Cell Membrane Essay

1161 words - 5 pages

Cell MembraneIn 1665, Robert Hooke, an English scientist observed cork under a microscope and noted that it was composed of small units. He called these units cells. Later it was observed that most living things are composed of cells. This led to cell theory. Cell theory is that living things are composed of cells.A theory is a hypothesis that scientific investigations have shown to be true most of the time. A law is a hypothesis that scientific investigations have shown to be true all of the time. Cell theory is not cell law. This is because life forms called viruses, viriods and priods are not composed of cells. Other than these limited exceptions, all life is composed of cells. The cell is the basic unit of life.Many organisms such as bacteria, amoeba, some algae, and yeast are composed of only a single cell. The single celled organisms are described as being "unicellular." However, most organisms are composed of many cells and are described as being "multicellular." All cells live in a fluid environment. The human body, for example, is about 70% water. To live, cells must be able to obtain material from and release substances into a liquid environment. It is the cell membrane which allows materials to come into a cell, as well as allowing substances to be released from a cell. An important property of the cell membrane is that it is semipermeable. Semipermeable means that the membrane only allows certain things to pass into or out of the cell. Generally, only those materials that need to enter the cell are allowed to enter. Generally, only those materials which need to be released from the cell are allowed to leave the cell.Cell membranes are composed of two layers of molecules called phospholipid. This phospholipid membrane is composed of combinations of atoms called a phosphate group, and lipids (fats) such as cholesterol. This phospholipid bilayer functions to keep water outside and inside of the cell. However, in the space between the layers, there is no water. The outside parts of the bilayer are described as being hydrophilic (water loving) and the inside parts are described as being hydrophobic (water fearing). Since water is the universal solvent, things can dissolve in water outside and inside the membrane and join with the membrane to enter or leave the cell.Embedded into the membrane are proteins. Some of these proteins are bonded together to form pores through which certain things can pass into and out of the cell. A mosaic is a work of art composed of bits and pieces of things inlaid into some uniform surface. Since the outside and inside of the cell membrane attract water, and because this surface is inlaid with protein, the model of the cell membrane is often described as being "fluid Mosaic Model.Some substances enter the cell by diffusion. Diffusion is the random movement of particles resulting in their movement from a region of greater concentration to one of lesser concentration. If you have a balloon filled with oxygen and...

Find Another Essay On Cell Membrane

Cell Wall and Extracellular Membrane and Their Importance

589 words - 3 pages of the cell on the ECM helps tissues to regenerate after an injury. In plants, the extracellular matrix form the cell wall. The plant cell wall is one of the most complex forms of extracellular matrices . The cell wall is a tough, rigid, yet fairly flexible layer that surrounds the cells of plants and located just outside of the cell membrane. Plant cell walls are primarily made up of cellulose (polysaccharide). Cellulose is a linear polymer

The Effects of Varying, Extreme Temperatures and Varying Organic Solvents on a Beet Root Cell Membrane

763 words - 4 pages One of the main structures of a biotic cell is a cell membrane which is produced from a phospholipid (Reece et al., 2011). When a huge number of phospholipids, each comprising a hydrophilic head and a hydrophobic tail, gather, they rearrange into what is known as a Fluid Mosaic plasma membrane (Reece et al., 2011). This membrane is always in motion and the mosaic created is due to the proteins within the membrane (Reece et al., 2011


527 words - 3 pages vacuole. A. Movement of water along a concentration gradient through a selectively permeable membrane Q. What is meant by a selectively permeable membrane? A. Water; Sugar; Sap; Salt(s); Protein Q. Give a feature of a plant cell that allows it to remain turgid for long periods. A. Allowing some substances to pass through Q. Give locations in a cell at which there is a selectively permeable membrane. A. Vacuole; Cell wall; Cell sap Q. True or

Investigate the Effect of Temperature on Cell Membranes and Membrane Structure

2132 words - 9 pages Investigate the Effect of Temperature on Cell Membranes and Membrane Structure If you read a recipe for cooked beetroot it will usually recommend that you don’t remove the outer skin of the beetroot and don’t cut off al the stalk and root if you want to avoid getting lots of red dye in the cooking water. Beetroot contains red pigments called betalains, located within the cell vacuole. Normally the pigments can’t pass through membranes

