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The functions of proteins

Proteins have a number of functions in living organisms.

  • Structural proteins such as collagen in animal connective tissue and keratin in hair, horns and feather quills, all provide support.
  • Storage proteins such as albumin in egg white provide a source of energy. Plants store proteins in their seeds to provide energy for the new growing plant.
  • Transport proteins transport other substances in the body. Haemoglobin in the blood for example, is a protein that contains iron. Haemoglobin has an affinity (attraction) for oxygen and so this is how oxygen is transported around the body in the blood.
  • Hormonal proteins coordinate the body's activities. Insulin for example, is a hormonal protein that controls the sugar levels in the blood.
  • Enzymes are chemical catalysts and speed up chemical reactions. Digestive enzymes such as amylase in your saliva, help to break down polymers in food. Enzymes play an important role in all cellular reactions such as respiration, photosynthesis and many others.

Research project : macromolecules in our daily diet

  1. In order to keep our bodies healthy, it is important that we eat a balanced diet with the right amounts of carbohydrates, proteins and fats. Fats are an important source of energy, they provide insulation for the body, and they also provide a protective layer around many vital organs. Our bodies also need certain essential vitamins and minerals. Most food packaging has a label that provides this information. Choose a number of different food items that you eat. Look at the food label for each, and then complete the following table:
    Food Carbohydrates (%) Proteins (%) Fats (%)
    1. Which food type contains the largest proportion of protein?
    2. Which food type contains the largest proportion of carbohydrates?
    3. Which of the food types you have listed would you consider to be the 'healthiest'? Give a reason for your answer.
  2. In an effort to lose weight, many people choose to diet . There are many diets on offer, each of which is based on particular theories about how to lose weight most effectively. Look at the list of diets below:
    • Vegetarian diet
    • Low fat diet
    • Atkin's diet
    • Weight Watchers
    For each of these diets, answer the following questions:
    1. What theory of weight loss does each type of diet propose?
    2. What are the benefits of the diet?
    3. What are the potential problems with the diet?

Carbohydrates and proteins

  1. Give the structural formula for each of the following:
    1. A polymer chain, consisting of three glucose molecules.
    2. A polypeptide chain, consisting of two molecules of alanine and one molecule of serine.
  2. Write balanced equations to show the polymerisation reactions that produce the polymers described above.
  3. The following polypeptide is the end product of a polymerisation reaction:
    1. Give the structural formula of the monomers that make up the polypeptide.
    2. On the structural formula of the first monomer, label the amino group and the carboxyl group.
    3. What is the chemical formula for the carbon side chain in the second monomer?
    4. Name the bond that forms between the monomers of the polypeptide.

Questions & Answers

Is the normal force always 0
Mpilo Reply
define the term rate of reaction in word
David Reply
I think it a chemical process in which substance act mutually on each other.
Sphesihle
how many bones are in the human body?
Asali
what is wave lengh
mama Reply
is the de broglie wavelength of the particle
Hope
calcium and magnesium, which one can displace aluminum from its compound?
Markia Reply
how is aluminum ion formed?
Dickens
molecules with the same molecular formula but different chain
Malaza Reply
what will be the answer
.angel
chain isomer
Anele
what does the newton's law says?
there are 3 newtons laws which are newton's law of universal gravitation, law of cooling, law of motion
Imagine
Did the feather or leaf hit the ground first?
Shaloom Reply
leaf
Pradip
2 to 30 minut long distance race 20 km what's the avarage speed for the race
Jamilla Reply
what is meaning of covalent bonds
Lungani Reply
bonds that exists between non metal atoms. each atom contribute electron(s) which will form a bond joining the two atoms. electrons in the bond now belongs to both atoms
Matome
how do we name haloalkanes
Thobeka Reply
how do we name haloalkanes
lesedi
what are examples of haloalkanes
Mpho
haloalkanes are compounds that consist of the halogen group chlorine bromine flourine and so on like 2-bromobutan
Samkele
give an example of calculating work
Nwabisa Reply
what is chain Isomer?
Christian Reply
chain isomer ar compounds with the same molecular formular but different chain length
Samkele
Where does the functional group of ketone in carbons belong
Keletso Reply
alkane
Isamkele
how can I find the structural formulae and IUPAC names of hexane?
Matshidiso Reply
@Matshidiso identify your compound which is an alkane..the general formula for alkane is CnH2n+2... hex-6 substitute n with 6 implying that you'll have 6 carbons and 14 Hydrogens then you can draw your structural formula *NB* every carbon has to have 4 bonds
Kgabo
what are disadvantages of primary cells and advantage of secondary cells?
Thabang Reply

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Source:  OpenStax, Siyavula textbooks: grade 12 physical science. OpenStax CNX. Aug 03, 2011 Download for free at http://cnx.org/content/col11244/1.2
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