Sylvia S Mader Immagini e concetti della biologia
Sylvia S. Mader Immagini e concetti della biologia Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
A 4 - Observing the Cell 3 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Cells are the basic units of life CELL THEORY • The cell is the basic unit of life • All living things are made up of cells • New cells evolve only from preexisting cells 4 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Cells are the basic units of life Unicellular Organisms Older organisms, consist of a single cell. Multicellular Organisms More evolved, have multiple cells organized in tissues, organs and systems. 5 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Cells have small dimensions Cells are small in size in order to maintain a correct surface/volume ratio. Smaller volumes Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Higher surfaces 6
Cells have small dimensions In order to observe cells smaller than 0. 1 mm a microscope is necessary 7 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Optical Light Microscope (LM) LM uses visible light and a system of lenses to magnify images. The power of a light microscope is about 0. 2 μm. 8 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Transmission Electron Microscope A TEM uses a beam of electrons to illuminate a specimen and produce a magnified image. The most powerful TEM have a resolution of about 0. 1 nm. 9 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Scanning Electron Microscope A SEM collects and focuses beams of electrons on a specimen’s surface and produce a three-dimensional image. 10 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
All organisms may be classified as prokaryotes or eukaryotes Prokaryotes and eukaryotes possess two basic features: a plasma membrane and a cytoplasm. 11 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Prokaryotic cell (pro = before, karyon = nucleus) • Evolved first • Lack a membrane-bounded nucleus • Simpler structure than Eukaryotic cells • Archaea and Bacteria 12 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Eukaryotic cell (eu = well, karyon = nucleus) • Membrane-bounded nucleus • Well organized organelles • Animal cell and plant cell 13 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Animal cell Nucleus: it contains chromatin and is enclosed in a nuclear envelop with double membrane and nuclear pores Plasma Endoplasmic reticulum: is divided into: • Rough E. R. , studded with ribosomes and membrane: composed of phospholipids and proteins, protects the cell and regulates the transport of substances involved in the synthesis of proteins • Smooth E. R. , lack in ribosome and involved in the synthesis of lipids Ribosomes: small particles that carry out protein synthesis Cytoskeleton: maintains cell shape and assists movements of cell products Peroxisome: Cytoplasms: vesicles with various functions semifluid matrix containing and supporting organelles Mitochondrion: Responsible respiration production Vesicles: membrane-bounded sac that store and transport cell material for nuclear and ATP Polyribosomes: string of ribosomes simultaneously synthesizing same protein Lysosomes: type of vesicles that digest macromolecules and cell parts Golgi Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 apparatus: packages proteins and secrets macromolecules 14
Plant cell Central Vacuole: store metabolites and help maintain cell turgor Nucleus Chloroplast: carries out photosynthesis, producing sugar E. R. Mitochondrion Golgi apparatus Plasma membrane Granum: a stack of chlorophyllcontaining thylakoids in chloroplast Cell wall: outer membrane that shapes, supports and protects the cell 15 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Protein Synthesis starts from DNA The genetic information needed for the protein synthesis is contained inside the nucleus. Here genes, composed of DNA, are located on chromosomes. 16 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Protein Synthesis starts from DNA m. RNA transports the genetic information to the cytoplasm where it joins with ribosomal subunits and the protein synthesis starts. 17 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Protein Synthesis starts from DNA Ribosomes in the cytoplasms and embedded on the E. R. carry out the protein synthesis. The new forming protein enters the Endoplasmic Reticulum lumen and folds into its final shape. 18 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Protein synthesis is the cell major Function Proteins (produced in the rough ER) and lipids (produced by the smooth ER) are secreted out to the Golgi apparatus through vesicles. 19 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
The Golgi apparatus packages the proteins into macromolecules Macromolecules Transport vesicles Golgi apparatus Vesicles, as lysosomes, leave the Golgi apparatus and travel to the plasma membrane where secretion occurs. ER 20 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Vesicles and vacuoles • Lysosomes: contain enzymes that digest macromolecules. • Peroxisomes: similar to lysosomes, break down fatty acids. • Vacuoles: usually are use as cell store (water, sugar, sap) and maintain turgor. Animal cell Plant cell 21 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Exocytosis (eso = out, cyto = cell) ER, Golgi apparatus and vesicles work in synergy in order to direct the contents of secretory vesicles out of the cell membrane. 22 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Energy Transformations Mitochondria and Chloroplast are the “power stations” of the cell as control the energy production through respiration and photosynthesis. 23 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Chloroplasts In plants, algae and some bacteria solar energy is used through photosynthesis to produce carbohydrates (glucose) and oxygen from carbon dioxide and water. 6 CO 2 + 6 H 2 O Carbon dioxide Water C 6 H 12 O 6 + 6 O 2 Glucose Oxygen 24 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Chloroplasts Stroma: protein-rich fluid where carbohydrates synthesis occur. Thylakoid membranes: contain chlorophyll and capture solar energy. 25 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Mitochondria Eukaryotic organisms generate energy (ATP) through the respiration, using oxygen to release the energy stored in glucose. C 6 H 12 O 6 + 6 O 2 Glucose Oxygen 6 CO 2 + 6 H 2 O Carbon dioxide Water 26 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Mitochondria are divided into compartments: the outer membrane, the intermembrane space, the inner membrane, the cristae and matrix. Matrix breaks down glucose while cristae produces ATP. 27 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Mitochondrial Diseases Mutations on Mitochondrial DNA (mt. DNA) have been linked to various diseases such as Alzheimer's disease and Parkinson's disease. Mitochondria in a muscular tissue 28 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Cytoskeleton The cytoskeleton consists of filaments and microtubules. It maintains the cell's shape and is involved in the transport of parts of the cell. The eukaryotic cytoskeleton is composed of actin filaments, intermediate filaments and microtubules. 29 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Actin filaments Organized in bundles and networks and play a key structural role in the cell. As they are flexible and relatively strong, actin filaments function in cell amoeboid movement and crawling. 30 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Intermediate filaments Rope like assemblies of polypeptides having structural function in the cell nucleus. Intermediate filaments have an average diameter of 10 nm. 31 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Microtubules Made of a globular protein called tubulin. They can be considered as the “motorway of the cell”. Motor proteins move along them and carry materials inside vesicles 32 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Cilia and flagella Whiplike appendages that protrude from the cell body of certain prokaryotic and eukaryotic cells. They typically serve as sensory organelles or for locomotion. Cilia (singular cilium) shorter (2 -10 μm). are Flagella (singular flagellum) are longer (200 μm). 33 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Communication through cells Plant cells are joined to one another through microscopic channels called plasmodesmata, enabling transport and communication between them. 34 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
Communication through cells Animal cells are joined by anchoring junctions (or desmosoma), tight junctions and gap junctions. 35 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012
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