• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The Various Roles Played By Proteins

Extracts from this document...

Introduction

Stephanie Ashton 11/11/07 An Essay On 'The Various Roles Played By Proteins In The Cell Membrane.' Throughout this essay I am going to be investigating the different types of proteins found in the cell membrane, and why their functions are important in everyday life. Proteins make up about half of the mass of the cell membrane and are responsible for most of the membrane's properties. On average a cell has about ten thousand different types of proteins within it, therefore each of these different types need to be localised to a specific area in order for them to do the job at hand adequately. Proteins which are known as membrane proteins can be split into two groups; the first of these groups is known as the 'extrinsic proteins' and the second is called the 'intrinsic proteins'. Extrinsic proteins can only be found on one side of the phospholipid bilayer, they do not alter the movement of substances and combine with specific substances which have a complimentary shape to their own; therefore act as receptor site. ...read more.

Middle

(Phillipallan,nov,1999) . On occasions the binding leads to other events in the cell being triggered like cell recognition. However cells do not always respond to the signals which are being given positively and this may result in the cells committing suicide. Throughout the cell membrane there are low density lipoproteins which have the job of binding the bad cholesterol from the cell and removing it from the circulation. It has also been proven that these proteins also contribute a lot to carrying the cholesterol from the membrane to other cells in the body which may need it. (Science Daily, Apr. 13, 2000). Similar to the intrinsic proteins trans-membrane protein molecules also help to control what passes through into the cell. These proteins are of specific shape and size (similar to the lock and key method in enzymes) and therefore only substances which match this are allowed to cross. Transport proteins can also be broken up into two groups; the channel proteins and the carrier proteins. ...read more.

Conclusion

Proteins in the membrane work together with the cytoskeleton; which is found in the cytoplasm of the membrane and provides structure and support for the proteins to attach themselves to. These work together to form appendage like organelles which extend from the cell such as; cilias. The majority of the cilia are covered by the cell membrane but do stick out slightly from the cell with little hair like structures called microvilli. Therefore the proteins help the membrane to act as a protecting body. The anchoring proteins are also the ones which restrict themselves to a particular cell surface. For example; 'the apical surface of epithelial cells that line the vertebrate gut' (www. wikipedia.org) and puts a limit on how far the organelles can diffuse within the bilayer. . Anchoring proteins restricts them to a particular cell surface - for example, the apical surface of epithelial cells that line the vertebrate gut - and limits how far they may diffuse within the bilayer. like projections, called microvilli, which increase cell surface area and thereby increase the absorption rate of nutrients. The cell membrane acts as a protecting body. ?? ?? ?? ?? ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a star student thought of this essay

3 star(s)

Response to the question

Overall a mediocre essay that outlines all the basic A level facts for this level of syllabus. Introduction could be more centered around the question, and the main analytical body of the text could be a lot more in depth ...

Read full review

Response to the question

Overall a mediocre essay that outlines all the basic A level facts for this level of syllabus. Introduction could be more centered around the question, and the main analytical body of the text could be a lot more in depth and explore topics of proteins around the a level syllabus to gain a higher mark. No conclusion. Response to the question is very scientifically accurate although basic.

Level of analysis

Introduction is good, but could set out the main examination basis of the essay better rather than concentrating on broad points about proteins. Language used is basic scientific A level terms that from the beginning stick to the syllabus and the basic sciences used at A level rather than scoping above and beyond. Link structure to function vaguely and makes a few points although they could make a few more real life examples. Do not include a conclusion for the essay and could include a lot more in depth analysis.

Quality of writing

Spelling, punctuation and grammar are all adequate and correct but the essay could be organised better, and references should be included in their own separate section at the end of the text.


Did you find this review helpful? Join our team of reviewers and help other students learn

Reviewed by skatealexia 28/03/2012

Read less
Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Investigate the water potential of celeriac.

    5 star(s)

    placed in the water bath, yet again there was a very subtle colour change; from the Copper II Sulphate blue, to a faint green solution. This led me to believe that celeriac had very little reducing sugar and also very little non-reducing sugar present.

  2. Marked by a teacher

    Describe the molecular structure of starch (amylase), glycogen and cellulose, and relate these structures ...

    4 star(s)

    Glycogen, another polymer of glucose, is the polysaccharide used by animals to store energy. Excess glucose is bonded together to form glycogen molecules, which the animal stores in the liver and muscle tissue as an "instant" source of energy. Both starch and glycogen are polymers of glucose, however starch is

  1. Marked by a teacher

    The Effect Of Temperature On The Permeability Of The Cell Membrane

    3 star(s)

    This will make it a fair experiment because uneven pieces of beetroot can mean that big pieces will leak more than smaller pieces. Weigh the beetroot using a balance at 1g. Wash the beetroot with distilled water because it is purer than tap water.

  2. Peer reviewed

    The comparison of antibacterial properties of herbal products and standard antibiotics

    5 star(s)

    Due to their simplistic nature, they are also very small an inhibit places such as water, air and human bodies. The majority of bacteria are harmless, however various bacteria that inhibit the body are known as pathogens and can cause disease and infection.

  1. Effect of Caffeine on the Heart Rate of Daphnia

    Put the pipette under the surface of the solution in the Petri dish and pipette carefully to avoid introducing air bubbles beneath the carapace of the Daphnia. (Air bubbles make Daphnia float at the surface, unable to swim, which will eventually kill them.)

  2. Investigating Water Potential Of Potatoes.

    This occurred due to osmosis taking place, however, rather than water moving into the cell, water was moving out instead, thus decreasing the weight of the potato. The solution surrounding the cell is said to be hypertonic and so therefore shrinks the cell, which is now known to be becoming flaccid.

  1. Photosynthesis - Absorption spectrum.

    * Phosphate deficiency - stunted growth, poor root growth, purple leaves. This is because of poor root growth so less photosynthesis because of less water and minerals being sucked up. * Potassium deficiency - yellow leaves, poor fruit and flower growth.

  2. Osmosis in Potato cells

    -11.01 -12.62 0.00 -15.60 -17.18 -10.68 -11.18 Percentage change in Length: Concentration of Sucrose Abdulla Jenny Mamta Candice Melanie Wendy Average Change in Length 0% 0.00 0.00 -1.82 -3.64 -8.00 0.00 -2.24 5% 0.00 0.00 0.00 0.00 0.00 1.82 0.30 10% 0.00 0.00 1.82 5.45 2.00 3.64 2.15 15% 0.00

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work