Cell Membrane

In: Science

Submitted By angelstar
Words 506
Pages 3
The aim of this experiment is to investigate the influence of various alcohols and temperature on the permeability of beetroot cell membrane. The different types of alcohol will include ethanol, methanol, propanol, butanol and the tissue from the beetroot will be exposed different salt concentrations (0%, 5% ,10% and 20%) . The stress affecting the membrane’s permeability will be assessed by the amount of leakage of pigment caused.
‘Homeostasis the ability of the body or a cell to seek and maintain a condition of equilibrium or stability within its internal environment when dealing with external changes’ (Biology, 2014). Organelle membranes and the plasma membrane are selectively permeable, allowing water to pass through freely, but regulating the movement of solutes. The function of a cell membrane is to transport and allow certain substances into the cell, while keeping other substances out. Surrounding the cytoplasm of a cell, the cell membrane (plasma membrane) is a thin semi-permeable membrane (Bailey, 2014) consisting mostly of lipids and proteins and composed up of a phospholipid bilayer. This contributes to the selectively permeable nature of the membrane.
70% of proteins contribute to the cell membrane, allowing communication outside and inside the cell. The phospholipids arrange themselves so that hydrophobic tails are shielded from the surrounding water exposing the hydrophilic heads to the water. While small molecules and non-charged ions cross freely, big charged oins cannot simply cross. They travel though either by passive or active transport.
Active transport requires energy from food, obtained by the cell, to move molecules through the membrane. However, unlike active transport passive occurs spontaneously requiring no energy required from (ATP). Diffusion is a form of passive movement. It is the tendency of molecules to spread into available…...

Similar Documents


...Plant Cell Organelles and Their Functions BIO 204 Cell Animation. 1) Golgi apparatus: The Golgi apparatus is flattened sacs involved in storing, modifying, and secreting proteins and lipids. 2) Chloroplast: The chloroplast contains green chlorophyll and is the site of photosynthesis and adenosine triphosphate (ATP) production. Mitochondria and chloroplasts contain their own deoxyribonucleic acid (DNA) molecules. a) Outer membrane: The chloroplast’s outer membrane is permeable to most ions. b) Intermembrane space: The intermembrane space separates the outer and inner membranes. c) Innermembrane: The innermembrane is specialized and permeable to specific transport proteins. d) Stroma: The stroma is the area of the chloroplast where carbon dioxide is converted into glucose during the light’s independent reactions of photosynthesis. e) Lamellae: Lamellae are connective strands between grana. f) Thykaloid disk: Each thykaloid disk contains chlorophyll, which is the pigment involved in capturing sunlight for photosynthesis. g) Granum (plural grana): Stacks of thykaloid disks where ATP is produced during photosynthesis. 3) Mitochondrion (plural mitochondria): The mitochondrion converts stored glucose into ATP during aerobic respiration. ATP is the energy molecule found in all life forms and is necessary for biochemical reactions in cells. 4) Cell wall: The cell wall is the......

Words: 447 - Pages: 2


...Why We Study the Cell and Its Components The cell is the basic unit of all living organisms. Some organisms like bacteria have only one cell while other organisms are multi cellular. It is important to study the cell and its components because it enables understanding of our own life and opens up windows of opportunity for the future generations. Understanding cells and their component functions allows for better understanding of disease and the possibility of cures or better treatment options. Biologists study the cell in healthy and diseased states to develop new vaccines, medicines, plants with improved qualities and to gain a better understanding of how all living things live. The study of cells and its components is also helpful in solving crimes through forensic science. In biotechnology, the study of cells is used to clone plants and animals, and with time possibly for the production of organs. In studying cells it is important to know what organism the cell comes from. There are two types of cells, the prokaryotic and eukaryotic. The prokaryotic were the first type of cells to evolve. Prokaryotic cells do not have a nucleus; bacteria are the best known prokaryotic cells. Organisms that contain eukaryotic cells include fungi, animals, and plants as well as some unicellular organisms. The eukaryotic cell is much bigger and contains membrane bound compartments where metabolic activities take place. The components of the cell include, plasma membrane,......

