1. Proteins

2. Proteins Proteins are polymers made of monomers called amino acids
All proteins are made of 20 different amino acids linked in different orders
Proteins are used to build cells, act as hormones & enzymes, and do much of the work in a cell

3. copyright cmassengale

4. Structure of Amino Acids
group
Carboxyl
group
Amino acids have a central carbon with 4 things boded to it:
R group
Amino group –NH2
Carboxyl group -COOH
Side groups
Hydrogen -H
Variable group -R
Serine-hydrophillic
Leucine -hydrophobic

5. 20 Amino Acid Monomers-these are the R groups

6. Linking Amino Acids Cells link amino acids together to make proteins
Carboxyl
Cells link amino acids together to make proteins
Amino
R Group
The process is called dehydration synthesis
Dehydration Synthesis
Peptide bonds form to hold the amino acids together
Peptide Bond

7. Proteins (Polypeptides)
Four levels of protein structure:
A. Primary Structure
B. Secondary Structure
C. Tertiary Structure
D. Quaternary Structure

8. Protein Structures or CONFORMATIONS
Hydrogen bond
Pleated sheet
Polypeptide
(single subunit)
Amino acid
(a) Primary structure
Hydrogen bond
Alpha helix
(b) Secondary structure
(c) Tertiary structure
(d) Quaternary structure

9. Primary Structure
Amino acids bonded together by peptide bonds (straight chains)
aa1
aa2
aa3
aa4
aa5
aa6
Peptide Bonds
Amino Acids (aa)

10. Primary Protein Structure
The primary structure is the specific sequence of amino acids in a protein
Called polypeptide
Amino Acid

11. Protein Structures
Secondary protein structures occur when protein chains coil or fold
When protein chains called polypeptides join together, the tertiary structure forms because R groups interact with each other
In the watery environment of a cell, proteins become globular in their quaternary structure

12. Secondary Structure
3-dimensional folding arrangement of a primary structure into coils and pleats held together by hydrogen bonds.
Two examples:
Alpha Helix
Beta Pleated Sheet
Hydrogen Bonds

13. Tertiary Structure
Secondary structures bent and folded into a more complex 3-D arrangement of linked polypeptides
Bonds: H-bonds, ionic, disulfide bridges (S-S)
Call a “subunit”.
Alpha Helix
Beta Pleated Sheet

14. Quaternary Structure Composed of 2 or more “subunits”
Globular in shape
Form in Aqueous environments
Example: enzymes (hemoglobin)
subunits

15. Changing Amino Acid Sequence
Substitution of one amino acid for another in hemoglobin causes sickle-cell disease 2 1 3 6 4 5
(a) Normal red blood cell
Normal hemoglobin 2 1 3 6 4 5
(b) Sickled red blood cell
Sickle-cell hemoglobin

16. Other Important Proteins
Blood sugar level is controlled by a protein called insulin
Insulin causes the liver to uptake and store excess sugar as Glycogen
The cell membrane also contains proteins
Receptor proteins help cells recognize other cells

17. Cell membrane with proteins & phospholipids
INSULIN
Cell membrane with proteins & phospholipids

18. Nucleic Acids

19. Nucleic acids
Nucleic acids are composed of long chains of nucleotides linked by dehydration synthesis.
Function:
Dictate amino acid sequences/how proteins are made
Source of all genetic information
Two types:
a. Deoxyribonucleic acid (DNA)
b. Ribonucleic acid (RNA)

21. Nucleotide-monomer/building block of nucleic acid
O=P-O
Phosphate
Group s N
Nitrogenous base
(A, G, C, or T)
CH2 O C1 C4 C3 C2 5
Sugar
(deoxyribose)

22. Another look at a Nucleotide – Nucleic acid monomer

23. Nucleic Acids Nucleic acids are polymers of nucleotides Nucleotide
Nitrogenous base
(A,G,C, or T)
Nucleic acids are polymers of nucleotides
Phosphate
group
Thymine (T)
Sugar
(deoxyribose)
Phosphate
Base
Sugar
Nucleotide

24. Nucleic acids Nucleotides include: phosphate group
pentose sugar (5-carbon)
nitrogen bases:
adenine (A)
thymine (T) DNA only
uracil (U) RNA only
cytosine (C)
guanine (G)

25. Bases Each DNA nucleotide has one of the following bases: Adenine (A)
Thymine (T)
Cytosine (C)
Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)
Adenine (A)
Guanine (G)

26. DNA Two strands of DNA join together to form a double helix Base pair

27. DNA - double helix P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A

28. RNA – Ribonucleic Acid Ribose sugar has an extra –OH or hydroxyl group
Nitrogenous base
(A,G,C, or U)
Uracil
Phosphate
group
It has the base uracil (U) instead of thymine (T)
Sugar (ribose)

29. ATP – Cellular Energy
ATP is used by cells for energy
Adenosine triphosphate
Made of a nucleotide with 3 phosphate groups

30. The Chemistry of Life
Organic Compounds Lab

31. Indicator A substance used to show the presence of another substance
Color change = positive test
(the substance is present)

32. Distilled Water
Use it as a control – to make sure the indicators are working.
No color change with water = indicators are working

33. Lipid Test Sudan III stain – red is a positive test
Brown paper bag – Lipids leave translucent spots (grease spots)

34. Carbohydrate Test Starch – Iodine- blue/black is a positive test
Sugar – Benedict’s solution – **MUST BE HEATED!!!!*
blue/green changes to orange/yellow = positive test

35. Protein Test
Biuret reagent - varying shades of purple = positive test