Proteins and Protein Synthesis Quiz Study Guide Flashcards
How are dipeptides formed?
All macromolecules are built by cells via condensation reactions, amino acids to dipeptide.
Reaction occurs between N-terminus of one amino acid and the C-terminus of another amino acid.
The bond between each amino acid is called a peptide bond.
How do you draw and label the structure of an amino acid?
How to draw a condensation reaction between two amino acids?
Distinguish between polar and nonpolar amino acids and where they are found within a membrane.
Position of polar/ nonpolar amino acids determines a protein’s shape
Polar amino acids
Hydrophilic : have stable interactions in water, R group is charged, help to keep protein in position in the membrane, form hydrophilic linings of protein channels in cell membrane (to allow polar/ hydrophilic/ charge molecules in)
Integral proteins have polar amino acids on the side of the membrane
Nonpolar amino acids
Hydrophobic: have stable interactions in lipid bilayer, R group is not charged, Form portion of protein channels in cell membranes that are in contact with nonpolar, fatty acid tails of the phospholipid bilayer
What is a proteome?
The totality of all proteins that are expressed within a cell, tissue or organism at a certain time is called the proteome
The proteome of any given individual will be unique as protein expression patterns are influenced by a genome
Examples of proteins and their specific function.
-Spider silk : Structure : Fiber spun by spiders and used to make webs
-Collagen : Structure : Supports structure of connective in skin/ ligaments/ tendons
-Insulin : Hormones : Produced by pancreas, causes cells to take up glucose in the blood (lowers blood sugar)
-Immunoglobulins/ antibodies : Immunity : Fight bacteria and viruses
-Haemoglobin : Transport : Found in red blood cells- carries oxygen in blood -Rhodopsin : Sensation : Pigment in photoreceptor cells of the retina that detect light
-Actin and Myosin : Movement : Filament responsible for muscle contraction
-Rubisco : Enzyme : Enzyme involved in light independent stage of photosynthesis
Example of the quaternary structure.
Haemoglobin
- Transports oxygen in your blood
- Has 4 polypeptide chains linked together
- Each polypeptide chain contains a linkage to a non-polypeptide group called haem
What is the fourth level of protein structure? What bonds are involved and why each is important to the overall structure and function of the protein?
Quaternary Structure:
- Involves linking several polypeptide chains to form one protein
- Not always present → many only consist of one polypeptide chain
- All types of bond from previous structure are present here
What is the third level of protein structure? What bonds are involved and why each is important to the overall structure and function of the protein?
Tertiary structure:
- Creates the 3D shape of the protein (a polypeptide chain bends and folds over itself)
- Caused by interactions between R groups of amino acids
- Disulfide bridges (between sulfur atoms)
- Hydrogen bonds (between polar R groups)
- Ionic bonds (between positively and negatively charged R groups)
- Important in enzyme function and in the formation of globular proteins
What is the second level of protein structure? What bonds are involved and why each is important to the overall structure and function of the protein?
Secondary Structure:
- Built by the amino acid sequence folding on itself
- Caused by hydrogen bonds → between carboxyl group (C=O) on one amino acid and the amine group (N-H) in another
- 2 types
- βeta (β)-pleated sheets (repeated folds)
- αlpha (α)-helix (repeated coils)
- Secondary organization stabilizes the structure of the polypeptide
What is the first level of protein structure? What bonds are involved and why each is important to the overall structure and function of the protein?
Primary Structure:
- The sequence of amino acids bonded together via peptide bonds
- The order that amino acids are put together is determined by the 3 nucleotide sequence on the mRNA called a codon
- The primary structure in a protein determines all other levels of protein structure and therefore a protein’s shape!
- Changing one amino acid can completely change the shape and function of the protein
What happens when a protein is denatured?
- Denaturation is a structural change in protein that can lead to permanent loss of biological properties
- The way a protein folds determines its function so a change in the tertiary structure will impact its functional abilities
- Changes in the chemical environment can change in shape and function
What can cause denaturation?
Temperature and pH can do this
Extra H+/ OH- ions in a solution bind with charged portions of proteins, preventing normal hydrogen/ ionic binding etc., causing protein to denature.
What results from denaturation?
What is an epigenome?
Gene expression in a cell is affected by an organism’s epigenome.
Its a collection of all the factors that modify/ impact the activity/ expression of genes without altering DNA sequences.
