Week 2 Prokaryotic and Eukaryotic Cells PDF

RMD003 - Biology Learning objective 2: Structure of the Cell 2.1: Comparative study on Prokaryotes and Eukaryotes  The Cell In the 1830s, Matthias Schleiden stated that all plants are composed of cells Theodor Schwann stated that all animals are composed of...

RMD003 - Biology Learning objective 2: Structure of the Cell 2.1: Comparative study on Prokaryotes and Eukaryotes  The Cell In the 1830s, Matthias Schleiden stated that all plants are composed of cells Theodor Schwann stated that all animals are composed of cells These scientists based their ideas not only on their own work but on the work of all who had studied tissues under  The Cell Today, we recognize that the organisms we see around us are made up of cells In our daily lives we observe whole organisms, but if it were possible to view them internally with a microscope, we would see their cellular nature So, a cell is the smallest unit of living matter  Organisms and Cells Unicellular organisms are quite prevalent, but plants and animals, including ourselves, are multicellular A cell is not only he structural unit, it is also the functional unit of organs, and therefore, of organisms  All organisms, whether plants or animals are composed of cells A microscope is needed to see the cells Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell  The Cell Theory Cell reproduce, once a growing cell gets to a certain size, it divides Unicellular organisms reproduce themselves when they divide Multicellular organisms grow when their cells divide Cells are also involved in the reproduction of multicellular organisms, therefore, there is always a continuity of cells from generation to generation  Cell theory So, the cell theory states that: 1. All living things are composed of one or more cells 2. Cells are the smallest units of living organisms 3. New cells come only from pre-existing 10 cells  Types of Cells Two different types of cells exist: Prokaryotic cells (pro: before, karyon: kernel, nucleus): are so named because they lack a membrane-bounded nucleus Eukaryotic cells: has a nucleus Comparing Prokaryotic and Eukaryotic Cells  Prokaryotic cells Prokaryotic cells are simpler and much smaller than eukaryotic cells Prokaryotic cells are present in great numbers in the air, in bodies of water, in the soil, and even in you Lack a membrane-enclosed nucleus They are divided into bacteria and archaea: Both small Bacteria- abundant, most not harmful Archaea- less common, often found in extreme environments  Typical bacterial cell Bacteria are quite small – an average size is 1.1 to 1.5 micrometer wide and 2 to 6 micrometer long Bacteria have the following structure: Plasma membrane- barrier Cytoplasm - contained inside plasma membrane Nucleoid - region where genetic material found Ribosomes - involved in protein synthesis 14  Typical bacterial cell Many structures are located outside the plasma membrane: Cell wall- support and protection Glycocalyx- traps water, protection Appendages- pilli (attachment), flagella (locomotion) 15 16  Eukaryotic cells Organisms with eukaryotic cells, namely: protists, fungi, plants and animals Unlike prokaryotic cells, eukaryotic cells do have a membrane- bounded nucleus which houses the DNA Eukaryotic cells are compartmentalized; they have small structure called organelles that are specialized to perform specific functions Eukaryotic cells, like prokaryotic cells, have a plasma membrane that separates the contents of the cells from the environment and regulate passage into and out of the cytoplasm Shape, size, and organization of cells vary considerably among different species and even among different cell types of the same species Animal Cell 18 19 Plant Cell 20  What is Cytosol? It is a region of a eukaryotic cell that is outside the cell organelles but inside the plasma membrane Cytoplasm on the other hand includes everything inside the plasma membrane Cytosol, the endomembrane system and the semiautonomous organelles 21  What is Cytosol? Cytosol is central coordinating region for many metabolic activities of eukaryotic cells These activities are called (metabolism): Catabolism- breakdown of a molecule into smaller components Anabolism- synthesis of cellular molecules and macromolecules 22  Cytoskeleton Network of three different types of protein filaments extends from the nucleus to the plasma membrane in eukaryotic cells Cytoskeleton maintains the