Algebra Class 10 Quiz

Learning Objectives

• Define proteins with examples
• Classify proteins with examples
• List the sources and properties of proteins
• Describe functions and biomedical importance of proteins

Chemistry of Proteins

• Proteins are complex, high molecular weight, nitrogenous organic compounds.
• The basic unit of a protein molecule is an amino acid.
• The properties of a protein are determined by the R-groups on the amino acids.

Amino Acids

• Amino acids are the subunits of proteins.
• Most commonly, there are 20 different amino acids coded in DNA
• Some bacteria also use 22 amino acids (Selenocysteine and pyrrolysine).
• Amino acid properties differ based on their R-groups.
  • Hydrophobic: Leucine, isoleucine, valine, methionine, phenylalanine, tryptophan
  • Positively charged (basic): lysine, arginine, histidine
  • Negatively charged (acidic): aspartate, glutamate
  • Polar but uncharged: serine, threonine, asparagine, glutamine
  • Chain bending (imino acid): proline
  • Disulfide bridge forming: cysteine
  • Small: glycine, alanine, serine

Essential and Non-Essential Amino Acids

• 10 amino acids are essential, meaning they must be consumed in the diet .
• Examples of essential amino acids include: arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine.
• Other amino acids are nonessential.

Protein Structure

• Proteins have a primary structure. This is a linear sequence of amino acids linked together by peptide bonds.
• Proteins have a secondary structure that consists of local spatial structures of peptide segments. Hydrogen bonds help stabilize this structure.
• The tertiary structure is the complete three-dimensional arrangement of all atoms in a protein, stabilizing through various interactions like hydrogen, ionic, and hydrophobic interactions. Disulfide bonds also contribute.
• The quaternary structure is the spatial arrangement of multiple subunits in a protein.

Rich Sources of Proteins

• The presentation listed various foods rich in protein, such as various meats, fish, poultry, eggs, dairy, vegetables and legumes.

Physical and Chemical properties

• Proteins are made up of carbon, hydrogen, oxygen, nitrogen and small amounts of sulphur.
• Proteins link amino acids through peptide bonds.
• Protein enzymes catalyze chemical reactions
• Proteins provide structural support for cells
• Proteins transport substances across cell membranes
• Proteins defend against pathogens (e.g. antibodies).
• Proteins secrete hormones
• Proteins are denatured by factors like heat, acids, and bases, causing a change in the protein's structure and function.
• Denaturation often involves precipitation or coagulation of the protein. This is seen in examples like cooking eggs or heating milk.

Classification of Proteins

• Simple proteins consist only of amino acids.

• Conjugated proteins combine with non-protein components (prosthetic groups).

• Derived proteins are degradation products of native proteins.

  -Examples of conjugated proteins include glycoproteins, lipoproteins, nucleoproteins, and chromoproteins. - Glycoproteins contain sugar molecules. - Lipoproteins contain lipid molecules. - Nucleoproteins contain nucleic acids. - Chromoproteins contain pigments (e.g., heme in hemoglobin).

Malnutrition

• Kwashiorkor and Marasmus can arise from protein and calorie deficiencies respectively.

Classification of Proteins by Nutritional Value

• First class proteins contain all essential amino acids in sufficient amounts.
• Second class proteins are missing one essential amino acid.
• Third class proteins lack many essential amino acids.

Colloidal Osmotic Pressure (COP)

• Protein molecules influence blood pressure.
• Plasma proteins, primarily albumins contribute to COP, maintaining blood volume.

Capillary Exchange

• Blood pressure and osmotic pressure determine fluid movement in and out of capillaries.

Hydration of Proteins

• Proteins absorb water, swelling up due to their hydration shells where polar groups interact favorably with surrounding water molecules.

Isoelectric Point (pI)

• pI is the pH at which a protein exists as a zwitter ion (neutral charge).
• Isoelectric point measurements can be used in protein separation and identification.

Precipitation of Proteins by Salts

• Hydrophobic amino acids in proteins cluster together, pushing out water.
• Increasing salt concentration can affect solvation layers and bring proteins together to precipitate.

Structual Shape

• Fibrous proteins have a long, thin shape, often forming fibers.
• Globular proteins are roughly spherical and are usually soluble in water. A variety of functions.

Function of Proteins

• Presentation details various functions of proteins including:
• Enzymes: Catalyzing biochemical reactions
• Hormones: Coordinating bodily functions
• Structural: Supporting bodily structures
• Transport: Moving substances through the body
• Contractile: Muscle movement
• Storage: Storing nutrients within cells
• Receptors: Responding to stimuli
• Protective: Defense against pathogens
• Proteins within blood plasma (e.g., albumin, immunoglobulins).