Upload
alisa-anderson
View
45
Download
1
Embed Size (px)
DESCRIPTION
The Chemical Building Blocks of Life. Chapter 3. Outline. Biological Molecules Macromolecules Proteins Structure and Denaturation Nucleic Acids DNA and RNA Lipids Fats and Phospholipids Carbohydrates Transport and Storage. Biological Molecules. - PowerPoint PPT Presentation
Citation preview
1
The Chemical Building Blocks of Life
Chapter 3
2
Outline
• Biological Molecules– Macromolecules
ProteinsStructure and Denaturation
Nucleic AcidsDNA and RNA
LipidsFats and Phospholipids
CarbohydratesTransport and Storage
3
Biological Molecules
• The framework of biological molecules consists of carbon bonded to other carbon molecules, or other types of atoms.
– Hydrocarbons consist of carbon and hydrogen.
Covalent bonds store considerable energy.
4
Biological Molecules
• Functional groups– specific groups of atoms attached to
carbon backbones retain definite chemical properties
• Macromolecules.– proteins– nucleic acids– lipids– carbohydrates
5
Macromolecules
• Macromolecules are often polymers.– long molecule built by linking together
small, similar subunits Dehydration synthesis removes OH and
H during synthesis of a new molecule. Hydrolysis breaks a covalent bond by
adding OH and H.
6
Proteins
• Protein functions:– enzyme catalysis– defense– transport– support– motion– regulation– storage
7
Amino Acids
• contain an amino group (-NH2), a carboxyl group (-COOH) and a hydrogen atom, all bonded to a central carbon atom
– twenty common amino acids grouped into five classes based on side groups
nonpolar amino acids polar uncharged amino acids charged amino acids aromatic amino acids special-function amino acids
8
Amino Acids
• Peptide bond links two amino acids.– A protein is composed of one or more long
chains of amino acids linked by peptide bonds (polypeptides).
9
Protein Structure
• Protein function is determined by its shape.– Protein structure
primary - specific amino acid sequence secondary - folding of amino acid chains motifs - folds or creases
supersecondary structure
10
Protein Structure
tertiary - final folded shape of globular protein
domains - functional units quaternary - forms when two or more
polypeptide chains associate to form a functional protein
11
Chaperone Proteins
• Chaperone proteins are special proteins which help new proteins fold correctly.
– Chaperone deficiencies may play a role in facilitating certain diseases.
12
Unfolding Proteins
• Denaturation refers to the process of changing a protein’s shape.
– usually rendered biologically inactive salt-curing and pickling used to preserve
food
13
Nucleic Acids
• Deoxyribonucleic Acid (DNA)– Encodes information used to assemble
proteins.• Ribonucleic Acid (RNA)
– Reads DNA-encoded information to direct protein synthesis.
14
Nucleic Acid Structure
• Nucleic acids are composed of long polymers of repeating subunits, nucleotides.
– five-carbon sugar– phosphate– nitrogenous base
purinesadenine and guanine
pyrimidinescytosine, thymine, and uracil
15
Nucleic Acid Structure
• DNA exists as double-stranded molecules.– double helix– complementary base pairing
hydrogen bonding• RNA exists as a single stand.
– contains ribose instead of deoxyribose– contains uracil in place of thymine
16
Structure of DNA
17
Lipids
• Lipids are loosely defined as groups of molecules that are insoluble in water.
– fats and oils• Phospholipids form the core of all biological
membranes.– composed of three subunits
glycerol fatty acid phosphate group
18
Fats and Other Lipids
• Fats consist a of glycerol molecule with three attached fatty acids (triglyceride / triglycerol).
– Saturated fats - all internal carbon atoms are bonded to at least two hydrogen atoms
– Unsaturated fats - at least one double bond between successive carbon atoms
Polyunsaturated - contains more than one double bond
usually liquid at room temperature
19
Fats as Energy Storage Molecules
• Fats, on average, yield about 9 kcal per gram versus 4 kcal per gram for carbohydrates.
– Animal fats are saturated while most plant fats are unsaturated.
Consumption of excess carbohydrates leads to conversion into starch, glycogen, or fats for future use.
20
Carbohydrates
• Carbohydrates are loosely defined as molecules that contain carbon, hydrogen, and oxygen in a 1:2:1 ratio.
– monosaccharides - simple sugars– disaccharides - two monosaccharides
joined by a covalent bond– polysaccharides - macromolecules made
of monosaccharide subunits isomers - alternative forms of the same
substance
21
Carbohydrate Transport and Storage
• Transport disaccharides– Humans transport glucose as a simple
monosaccharide.– Plants transform glucose into a
disaccharide transport form.• Storage polysaccharides
– plant polysaccharides formed from glucose - starches
most is amylopectin
22
Structural Carbohydrates
• Cellulose - plants– alpha form or beta form of ring
• Chitin - arthropods and fungi– modified form of cellulose
23
Summary
• Biological Molecules– Macromolecules
ProteinsStructure and Denaturation
Nucleic AcidsDNA and RNA
LipidsFats and Phospholipids
CarbohydratesTransport and Storage
24