molecular cell biology 1 basics of molecular biology

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


EUKARYOTES

PROKARYOTES

All organisms: 1 or more cells


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)


Chromosomes
in a cell that is about to divide

Mitochondria:
factories of energy
glucose

ADP
Pi

O2

CO2
H2O

ATP


smooth (metabolism+synthesis of lipids)

The endoplasmic reticulum

rough (protein synthesis)


The Golgi apparatus

trans

cis

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