Molecules of Life

1
Molecules of Life

• Molecules of life are synthesized by living cells
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

2
Structure to Function

• Molecules of life differ in three-dimensional
  structure and function
• Carbon backbone
• carbon and hydrogen atoms
• bond covalently with up to four other atoms,
  often in long chains or rings
• Attached functional groups
• Influence organic compounds properties
• Structures
• give clues to how they function
• Four models

3
Processes of Metabolism

• Cells use energy
• grow and maintain themselves
• Enzyme-driven reactions build,
• rearrange, and split organic molecules

4
Building Organic Compounds

• Cells form complex organic molecules
• Simple sugars ? carbohydrates
• Fatty acids ? lipids
• Amino acids ? proteins
• Nucleotides ? nucleic acids
• Condensation combines monomers to form polymers

Condensation and Hydrolysis
5
What are carbohydrates?

• Three main types of carbohydrates
• Monosaccharides (simple sugars)
• Oligosaccharides (short chains)
• Polysaccharides (complex carbohydrates)
• Carbohydrate functions
• Instant energy sources
• Transportable or storable forms of energy
• Structural materials

6
What are complex carbohydrates?

• Starch
• Stored form of polysaccharide in plants.
• Cellulose
• Structural polysaccharide found in plants.
• Glycogen.
• Stored polysaccharide in animals
• abundant in liver and muscles of highly active
  animals, including fishes and people.

7
What are lipids?

• Lipids
• Fats, phospholipids, waxes, and sterols
• Dont dissolve in water
• Dissolve in nonpolar substances (other lipids)
• Lipid functions
• Major sources of energy
• Structural materials
• Used in cell membranes

8
What are fats?

• Lipids with one, two, or three fatty acid tails
• Saturated
• Unsaturated (cis and trans)
• Triglycerides (neutral fats )
• Three fatty acid tails
• Most abundant animal fat (body fat)
• Major energy reserves

9
What are phospholipids?

• Main component of cell membranes
• Hydrophilic head, hydrophobic tails

10
What are steroids?

• Cholesterol
• Membrane components precursors of other
  molecules (steroid hormones)

11
What are proteins ?

• Proteins have many functions
• Structures
• Nutrition
• Enzymes
• Transportation
• Communication
• Defense

Built from 20 kinds of amino acids
12
Protein Synthesis

• Carbonyl group and amino group react to form new
  linkages.

13
Four Levels of Protein Structure

• 1. Primary structure
• Amino acids joined by peptide bonds form a linear
  polypeptide chain
• 2. Secondary structure
• Polypeptide chains form sheets and coils
• 3. Tertiary structure
• Sheets and coils pack into functional domains
• 4. Quaternary structure
• Many proteins (e.g. enzymes) consist of two or
  more chains

14
Why is protein structureso important?

• Protein structure
• dictates function
• mutation in DNA results
• in an amino acid substitution that alters a
  proteins structure and compromises its function
• Example Hemoglobin and sickle-cell anemia

15
Denatured proteins

• If a protein unfolds and loses its
  three-dimensional shape (denatures), it also
  loses its function
• Caused by shifts in pH or temperature, or
  exposure to detergent or salts
• Disrupts hydrogen bonds and other molecular
  interactions responsible for proteins shape

16
What are nucleotides?

• DNA and RNAs
• Nucleotide structure, 3 parts
• Sugar
• Phosphate group
• Nitrogen-containing base

17
What are functions of nucleotide ?

• Reproduction, Metabolism, and Survival
• DNA and RNAs are nucleic acids, each composed of
  four kinds of nucleotide subunits
• ATP energizes many kinds of molecules by
  phosphate-group transfers
• Other nucleotides function as coenzymes or as
  chemical messengers

18
DNA vs RNA

• DNA (double-stranded)
• Encodes information about the primary structure
  of all cell proteins in its nucleotide sequence
• RNA molecules (usually single stranded)
• Different kinds interact with DNA and one another
  during protein synthesis