Course in Molecular Biology

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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

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Lesson 1: Basics of molecular biology

I. The Cell’s Organization

II. Cell Cycle and Cell Division III. Cellular Molecules

IV. The Genetic Dogma

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The Cell’s Organization

(4)

All organisms: 1 or more cells

P R O K A R Y O T E S E S

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The animal cell

(6)

A plant cell

(7)

A bacterium

(8)

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

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Compartimentation of the eukaryote cell:

various organelles

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Cell nucleus

Contains genetic information: DNA

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Each human cell contains 46 chromosomes (except sperm or egg cells)

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Chromosomes

in a cell that is about to divide

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Mitochondria:

factories of energy

glucose O₂

P_i ADP

H₂O ATP

CO₂

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The endoplasmic reticulum

smooth (metabolism+synthesis of lipids)

rough (protein synthesis)

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The Golgi apparatus

cis trans

medial

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Inside the cytosol:

the cytoskeleton

 “microtubules”

 maintainance of cell shape and mobility

 ancor for other cellular structures

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Presentation:

DNA

(19)

Cell Cycle and Cell Division

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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

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The eukaryotic cell cycle

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Separation of sister chromatides during mitosis

(mitosis = normal cell division)

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Microtubuli:

assist chromosomes during cell division (mitosis)

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Different stages of the M phase during cell division (mitosis)

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The three DNA sequence elements needed to produce a eukaryotic

chromosome that can be replicated and then segregated at mitosis

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Kinetochores and kinetochore microtubules

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Gametogenesis: meiosis

(= specialized form of cell division giving rise to sperm and egg cells)

M e io si s I

(28)

Meiosis I (continued) Meiosis II

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Presentation:

Chromosomes, mitosis and meiosis

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Cellular Molecules

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The four main families of small organic molecules in cells

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Macromolecules are abundant in cells

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The general reaction by which a macromolecule is made

Condensation reaction: H

₂

O molecule is released

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The four main families of small organic molecules in cells

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Glucose, a simple sugar

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Monosaccharides

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Sugar ring formation in aqueous solution

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Disaccharides:

formed by two sugar monomers

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Oligo- and polysaccharides

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Complex oligosaccharides

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The four main families of small organic molecules in cells

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Phospholipid structure and orientation of phospholipids in membranes

(46)

The four main families of small organic molecules in cells

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A simple amino acid: alanine

(48)

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A small part of a large protein molecule

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The four main families of small organic molecules in cells

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ATP:

the energy carrier in cells

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Various functions of proteins

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Proteins as polypeptide chains

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Three types of noncovalent bonds that help proteins fold

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The size of proteins

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Several levels of protein organization

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Many protein molecules contain multiple copies

of a single protein subunit

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Proteins often have highly specific binding sites

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How a set of enzyme-catalyzed reactions generates a metabolic pathway

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Phosphorylation and ATP hydrolysis drive protein functions

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Genetic information is stored in the DNA

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DNA and its building blocks

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DNA has an orientation

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DNA encodes proteins

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“Genes” encode proteins

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DNA replication

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DNA synthesis and proofreading

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Replication of eukaryotic chromosomes

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The replication fork in detail

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DNA replication can cause mutations

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DNA repair

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Mutations:

possible cause of diseases and disfunctionalities

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The Genetic Dogma

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From DNA to protein

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Transcription by RNA polymerase

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RNA vs DNA

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Genes contain introns and exons

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