Proteins

1
Proteins

• provide the structure of living things

• play an important role in chemical reactions in
  the cell

• are large, complex molecules
• Made by DNA sequences in ribosome

2
Elements found in proteins
C, H, O, nitrogen (N) and sometimes sulfur (S)
The simplest part of a protein (monomer) is
called

• an amino acid
• (there are 20 different types)

3
?The 20 amino acids link together in various
combinations to form different proteins ?Ex
skin protein, muscle protein, blood protein, etc
4
All proteins

• are long chains of amino acids
• are held together by covalent bonds
• called peptide bonds
• are also called polypeptides
• (because of the type of covalent bond)

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How amino acids link
Peptide bond is between C N
R
H2N--C--C--OH
H O
R
H2N--C--C--OH
H O

• H is removed from one a.a. and OH is removed
  from another a.a. ?

H2O . . .
condensation!
6
How amino acids Break Apart
Peptide bond is between C N
R
H2N--C--C---
H O
R N--C--C--OH
H H O

• H is added to one a.a. and OH is added to the
  other a.a. ?

H2O was used to break it up . . .
Hydrolysis!
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Protein Structure

• Primary
• AA sequence
• Secondary
• H-bonds form a or ß structures
• Tertiary
• Folding up side chains bond together
• Quaternary
• Many polypeptides together
• Structure determines function

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Primary structure of a proteinThe sequence of
AAs
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Secondary structure of a proteinH-bonds forms
a-helix or ß-sheet
10
Tertiary structure of a proteinfolding up can
have a ß structures
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Quaternary structure of proteinsMany
polypeptides together
12
Review the four levels of protein structure
13
Denaturation and renaturation of a protein
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Examples of Proteins

• structural proteins- hair, nails, horns, and
  hooves

• muscles (all meats are protein)

• enzymes (they enhance the speed of a chemical
  reaction ex amylase an enzyme in your saliva)

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Energy Reactions

• ENZYMES!

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Chemical Reactions and Enzymes

• Enzymes speed up a reaction by lowering the
  activation energy of a reaction
• Enzymes act as a site of a reaction and are not
  used up

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Enzymes very important proteins

• Changes the rate of a chemical reaction
• Enable specific molecules, called substrates, to
  undergo chemical change
• See Inside Story page 166

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Chemical Reactions and Enzymes

• Activation energy- energy needed to get a
  reaction started
• Enzymes are proteins that act as biological
  catalysts (speed up a reaction)

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Spider webs are made of protein
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Recap for proteins

• made of C, H, O, N, and sometimes S
• can be enzymes or structural
• they are long chains (trains)
• the chains are made of amino acids
• (cars in the train)
• DNA determines the proteins made ? traits!

21
Protein Test

• Biurets Reagent used to indicate protein
• Positive Protein
• From Blue to Purple ? Positive ? Protein
• No Change no protein

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Enzymes Induced Fit

• Structure Function
• Reactants substrates
• Substrates must FIT into enzyme active site
  lock and key for rxn to occur
• If shapes do not fit, rxn will not be catalyzed

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2. Nucleic Acids
Function heredity (passing on traits)
They store information in a code form that is
responsible for making proteins
Found in all cells as DNA or RNA
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What is DNA and RNA?
DNA- deoxyribonucleic acid
RNA- ribonucleic acid
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The elements found in nucleic acids
Carbon Hydrogen Oxygen Nitrogen Phosphorus
Monomers of nucleic acids 3 basic units
phosphate, sugar and a nitrogen base
NUCLEOTIDE
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DNA the genetic code

• DNA is found in the nucleus of all cells

• DNA holds the master code for making all proteins

• DNA determines how one looks and acts

27
All about RNA

• RNA is important in actually making proteins/
  protein synthesis

• RNA takes the code from DNA (in the nucleus) and
  carries outside the nucleus, where proteins are
  made

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Well do a unit on DNA/RNA later

• Stay tuned