the alpha helix is made when a hydrogen bond is formed between oxygen from the -CO group of an amino acid and hydrogen from the -NH group of another amino acid. The bond is formed every four amino acid
describe the beta-sheet
when a hydrogen bond is formed between oxygen and hydrogen, instead of a alpha-helix being formed a beta-sheet is formed which is a loser form of alpha-helix
summarize the secondary structure
protein folding of a polypeptide chain to give either alpha-helix or beta-sheet
describe the tertiary structure
protein folding to form 3D shape with 4 bonds formed
what are 4 bonds which can be formed in protein?
1- hydrogen bond
2- ionic bond
3- covalent bond/disulfide bond
4- hydrophobic interactions
describe the hydrogen bond
bond formed between oxygen from -CO and hydrogen from -NH every four amino acid. the bond is not very strong but a lot of it is strong
describe the ionic bond
intermolecular forces between COO- and NH3+
which are not very strong
describe the disulfide bond
the disulfide bond is a covalent bond which forms between 2 sulfur atoms forming strong intramolecular forces
describe the hydrophobic interaction
non-polar groups cluster together away from water
describe the quaternary structure
2 or more polypeptide chains interacting where they are held by the 4 bonds
What are the characteristic of globular proteins/ describe globular proteins
* explain each character
1- they are soluble
* contains the hydrophobic group in the center and hydrophilic group outside
2- physiological roles: working functions like enzymes, antibodies
3- spherical like shaped
what are the characteristics of fibrous proteins
* explain each character
1- they are insoluble
2- long strands
3- have structural roles instead
* to make up parts in humans like hair, nails, muscles
what type of protein is hemoglobin?
globular protein
describe the structure of hemoglobin
a quaternary structure made up by 4 polypeptide chains where 2 are alpha- globin and another 2 are beta-globin. in each poly peptide chain, a haem group is found containing iron
relate main function of hemoglobin to its structure
hemoglobin is found in red blood cells and are used to transport oxygen. in the haem group found in hemoglobin, an iron ion is found which oxygen molecules bind to to be transported.
what are 2 things the haem group is responsible for?
1- the color of hemoglobin
2- binding oxygen molecules to iron allowing transportation
what type of protein is collagen?
fibrous proteins
describe the structure of collagen
a quaternary structure of 3 polypeptide chain of
alpha-helix where they wind together to form helices and have hydrogen bonds between them to maintain their structure. every 3rd amino acid is a glycine
why is every 3rd amino acid a glycine in the collagen polypeptide chain
glycine is small allowing the 3 polypeptide chains to be closer together
what are 3 functions of collagen related to its structure
1- flexible due to the helices shape
2- high tensile strength
3- collagen fibers are able to line up in different ways to withstand different forces
