Molecules of Life

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Molecules of Life

• Chapter 2

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Protein Functions

• Act as enzymes
• Structural- cytoskeleton (actin, tubulin, others)
• Mechanical- actin and myosin in muscle
• Cell signaling
• Immune responses
• Cell adhesion
• Cell cycle
• transport

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The 20 amino acids
You dont Have to memorize these
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Proteins

• Built from 20 common monomers called amino acids
  (aa)

Peptide bond
Amino acid monomer
aa
aa
aa
aa
aa
aa
aa
polypeptidepolymer
Polypeptide- A chain of amino acids bonded
together by peptide bonds in a condensation
reaction
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Peptide Bond Formation
A DNA encodes the order of amino acids in a
new polypeptide chain. Methionine (met) is
typically the first amino acid.
B In a condensation reaction, a peptide bond
forms between the methionine and the next amino
acid, alanine (ala) in this example. Leucine
(leu) will be next. Think about polarity, charge,
and other properties of functional groups that
become neighbors in the growing chain.
Fig. 3-16a, p. 44
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Stepped Art
Fig. 3-16b, p. 45
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Globin Chains in Hemoglobin
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Molecular Basis of Sickle Cell Anemia
glutamic acid
glutamic acid
valine
histidine
leucine
threonine
proline
A Normal amino acid sequence at the start of the
hemoglobin beta chain.
Fig. 3-19a, p. 47
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Molecular Basis of Sickle Cell Anemia
valine
histidine
leucine
threonine
proline
valine
glutamic acid
B One amino acid substitution results in the
abnormal beta chain of HbS molecules. The sixth
amino acid in such chains is valine, not glutamic
acid.
Fig. 3-19b, p. 47
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Nucleotides

• Nucleotide (the monomer of nucleic acid)

Monomer
Two kinds of nucleic acids RNA DNA
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Four Nucleotides of DNA
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The DNA Molecule
covalent bonding in sugar phosphate backbone
hydrogen bonding between bases
Fig. 3-22, p. 49
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Nucleic Acids- Informational Polymers
Nucleic acids
Proteins
Lipids
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Summary Organic Molecules in Living Things