Title: Proteins
1Proteins
- The most diverse molecules in living organisms!
2- Proteins have 2 main roles
- Structural building blocks (ex spider web)
- Functional molecules (ex enzymes)
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3Examples of proteins
- Functional
- Enzymes biological catalysts
- Immunoglobulins protect animals from foreign
microbes and cancer cells (antobodies) - Hemoglobin shuttles oxygen
- Structural
- Keratin tough structures in hair, fingernails
- Fibrin helps clot blood
- Collagen forms protein component of bones, skin,
ligaments and tendons
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4What are they made of?
- Amino acids (a.a.) are the subunits
R group side chain
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5A bit about the amino acids
- There are 20 a.a.s (p42 43)
- 8-10 are essential because our body cannot
synthesize them so we need to get them from our
diet.
6The amino acids
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No you dont have to memorize them maybe in
university though
7How are proteins made?
- DNA directs ribosomes, RNA and enzymes to join
a.a.s together in the correct sequence (this is
called protein synthesis) - The aas are joined together by peptide bonds
(aka amide bond) - Resulting polymer is called a polypeptide
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8Polypeptides are formed by condensation reaction
between the amino group of one amino acid and the
carboxyl group of the adjacent amino acid
9Two general categories of proteins
- Polypeptide a few aa in length to gt1000.
Usually linear strands or sheets - AND
- Globular are made of 1 or more polypeptide
chains in a rounded, spherical shape (ex
enzymes)
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10- The final shape (conformation) of a protein is
determined by a.a. sequence and can be - Primary straight chain of a.a (ex insulin)
- Secondary The a.a. chain coils and folds making
helices and pleated sheets (ex keratin, spider
silk) - Tertiary A secondary protein undergoes more
folding due to environmental forces. This can be
done by a chaperone protein. Is now globular. - Quarternary 2 or more polypeptides come together
to make one functional protein (ex keratin,
collagen, hemoglobin). Is also globular.
11Images courtesy of google images
12Denaturation
- Chemical and physical environmental factors
(temperature, pH, ionic concentration) can cause
proteins to change shape (denature) and lose
their function. - Denaturation can be
- Dangerous example- prolonged fever above 39
celcius can denature critical enzymes in the
brain. - Useful blanching of fruit, straightening hair,
cooking meat to make it easier to chew
13Images courtesy of google images