Part 1 Flashcards
What are proteins?
Proteins are large molecules containing Carbon, Hydrogen, Oxygen, and Nitrogen. Some proteins also contain sulphur.
What percentage of a lean adult body is protein?
A lean adult body normally contains 12-18% protein.
How is protein stored in the body?
Only small amounts of protein are temporarily stored in the body, which can be quickly used up on demand compared to carbohydrates and lipids.
What do the symbols H, N, C, O, and R represent in proteins?
H = Hydrogen, N = Nitrogen, C = Carbon, O = Oxygen, R = Variable Side Chain.
• is a covalent bond that connects each amino acid to another amino acid that is formed through dehydration reaction. The long chains of amino acids are called polypeptides.
PEPTIDE BOND (Amide Linkages)
• A protein is a natural polymer composed of amino acid monomers joined together
PEPTIDE BOND (Amide Linkages)
The long chains of amino acids
polypeptides
• An index used to determine whether physiological requirements are being met.
NITROGEN BALANCE
Nitrogen ingested
(Primarily as protein)
-
Nitrogen Excreted
(Primarily as urea)
Nitrogen balance
0 (Nitrogen equilibrium)
Nitrogen balance
protein degradation
Protein synthesis
protein synthesis > protein degradation
Positive Nitrogen Balance
protein synthesis < protein degradation
Negative Nitrogen Balance
• Most proteins do not occur as long chains inside the cells unlike polysaccharides. Instead, they are folded into three - dimensional structures, which determine the structures and kinds of amino acids.
PROTEIN FOLDING
Types of Protein Structures
Primary Structure
Secondary Structure Tertiary Structure
Quaternary Structure
• The unique sequencing of amino acids in a polypeptide chain.
- Primary (1°) Structure
• Localised folding in some regions of the chain of amino acids - alpha helix and beta sheet
- Secondary (2°) Structure
• Overall shape of a polypeptide as a result of interactions of the R Group and water
- Tertiary (3°) Structure
• Arrangement of two or more polypeptide chains relative to one another.
- Quaternary (4º) Structure
2 PROTEIN CLASSIFICATION BASED ON THEIR
CHEMICAL COMPOSITION
- SIMPLE PROTEINS
- COMPLEX PROTEINS
• Only made up of amino acids
SIMPLE PROTEINS
• These proteins have other chemical components in addition to amino acids
- organic or inorganic additional components known as “prosthetic groups”
COMPLEX PROTEINS
PROSTHETIC
GROUP
-Heme Unit
SPECIFIC EXAMPLE
-Haemoglobin/Hemoglobin
Myoglobin
FUNCTION
-Carries oxygen in the blood Binds oxygen in muscles
Haemoproteins/
Hemoproteins
PROSTHETIC
GROUP
-Lipid
SPECIFIC EXAMPLE
-Low-density Lipoprotein (LDL)
High-density Lipoprotein (HDL)
FUNCTION
-Carries Lipid
Lipoproteins
PROSTHETIC
GROUP
-Carbohydrates
SPECIFIC EXAMPLE
-Gamma Globulin
Mucin
Interferon
FUNCTION
-Antibody
Lubricant in mucous secretions
Antiviral protection
Glycoproteins
PROSTHETIC
GROUP
-Phosphate Group
SPECIFIC EXAMPLE
-Glycogen Phosphorylase
FUNCTION
-Enzyme in glycogen phosphorylation
Phosphoproteins
PROSTHETIC
GROUP
-Nucleic Acid
SPECIFIC EXAMPLE
-Ribosomes
-Viruses
FUNCTION
-Site for protein synthesis in cells
Self-replicating, infectious complex
Nucleoproteins
PROSTHETIC
GROUP
-Metal Ion
SPECIFIC EXAMPLE
-Iron - ferritin
-Zinc - alcohol dehydrogenase
FUNCTION
-Storage complex for iron
-Enzyme in alcohol oxidation
Metalloproteins
PROTEIN CLASSIFICATION BASED ON SHAPE
- FIBROUS PROTEINS
- GLOBULAR PROTEINS
• These proteins are spiral and helical and are cross linked by disulphide and hydrogen bonds
FIBROUS PROTEINS
HIGH PROTEIN VEGETABLES
(RANKED FROM HIGHEST TO LOWEST)
GREEN PEAS
SPINACH
ARTICHOKES
CORN
AVOCADO
ASPARAGUS
BRUSSELS
SPROUTS
MUSHROOMS
KALE
POTATOES
• They represent about 25-30% of all proteins among vertebrates.
