2.4 Membranes | BioNinja 2.4.1 Draw and label a diagram to show the structure of membranes 2.4.2 Explain how the hydrophilic and hydrophobic properties of phospholipids help to maintain the structure of cell membranes Structure of Phospholipids Consist of a polar head (hydrophilic) made from glycerol and phosphateConsist of two non-polar fatty acid tails (hydrophobic) Arrangement in Membrane Phospholipids spontaneously arrange in a bilayerHydrophobic tail regions face inwards and are shielded from the surrounding polar fluid while the two hydrophilic head regions associate with the cytosolic and extracellular environments respectively Structural Properties of Phospholipid Bilayer 2.4.3 List the functions of membrane proteins Transport: Protein channels (facilitated) and protein pumps (active) Receptors: Peptide-based hormones (insulin, glucagon, etc.) Anchorage: Cytoskeleton attachments and extracellular matrix Cell recognition: MHC proteins and antigens Intercellular joinings: Tight junctions and plasmodesmata Osmosis:
5.7: Cell Transport - Biology LibreTexts Simple Diffusion Diffusion Although you may not know what diffusion is, you have experienced the process. Can you remember walking into the front door of your home and smelling a pleasant aroma coming from the kitchen? It was diffusion of molecules from the kitchen to the front door of the house that allowed you to detect the odors. The molecules in a gas, a liquid or a solid are in constant motion due to their kinetic energy. Osmosis is a specific type of diffusion; it is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration. Semi-permeable membranes are very thin layers of material that allow some things to pass through them but prevent other things from passing through. The classic example used to demonstrate osmosis and osmotic pressure is to immerse red blood cells into sugar solutions of various concentrations. Facilitated Diffusion Channel proteins form pores, or tiny holes, in the membrane.
Real-life applications - Osmosis - Cell Behavior and Salt Water, Osmosis in Plants, Osmosis and Medicine Cell Behavior and Salt Water Cells in the human body and in the bodies of all living things behave like microscopic bags of solution housed in a semipermeable membrane. The health and indeed the very survival of a person, animal, or plant depends on the ability of (Bettmann/Corbis . Reproduced by permission.) the cells to maintain their concentration of solutes. Two illustrations involving salt water demonstrate how osmosis can produce disastrous effects in living things. Worse still is the process that occurs when a person drinks salt water. How, then, do fish and other forms of marine life survive in a salt-water environment? Osmosis in Plants Plants depend on osmosis to move water from their roots to their leaves. Crucial to the operation of osmosis in plants are "guard cells," specialized cells dispersed along the surface of the leaves. In some situations, external stimuli such as sunlight may cause the guard cells to draw in potassium from other cells. Osmosis and Medicine
Interactive Eukaryotic Cell Model The cells of eukaryotes (protozoa, plants and animals) are highly structured. These cells tend to be larger than the cells of bacteria, and have developed specialized packaging and transport mechanisms that may be necessary to support their larger size. Use the following interactive animation of plant and animal cells to learn about their respective organelles. Nucleus: The nucleus is the most obvious organelle in any eukaryotic cell. It is enclosed in a double membrane and communicates with the surrounding cytosol via numerous nuclear pores. Nucleolus: The prominent structure in the nucleus is the nucleolus. Cytosol: The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. Cytoplasm: This is a collective term for the cytosol plus the organelles suspended within the cytosol. Centrosome: The centrosome, or MICROTUBULE ORGANIZING CENTER (MTOC), is an area in the cell where microtubules are produced.
