B1.2 Proteins Flashcards
OH in condensation reaction comes from…
COOH Group
H comes from… in condensation reaction.
NH2 Group
Essential amino acids are..
Amino acids that cannot be synthesized by the body and must be obtained from diet.
How many essential amino acids are there?
9
Phenylaline is…
Essential
What determines the sequence of amino acids in a polypeptide?
The sequence of bases in the DNA of the gene it’s is coded for by.
How many polypeptides have been identified?
Over 2 million
What does heat do to proteins?
Causes vibrations that break intermolecular H bonds and cause their conformation to change
Half of R-Groups are
Hydrophobic, some with rings of atoms and one containing sulfur (methionine).
1st Third of Hydrophilic R-groups are
- polar, but don’t ionize
- Can form H bonds with other r-groups
2nd third of hydrophilic R-groups…
are basic as they have an amine group that can accept a proton
Final third of hydrophilic R-Groups…
are acidic because they can donate a proton and can form ionic bonds with positive R-Groups.
Pairs of R-groups that are mildly hydrophilic and contain a -SH group form:
a covalent S-S bond called a disulfide bond
Glycine has a
single hydrogen atom
Largest R-Group?
Tryptophan
Primary Structure
The number and sequence of amino acs in a polypeptide
Carbon and changes in structure?
Due to bond rotation, alternative structures for the same compound can be formed.
Each N in the repairing sequence of the polypeptide back bone has…
an H bonded to it
Hydrogen bonds on secondary structures are formed between…
N-H groups and C=O groups
Four types of interaction between amino acids in a tertiary structure:
- Hydrogen bonds between polar R-groups
- Ionic bonds between NH+ and COO- groups
- S-S covalent bonds
- Hydrophobic interactions between non-polar R-groups
Proteins with ……… amino acids on their outer surface have …… amino acids at there core.
What does that do?
- 1) Hydrophilic, Hydrophobic
- Stabilizes protein’s tertiary structure in aqueous solutions.
Some proteins have hydrophobic amino acids on their outer surface and are therefore attracted to the non-polar core of membranes, what does that make them?
Integral Membrane proteins
What determines the tertiary structure of proteins and where they are located in cells?
The distribution of polar and non-polar amino acids.
Water soluble protein are more likely to be located where in a cell?
Dissolved in cytoplasm or in aqueous solutions
Proteins that contain a non-polypeptide structure known as a “prosthetic” group are called…
Conjugated Proteins
Why is Hemoglobin a conjugated protein?
It contains haem groups which are not polypeptides.
Quaternary structures?
Structures that contain two or more polypeptides linked to form a protein.
What form feature of fibrous proteins gives them structural roles within and between cells?
- Unfolded Polypeptides, which give them a narrow and elongated shape.
Why do globular proteins have a rounded shape?
They have folded polypeptides
Collagen is a ….. protein.
Fibrous
What feature of collagen allows it to be wound together into a triple helix?
It has three polypeptides that are more elongated than then alpha helix.
Form: Collagen has three polypeptides with an amino acid sequence that prevents the formation of an alpha helix.
What is the function?
This gives it a rope-like formation, it can withstand tensions by stretching rather than breaking, it’s released into extracellular matrix of tissues where tensile strength is needed. (Skin, bones, tendons, and ligaments.)
Insulin is a ……. Protein
Globular
Form: Insulin has a small size and a hydrophilic surface.
What is the function?
Allows insulin to be carried dissolved in blood plasma.
Form: Insulin has a distinctive shape
Function?
Allows it to bind to a site on a specific receptor protein located in the plasma membrane of target cells.
Insulin’s A-Chain has …… amino acids.
21
Insulin’s chain has ……. amino acids.
30