Words: 523 - Pages: 3


...Cell Structure and Function AbstractThis report is about cell structure and function. The cell is the basic unit of life. All living things are madeof cells. By doing this lab, I hoped to learn how a cell looked and how it functioned. I also wanted toknow the differences between prokaryotic cells and eukaryotic cells Introduction The concept of this lab is producing a replica of an animal cell, and a plant cell. Producing the models of the cells helps to provide a better understanding of each cell and its contents also, to explore thedifferences between prokaryotes and eukaryotes. Cell theory states that all cells reproduce new cells,while passing their genetic information. In addition, cells make up all living things, metabolize energyand that the chemical make-up of cells is similar. The objectives for this lab are to gather the materials,which include gelatin packs, plastic bags, water, Tupperware, bowls, and some small various householditems. The other objectives are preparing the gelatin as directed, gathering the household items that willserve as cell organelles, pouring the gelatin in the bag and placing the items in the plastic bags. Thenplace the cell replicas in the refrigerator for 24 hours. Results After twenty-four hours, I removed the cell replicas from the refrigerator and observed them. They didnot look exactly like I planed but they were understandable. Discussion Replicating the cell structures provides better understand the structure......

Words: 403 - Pages: 2

Cell Membrane

...Cells are the smallest form of life possible. All organisms have to consume air. Water is the building block of all life. Air is consumed, this process is referred to as respiration. In smart people talk this means an exchange of gases. Once the air is used to fuel the machine it is discarded as Carbon Dioxide. “Biologists also define respiration as the aerobic harvesting of energy from food molecules by cells. This process is called cellular respiration to distinguish it from breathing.” In everyday life we breathe, as we work harder physically like running, lifting heavy weight or any type of strenuous physical activity we require more oxygen. The air we breathe is taken in and deposited into the lungs, the lungs then distribute this air to the bloodstream to fuel the muscle cells in support of the higher demand of oxygen. The muscle cells extract energy from the protein and other valuable nutrients to generate ENERGY. This process is referred to as ATP. “Tonicity is how a cell loses or gains water from its surrounding solution. From here cells maintain the mass balance through a process called diffusion, all this means is the ability to spread out evenly in an available area. Isotonic simply means the ability to replace air, water, energy at the rate it is losing it. Hypotonic is a solution with a solute concentration less than the cell. Hypertonic is the opposite a solution with a higher solute concentration. Osmosis, the diffusion of water across a......

Words: 298 - Pages: 2

Diffusion of a Membrane

...Mikayla Moreno Diffusion through a Membrane Purpose: In this experiment one of the questions asked, is water able to diffuse through a cell membrane. The prediction to this question is that yes the water will be able to diffuse. The next question asked, will glucose be able to diffuse through a cell membrane. The prediction is yes it will be able to diffuse. The next question is will iodine be able to diffuse. Again the prediction is yes it will be able to diffuse. The next question asked was will starch be able to diffuse. The prediction was actually no the starch will not diffuses through a membrane. Finally the last question asked was will the weight of the bag change. The prediction was yes the weight will increase. Procedure: The first thing you need to do for this experiment is get a 15cm cellophane dialysis tube and soak it in water until it is soft. Then you need to rub the cellophane between some fingers until it is possible to get an opening on either side. After that put a glass rod between the opening in the tube. Next, take the glass rod out and tie one of the ends with a piece of thread as tight as you can. The next step is to fill the tube about half way with the starch solution and 10ml of a glucose solution. After these steps are completed, tie the other end off with another piece of thread. Then take the tube and weight it on a scale. Once completed, record the weight of the tube. Next fill a beaker to 150ml with tap water and add 6 drops of......

