Course in Molecular Biology Leuven, October – November 2002 Program Basics of molecular biology Transcription Translation Regulatory pathways DNA and diseases 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 EUKARYOTES PROKARYOTES
The animal cell
A plant cell
A bacterium
The Main Functions of the Membrane-bounded Compartments of a Eukaryotic Cell Compartment Main Function Cytosol contains many metabolic pathways protein synthesis Nucleus contains main genome DNA and RNA synthesis Endoplasmic reticulum (ER) synthesis of most lipids synthesis of proteins for distribution to many organelles and plasma membrane Golgi apparatus modification, sorting, and packaging of proteins and lipids for either secretion or delivery to another organelle Lysosomes intracellular degradation Endosomes sorting of endocytosed material Mitochondria ATP synthesis by oxidative phosphorylation Chloroplasts (in plant cells) ATP synthesis and carbon fixation by photosynthesis Peroxisomes oxidation of toxic molecules
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)
in a cell that is about to divide Chromosomes in a cell that is about to divide
Mitochondria: factories of energy glucose O2 Pi ADP ATP H2O 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 “microtubules” maintainance of cell shape and mobility ancor for other cellular structures
Presentation: DNA
Cell Cycle and Cell Division
Some Eukaryotic Cell-Cycle Times Cell Type Cell-Cycle Times Early frog embryo cells 30 minutes Yeast cells 1.5-3 hours Intestinal epithelial cells about 12 hours Mammalian fibroblasts in culture about 20 hours Human liver cells about 1 year
The eukaryotic cell cycle
Separation of sister chromatides during mitosis (mitosis = normal cell division)
assist chromosomes during cell division (mitosis) 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) Meiosis I
Meiosis I (continued) Meiosis II Haploid cell Cell division without DNA replication Haploid cell
Chromosomes, mitosis and meiosis 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: H2O molecule is released
The four main families of small organic molecules in cells
Glucose, a simple sugar
Monosaccharides
Sugar ring formation in aqueous solution
formed by two sugar monomers 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
the energy carrier 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
possible cause of diseases and disfunctionalities Mutations: possible cause of diseases and disfunctionalities
The Genetic Dogma
From DNA to protein
Transcription by RNA polymerase
RNA vs DNA mRNAs codes for proteins rRNAs forms part of the structure of the ribosome and participates in protein synthesis tRNAs used in protein synthesis as an adaptor between mRNA and amino acids Small RNAs used in pre-mRNA splicing, transport of proteins to ER, and other cellular processes
Genes contain introns and exons
Heredity and inheritance Presentation: Heredity and inheritance