Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Cell growth wikipedia , lookup
Cell culture wikipedia , lookup
Cellular differentiation wikipedia , lookup
Signal transduction wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cytokinesis wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cell membrane wikipedia , lookup
List of types of proteins wikipedia , lookup
Objectives The Nucleus form and information Tom Hartman • • • • • • Detecting the nucleus. Observing the nucleus. Ultrastructure of the nucleus. Properties of the nucleus. Physical components of the nucleus. Activities of the nucleus. Cell theory • Robert Hooke was the first person to observe cells in 1665. – He observed thin slices of cork under a simple microscope. – He saw tiny empty compartments that he called cells after the ‘bedrooms’ in monasteries. – He noted that other plant cells contain ‘juices’. • In 1820 Robert Brown observed a sphere-like structure in every cell. He named it the nucleus. • In 1855 Rudolf Virchow stated that new cells arise from the division of pre-existing cells and that chemical reactions needed for life occurred inside the cell. • In 1883 Mathias Schleiden and Theodor Schwann proposed that all plants and animals were composed of cells. Cell theory 1. All organisms are composed of one or more cells. 2. The cell is the basic, living unit of organisation. 3. Cells arise from pre-existing cells. 4. Each cell maintains itself within optimal parameters: homeostasis. The study of cells is called cytology. What has a nucleus? • No nucleus is found in: – – – – Bacteria Viruses Prions Some specialised cells • Possession of a nucleus defines a domain of life: the eukaryotes. 1 PDF created with pdfFactory Pro trial version www.software-partners.co.uk Why prokaryotes are relevant to crime scenes. Life • Bacteria Bacteria Eukaryotes – – – – Vast populations and species. Vital component of our bodies. Decomposition and disease. Component of cells (mitochondria). • With own specific genome. • Allows for relationships to be investigated in ‘deep time’. Prokaryotes • Archaebacteria Archaebacteria – Extremophiles with amazing biochemistry. – Their DNA metabolism is the basis of most DNA tests: the PCR. Eukaryote and Prokaryote PCR • Polymerase Chain Reaction – Uses an enzyme from Thermus aquaticus (Taq). – Specific DNA sequences can be bulked up quickly and ‘easily’. The size of cells A prokaryotic cell 10 m Human height 1m Nucleoid: region where the cell’s DNA is located (not enclosed by a membrane) 0.1 m Chicken egg 1 cm Ribosomes: organelles that synthesize proteins Frog egg 100 µm Most plant and animal cells Capsule: jelly-like outer coating of many prokaryotes 10 µm 0.5 µm Flagella: locomotion organelles of some bacteria (b) A thin section through the bacterium Bacillus coagulans (TEM) 1 µm 100 nm nucleus Nucleus Most bacteria Most bacteria Mitochondrion Smallest bacteria Viruses Ribosomes 10 nm Electron m icroscope Cell wall: rigid structure outside the plasma membrane Light m icroscope 1 mm Plasma membrane: membrane enclosing the cytoplasm (a) A typical rod-shaped bacterium Length of some nerve and muscle cells Unaided eye Pili: attachment structures on the surface of some prokaryotes Proteins Lipids 1 nm 0.1 nm Small molecules Atoms Measurements 1 centimeter (cm) = 10−2 meter (m) = 0.4 inch 1 millimeter (mm) = 10–3 m 1 micrometer (µm) = 10–3 mm = 10−6 m 1 nanometer (nm) = 10–3 µm = 10− 9 m 2 PDF created with pdfFactory Pro trial version www.software-partners.co.uk Light Microscopy Double membrane TECHNIQUE RESULTS (a) Brightfield (unstained specimen). 50 µm (b) Brightfield (stained specimen). (c) Phase-contrast. A cell seen with fluorescence (d) Differential-interference-contrast (Nomarski). (e) Fluorescence. 50 µm (f) Confocal. 10 µm 50 µm Electron Microscopy TECHNIQUE (a) Scanning electron microscopy (SEM). RESULTS Cilia 1 µm Cell Fractionation APPLICTION Cell fractionation is used to isolate (fractionate) cell components, based on size and density. Longitudinal section of cilium Cross section of cilium 1 µm TECHNIQUE First, cells are homogenized in a blender to break them up. The resulting mixture (cell homogenate) is then centrifuged at various speeds and durations to fractionate the cell components, forming a series of pellets. (b) Transmission electron microscopy (TEM). 