Words: 726 - Pages: 3

Cell Membrane

...AP October 2, 2014 In the early twentieth century, little was known about cell membranes. For years scientists looked through the microscope in search of answers. Since the discovery of many new information conducted through observations and research, they were able to understand that plasma membrane is an essential biological structure to all cells. It functions as an envelope by keeping all a cells organelles contained. It also serves as a gateway and barrier to certain foreign substance. Although plasma membrane may seem simple on the outside, it’s actually a complex structure of molecules working in coordination with each other to function properly. The cell membrane, also known as the plasma membrane, is a phospholipid bilayer, which consists of Polar, hydrophilic phospholipid heads and non-polar, hydrophobic fatty acid tails. The plasma membrane is constructed in a specific way where phospholipid tails point towards each other, away from polar substances and the polar heads are positioned in the other direction towards aqueous environments. Because of this special chemically influenced arrangement of molecules, an impermeable membrane selective to small, non-polar is formed substances. The cell’s plasma membrane also contains a diverse array of proteins amidst its phospholipid layer. Proteins are extremely important as they carry out many specialized functions for the plasma membrane. Proteins imbedded in between the phospholipid bilayer are called integral......

Words: 1191 - Pages: 5

Outline the Roles of Membranes at the Surface and Within Cells

...Outline the roles of membranes at the surface of cells and within cells (10 marks) Both the cell surface membrane and the membranes surrounding certain organelles have the same basic structure and similar functions. There are 5 major roles of membranes including separating cell contents from the outside environment; separating cell components from cytoplasm; cell recognition and signalling; holding the components of some metabolic pathways in place and regulating the transport of materials into or out of cells. The phospholipid bilayer is the basic structural component of all biological membranes. A bilayer is formed when phospholipid molecules are completely surrounded by water. The hydrophilic (water-loving) heads stick in the water, while the hydrophobic (water-hating) fatty acid tails point towards each other in a mirror image. The formation of the tails creates a barrier to many molecules, separates the cell contents from the outside world and gives stability. Mechanical stability is supported by cholesterol in the bilayer. This steroid molecule fits between fatty acid tails and helps make the barrier more complete, so substances like water molecules and ions cannot pass easily and directly through the membrane. The structure of the membrane is called the fluid mosaic model because the membrane is fluid (the phospholipid molecules are not actually bonded) and because of the mosaic arrangement of the protein molecules. Inside the fluid mosaic model are various protein...

Words: 945 - Pages: 4


...Animal Cell | Cell functions | Smooth endoplasmic reticulum | associated with the production and metabolism of fats and steroid hormones | Rough endoplasmic reticulum | involved in some protein production, protein folding, quality control and despatch. | Nuclear envelope | surrounds the nucleus with a double membrane with multiple pores. | Chromatin | Mass of genetic material composed of DNA and proteins that condense to form chromosomes during eukaryotic cell division. | Nucleolus | A small, typically round granular body composed of protein and RNA in the nucleus of a cell. It is usually associated with a specific chromosomal site and involved in ribosomal RNA synthesis and the formation of ribosomes. | Ribosomes | Ribosomes are cell organelles that consist of RNA and proteins. They are responsible for assembling the proteins of the cell. | Golgi apparatus | a cell structure mainly devoted to processing the proteins synthesized in the endoplasmic reticulum (ER). | Mitochondrion | which is to generate large quantities of energy in the form of adenosine triphosphate (ATP). | Plasma membrane | forms a stable barrier between two aqueous compartments | Microfilament | involved in cytoplasmic movement and changes in cell shape. | Intermediate filament | to reinforce cells and to organize cells into tissues | Microtubule | involved in nuceic and cell division, organization of intracellular structure, and intracellular......

Words: 262 - Pages: 2


...Structures in All Eukaryotic Cells We're going to start with eukaryotic cells even though they tend to be more complex than prokaryotic. But, there is a method to our madness: you are a eukaryote and have eukaryotic cells, so we thought you might relate better. And, eukaryotic comes before prokaryotic alphabetically. Come up with whatever reasons you want for it, but eukaryotes are up first. Tough cookies. Eukaryotic Cell Structure and Function A cell is defined as eukaryotic if it has a membrane-bound nucleus. Any organism composed of eukaryotic cells is also considered a eukaryotic organism. Case in point: You. Biologists do not know of any single organism on Earth that is composed of both eukaryotic and prokaryotic cells. However, many different types of prokaryotic cells, usually bacteria, can live inside larger eukaryotic organisms. Creepy, but true. We humans, for example, have trillions of bacteria living in our colons, not to mention in our mouths and stomachs and small intestines and…you get the picture. Despite the fact that we have gobs of prokaryotic cells living inside and on us, humans are still categorically eukaryotic organisms. Deal with it. This means that all human cells, including those found in the brain, the heart, the muscles, and so on, are also eukaryotic. Here is what one of these little guys looks like: OK, we are slightly impressed. That is a lot of stuff jam-packed into something we can't see too well with the naked eye. All......

