Cell and Molecular Biology (2141591) Instructors: Pimpon Uttayarat, Ph.D. (Course Coordinator) Kanokporn Boonyasirichai, Ph.D. Suwimol Jetawattana, Ph.D. Siraprapha Sanchatjate, Ph.D. [email protected]textBook: Molecular Biology of the Cell, 4 th edition by Alberts et al. and also selected journal paper Grading: Homework 20% Midterm 30% Class Participation 10% Final 30% Presentation 10%
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Nitrogen in ring compounds: purine and pyrimidines
covalent bond: P bonds covalent bond: P bonds
Panel 2-1 Molecular Biology of the Cell, 4th edition
Bonds of Pi to OH, COOH, Pi
Phosphorylation of protein
The folded structures and macromolecular interactions that determine much of the cell biology are governed largely by noncovalent bonds and repulsion forces that have energy greater than kT but less than a typical covalent bond.
Non-covalent bonds have less than 1/20 the strength of a covalent bond
Panel 2-3 Molecular Biology of the Cell, 4th edition
• van der Waals interactions
• hydrogen bonds
• ionic interactions
• the hydrophobic effect
determined by the unusual chemical properties of water
Noncovalent bond Noncovalent bond
Bond energy
Figure 2-7 Molecular Biology of the Cell, 4th edition
Table 2-2 Molecular Biology of the Cell, 4th edition
Panel 2-3 Molecular Biology of the Cell, 4th edition
Panel 2-3 Molecular Biology of the Cell, 4th edition
Example of ionic interaction Example of ionic interaction
Electrostatic attraction brings molecules together in cells
Panel 2-3 Molecular Biology of the Cell, 4th edition
Any molecules that can form hydrogen bonds to each other can alternatively form hydrogen bonds to water molecules. This is relatively a weak bond.
Noncovalent bond: hydrogen bond Noncovalent bond: hydrogen bond
Hydrogen bonds form when a hydrogen atom is “sandwiched” between two electron-attracting atoms (usually O or N)
Hydrogen bonds among H2O molecules Hydrogen bonds among H2O molecules
Each water molecules can form H-bond through its two H atoms to two other water molecules, producing a network in which H bonds are being continually broken and formed.
Because of these interlocking H bonds, water is liquid at RT with high boiling point and high surface tension and not a gas.
Panel 2-3 Molecular Biology of the Cell, 4th edition
Panel 2-3 Molecular Biology of the Cell, 4th edition
Oil is immiscible in water
Panel 2-2 Molecular Biology of the Cell, 4th edition
Hydrophilic molecules are readily dissolved in water.
Hydrophobic effect drives phospholipids to aggregate and form lipid bilayers
Figure 2-22 Molecular Biology of the Cell, 4th edition
Figure 2-12 Molecular Biology of the Cell, 4th edition
Figure 2-17
5 > 1 mm
20 5-1000 nm
2 nm1000
100 ~ 100 um
Building blocks of cells Building blocks of cells
Figure 2-29
Figure 2-24
Amino acids are the subunits of proteins. All amino acids possess a carboxylic acid group and an amino group, both linked to a single carbon atom called -carbon.
Condensation reaction strings the building blocks together
Figure 2-65
amino acids proteins amino acids proteins
Proteins are polymers of amino acids joined head-to-tail by a peptide bond into a long chain that is then folded into a three-dimensional structure. A chain of amino acids is also known as polypeptide.
Figure 2-24Figure 3-24
Panel 2-4 Molecular Biology of the Cell, 4th edition
Monosaccharides that contain an aldehyde group are called
aldoses and those that contain a ketone group are called ketoses.
Figure 2-19 Molecular Biology of the Cell, 4th edition
In a condensation (dehydration) reaction, hydroxyl groups on each monosaccharide forms a glycosidic bond with a loss of one water molecule. When a water molecule is added during hydrolysis, this newly formed disaccharide is broken into two monosaccharides.
Glycosidic bond ties monosaccharides together Glycosidic bond ties monosaccharides together
Large linear and branched molecules can be made from repeating sugar subunits. Short chains are called oligo saccharides and long chains are called polysaccharides. Glycogen is polysaccharides made entirely of glucose units.
Panel 2-4 Molecular Biology of the Cell, 4th edition
Panel 2-5 Molecular Biology of the Cell, 4th edition
fatty acids fatty acids
Panel 2-5
phospholipids are the major constituents of cell membranes phospholipids are the major constituents of cell membranes
Phosphate head
Fatty acid tail
glycerol
Fig. 10-1
triacylglycerols triacylglycerols
Panel 2-5
Other lipids Other lipids
Panel 2-5
A nucleotide consists of a nitrogen-containing base, a five-carbon sugar and one or more phosphate groups.
Panel 2-6 Molecular Biology of the Cell, 4th edition
Phosphate group makes nucleotide negatively charged.
The presence of hydroxyl group on the 2nd carbon of ribose differentiates RNA from DNA.
Bases are nitrogen-containing ring compounds. DNA and RNA are different in their bases.
The sugar constituents of nucleic acids are five-carbon sugars that belong to the aldose type.
Panel 2-6 Molecular Biology of the Cell, 4th edition
sugars sugars
nomenclature
DNA: A T C G
RNA: A U C G
Panel 2-6 Molecular Biology of the Cell, 4th edition
bases bases
Nucleotides are joined together by a phosphodiester linkage between 5’ and 3’ carbons to form nucleic acids.
Panel 2-6 Molecular Biology of the Cell, 4th edition
The linear sequence is read in a one-letter code such as G-A-T-C from 5’ to 3’.
-H2O
nucleic acids nucleic acids
The synthesis of polysaccharides, proteins and nucleic acids
Key: condensation reaction to form macromolecules from small subunits (monomers) consumption of energy from nucleotide triphosphates to activate the monomers