Investigating osmosis in chickens’ eggs In this procedure, you can observe osmosis in an animal system by using chickens’ eggs from which the shells have been removed by dissolving in acid. The eggs are weighed and placed in solutions of different strength for 24-48 hours before being weighed again. You can run this as a demonstration, or a class practical where pairs of pupil have an egg and each pair place their eggs in different solutions (amalgamating results to provide whole-class data). Paper towel Beaker, 200 cm3 150 cm3 of each salt solution to be used. Balance De-shelled eggs (Note 1) Sodium chloride solutions in a range of concentrations, for example, 0%, 10%, 20%. (150 cm3 of each concentration for each working group) Hydrochloric acid (HCl) is described as IRRITANT at concentrations above 2.0 M, causes burns and is irritating to the respiratory system. Sodium chloride is described as low hazard. Wear eye protection as some of the sodium chloride solutions are strong. Rinse hands if splashed by solutions. Preparation
Zellen - Aufgaben und Übungen Diese Website verwendet Cookies. Wir können damit die Seitennutzung auswerten, um nutzungsbasiert Inhalte und Werbung anzuzeigen. Weitere Informationen zu Cookies und insbesondere dazu, wie Sie deren Verwendung widersprechen können, finden Sie in unseren Datenschutzhinweisen. Datenschutzerklärung Ich akzeptiere Biologie Test – Zellen Welche der folgenden Aussagen sind richtig? 1) Die Zellen von Eukaryoten bezeichnet man auch als Ecyten. 2) Wodurch unterscheidet sich die Zelle eines Eukaryoten von der Zelle eines Prokaryonts? 3) Das Cytoplasma ist der wesentliche Bestandteil von Zellen, so werden beispielsweise die Zellorganellen im Cytoplasma eingebettet. 4) Im Unterschied zu einem Eukaryoten hat die Zelle eines Prokaryonten keine Zellmembran, die den Zellkern umgibt. 5) Im Vergleich zur Zelle eines Eukaryoten fehlt der Zelle eines Prokaryonten eine Kernmembran. 6) Betrachten wir die Vermehrung eines Procyten. Navigation Weitere Aufgaben & Tests:Zellbiologie Themen & Inhalte:Zellbiologie Suche
Create a Paper The two diagrams below show nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD), two nucleotides used in respiration. (a) State two chemical features which these two molecules have in common and one difference between the two molecules. Features in common. (i) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (ii) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Difference (b) Substrate level phosphorylation (SLP) is the simplest, oldest and least-evolved way to make ATP. (i) Describe the position of the ‘high energy bond of ATP’ referred to in the paragraph above. (ii) Suggest why SLP is referred to as the ‘simplest and oldest way to make ATP’. (c) (i) Where does the link reaction occur in cells?
Climate Change Challenge | National Geographic Society Climate change has far-reaching effects on our planet, from increasing the frequency and intensity of many extreme weather events, including flooding and drought, to changing sea temperature, ocean acidity, and sea level. In this unit, students apply concepts such as the greenhouse effect, weather variables, and thermohaline circulation to model how climate change impacts the atmosphere, the oceans, and human communities. For each major effect of climate change studied in this unit, students examine related, long-term primary datasets. They collaborate to organize variables into tables, calculate summary statistics, and create graphical representations of climatic trends. They move from performing these key skills by hand to digitally, as they gain mathematical and technical fluency. Use this unit at a glance to explore a brief outline of the materials included in this resource. Unit Driving Question: How can we communicate evidence of climate change to convince our community to act?
How do you identify the genes in a genome? | Facts After the sections of DNA sequence have been assembled into a complete genome sequence we need to identify where the genes and key features are, but how do we do this? What’s the challenge? We have our aligned and assembled genome? sequence but how do we identify where the genes? and other functional regions of the genome are located? What do we need to do? Annotation involves marking where the genes start and stop in the DNA? Gene prediction There are two types of gene prediction: Ab initio – this technique relies on signals within the DNA sequence. Illustration showing the structure of a gene. Evidence-based – this technique relies on evidence beyond the DNA sequence. Manual annotation Once gene prediction is completed the second phase, manual annotation or “curation”, can begin. Comparing genomes Once annotated, the sequence can be compared to the known genome sequence of similar or closely related organisms in order to identify any key similarities or differences.
What is DNA replication? | Facts DNA replication is the process by which DNA makes a copy of itself during cell division. The first step in DNA replication is to ‘unzip’ the double helix structure of the DNA? molecule. This is carried out by an enzyme? An illustration to show replication of the leading and lagging strands of DNA. Leading Strand: A short piece of RNA ?