Words: 1363 - Pages: 6

The Cell Membrane

...An Educational Study on Cell Membrane Radiologic Pathology GUBALLO, MARIBETH S. BS RADTECH III INSTRUCTOR: DR. EMMANUEL PAGALA The Cell Membrane Cells are made of many vital parts that work together and perform specific functions. One important part of the cell structure is the cell membrane also known as the plasma membrane or cytoplasmic membrane. Historically, the plasma membrane was also referred to as the plasmalemma. The cell membrane is a microscopic lipid-based sheath that encloses the cytoplasm of a cell and separates the interior of all cells from the outside environment. It acts as a gatekeeper to ions and organic molecules such as DNA, RNA and other proteins by its selectively permeable barrier which enables the cell to regulate its internal environment and keep out foreign molecules that might damage or destroy the cell's contents, including molecules essential for life. Cell membranes also functions in different cellular processes such as cell adhesion, cell signaling and serve as the attachment surface for several extracellular structures. FUNCTION All prokaryotic cells have a phospholipid bilayer called the plasma membrane. It defines the boundary between the inside and outside of the cell even though it is found on the inside of the prokaryotic cell wall. The cytoplasm and other prokaryotic cellular contents are found inside the plasma membrane. On the other hand, all eukaryotic cells have a plasma membrane as well, but they also have......

Words: 1098 - Pages: 5

Cell Membrane

...Cell membrane - forms the outer covering of the cell, and is semi-permeable. Cytoplasm - is a gel-like matrix where all the other cell organelles are suspended inside the cell. Nucleus - contains the hereditary material DNA and directs the activities of the cell. Centrioles - organize the microtubules assembly during cell division. Endoplasmic Reticulum - are a network of membranes composed of rough and smooth endoplasmic reticulum. Golgi complex - is responsible for storing, packaging of cellular products. Lysosomes - are enzyme sacs, that digest cellular wastes. Microtubules - are hollow rods, function primarily as support and shape to the cell. Mitochondria - is the site for cellular respiration and producers of energy. Ribosomes - are made of RNA and proteins, and are sites for protein synthesis. Nucleolus - is the structure within the nucleus and helps in synthesis of ribosomes. Nucleopore - is the tiny hole in the nuclear membrane, allows the movement of nucleic acids and proteins in/out of the cell Cell wall is the outermost rigid covering of the plant cell. It is a salient feature of plant cell. Cell membrane or the plasma membrane is the outer lining of the cell inside the cell wall. Cytosol or cytoplasm is the gel-like matrix inside the cell membrane which constitutes all other cell organelles. Nucleus is the control center of the cell. It is a membrane bound structure which contains......

Words: 302 - Pages: 2


...www.asbiology101.wordpress.com An introduction to the microscope and magnification MAGNIFICATION AND RESOLUTION Because cells are too small to be seen with the naked eye, the light microscope was developed to produce enlarged and more detailed images of cells. The magnification of an image is how much bigger it appears under the microscope than it is in real life, and is worked out using the following formula: magnification = image size ÷ actual size unit metre decimetre centimetre millimetre micrometre nanometre picometre symbol m dm cm mm μm nm pm metres 1 0.1 0.01 0.001 0.000 001 0.000 000 001 0.000 000 000 01 However, magnification on its own does not increase the level of detail seen, it just increases the size. The term resolution refers to the ability to see two distinct points separately. For example, if the resolution of a light microscope is 200nm (0.2μm), this means it can see any two different points as separate objects if they are 200nm apart or more; but if they are any closer than this amount, they appear as one object. THE LIGHT MICROSCOPE Light microscopes use a number of lenses to produce an image that can be viewed directly at the eyepiece. Light passes from a bulb under the stage, through a condenser lens and then through the specimen. This beam of light is passed through an objective lens and then the eyepiece lens. The light microscope usually has a number of objective lenses which can be rotated into......

