The Cell
Cell Biology 1 A discipline of biology: 1. Cell structure 2. Cellular processes 3. Cell division Tight connection with 1. Molecular biology 2. Biochemistry
Cell theory 2 1838, 1839 Theodor Schwann Matthias J. Schleiden 1. All living things are composed of one or more cells 2. Cells are the basic units of structure and function in living things
Cell theory 2 3. Omnis cellula e cellula All cells are derived from cells (by means of multiplication) Rudolph Virchow
Germ theory 3 Louis Pasteur 1860 s Microorganisms are not generated from inanimate material but rather as a result of biogenesis (from other microbes) - The discovery that a prokaryotic cell stems from another prokaryotic cell
5 Classification of living beings Prokaryotes Eukaryotes Plants Animals Fungi III. Protista Eubacteria Archaebacteria I. II.
What about the viruses? 6 They are not living beings, since they are not capable for independent life (cell parasites) Origin: I. Simplified cells II. Derived from the DNA of host cell
The origin of cells 7 DNA RNA DNA nucleus cytoplasmic DNA RNA cells prokaryotic cell eukaryotic cell
8 The origin of DNA DNA world RNA world The virus hypothesis: - viruses discovered the DNA
9 The origin of proteins RNA world protein world
Origin of nucleus The arhaezoa hypothesis 10 Thomas Cavalier-Smith Origin of ER andgolgi
Lynn Margulis 11 Origin of mitochondrion - Endosymbiotic theory
Origin of chloroplast - Endosymbiotic theory 12 Lynn Margulis Elysia chlorotica A plant-animal
Prokaryotic cell plasmid
Prokaryotic cell Spherical cells e.g. Streptococcus Rod-shaped cells e.g. Escerichia coli Spiral cells e.g. Treponema pallidum
Multicellular prokaryotes Nitrogen fixation spore photosynthesis Anabaena cylindrica
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Compartmentalization
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Nucleus
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Mitochondrion
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Cytoskeleton
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Ribosomes Rough ER
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Golgi apparatus
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Smooth ER
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Extracellular space Intracellular space Cell membrane
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Ribosomes bound to rough ER
Figure 4.7 Eukaryotic Cells (Part 1) Animal cell Centrioles
Plant cell
Plant cell Free ribosomes
Plant cell Nucleus Nucleolus
Plant cell Golgi apparatus
Plant cell Plasmodesm
Plant cell Chloroplast
Plant cell Mitochondrion
Cell wall Plant cell
Peroxisome Plant cell
Cell membrane Plant cell
Smooth ER Plant cell
Plant cell Rough ER
Inclusion body Plant cell
Animal cell Plant cell Inclusion body chloroplast cell wall
Prokaryotic cells vs. eukaryotic cells Differences Only in eukaryotes: 1. Cell nucleus 2. Membrane-bound organelles Only in prokaryotes 1. Proteoglycan cell wall 2. Capsule Prokaryotic cell Eukaryotic (animal) cell
Cell membrane 1. Separation selective transport 2. Communication
Cell membrane - fluid mosaic model 1. Phospholipid molecules 1. Protein molecules lipid double layer 2. Phospholipid molecule Protein 1. 3.
Phospholipids Cholesterol: decreases fluidity phosphatidyl choline
22 Glycocalyx glycocalyx cytoplasm nucleus cell membrane
Membrane microdomains - lipid rafts phospholipids and membrane proteins are not randomly distributed in cell membranes
Nucleus Nucleoplasm Outer membrane Inner membrane Nucleolus Chromatin Nuclear lamina Nuclear membrane Pore
importin Nuclear membrane exportin Nuclear membrane inner outer ER membrane ER lumen protein protein protein Nuklear lamina RNA perinuclear space Nuclear pore NLS: nuclear localization signal NES: nuclear export signal Signal peptides
Chromosomes Human: haploid chromosome set Giemsa staining
Chromatin Metaphase chromosome DNA 8 histone core Histone H1 Solid form Relaxed form DNA H1 H2A DNA and nucleosomes H3 H4 NUCLEOSOME H2B DNA and nucleosomes 8 histone core DNA
Ribosomes Ribosomes are complexes of proteins and RNA molecules. They carry out the synthesis of proteins. Soluble proteins are synthesized by cytoplasmic ribosomes, while membrane and exported proteins are produced by ribosomes of the rough endoplasmic reticulum. 30S subunit Proteins: blue RNAs: orange
Endoplasmic reticulum Rough ER Rough ER Smooth ER Smooth ER ribosomes FUNCTION 1. Lysosomal enzymes 2. Secreted proteins 3. Trans-membrane proteins 4. Glycosylation 1. Lipid and steroid synthesis 2. Carbohydrate metabolism 3. Calcium storage 4. etc.
Protein maturation in the rough ER
Golgi apparatus FUNCTION: 1. Proteins and lipids (a) chemical modification (glycosylation and phosphorylation) (b) packaging and (c) sorting 2. Carbohydrate synthesis 3. Proteoglycan synthesis cisterns incoming (from ER) Transport vesicles outgoing
Golgi apparatus Nucleus Inside of cell Rough endoplasmic reticulum cis region medial region Golgi apparatus Proteins for use within the cell trans region Plasma membrane Proteins for use outside the cell Outside of cell
Peroxysomes, lysosomes peroxysome lysososome - Small membrane vesicles, containing enzymes that degrade peroxides and free radicals - Metabolism of fatty acids - Enzymes of the peroxisomes are found in crystalline form Acidic vesicles full of enzymes (they digest: proteins, nucleic acids, lipids, polysaccharides)
Lysosomes Inside of cell Primary lysosome Secondary lysosome Phagosome Food particles taken in by phagocytosis Plasma membrane Outside of cell
Proteasomes Proteasomes are enzyme complexes degrading proteins Proteins are degraded for several reasons: - misfolded (abnormal) proteins are destroyed - some proteins are made only for short periods of time - enzymes, regulatory proteins are degraded, when not needed - when cells are starving for amino acids There are labels (ubiquitin peptide), which identify protein molecules to be degraded. lysosome
Mitochondrion outer membrane matrix inner membrane Inter-membrane space
Chloroplast
Chloroplast Granum - stacks of thylakoids
Cytoskeleton
Cytoskeleton Microtubule Intermediate filament Microfilaments rough ER
Cytoskeleton 1. Maintains cell shape 2. Provides for various types of cell movement 3. Helps move things within the cell Microtubules Intermediate filament rough ER Microfilament cell membrane
Microfilaments Made up of strands of the protein actin and often interact with strands of other proteins They change cell shape and drive cellular motion, including contraction, cytoplasmic streaming, and the pinched shape changes that occur during cell division Microfilaments and myosin strands together drive muscle action Actin monomer
Intermediate filaments Made up of fibrous proteins organized into tough, ropelike assemblages that stabilize a cell s structure and help maintain its shape Some intermediate filaments help to hold neighboring cells together Others make up the nuclear lamina Fibrous subunit
Long, hollow cylinders made up of many molecules of the protein tubulin. Tubulin consists of two subunits, a-tubulin and b-tubulin Microtubules lengthen or shorten by adding or subtracting tubulin dimers Microtubule shortening moves chromosomes Interactions between microtubules drive the movement of cells Microtubules serve as tracks for the movement of vesicles Microtubules b-tubulin monomer a-tubulin monomer Tubulin dimer
Cytoskeleton - Cell division