Carbon Compounds in Cells

1
Carbon Compounds in Cells

• Chapter 3

2
Importance of Carbon

• Carbon permeates the world of lifefrom the
  energy-requiring activities and structural
  organization of cells, to physical and chemical
  conditions that span the globe and influence
  ecosystems everywhere.

3
Humans and Global Warming

• Fossil fuels are rich in carbon
• Use of fossil fuels releases CO2 into atmosphere
• Increased CO2 may contribute to global warming

4
Organic Compounds

• Hydrogen and other elements covalently bonded to
  carbon
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

5
Carbons Bonding Behavior

• Outer shell of carbon has 4 electrons can hold 8
• Each carbon atom can form covalent bonds with up
  to 4 atoms

6
Methane Simplest Organic Compound
Figure 3.2Page 36
7
Bonding Arrangements

• Carbon atoms can form chains or rings
• Other atoms project from the carbon backbone

Glucose (ball-and-stick model)
In-text figurePage 36
8
Hemoglobin Molecular Models
Ball-and-stick model
Space-filling model
Figure 3.3Page 37
Ribbon model
9
Functional Groups

• Atoms or clusters of atoms that are covalently
  bonded to carbon backbone
• Give organic compounds their different properties

10
Examples of Functional Groups

• Methyl group - CH3
• Hydroxyl group - OH
• Amino group - NH3
• Carboxyl group - COOH
• Phosphate group - PO3-
• Sulfhydryl group - SH

11
Carbohydrates

• Monosaccharides
• (simple sugars)
• Oligosaccharides
• (short-chain carbohydrates)
• Polysaccharides
• (complex carbohydrates)

12
Lipids

• Most include fatty acids
• Fats
• Phospholipids
• Waxes
• Sterols and their derivatives have no fatty acids
• Tend to be insoluble in water

13
Phospholipids

• Main component of cell membranes
• Hydrophobic head
• Hydrophilic tails

Fig. 3.14a,bPage 43
14
Sterols and Derivatives

• No fatty acids
• Rigid backbone of four fused-together carbon
  rings
• Cholesterol - most common type in animals

Cholesterol
Figure 3.15aIn-text p43
15
Waxes

• Long-chain fatty acids linked to long-chain
  alcohols or carbon rings
• Firm consistency, repel water
• Important in water-proofing

16
Protein Synthesis

• Peptide bond
• Condensation reaction links amino group of one
  amino acid with carboxyl group of next

Water forms as a by-product
Fig. 3.18aPage 45
17
Primary Structure

• Sequence of amino acids
• Unique for each protein
• Two linked amino acids dipeptide
• Three or more polypeptide
• Backbone of polypeptide has N atoms
• -N-C-C-N-C-C-N-C-C-N-

18
Second and Third Levels

• Hydrogen bonding produces helix or sheet
• Domain formation

Tertiary structure
Figure 3.19aPage 46
Secondary structure
19
Fourth Level Structure

• Some proteins are made up of more than one
  polypeptide chain

Figure 3.20Page 47
HLA-A2 quaternary structure
20
Hemoglobin
beta chain
beta chain
alpha chain
21
Nucleotide Structure

• Sugar
• At least one phosphate group
• Nitrogen-containing base

ATP
Figure 3.23aPage 50
22
Nucleotide Functions

• Energy carriers
• Coenzymes
• Chemical messengers
• Building blocks for nucleic acids

23
DNA

• Double-stranded
• Sugar-phosphate backbone
• Covalent bonds in backbone
• H bonds between bases

Figure 3.25Page 51
24
RNA

• Usually single strands
• Four types of nucleotides
• Unlike DNA, contains the base uracil in place of
  thymine
• Three types are key players in protein synthesis