Words: 8313 - Pages: 34

How Substances Cross the Cell Membrane

...How substances cross the cell membrane. A cell’s membrane has many functions including forming a boundary in order to organise the contents and keep them separate from the extracellular environment. Yet in order for the cell to ‘live’ and perform its particular function, it needs to be able to take in substances and nutrients and to get rid of waste products. But with such a vast array of substances in the extracellular environment, it is a difficult task to control the influx and out-pouring of substances. There are several ways that this is accomplished and these are set out below. Cell, or plasma, membranes are formed from two layers of phospholipids which have a polar, hydrophilic head and a nonpolar, hydrophobic tail. This is known as the fluid mosaic model. It is this feature of membranes which makes them semipermeable and dictates how substances may cross them. Figure 1 shows a simplified structure of the cell membrane. Small, nonpolar molecules such as (O2), carbon dioxide (CO2) and nitrogen (N2) are able to diffuse passively across the membrane and do so down their concentration gradients or electrochemical gradients in the case of ions. However larger or charged molecules and ions require assistance of some type as they are too large or have a charge on them which prevents them crossing the hydrophobic interior of the membrane. In many cases a substance crosses the membrane with the assistance of membrane proteins, this is known as facilitated diffusion.......

Words: 925 - Pages: 4


...The structure and functions of Cell The purpose of this report is to explain the structure and functions of Cell. Cell is the basic unit of life and it contains other membrane-bound organelles structures that carry out specific functions necessary for normal cellular operation. Organelles have a wide range of roles and functions that include everything from producing hormones and enzymes to providing energy for Cells. Organelles Location Structure Functions Nucleus Centre - Nucleus is spherical in shape - Nucleus is surrounded by a nuclear envelope - Nucleus is separated from cytoplasm by double membrane - It functions as an intermediary when DNA replication is taking place during cell cycle. - It contains hereditary materials DNA and RNA - It directs activities of the cell such as growth, metabolism and reproduction. - It create different type of RNA from DNA in the process called Transcription - It is control centre of the cell Nucleolus Inside the Nucleus (Centre) - It is spherical in shape - It is made of Protein and RNA - It helps in synthesis of Ribosome - It helps in assembly of signal recognition particles in the cell - It helps in sensing stress in the cell Golgi body They are found in Cytoplasm of the cell - It is sac-like - It comprises stacks of membrane structure - It is involve in movement of Lipid molecules around the cell - It helps in process and package of macromolecules e.g. Protein - It modifies protein after Endoplasmic Reticulum......

Words: 614 - Pages: 3

Cell Membrane

...CELL BIOLOGY AND GENETICS ASSIGNMENT TOPIC: CELL MEMBRANE [pic] INTRODUCTION Cell membranes are crucial to the life of the cell. It encloses the cell defines its boundaries, and maintains the essential difference between the cytosol and the extra cellular environment. Inside the cell the membranes of the endoplasmic reticulum, Golgi apparatus, mitochondria, and other membrane bound organelles in a eukaryotic cell maintain the characteristic differences between the contents of each organelle and the cytosol. Ion gradients across membranes, established by the activities of specialized membrane proteins, can be used to synthesize ATP to drive the transmembrane movement of selected solutes, or in nerve and muscle cells, to produce and transmit electrical signals. In all cells the plasma membrane also contains proteins that act as sensors of external signals allowing the cell to change its behavior in response to environmental cues; these protein sensors, or receptors, transfer information rather than ions or molecules across the membrane. [pic] THE STRUCTURE OF THE CELL MEMBRANE All biological membranes have a common general structure: each is a very thin film of lipid and protein molecules, held together mainly by non covalent interactions. Cell membranes are dynamic, fluid structures, and most of their molecules are able to move about in the...

Words: 1815 - Pages: 8