1 Biol115 The Thread of Life Lecture 13 A panoramic tour of the cell It is the cells which create and maintain in us, during the span of our lives, our will to live and survive, to search and experiment, and to struggle. ~Albert Claude
2 Objectives Describe key elements of cell theory. Explain why cells are limited in size. Compare and contrast light and electron microscopes. Compare and contrast eukaryotic and prokaryotic cells. Identify and discuss functions of prokaryotic cellular structures. Relate the forms of different cell structures to their functions. Compare and contrast the structure and function of organelles found in animal and plant cells. Explain how microtubules cause flagellar movement. Biol115_2014_Lecture 13 2
3 Objectives Keywords: light microscopy, cell theory, cell wall, cilia, cytoplasm, cytosol, endosymbiotic theory, eukaryote, extracellular matrix (ECM), flagellum, fluorescence microscopy, magnification, organelle, phase-contrast microscopy, plasma membrane, scanning electron microscopy (SEM), autophagy, vacuole, chlorophyll, chloroplast, contractile vacuole, cristae, endomembrane system, endoplasmic reticulum (ER), endosymbiotic theory, food vacuole, Golgi apparatus, granum (plural: grana), lumen, lysosome, matrix, mitochondria, nuclear envelope, nuclear pore, nucleolus, peroxisome, phagocytosis, photosynthesis, rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), stroma, vacuole, vesicle, cytoskeleton, depolymerisation, doublet, dynein, kinesin, motor proteins, microtubule, polymerization, tubulin Biol115_2014_Lecture 14 3
4 Principles of Biology Chapter Cells. Chapter Eukaryotic cells Chapter Cytoskeleton Biol115_2014_Lecture 14 4
5 Overview: the fundamental units of life All organisms are made of cells. The cell is the simplest collection of matter that can live. Cell structure is correlated to cellular function. All cells are related by their descent from earlier cells. Biol115_2014_Lecture 14 5
6 Cells compose organisms or can be organisms Unicellular organisms (bacteria, protists) perform all functions in a single cell. Multicellular organisms have specialized cells for different functions, but cells have same basic structure.
7 Cell theory 1. Cells are the basic unit of life. 2. Cells come from other cells.
8 Why aren t there giant cells? Large cells have less surface area per unit volume. Large cells less capable of transporting materials across plasma membrane.
10 How do we observe cells? light microscopy transmission electron microscopy scanning electron microscopy fluorescence microscopy
11 Eukaryotes (protists, fungi, plants, animals) have complex membranes around organelles.
13 Eukaryotic cells have internal membranes that compartmentalise their functions The basic structural and functional unit of every organism is one of two types of cells: prokaryotic, or eukaryotic. Eukaryotic cells are characterised by having: DNA in a nucleus that is bounded by a membranous nuclear envelope, membrane-bound organelles, Eukaryotic cells are generally much larger than prokaryotic cells. Biol115_2014_Lecture 14 13
14 Components of the eukaryotic cell The evolution of compartmentalization allowed eukaryotes to exploit new food sources. Compartments are organelles bound by semi-permeable membrane. Several linear chromosomes within a double membrane nucleus.
15 The nucleus Control center of the cell. Contains chromosomes made up of DNA.
16 Endomembrane system Nuclear envelope: retains DNA. Smooth endoplasmic reticulum: lipid synthesis and breaking down toxins. Rough endoplasmic reticulum: contains ribosomes, which synthesize proteins. Vesicle: transports synthesized proteins. Golgi apparatus: modifies, stores and exports proteins from the cell.
17 A cell (amoeba) eating a yeast particle
18 Mitochondria: powerhouses of the cell Transform chemical energy via cellular respiration by breaking down glucose and converting it to ATP. Possess separate type of DNA (mtdna). Likely arose from an endosymbiosis with prokaryotic cells.
19 Chloroplasts Photosynthesis: Conversion of light energy, carbon dioxide (CO 2 ) and water into carbohydrates.
20 Peroxisomes Peroxisomes: eliminate waste by converting it to hydrogen peroxide and then to water.
21 Vesicles for transporting food and waste. Vacuoles
23 Cytoskeleton complex protein network Structural support Locomotion Intracellular anchor Involved in mitosis
24 Cytoskeletal components Microfilaments, Intermediate filaments (not covered in Biol115) Microtubules -motility (cilia, flagella), cell division -made of tubulin
26 Eukaryotic flagellum
27 Flagella & cilia bend
29 Endosymbiotic theory Eukaryotic organelles (mitochondria, chloroplasts) arose from symbiosis with prokaryotes: - Divide independent from nucleus. - Contain DNA that differs from nuclear DNA but similar to bacterial DNA. - Contain ribosomes smaller and more similar to bacterial ribosomes.
30 The cell: a living unit greater than the sum of its parts Cells rely on the integration of structures and organelles in order to function. For example, the destruction of bacteria by a macrophage involves the whole cell, coordinating components such as the cytoskeleton, lysosomes, and plasma membrane. Biol115_2014_Lecture 14 30
31 Fig Biol115_2014_Lecture 14 31
32 You should now be able to: 1. Distinguish between the following pairs of terms: prokaryotic and eukaryotic cell; free and bound ribosomes; smooth and rough ER. 2. Describe the structure and function of the components of the endomembrane system. 3. Briefly explain the role of mitochondria, chloroplasts, and peroxisomes. 4. Describe the functions of the tubulin cytoskeleton, using the cilia or flagella as an example. Biol115_2014_Lecture 14 32
33 You should now be able to: 5. Compare the structure and functions of microtubules, microfilaments, and intermediate filaments. 6. Explain how the ultrastructure of cilia and flagella relate to their functions. Biol115_2014_Lecture 14 33