3.2 Flashcards
(22 cards)
What are R-groups?
Grouping of the 20 amino acids
What are proteins/polypeptides?
Amino acids joined by peptide bonds giving backbone
What is at the end of an amino acid sequence?
Carboxyl end (C-terminus) and amino end (N-terminu)
Describe protein structure
There are four levels
Different types of interactions holding 3D shape
Structure is necessary for function
How are amino acids linked?
By covalent bonds called peptide bonds
What is the primary structure of a protein?
The sequence of amino acids, determined by genetic info
What are the four levels of protein structure?
Primary, secondary, tertiary and quaternary
What makes up the secondary structure of proteins?
Coils and folds in the polypeptide chain
Coils are from hydrogen bonds between the polypeptide backbone
Typical structure include alpha helix and beta pleated sheet.
What makes up the tertiary structure of proteins?
Interactions between various R groups
Include hydrogen and ionic bonds and hydrophobic interactions
Strong covalent bonds called disulfide bridges may reinforce structure.
What makes a quaternary structure protein?
When a protein consists of multiple polypeptide chains
What physical and chemical conditions can affect structure of proteins?
pH, salt concentration, temperature
What was the process of Anfinsens experiment?
Used urea to disrupt hydrogen bonds and dneature ribonuclease A, unfolding into a linear non functional form.
When the denaturing agent was removed the protein resolved spontaneously to its natural function structure
What did Anfinsens experiment show?
The primary structure alone determines the secondary and tertiary structure of proteins
Describe spontaneous processes?
Can happen quickly or slowly
Enzymes increase the speed
Free-energy change is negative
Energy is released = exergonic reaction
Describe non-spontaneous reactions
Will only occur if energy is provided
Free-energy change is positive
Energy is required = endergoinc reaction
What ar the three main kinds of work in a cell?
Chemical work: push in ednergoinc reactions
Transport work: pumping substances against the direction of spontaneous movement
Mechanical work: such as contraction of muscles
What is ATP composed of?
Ribose, adenine and three phosphate groups
How is energy released from ATP?
The bonds between the phosphate groups can be broken in hydrolysis, this releases energy
What is a catalyst?
A chemical agent that speeds up a reaction without being consumed
How do enzymes speed up reaction?
They lower the activation energy,
They do not affect the change in free energy
What are competitive inhibitors?
Bind to the active site of an enzyme competing with the substrate
What are non-competitive inhibitors?
Bind to another part of an enzyme causing the enzyme to change shape making the active site less effective.
