Biological Macromolecules

1
Biological Macromolecules

• continued

2
Recall Big Four

• Carbohydrates
• Monosaccharides, Disaccharides Polysaccharides
• Lipids (Fats)
• Glycerides Sterols
• Proteins
• Enzymes
• Nucleic acids
• DNA, RNA

3
Monomers -gt Polymers

• Monomer simple molecule
• Polymer strings of similar, simple molecules
• Recall
• Dehydration synthesis
• Hydro water
• Hydrolysis
• Lysis to separate

4
Protein Function

• Support - Structural proteins in cell membranes
• Movement - Contractile proteins move muscles and
  cells
• Transport - Transport proteins bind insoluble
  compounds and molecules to allow transport in
  bloodstream
• Buffering - Buffer against detrimental pH changes
• Metabolic regulation - Enzymes accelerate
  chemical reactions
• Coordination Control - hormones
• Defense - Antibodies, clotting proteins
  (globulins), keratin

5
Making a protein

• Join amino group to carboxyl group
• Peptide bond
• Any chain of two or more amino acids joined
  together are peptides
• R side chain functional group

6
Protein structure

• Primary (covalent, peptide bond)
• AA sequence
• Secondary (H-bonding)
• ?-helices
• ?-pleated sheets
• Tertiary (H- bonding)
• Quaternary
• Additions of other polypeptides

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Primary structure

• Polypeptide chain linear sequence of AA

8
Secondary structure

• Common macro-structures formed by H-bonding
  between functional groups of AA.
• ?-helices common in fibrous proteins
• pleated sheets common in globular proteins

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Tertiary Structure
10
Quaternary Structure

• Final, assembled functional protein
• Consist of
• Multiple polypeptides joined by hydrogen bonds
  OR,
• Single functional polypeptide

11
Various protein shapes
12
Concept Check
0

• This lysozyme protein is found in tears
  protects the eye from bacterial infections.
  Which of the following best describes the outside
  of the molecule?

• The R-groups on the surface of the molecule are
  mostly hydrophobic.
• The R-groups on the surface of the molecule are
  mostly hydrophilic.
• The R-groups on the surface of the molecule are
  mostly non-polar.
• The R-groups on the surface of the molecule are
  constantly changing between non-polar and polar
  as the protein chain bends and folds.

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Answer
0

• This lysozyme protein is found in tears and
  protects the eye from bacterial infections.
  Which of the following best describes the outside
  of the molecule?

• 2) The R-groups on the surface of the molecule
  are mostly hydrophilic.

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Example Hemoglobin

• HbA, HbB, HbE
• Multiple Hb proteins exist only two
  producenormal O2 binding to RBCs

15
Hemoglobin

• HbA, HbB, HbE
• Small changes in AA sequence result in major
  functional changes
• Less functional protein produced Fewer competent
  RBCs are made HbE
• Defective protein is produced RBCs sickle
  (collapse) HbS
• Each altered phenotype results from a single AA
  change

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Denaturation

• Loss of function due to shape change
• Caused by changes in pH or temperature

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Nucleic Acids

• Polymers that serve as recipes for proteins
• DNA (deoxyribonucleic acid) double stranded
  polymer duplicate, read in reverse (think of
  this entire molecule as a cookbook)
• RNA (ribonucleic acid) single stranded polymer
  usually, a short transcript (copy) of a tiny
  portion of a single strand of DNA (recipe)
• Monomers nucleotides

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Nucleotides

• 5 nucleotides
• DNA Adenine, Thymine, Guanine, Cytosine
• RNA Adenine, Uracil, Guanine, Cytosine
• Consist of Phosphate, Sugar, Nitrogenous base
• The base is variable
• Where are they joined? What reaction joins them?

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RNA

• Single polynucleotide strand
• Repeated Sugar - phosphate ladder
• Base protrudes from sugar
• Many varieties
• mRNA, tRNA, rRNA

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RNA

• Single polynucleotide strand
• Repeated Sugar - phosphate ladder
• Base protrudes from sugar
• Many varieties
• mRNA, tRNA, rRNA
• 3-D shape also due to H-bonds

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DNA

• Double stranded ladder
• Each base binds to one specific counterpart
• A-T C-G (base pairs)
• What type of bonds hold base pairs (bp) together?
• thousands - millions of bp in length
• Codes for hundreds - thousands of genes

22
Concept Check
0

• When proteins are heated, they denature. If
  moderate heat was applied to this molecule of DNA
  what part of the molecule would break apart
  first? (Use your knowledge of chemical bonds.)
• The nucleotides along each side would break
  apart.
• The sugar-phosphate backbone would separate from
  the nitrogen bases.
• The nitrogen base pairs would separate in the
  interior of the molecule.

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Answer
0

• When proteins are heated, they denature. If
  moderate heat was applied to this molecule of DNA
  what part of the molecule would break apart
  first? (Use your knowledge of chemical bonds.)
• The nitrogen base pairs would separate in the
  interior of the molecule.