1 Molecular Biology: The Science of the Origins of Life, its Maintenance, and Reneval Mill Adopted from
2 Gl. Der Mol. Biol. WS2010 Assoc. Prof. Dr. Juliane Bogner-Strauss Inst. Genomik and Bioinformatik Grundlagen der Zell- und Molekular-Biologie Folien finden sie auf der IGB-homepage unter Education, Molecular Biology Zusatzinfos (http://whfreeman.com/lodish6e) Molecular Biology, Author: David P. Clark, Publisher: Spektrum Akademischer Verlag.
3 Inhalt Grundlegendes The Dynamic Cell Einleitung Chemische Grundlagen Protein Struktur und Funktion (Aminosäuren, Proteinsynthese (Translation & Faltung), Proteinanalysen) Nukleinsäuren, der genet. Code, und die Synthese von Makromolekülen (Struktur der Basen, Transkription, Analyse der RNA) DNA Replikation, Reparatur, und Rekombination Funktionelle Konzepte Rekombinierte DNA und Genomik (Manipulation von DNA durch Viren usw.) Genetische Analysen in der Zelle (Methoden zur Analyse von Genen) Molekulare Struktur von Genen (packaging, functional modifications, etc.) Kontrolle der Genexpression (Transkriptionelle und posttranskriptionelle Modifikationen) Biomembranen und die subzelluläre Organisation eukaryotischer Zellen (basic structures, function and structure of major organelles + visualization techniques) Transport durch die Zellmembranen (basic classes of transport mechanisms and their function) Zellulärer Energiehausalt (Glycolysis, Aerobic Oxidation, and Photosynthesis) Zell-Zell Signaling: Hormone und Rezeptoren (Gene werden über Signale reguliert-leptin)
4 Chapter 1 The Dynamic Cell An overview
5 The molecules of life The activities of cellular molecules are governed by the basic principles of chemistry Cellular water, inorganic ions, and small organic molecules account for 75-80% of the living weight of a cell Macromolecules (proteins, polysaccharides, DNA, RNA, triglycerides, phospholipids) account for the remainder
6 Cells are packed with molecules of various sizes Figure 1-2
7 Examples of cellular macromolecules Figure 1-3
8 The plasma membrane separates the cell from the environment The fundamental structure of all cell membranes is the lipid bilayer Various membrane proteins present in the different cell membranes give each membrane a specific function Figure 1-6
9 Prokaryotic cells Single cell organisms, single chromosome (circular), haploid Two main types: bacteria (E. coli) and archaea Relatively simple structure (4000 genes and more), 1-10 µm Figure 1-7a
10 Eu- and Archaeabacteria Archaeabacteria grow in extreme environments (high temp, acidic or very salty environment) Archaeabacteria show unusual pathways Cell membranes are totally different in eu- and archaeabacteria (eu:peptidoglycans) Archaeabacteria have ether linkages to build more resistant cell walls (extreme environments!!!)
11 Gram-negativ and gram-positiv Gram-negativ: cytoplasmic membrane, cell wall and outer membrane The outer membrane hinders protein secretion. Not interesting for biotchnological application (such as protein synthesis) Gram-positiv: cytoplasmic membrane and a cell wall
12 Eukaryotic cells Single cell or multicellular organisms, several chromosomes (linear), genes, diploid Plants, animals, protists (Algen) and fungi Structurally more complex: organelles, cytoskeleton Figure 1-7b
13 Cell organelles of eukaryotes Nucleus with nuclear envelope and nuclear pores: contains DNA and mrna. Replication & transcription. Endoplasmatic reticulum: continuous with the nuclear envelope. Lipid and protein synthesis Golgi vesicles: process and modify proteins Mitochondria: generate energy by respiration Lysosomes: digestion (and recycling) of cell material using degradive enzymes Peroxisomes: process molecules using oxygen Secretory vesicles: carry cell material to the plasma membrane to release them Chloroplasts (plants): photosynthesis
14 Begriffserklärungen Totipotency is the ability of a single cell to divide and produce all the differentiated cells in an organism (eg. Plant cells) Pluripotency: Pluripotent stem cells can give rise to any fetal or adult cell type. However, alone they cannot develop into a fetal or adult animal because they lack the potential to contribute to extraembryonic tissue, such as the placenta.
15 Begriffserklärung Multipotent progenitor cells have the potential to give rise to cells from multiple, but a limited number of lineages. An example of a multipotent stem cell is a hematopoietic cell a blood stem cell that can develop into several types of blood cells, but cannot develop into brain cells or other types of cells.
