Introduction to Molecular Biology
By
Dr Anjana Bhatia
Head, PG Deptt of Botany
HMV, Jalandhar
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
Cell is the basic unit of life
PROKARYOTES
EUKARYOTES
A plant cell
The animal 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
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
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)
Meiosis I
Meiosis I (continued)
Meiosis II
Cell division without DNA replication
⇒ Haploid cell