3 PDF created with pdfFactory Pro trial version www.software-partners.co.uk Hom ogenization Tissue cells 1000 g Homogenate (1000 times the force of gravity) Differential centrifugation 10 min Supernatant poured into next tube 20,000 g 20 min Pellet rich in nuclei and cellular debris 80,000 g 60 min RESULTS In the original experiments, the researchers used microscopy to identify the organelles in each pellet, establishing a baseline for further experiments. In the next series of experiments, researchers used biochemical methods to determine the metabolic functions associated with each type of organelle. Researchers currently use cell fractionation to isolate particular organelles in order to study further details of their function. 150,000 g 3 hr Pellet rich in mitochondria (and chloroplasts if cells are from a Pellet rich in plant) “microsomes” (pieces of plasma membranes and Pellet rich in cells’ internal ribosomes membranes) Somatic Cells • Somatic cells (soma = body): – all body cells except sex cells Sex Cells • Sex cells (germ cells): – reproductive cells – male sperm – female oocytes (eggs) The Cell • Performs all life functions The nucleus within the cell Figure 3–1 From Martini ‘Fundamentals of Anatomy and Physiology’ 4 PDF created with pdfFactory Pro trial version www.software-partners.co.uk Animal Cell Nuclear envelope ENDOPLASMIC RETICULUM (ER) Rough ER The Nucleus NUCLEUS Nucleolus Smooth ER Chromatin Flagelium Plasma membrane Centrosome • Is the cell’s control center CYTOSKELETON Microfilaments Intermediate filaments Ribosomes Microtubules Microvilli Golgi apparatus Peroxisome Mitochondrion Lysosome In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm) From Campbell and Reece ‘Biology’ Figure 3–10a Structure of the Nucleus • Nucleus: – largest organelle • Nuclear envelope: – double membrane around the nucleus • Perinuclear space: – between 2 layers of nuclear envelope • Nuclear pores: – communication passages Nucleoli in Nucleus Within the Nucleus • DNA: – all information to build and run organisms – kept in various levels of condensation • Nucleoplasm: – fluid containing ions, enzymes, nucleotides, and some RNA • Nuclear matrix: – support filaments The nucleus and its envelope Nucleus Nucleus 1 µm • Are related to protein production • Are made of RNA, enzymes, and histones • Synthesize rRNA and ribosomal subunits Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Rough ER Surface of nuclear enve lope. TEM of a specimen prepared by a special technique known as freeze-fracture. 0.25 µm Ribosome 1 µm Close-up of nuclear envelope Pore complexes (TEM). Each pore is ringed by protein particles. Nuclear lamina (TEM). The netlike lamina lines the inner surface of the nuclear envelope. 5 PDF created with pdfFactory Pro trial version www.software-partners.co.uk The nucleus and its envelope The nucleus and its envelope Nucleus Nucleus Nucleus 1 µm Nucleus 1 µm Nucleolus Nucleolus Chromatin Chromatin Nuclear envelope: Inner membrane Nuclear envelope: Inner membrane Outer membrane Outer membrane Nuclear pore Nuclear pore Pore complex Pore complex Rough ER Surface of nuclear enve lope. TEM of a specimen prepared by a special technique known as freeze-fracture. 0.25 µm Ribosome Rough ER Surface of nuclear enve lope. TEM of a specimen prepared by a special technique known as freeze-fracture. 0.25 µm 1 µm Ribosome Close-up of nuclear envelope Pore complexes (TEM). Each pore is ringed by protein particles. Nuclear lamina (TEM). The netlike lamina lines the inner surface of the nuclear envelope. Pore complexes (TEM). Each pore is ringed by protein particles. The nucleus and its envelope Nuclear lamina (TEM). The netlike lamina lines the inner surface of the nuclear envelope. The nucleus is not in isolation. Nucleus Nucleus 1 µm 1 µm Close-up of nuclear envelope Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Rough ER Surface of nuclear enve lope. TEM of a specimen prepared by a special technique known as freeze-fracture. 