1-3 Protein structure and function Flashcards
What determines the folding of a polypeptide to form a protein?
The sequence of amino acids.
What are the four levels of protein structure?
- Primary
- Secondary
- Tertiary
- Quaternary
What is the primary structure of a protein?
The unique sequence of amino acids.
What characterizes the secondary structure of a protein?
Coiling or folding of sections of the polypeptide (alpha helix or beta sheet) due to hydrogen bonds.
What is the tertiary structure of a protein?
The 3D shape of a single polypeptide chain due to disulphide and hydrogen bonds.
What is the quaternary structure of a protein?
The 3D shape of two or more polypeptides.
How many different amino acids are there?
20 different amino acids.
What type of bond links amino acids together?
Covalent peptide bonds.
What are proteins also known as?
Polypeptides.
What is the polypeptide backbone?
The repeating sequence along the core of the polypeptide chain.
What are the building blocks of proteins?
Amino acids.
What elements do proteins contain?
- Carbon
- Nitrogen
- Oxygen
- Hydrogen
- Some contain sulphur
Which two amino acids contain sulphur?
- Methionine
- Cysteine
Why is precise folding essential for proteins?
Nearly all proteins carry out their function by recognizing and binding to a specific molecule.
Fill in the blank: Proteins are long unbranched chains of _______.
Amino acids.
Fill in the blank: From smallest to largest, the order is Amino acid, Peptide, _______ , Protein.
Polypeptide
Why are proteins essential to cell structure and function?
Proteins are essential because they play key roles in cell structure and function.
What are examples of proteins with specific shapes?
- Enzymes
- Some hormones
- Receptor proteins
- Antibodies
Why is the three-dimensional shape of a protein critical to its function?
The three-dimensional shape determines how a protein recognizes, binds, and responds to other molecules.
What is the role of enzymes in biochemical reactions?
Enzymes are specific for their substrate and increase reaction rates by lowering activation energy.
What does the induced-fit model of enzyme-substrate binding describe?
The induced-fit model describes how the active site of the enzyme changes shape to fit the substrate.
What is molecular recognition?
Molecular recognition is the specific interaction between two or more molecules exhibiting molecular complementarity.
What forces are involved in molecular recognition?
- Hydrogen bonding
- Other weak intermolecular interactions
What is a hormone?
A hormone is a chemical released by cells that affects other cells in the organism.
How do hormones work?
- Secreted into the bloodstream
- Act on target cells with complementary receptors
- Trigger a cellular response
What are transport proteins?
Transport proteins are located in the cell membrane and allow specific molecules to pass through.
What is the importance of protein structure and shape?
Protein structure and shape are essential for their function, including binding and interaction with other molecules.
What are some conditions associated with abnormal 3D protein structures?
- Cystic fibrosis
- Sickle cell anemia
Define enzymes.
Enzymes are biological catalysts that speed up reactions without being used up.
What is the active site of an enzyme?
The active site is the part of the enzyme where the substrate binds and undergoes a reaction.
What is activation energy?
Activation energy is the amount of energy required for a chemical reaction to take place.
How do enzymes affect activation energy?
Enzymes lower the amount of energy required for a reaction.
What are the two models for enzyme action?
- Lock-and-Key Model
- Induced-Fit Model
What does the Lock-and-Key Model suggest?
It suggests that the enzyme and substrate have identical matching shapes.
What does the Induced-Fit Model propose?
It proposes that the enzyme changes shape slightly to allow binding with the substrate.
What happens during the induced-fit mechanism?
The substrate is drawn into the active site, causing a conformational change in the enzyme.
What is released after the substrate reaction in enzymes?
The resulting end product/s is released, and the enzyme returns to its normal shape.
True or False: Enzymes are used up in the reactions they catalyze.
False
Fill in the blank: Enzymes are biological catalysts that speed up reactions by lowering _______.
activation energy