shape and assist movement of its part 1. Microtubules Dynamic instability Centrosome or microtubule-organizing center in animals 2. Intermediate filaments Tend to be more stable than microtubules and actin filaments, which readily polymerize and depolymerize 3. Actin filaments Also known as microfilaments 23 24  Flagella and cilia involved in the movement of cells Flagella usually longer than cilia and present singly or in pairs Cilia are often shorter than flagella and tend to cover all or part of the surface of a cell Share the same internal structure Microtubules, dynein, and axoneme Movement involves the propagation of a bend, which begins at the base of the structure and proceeds toward the tip 25 26 27  Endomembrane system Network of membranes enclosing the nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles, that work together and communicate by means of transport vesicles Also includes plasma membrane May be directly connected to each other or pass materials via vesicles 28 29  Endomembrane system The organelles in the endomembrane system work together to carry out the functions noted Plant cells do not have lysosomes  Nuclear envelope Double-membrane structure enclosing nucleus Outer membrane of the nuclear envelope is continuous with the endoplasmic reticulum membrane Nuclear pores provide passageways Materials within the nucleus are not part of the endomembrane system 31 32  Nucleus Contains chromosomes Composed of DNA and protein Chromatin Primary function involves the protection, organization, and expression of the genetic material Ribosome assembly occurs in the nucleolus 33  Endoplasmic reticulum (ER) Network of membranes that form flattened, fluid-filled tubules or cisternae ER membrane encloses a single compartment called the ER lumen Rough endoplasmic reticulum (rough ER) Studded with ribosomes Involved in protein synthesis and sorting Smooth endoplasmic reticulum (smooth ER) Lacks ribosomes Detoxification, carbohydrate metabolism, calcium balance, synthesis and modification of lipids 34 35  Golgi apparatus Also called the Golgi body, Golgi complex, or simply Golgi Stack of flattened, membrane-bounded compartments, which are not continuous with the ER Vesicles transport materials between stacks Three overlapping functions Secretion, processing, and protein sorting 36 37  Lysosomes Contain acid hydrolases that perform hydrolysis Many different types of acid hydrolases to break down proteins, carbohydrates, nucleic acids, and lipids Autophagy Recycling of worn-out organelles through endocytosis 38 39  Vacuoles Functions of vacuoles are extremely varied, and they differ among cell types and even environmental conditions Central vacuoles in plants for storage and support Contractile vacuoles in protists for expelling excess water Phagocytic vacuoles in protists and white blood cells for degradation 40 41  Plasma membrane Boundary between the cell and the extracellular environment Membrane transport in and out of cell Selectively permeable Cell signaling using receptors Cell adhesion 42 43  Semiautonomous organelles Can grow and divide to reproduce themselves, but they are not completely autonomous because they depend on other parts of the cell for their internal components Mitochondria, chloroplasts, and peroxisomes 44 45  Mitochondria Outer and inner membrane Intermembrane space and mitochondrial matrix Primary role is to make energy in the for of ATP Also involved in the synthesis, modification, and breakdown of several types of cellular molecules Can also generate heat in brown fat cells 46 47  Chloroplasts Photosynthesis capture light energy and use some of that energy to synthesize organic molecules such as glucose Found in nearly all species of plants and algae Outer and inner membrane with an intermembrane space Third membrane, the thylakoid membrane, forms flattened tubules that stack to form a granum (plural, grana) 48 49  Peroxisomes Relatively small organelles found in all eukaryotic cells General function to catalyze certain chemical reactions, typically those that break down molecules by removing hydrogen or adding oxygen Reaction by-product is hydrogen peroxide (H2O2) Catalase breaks down H2O2 without forming dangerous free radicals 50 51  Extra resources and videos (Prokaryotes and eukaryotes) https://www.khanacademy.org/science/ap-biology/cell-stru cture-and-function/cell-compartmentalization-and-its-origi ns/v/prokaryotic-and-eukaryotic-cells