0.25 µm Ribosome 1 µm Close-up of nuclear envelope Pore complexes (TEM). Each pore is ringed by protein particles. Nuclear lamina (TEM). The netlike lamina lines the inner surface of the nuclear envelope. Ribosomes Ribosomes ER Ribosomes Ribosomes Cytosol ER Cytosol Endoplasmic reticulum (ER) Endoplasmic reticulum (ER) Free ribosomes Free ribosomes Bound ribosomes Bound ribosomes Large subunit 0.5 µm TEM showing ER and ribosomes Small subunit Diagram of a ribosome Large subunit 0.5 µm TEM showing ER and ribosomes Small subunit Diagram of a ribosome 6 PDF created with pdfFactory Pro trial version www.software-partners.co.uk Endoplasmic reticulum (ER) Smooth ER Rough ER • endo = within, plasm = cytoplasm, reticulum = network • Cisternae are storage chambers within membranes Nuclear envelope ER lumen Cisternae Ribosomes Transport vesicle Smooth ER Endoplasmic Reticulum (ER) Transitional ER Rough ER 200 µm Relationships among organelles of the endomembrane system 1 Nuclear envelope is connected to rough ER, which is also continuous with smooth ER Nucleus Relationships among organelles of the endomembrane system 1 Nuclear envelope is connected to rough ER, which is also continuous with smooth ER Nucleus Rough ER Rough ER 2 Membranes and proteins produced by the ER flow in the form of transport vesicles to the Golgi Smooth ER Smooth ER cis Golgi Nuclear envelope Nuclear envelope Transport vesicle 3 Golgi pinches off transport vesicles and other vesicles that give rise to lysosomes and vacuoles 3 trans Golgi 4 Lysosome available 5 Transport vesicle carries for fusion with another proteins to plasma vesicle for digestion membrane for secretion Relationships among organelles of the endomembrane system Centrosome containing a pair of centrioles Centrosome 1 Nuclear envelope is connected to rough ER, which is also continuous with smooth ER Nucleus Rough ER Microtubule 2 Membranes and proteins produced by the ER flow in the form of transport vesicles to the Golgi Centrioles Smooth ER cis Golgi Nuclear envelope 0.25 µm Transport vesicle 33 Golgi pinches off transport vesicles and other vesicles that give rise to lysosomes and vacuoles trans Golgi Plasma membrane 4 Lysosome available 5 Transport vesicle carries 6 Plasma membrane expands for fusion with another proteins to plasma by fusion of vesicles; proteins vesicle for digestion membrane for secretion are secreted from cell Longitudinal section of one centriole Microtubules Cross section of the other centriole 7 PDF created with pdfFactory Pro trial version www.software-partners.co.uk Nucleus summary 1 Nucleus summary 2 STRUCTURE FUNCTION • • • Largest organelle in the cell (size depends on species DNA amount). Surrounded by a nuclear membrane / envelope / mucleolemma – Double membrane – outer is continuous with the ER • • • Nuclear pores in the membrane allow the passage of large molecules in & out (e.g. messengerRNA) The contents of the nucleus is called nucleoplasm – this contains chromatin which makes up the DNA of the cell – in non-dividing cells it is spread out and during cell division it condenses to form the chromosomes Contains the structure called the nucleolus is found in the nucleus. • • • Acts as the control centre of the cell through the production of mRNA and protein synthesis Retains the genetic material in the cell in the form of DNA / chromosomes Nucleolus responsible for the manufacture of ribosomal RNA (rRNA) & ribosomes Central role in the process of cell division Nuclei in the news • Cells taken from a sixsixyearyear-old Finnish Dorset ewe and cultured in a lab. • 277 cells then fused with 277 unfertilized eggs (each with the nucleus removed). • 29 viable reconstructed eggs survived and were implanted in surrogate Blackface ewes. • 1 gave birth to Dolly. Dolly 8 PDF created with pdfFactory Pro trial version www.software-partners.co.uk