The effect of temperature on the cell membrane of a beetroot

2458 words - 10 pages tube.I will also be controlling the amount of time the solutions are left at their designated temperatures, as unequal time spans will results in unfair results. In order to do this, I will be using a stop clock and allowing each solution to be at the desired temperature for 3 minutes.ControlThe main variable in this experiment will be temperature as I am trying to find out how this specifically affects the cell membrane. In order to certify that

The Structure and Role of Proteins in Cell Membranes

1564 words - 6 pages The Structure and Role of Proteins in Cell Membranes Cells are the building blocks of which all living organisms are composed. There are lots of different types of cells that make up living organisms but they are all similar in structure. All cells are surrounded by a cell membrane (or plasma membrane), which controls the movement of substances into and out of the cell. Cell membranes are described as partially


622 words - 3 pages INTRODUCTION There are three main topics in the study of CELLULAR STRUCTURE AND FUNCTION which support the cell to do it activities. The first topic of cellular structure and function is the cell theory the second topic is the basic cells type. The least but not the last topic is the plasma membrane. BODY 1

The Cell of the Human

2960 words - 12 pages nerve cells (Reec et al., 2009). Moreover, every process of performing complex work that cells take part in happens because of dividing the functions of the cell particularly between its parts. One of the cell parts is the cell membrane which has many organelles, and these organelles are the same in the animal cell which is the human cell type. The important organelles in the cell membrane are nucleus of the cell and mitochondria. All of these


1167 words - 5 pages In life, it is critical to understand what substances can permeate the cell membrane. This is important because the substances that are able to permeate the cell membrane can be necessary for the cell to function. Likewise, it is important to have a semi-permeable membrane in the cell due to the fact that it can help guard against harmful items that want to enter the cell. In addition, it is critical to understand how water moves through the

Study guide chapter 8 for AP Bio (Biology by Campbell and Reece)

961 words - 4 pages This study guide is my completed questions to the questions that are issued by the teacher using the text "Biology" by Campbell and Reece.Chapter 8: Membrane Structure and Function1. Phospholipids consist of a hydrophilic head, and a hydrophobic tail. The cell membrane is a phospholipid bilayer two membranes thick. The bilayer is a stable boundary between two compartments because the molecular arrangement shelters the hydrophobic tails of the

Notes on Membrane Structure and Function

1153 words - 5 pages remained as a film covering the surface of water with only the hydrophilic heads immersed in the water*Gorter | Grendel reasoned that cell membranes were two molecules thick (bilayers)*Davson | Danielli proposed the model of a bilayer sandwiched between two layers of protein*Singer | Nicolson proposed that proteins are dispersed and individually inserted into the bilayer*Fluid mosaic model- the membrane is a fluid structure with various proteins

Similar Essays

Cell Membrane Essay

896 words - 4 pages Cell Membrane The cell membrane is a phospholipid bilayer that surrounds both eukaryotic and prokaryotic cells. It is made up of a double layer of phospholipids which forms a selectively permeable barrier between two aqueous compartments, allowing only certain molecules to pass. Embedded within this bilayer are proteins which have carry out specific functions. Integral proteins act as pathways for ion and molecules. Peripheral proteins act as

Beetroot Cell Membrane Permeability Experiment Essay

1414 words - 6 pages Practical AssessmentPlanningAIMBeetroot cells contain a red pigment, which is stored in the cell vacuole and a vacuole membrane to prevent this leaking out of the cell surrounds it. The outer of the cell is also surrounded by a membrane, which again helps contain the pigment inside the cell. In this experiment I aim to find out the relationship between the leakage of red pigment from a beetroot cell and the surface area. To do this successfully

The Poylmer Electrolyte Membrane Fuel Cell

866 words - 4 pages A fuel cell is mainly used to provide electricity from chemical reactions. It harnesses the chemical energy of hydrogen and oxygen to generate electricity without combustion one of the basic types of fuel cells is the Polymer Electrolyte Membrane Fuel Cell (PEMFC). This section will give a general description of its parts, how do they function and the material they are consisted of. 3.2 Background Polymer electrolyte membrane fuel cells

Essay On Bacteria; Includes Bacteria, Eukaryotic Cells, Cell Membrane, Etc

604 words - 2 pages environment. If conditions are not right, most can be dormant for years until conditions are good. Some can even change what they eat, change the temperature in which they can resist, or even resist some biocides if dosage is small enough. Some bacteria can even form a slime layer on themselves acting almost like a "cell membrane", choosing what goes inside the bacteria and out. Bacteria are very adaptable and can survive in almost any condition.Why