Course in Molecular BiologyLeuven, 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

PR

OK

AR

YO

TE

SE

UK

AR

YO

TE

S

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 pathwaysprotein synthesis

Nucleus contains main genomeDNA and RNA synthesis

Endoplasmic reticulum (ER)

synthesis of most lipidssynthesis 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)

Chromosomesin a cell that is about to divide

Mitochondria: factories of energy

glucose

O2

Pi

ADP

ATPH2O

CO2

The endoplasmic reticulumsmooth (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)

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)

Me

iosi

s I

Meiosis I (continued) Meiosis II

Cell division without DNA replication

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: 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

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 copiesof 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

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

Presentation:Heredity and inheritance