Biomolecules: Carbohydrates

• Quarter 4, Weeks 3-4, are focused on biomolecules

What are Biomolecules?

• Biomolecules are organic molecules produced by living organisms
• Biomolecules mainly consist of elements carbon, hydrogen, oxygen, and nitrogen.

Four Classes of Biomolecules

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

Objectives

• Identify and describe the categories of biomolecules.
• Illustrate the structural composition of each category of biomolecules.
• Develop awareness on the different sources and benefits of biomolecules.

Carbohydrates

• Molecules made from aldehydes and ketones
• Mainly composed of carbon, hydrogen, and oxygen atoms
• These atoms are in a ratio of one carbon to two hydrogen to one oxygen, written (CH2O).
• The most abundant class of biomolecules
• Can be classified into monosaccharides, disaccharides, or polysaccharides.

Monosaccharides

• Single unit of carbohydrates
• Glucose (referred to as dextrose) is the most important and abundant monosaccharide in nature.
• Fructose is known as fruit sugar found in fruits.

Disaccharides

• Two monosaccharides that are chemically combined

Polysaccharides

• Polymers containing numerous monosaccharide monomers

Types of Polysaccharides include

• Starch
  • Used for energy storage in plants.
  • Potatoes, pasta, and rice are starches.
  • Provide a quick form of energy for the body.
• Glycogen
  • Used for energy storage in animals.
• Cellulose
  • Provides structural support in plants and are found in the cell wall
• Chitin
  • Found in exoskeletons of arthropods (insects, spiders)
  • Also found in cell walls of some fungi

Lipids

• Water insoluble and composed of carbon, hydrogen, and oxygen.
• Classified in three major groups (triglycerides, phospholipids, and cholesterol)
• Each class differs in terms of their structure and function.
• Lipids are hydrophobic (water fearing) and do not dissolve in water.

Types of Lipids

• Triglycerides
  • Fats and oils consist of a glycerol "backbone" to which three fatty acids are attached.
• Phospholipids
  • Similar to triglycerides, except one of the three fatty acids is replaced with a phosphate group.
  • This phosphate group has other highly polar (hydrophilic, water-loving) entities attached.
• Cholesterol
  • Contains various hydrocarbon ring structures.

Bond Types and their Effect on Lipids

• Saturated
  • The bonds between all the carbons are single bonds.
  • Solid at room temperature
  • Mainly animal fats (bacon grease, lard)
• Unsaturated
  • There is at least one double or triple bond between carbons present.
  • Liquid at room temperature
  • Mainly plant-based fats (olive oil, peanut oil) as well as oily fish (tuna, sardines)

Proteins

• Polypeptides composed of long chains of amino acids connected by peptide bonds.
• Composed of an alpha-carbon in the middle, with an amino group, and a carboxyl group.
• Each protein only differs in the R-group.
• Classified according to the properties of their side chains such as nonpolar, polar, and electrically charged.
• The building blocks of proteins are Amino Acids

AMINO ACIDS

• Amino acids are classified into essential and non-essential amino acids
  • There are 20 common amino acids.
  • These feature different structural arrangements of carbon, hydrogen, nitrogen, oxygen, and sulfur.
• Essential Amino Acids must be obtained in the diet.
• Non-essential Amino Acids can be synthesized in the body

Protein Structure & Function

• Function depends on structure and 3-D structure (twisted, folded, coiled into unique shape)
• Primary structure = Order of amino acids in chain
  • amino acid sequence determined by gene (DNA)
  • slight change in amino acid sequence affect protein's structure & its function

Secondary Structure of Proteins

• Is the "Local folding"
• folding is along short sections of polypeptide
• involves interaction between adjacent amino acids and H bonds between backbones (O:H)
  • α-helix
  • β-pleated sheet
• Fibrous proteins have only secondary structure

Tertiary Structure of Proteins

• Is "Whole molecule folding”
• created when the secondary structure folds and forms bonds to stabilize the structure into a unique shape
• determined by interactions between R groups
  • Hydrophobic and Ionic Bond interactions
  • anchored by disulfide bridges
  • Hydrogen bonds between backbones
  • Van der Waals Force (velcro)
• Globular (spherical) proteins – have a tertiary structure made if enzymes.

Quarternary Structure of Proteins

• Two or more tertiary folded peptide subunits bonded together to make a functional protein
  • Hemoglobin is composed of 4 polypeptides
  • Collagen is composed of 3 polypeptides

Nucleic Acids

• Polymers consisting of long chains of nucleotides.
• Each nucleotide is composed of a pentose sugar, phosphate group, and nitrogenous bases.
• Nucleotides are organic molecules,the building block of DNA and RNA.
• Consists of a five-carbon sugar, a nitrogen-containing base, and a phosphate group.

Types of Nucleic Acids

• DNA (deoxyribonucleic acid)
  • Is a double-helix molecule composed of a deoxyribose, phosphate backbone and nitrogenous bases adenine, guanine, cytosine and thymine.
  • Contains the genetic instructions of all modern organisms.
• RNA (ribonucleic acid)
  • Is a single-stranded molecule composed of ribose sugar, phosphate backbone and nitrogenous bases adenine, uracil, cytosine and guanine.

Importance of Biomolecules:

• Carbohydrates: Energy Production and Storage, Building Macromolecules, Sparing Proteins, Assisting in Lipid Metabolism
• Lipids: Serve as Structural Components of Cell Membranes, Function as Energy Storehouses and Important Signaling Molecules
• Protein: Acting as Enzymes and Hormones, Providing for Fluid and Acid-Base Balance, Transport, Protection, Wound Healing and Tissue Regeneration and Energy Production
• Nucleic Acids: DNA or deoxyribonucleic acid: double-helix Molecule Composed Of Deoxyribose, Phosphate Backbone, Nitrogenous Bases such as Adenine, Guanine, Cytosine and Thymine
• Nucleic Acids: RNA or ribonucleic acid: Single-Stranded Molecule Composed of Ribose Sugar, Phosphate Backbone and Nitrogenous Bases such as Adenine, Uracil, Cytosine and Guanine.