16 Molecular Biology Gene: (ethymology) ancient greek: genos = birth Old Roman meaning of the word genius (Genie): a spirit representing the inborn power of individuals Current Biology: It is becoming increasingly apparent that interactions go in both directions. The 3 core diciplines are becoming overlapping
17 Eukaryotic DNA is packaged into chromosomes Each chromosome is a single linear DNA molecule associated with proteins: chromatin The total DNA in the chromosomes of an organism is its genome Human Chromosome: 46 chromosomes (2n): 44XY or 44XX 22X, 22Y (1n) Each gene in two copies: 1 paternal & 1 maternal give rise to two identical chromosomes = homologous chromosomes = one pair Figure 1-8
18 Basic genetic concepts illustrate the power of genes Gene unit of genetic information Genetics: the study of (whole) individual genes Genome the total genetic information of an organism Genomics: the study of genes in the context of all genes Phenotype apparent difference Genotype genetic difference (not always apparent) Diploid (somatic cells, each gene in two copies) Haploid (gametocytes, germline cells, each gene in one copy) aploid (mature red blood cells, no nucleus, no chromosomes)
19 Basic genetic concepts illustrate the power of genes Allele: alternative forms of a single gene (red and white flower) Alleles: (Dominant/Recessive/Codominant) R + R -> Red Petunia B+r -> Blue Petunia B+R -> Purple Petunia R + r -> Red Petunia B+B -> Blue Petunia r+r -> White Petunia R_red dom, r_white rez, B_blue dom Homozygous (two identical alleles) Heterozygous (two different alleles) Mendelian Ratios (Gregor Mendel )
20 Begriffserklärungen Dominant: Allel, dessen Eigenschaften im Phänotyp in Erscheinung treten, egal ob es nur in einer oder in beiden Kopien vorhanden ist. Rezessiv: Allel, dessen Eigenschaften nur im homozygoten Zustand in Erscheinung treten, im heterozygoten Zustand vom dominanten Allel überdeckt. Co-dominant: zwei verschiedene Allele tragen gemeinsam zur Merkmalsausprägung bei Penetranz: Wahrscheinlichkeit, mit der sich ein Allel phänotypisch ausprägt.
21 Classical Mendelian inheritance CC x cc: F1: c c C C Cc Cc Cc Cc F2: (Cc x Cc) C c C c CCCc Cc cc
22 Mol Biol history Key Discoveries: 1928 Heritable changes can be transmitted from bacterium to bacterium through a chemical extract (the transforming factor) taken from other bacteria The transforming factor appears to be DNA The tetranucleotide hypothesis of DNA structure is overthrown (triplet code discovered) The structure of DNA is established to be a double helix The first complete draft of the nucleotide sequence of a copy of the human genome is completed (human genome project, HGS) Recent Epigenetics, variations in reversible chemical modifications of the human genome structure, is being recognized as equally important as the DNA nucleotide sequence in determining heritance
23 The Human Genome Project A complete draft of the nucleotide sequence of one copy of a human genome 3 x 10 9 nucleotides in the human genome Average gene ~ 10 kb Number of genes now estimated at (~ 10% of the genome) Genome Project as Database What will remain, as the project's enduring contribution, is a vast amount of computerized knowledge. Seen in this light, the Human genome Project is nothing but the effort to create the most important database ever attempted the database containing instructions for creating life. (First genome sequence finished in 2003) -But how to read these instructions...?
24 Overview of four basic molecular genetic processes
25 The life cycle of cells Cell division occurs when one cell, after a period of growth, divides to become two daughter cells Most eukaryotic cells follow the cell cycle, an internal clock that determines the phases of cell growth and division Progress through the cell cycle is controlled at checkpoints Cells may leave the cell cycle and differentiate to perform specialized functions Cells may undergo programmed cell death as a way of balancing cell growth or generating structures during development (apoptosis)
26 Cells associate to form tissues Tissues are composed of cells and extracellular matrix Tissues may form organs Rudimentary tissues and an overall body plan form early in development due to a defined pattern of gene expression and the ability of cells to interact with other cells Many animals share the same basic pattern of development, which reflects commonalities in molecular and cellular mechanisms controlling development
27 Multiple tissues combine to create this artery Figure 1-11
28 -or identical sheep Sharing identical genetic material (genomes)
29 At the completion of this lecture you should be able to: Name the basic contents of cells (water, salts, different macromolecules) Describe the basic concepts of genetics Explain Mendelian heritance Name the 4 basic molecular genetic processes