Proteins Flashcards
Proteins
- large macromolecules
- made of repeating amino acid subunits
- perform a large variety of roles within living organisms
Polymer
a molecule that is made up of repeating subunits (polypeptide chain or protein)
Monomer
the repeating subunits of polymer (amino acid)
Amino acid to Protein
Amino Acid- Polypeptide chain- protein
AA- PC- P
Proteins can act where?
Intracellular and Extracellular
DNA in proteins
encodes the info for protein synthesis
Protein types and functions
(TEACHERS)
- Transport (Hemoglobin)
- Enzyme (catalyst)
- Antibodies (immune response)
- Contractile (think muscles)
- Hormonal (cell signalling)
- Extra Storage
- Receptor (cell signalling)
- Structural (maintain shape)
What makes amino acid different?
- variable R group is the differing factor between 20 AMINO ACIDS
- diff R groups have diff chemical properties (which influences folding of the polypeptide chain)
20 Amino acids
- non-essential amino acids: can be synthesised by the organism
- essential amino acids: must be sourced via diet
- diff organisms have diff essential vs non-essential amino acids
5 components of an amino acid
- Central carbon atom
- Amine group (-NH2)
- Carboxyl Group (-COOH)
- Hydrogen atom
- Variable R group
Factors that can be changed
- no. of amino acids in proteins
- order of amino acids in proteins
- type of amino acids in proteins
Bonding
determines the shape of the protein (shape= function)h
The way bonds are formed between ___ changes the way the protein __ is formed.
amino acids; shape
How do different bonds affect a protein’s final shape and function?
Different bonds= different final shape= different function
Conformation
the shape of the protein
Complementary
shapes match
Chemical Bonds
- attractions between atoms that enables the formation of molecules
- arise via attraction between +ve and -ve charges
Types of bonds
Intermolecular and Intramolecular
Intermolecular bonding
between molecules
- ‘Hydrogen bonding’
- dispersion forces
- dipole-dipole interactions
Intramolecular bonding
within molecules
- ‘Covalent’ (ie. joins amino acids)
- peptide bonds (joins amino acids)
- phosphodiester bonds (joins nucleotides together- DNA/RNA)
- Ionic
- Metallic
Protein Structures
- primary (1°) (polypeptide chain of amino acids) → Order
- secondary (2°) (beta pleated sheets, alpha helix) → Shape
- tertiary (3°) (3D folding of the polypeptide chain due to interactions between R groups) → Function
- quaternary (4°) (multiple polypeptide chains into a functional protein) → Complex
What do the structures represent?
- protein structures coexist with each other
- not standalone structures
- all have 1°-3° structure
- only more structurally complex proteins have 4° structure
Primary Structure
the specific order of amino acids in the polypeptide chain
bonding type between amino acids
peptide bonds
Peptide bonds
A type of covalent intramolecular bonding formed between the amine and carboxyl groups of ADJACENT amino acids.
How are peptide bonds formed?
via condensation (water produced) polymerisation (making a polymer) reactions - proteins/ nucleic acids/ carbs/ fats
Input energy- ATP
water is produced as byproduct
Secondary Structure
the coiling and folding of the primary structure due to hydrogen bonding, that gives the polypeptide chain its INITIAL 3D shape
Bonds in secondary structure
hydrogen bonds between amine and carboxyl groups in distant amino acids
Structures formed in secondary structure
alpha helices, beta-pleated sheets
random loops (non-folding)
Tertiary Structure
comprehensive 3D structure of the protein that determines biological function which is formed through the further folding of the secondary structure
NOTE: 3° determines biological function
Bonds in Tertiary Structure
Intermolecular bonds between R groups
changing amino acid sequence (mutation can change a.a. sequence)= changing R groups=(changed intermol bonds)= changed 3° structure= altered fn
Types of Bonds
- dispersion forces (Van der Waals forces)>
- Dipole-dipole interactions>
- hydrogen bonds>
- ionic interactions>
- Disulphide bridges
Quaternary Structure
two or more polypeptide subunits bonded together to form the complete protein
not proteins have Quaternary Structure
only more structurally complex
NOTE: more complex: only referring to complexity in structure NOT complexity in function
A protein having a 4° structure does NOT mean it’s more __ complex than proteins with 3° structures
functionally
Amino Acid Components
“CHARR” (Central Carbon, Hydrogen, Amine Group, R Group, Carboxyl Group)
Condensation Reaction
Condensation = Peptide Bond Formation + Water Release (Requires ATP)
How are peptide bonds are formed
through condensation polymerisation
carboxyl group (-COOH) of one amino acid bonds with the amine group (-NH₂) of another
Type of Bonding in Primary Structure is__ and between __ and __.
Examples?
Intramolecular, Amine+ Carboxylic
Peptide (type of COVALENT bond)
Type of Bonding in Secondary Structure is__ and between __ and __.
Examples?
Intermolecular (distant a.a), Amine+ Carboxylic
Hydrogen
Type of Bonding in Tertiary Structure is__ and between __ .
Examples?
Intermolecular (distant a.a), R groups
Hydrogen, Ionic Interactions, Dispersion Forces, Disulphide bridges, dipole-dipole interactions
Type of Bonding in Quaternary Structure is__ and between __ .
Examples?
Intermolecular, R groups
Hydrogen, Ionic Interactions, Dispersion Forces, Disulphide bridges, dipole-dipole interactions
Proteome
The entire set of proteins expressed by a cell, tissue, or organism at a given time.
- varies depending on cell type, environment, and conditions.
Genome
The complete set of genetic material (DNA) in an organism, containing all the information needed for protein synthesis.
- constant for an individual organism.
What is the role of transport proteins?
Carry molecules throughout the body or across cell membranes.
Example: Hemoglobin (transports oxygen in blood), Transport Proteins in membranes
What is the role of enzymes?
Biological catalysts that speed up chemical reactions.
Example: Amylase (breaks down starch into sugars).
What is the role of antibodies?
Recognize and neutralize pathogens in the immune response.
Example: Immunoglobulins.
What is the role of contractile proteins?
Involved in muscle contraction and movement.
Example: Actin and Myosin.
What is the role of hormonal proteins?
Act as chemical messengers, coordinating physiological processes.
Example: Insulin (regulates blood sugar levels).
What is the role of storage proteins?
Store essential nutrients for later use.
Example: Ferritin (stores iron).
What is the role of receptor proteins?
Receive and transmit signals for cell communication.
Example: Insulin receptor.
What is the role of structural proteins?
Maintain cell shape and provide support to tissues.
Example: Collagen (found in skin and connective tissues).
