microbiology for nursing students: 2. review of macromolecules
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Review of macromolecules in biochemistry Protein levels of foldingTRANSCRIPT
Chemistry and Biochemistry for MicrobiologyPart 2: Macromolecules
By BugLady
CarbonForms up to 4 bonds with other atoms and assembles into large molecules with carbon backbone
Carbon forms nonpolar and polar covalent bonds with other atoms.
oMolecules with nonpolar bonds (hydrocarbons) do not dissolve in water
oMolecules with polar bonds are more water soluble
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Organic Compounds
Organic compounds always contain carbon and hydrogen.
oWhat is CO2? And C6H12O6? What about CaCO3?
Inorganic compounds typically lack carbon.
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Organic CompoundsSmall organic molecules can combine into large macromolecules
Macromolecules are polymers consisting of many small repeating molecules
The smallest molecular unit is called a monomer
An oligomer contains 2-20 repeating units
Monomers join by dehydration (losing water molecules) synthesis or condensation (adding water molecules) reactions
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Proteins are polymers.
Carbohydrates
Consist of C, H, and O with the formula (CH2O)n
Energy sources: glucose, glycogen, starch
Structureo Nucleic acid component
o Cell walls in bacteria and plant cells
o Glycocalyx: slime layers and capsules
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NIH
Wikicommons
CDC
USDA
CarbohydratesOligosaccharides: 2 to 20 monosaccharides.
Polysaccharides: tens or hundreds of monosaccharides joined through dehydration synthesis.
Starch, glycogen, dextran, and cellulose are polymers of glucose.
Polysaccharides are insoluble in water.
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LipidsDefining feature: Insoluble in waterSmallest of the four macromoleculesCan be divided into two general classes
o Simple lipidso Compound lipids
Critical component of the cell membraneHeterogeneous group of molecules
oMade up of different subunits
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Triglycerides
Glycerol is esterified with three fatty acids. It is the main constituent of vegetable oil and animal fats.
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By Wolfgang Schaefer on Wikicommons
Steroids
Unlike other lipids, 4-ring structure
Cholesterol: plasma membrane of animal cells
Ergosterol: plasma membrane of fungi
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Ergosterol (NCBI PubChem)
PhospholipidsDerivative of triglyceride
Two fatty acid hydrophobic tails
One phosphate group
Amphipatic moleculesHead is hydrophilic
Tails are hydrophobic
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By Ties van Brussel Wikicommons
Proteins
Are essential in cell structure and function.
Enzymes are proteins that speed chemical reactions.
Transporter proteins move chemicals across membranes.
Flagella are made of proteins.
Some bacterial toxins are proteins.
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Amino Acid Subunits
There are 20 common amino acidsAll amino acids have
o A carboxyl group (COO-)
o An amino group (NH3+)
o A central carbono A side chain
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Biology.arizona.edu
Amino Acid SubunitsAll common amino acids are L optical isomersD isomers found in cell walls of prokaryotes
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RSC
Levels of Structure: The Primary Structure
Peptide bonds between amino acids are formed by dehydration synthesis.
The primary structure is the sequence of amino acids joined by peptide bonds
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Levels of Structure: The Secondary Structure
The secondary structure occurs when the amino acid chain folds and coils in a regular helix or pleats.
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Hydrogen bondsThese form in all proteins. The hydrogen atom of the peptide link is attracted to the oxygen of another peptide link.
C
NH
O
C
NH
O
peptide chains
RSC
Levels of Structure: The Tertiary Structure
The helix folds irregularly, forming disulfide bridges, hydrogen bonds, nonpolar interactions and ionic bonds between the side chains of amino acids.
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Covalent bondsIn a small number of proteins, sulfur-sulfur covalent bonds (also called cystine bonds or disulfide bridges) are present.
- CH2 – S – S – CH2 -
Ionic bondsIf some of the amino acids in the proteins have carboxylic acid or amine side groups, an ionic bond can form.
- COO- H3N+ - RSC
Protein StructureProteins have four structures
o Primaryo Secondaryo Tertiaryo Quaternary
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National Institute of General Medical Sciences
Protein Denaturation
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Denaturation: shape change causes protein to stop functioning
Can be reversible or irreversible
Heat, acids, bases, heavy metals, some organic solvents cause denaturation
Proteins must have a specific shape to have proper function
Check point
Which of the 4 protein structures is not affected by denaturation?
How is protein denaturation used in microbiology?
Sterilization and disinfection use chemical and physical methods that denature the proteins in microorganisms : heat, alcohol, aldehydes.
Primary Structure
Nucleic Acids
Polymers of nucleotides
Storage of genetic information
Processing of genetic informationApr 11, 2023 20
NHGRI
Deoxyribose (sugar)
Base pairing in DNAo A with T
o C with G
Information storage
Stability
National Institute of General Medical Sciences
DNA
RNAStructureo Usually single-strandedo Ribose (sugar)o A bonds with U and C bonds with G
Different types of RNA omessenger RNA (mRNA)o ribosomal RNA (rRNA)o transfer RNA (tRNA)o small RNAs involved in regulating gene expression.
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NHGRI
DNA vs. RNA
DNA RNA
Deoxyribonucleic acid Ribonucleic acid
Deoxyribose Ribose
Thymine (T) Uracil (U)
Adenine (A), guanine (G), cytosine (C) used in both
2 strands- double helix Single strand
1 form Several forms
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Adenosine Triphosphate
A special nucleotide
Energy currency for cell metabolism
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