Collagen
• They are found in different tissues and organs, including tendons and the organic matrix of bone - in which they are present in very high percentages.
Collagen
COLLAGEN RICH FOODS
(FOR SKIN)
Berries
Leafy Greens
Citrus Fruits
Nuts and Seeds
Soy Products
Tomatoes
Avocado
COLLAGEN RICH FOODS
(FOR SKIN)
Berries
Leafy Greens
Citrus Fruits
Nuts and Seeds
Soy Products
Tomatoes
Avocado
• They constitute almost the entire dry weight of nails, claws, beak, hooves, horns, hair, wool, and a large part of the outer layer of the skin.
a -Keratins
• This protein provides elasticity to the skin and blood vessels due to its random coiled structure, different from the structures of collagen and
a - keratin.
Elastin
• Most of the proteins belong to this class, in which they have a compact and spherical structure and more complex than fibrous proteins.
GLOBULAR PROTEINS
They are generally soluble in water but can also be found inserted into biological membranes (transmembrane proteins). Hence, in a hydrophobic environment.
GLOBULAR PROTEINS
PROTEIN CLASSIFICATION BASED ON FUNCTION
Types:
Enzymes
Transport
Structural
Hormones
Defence
Contractile
Storage
EXAMPLES
-Digestive enzymes:
Amylase, lipase, pepsin, trypsin
FUNCTIONS
-Serve as catalysts in biochemical reactions such as digestive enzymes, which aid in digestion of food by breaking down nutrients to monomers.
Enzymes
EXAMPLES
-Haemoglobin, Albumin
FUNCTIONS
-Carry substances in the blood or lymph throughout the body.
Transport
EXAMPLES
-Actin, Tubulin, Keratin
FUNCTIONS
-Construct different structures like the cytoskeleton, hair, and nails.
Structural
EXAMPLES
-Insulin, thyroxine
FUNCTIONS
-Coordinate the activity of different body systems
Hormones
EXAMPLES -Immunoglobulins (Antibodies)
FUNCTIONS
-Protect the body from invading pathogens
Defence
EXAMPLES
-Actin, myosin
FUNCTIONS
-Effect of muscle contraction - for movement
Contractile
EXAMPLES
-Legume storage of proteins, egg white (albumin)
FUNCTIONS
-Provide nourishment in early development of the embryo and the seedling.
Storage
IMMUNOGLOBULINS
IgA
IgD
IgE
IgG
IgM
Found in mucous, saliva, tears, and breastmilk
Protects us against pathogens
Transferred to an infant through breastmilk and colostrum.
IgA
Part of the B cell receptor - helps them to start the immune response.
Activates basophils and mast cells
IgD
Protects against parasitic worms.
Responsible for allergic reactions.
Found mainly on tonsils, skin and mucous membranes.
IgE
Secreted by plasma cells in the blood
Able to cross the placenta into the fetus - important in the immunity of newborn
IgG
May be attached to the surface of a B cell or secreted into the blood - with strong agglutinating ability
Responsible for early stages of immunity.
IgM
• A protein is defined by its 1°, 2°, and 30 structures. These give proteins certain identifying properties - biological, enzymatic, solubility, ionic, reactivity of side group, molecular weight, size, native structure.
Denaturation of Proteins
-is the result of any changes in the native structure of proteins, which is caused about by breaking of any bond except the peptide bond.
Denaturation of Proteins
