Course in Molecular Biology
Leuven, October – November 2002
Program
I. Basics of molecular biology II. Transcription
III. Translation
IV. Regulatory pathways
V. DNA and diseases
VI. Biotechnology
Lesson 1: Basics of molecular biology
I. The Cell’s Organization
II. Cell Cycle and Cell Division III. Cellular Molecules
IV. The Genetic Dogma
The Cell’s Organization
All organisms: 1 or more cells
PROKARYO T ES EUKARYOT ES
The animal cell
A plant cell
A bacterium
The Main Functions of the Membrane-bounded Compartments of a Eukaryotic Cell
oxidation of toxic molecules Peroxisomes
ATP synthesis and carbon fixation by photosynthesis Chloroplasts (in plant
cells)
ATP synthesis by oxidative phosphorylation Mitochondria
sorting of endocytosed material Endosomes
intracellular degradation Lysosomes
modification, sorting, and packaging of proteins and lipids for either secretion or delivery to another organelle
Golgi apparatus
synthesis of most lipids
synthesis of proteins for distribution to many organelles and plasma membrane
Endoplasmic reticulum (ER)
contains main genome DNA and RNA synthesis Nucleus
contains many metabolic pathways protein synthesis
Cytosol
Main Function
Compartment
Compartimentation of the eukaryote cell:
various organelles
Cell nucleus
Contains genetic information: DNA
Nucleolus:
Ribosome building machine
Protein factories in the cytoplasm
Each human cell contains 46 chromosomes (except sperm or egg cells)
Chromosomes
in a cell that is about to divide
Mitochondria:
factories of energy
glucose O2
Pi ADP
H2O ATP
CO2
The endoplasmic reticulum
smooth (metabolism+synthesis of lipids)
rough (protein synthesis)
The Golgi apparatus
cis trans
medial
→
→
→
→ processing of secretory proteins
→
→
→
→ sorting cellular proteins
Inside the cytosol:
the cytoskeleton
ü “microtubules”
ü maintainance of cell shape and mobility ü ancor for other cellular structures
Presentation:
DNA
Cell Cycle and Cell Division
Some Eukaryotic Cell-Cycle Times
about 1 year Human liver cells
about 20 hours Mammalian fibroblasts in culture
about 12 hours Intestinal epithelial cells
1.5-3 hours Yeast cells
30 minutes Early frog embryo cells
Cell-Cycle Times
Cell Type
The eukaryotic cell cycle
Separation of sister chromatides during mitosis
(mitosis = normal cell division)
Microtubuli:
assist chromosomes during cell division (mitosis)
Different stages of the M phase during cell division (mitosis)
The three DNA sequence elements needed to produce a eukaryotic
chromosome that can be replicated and then segregated at mitosis
Kinetochores and kinetochore microtubules
Gametogenesis: meiosis
(= specialized form of cell division giving rise to sperm and egg cells)
Meiosi s I
Meiosis I (continued) Meiosis II
Cell division without DNA replication
Þ Þ Þ
Þ Haploid cell
Presentation:
Chromosomes, mitosis and meiosis
Cellular Molecules
The four main families of small organic molecules in cells
Macromolecules are abundant in cells
The general reaction by which a macromolecule is made
Condensation reaction: H
2O molecule is released
The four main families of small organic molecules in cells
Glucose, a simple sugar
Monosaccharides
Sugar ring formation in aqueous solution
Disaccharides:
formed by two sugar monomers
Oligo- and polysaccharides
Complex oligosaccharides
The four main families of small organic molecules in cells
Phospholipid structure and orientation of phospholipids in membranes
The four main families of small organic molecules in cells
A simple amino acid: alanine
A small part of a large protein molecule
The four main families of small organic molecules in cells
ATP:
the energy carrier in cells
Various functions of proteins
Proteins as polypeptide chains
Three types of noncovalent bonds that help proteins fold
The size of proteins
Several levels of protein organization
Many protein molecules contain multiple copies
of a single protein subunit
Proteins often have highly specific binding sites
How a set of enzyme-catalyzed reactions generates a metabolic pathway
Phosphorylation and ATP hydrolysis drive protein functions
Genetic information is stored in the DNA
DNA and its building blocks
DNA has an orientation
DNA encodes proteins
“Genes” encode proteins
DNA replication
DNA synthesis and proofreading
Replication of eukaryotic chromosomes
The replication fork in detail
DNA replication can cause mutations
DNA repair
Mutations:
possible cause of diseases and disfunctionalities
The Genetic Dogma
From DNA to protein
Transcription by RNA polymerase
RNA vs DNA
used in pre-mRNA splicing, transport of proteins to ER, and other cellular processes
Small RNAs
used in protein synthesis as an adaptor between mRNA and amino acids tRNAs
forms part of the structure of the ribosome and participates in protein synthesis
rRNAs
codes for proteins mRNAs
