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Edited by Janet A Renshaw

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1 Edited by Janet A Renshaw
Biological Molecules Carbohydrates Proteins Water Lipids School of Biological Sciences Edited by Janet A Renshaw

2 Contents Introduction Carbohydrates Proteins Lipids Water
Questions and Answers EXIT

3 Introduction The three main organic molecules are carbohydrates, proteins and lipids. These molecules are very important in living organisms, they can be used as building blocks for cells and also for energy They are all based on the chemical elements carbon, hydrogen and oxygen. Proteins can also contain the elements nitrogen, sulphur and phosphorous

4 Carbohydrates Proteins Lipids
The structures of these molecules are of key importance to their functions Water is a very important molecule, it makes up between % of the body mass of most organisms and without it life on earth would not have evolved.

5 Carbohydrates starches cellulose glycogen sugars carbon hydrogen
oxygen Carbohydrate molecules consist of 3 elements Carbohydrates have roles in all forms of life and make up most of the organic matter on earth. Monosaccharides are the basic monomer units of which carbohydrates are composed. The most common monosaccharide is glucose

6 Glucose Glucose can exist in two forms, the  form and the  form.
The two forms of glucose have the same properties. The only difference between them is the position of one of the OH groups. HO OH H O H2COH H in the  form the OH is here OH in the  form the OH is here H OH This has a great effect on the property of molecules made when glucose molecules link together.

7 Disaccharides When 2 monosaccharides join together they form a larger disaccharide molecule. Two monosaccharides can become linked by a condensation reaction. Disaccharide Monosaccharide Monosaccharide share oxygen Removal of H20 The linkage is via a glycosidic bond where they share an oxygen molecule and a water molecule is eliminated.

8 Condensation Reaction between 2 glucose monomers
Glycosidic Bond H2O

9 Examples of Disaccharides
Maltose Formed from 2 glucose molecules, formed in germinating seeds from the breakdown of starch, providing energy Sucrose Formed from 1 glucose and 1 fructose molecule and is the form in which carbohydrates are transported in the phloem in plants Lactose Formed from 1 glucose and 1 galactose molecule, it is an energy source found in the milk of nearly all mammals

10 Polysaccharides glycogen starch cellulose
Carbohydrates which are made from many linked monosaccharide monomers form long chain-like molecules called polymers. glycogen starch polysaccharides cellulose - made from glucose monomers

11 Starch Found in two forms, which are both made up of  glucose
One form is amylose which consists of un-branched chains of  glucose,this coils into a helical compact structure The other form is amylopectin which consists of branched chains of  glucose, this forms a branched compact brush.

12 Starch is the main storage carbohydrate in plants.
Amylase (enzyme) Breaks down sources of maltose Starch glucose energy H2O Hydrolysis reaction:- A chemical process whereby a compound is cleaved into two or more simpler compounds along with the uptake of water

13 Glycogen A polymer of  glucose monomers.
It is the main storage carbohydrate in mammals found in liver and muscle cells. It is more branched in structure than amylopectin. The more branched the molecule, the quicker it can be made and broken.

14 Cellulose Is a polymer of  glucose monomers.
It is an important component of plant cell walls. It does not spiral as with  glucose  glucose consists of chains that are straight and long, they lie parallel to each other bound together by hydrogen bonds.

15 Proteins Proteins have many roles in living organisms and are extremely important. There are many different types of proteins with different functions, for example, Enzymes are proteins which speed up the rate of biological reactions Biological molecule Biological molecule with enzyme Biological molecule with enzyme Biological molecule with enzyme Enzyme Antibodies are protective proteins and as part of the immune system they help fight disease ANTIBODIES DISEASE Haemoglobin is a protein that transports oxygen in the blood.

16 Proteins are polymers made up of monomers called amino acids.
There are 20 different amino acids, amino acids can join in any order to produce an infinite number of different proteins. The only thing that changes between different amino acids is the R group The R group can contain hydrogen and/or carbon and sometimes oxygen, sulphur and nitrogen. This is the basic structure of an amino acid.

17 A condensation reaction joins two amino acids together forming a dipeptide. The bond formed between them is called a peptide bond Peptide Bond H2O A chain of many amino acids linked by peptide bonds is called a polypeptide. A protein can consist of one or more polypeptides. Proteins can get broken down by hydrolysis reactions into polypeptides, dipeptides and amino acids.

18 Protein Structure There are four different levels of protein structure. The primary structure :- this is the sequence of amino acids in the polypeptide formed from many condensation reactions amino acid amino acid amino acid amino acid amino acid amino acid amino acid amino acid amino acid amino acid H2O H2O H2O H2O H2O H2O H2O H2O H2O

19 The secondary structure :- where the polypeptide chains can fold
into stable 3D regular shapes. One secondary structure is the -helix where the chains fold into a helical shape. Another structure is the  strand -helix structure

20 The tertiary structure :- this is when further folding occurs and this is the overall shape of the polypeptide chain. This 3D shape is maintained by a series of weak interactions which are mostly hydrogen bonds. This is the tertiary structure of the alpha chain of the protein, haemoglobin.

21 Quaternary Structure taken by means of rasmol (www.dkfz-heidelberg.de)
The quaternary structure :- polypeptides can associate with other polypeptides and they way in which they bind together to form the molecule is the quaternary structure. Quaternary Structure taken by means of rasmol (www.dkfz-heidelberg.de)

22 Protein Subgroups Proteins fit into two subgroups, globular proteins and fibrous proteins. Globular proteins, for example enzymes, form roughly a spherical shape and most of them are soluble in water. Substrate The function of a globular protein is determined by its shape, so its shape is vital. Molecular representation of an enzyme The usual function for this subgroup is a chemical function.

23 Fibrous proteins do not form a spherical structure they form long chains
and they are insoluble. Fibrous proteins have structural roles, like giving strength or elasticity to certain tissues. Muscle Fibre (www.uoguelph.ca)

24 Proteins can become denatured causing their shape to change therefore affecting their function.
A protein can vibrate due to an increase in temperature, which can cause it to become denatured, causing the weak bonds holding the tertiary or quaternary structure together to break. Example shows an enzyme becoming denatured and losing hold on a substrate

25 Lipids hydrogen oxygen fats oils steroids waxes
Lipid molecules consist of 3 elements carbon hydrogen oxygen Lipids are insoluble. They are important dietary constituents as they are full of energy, contain certain vitamins and have a major role in cell membranes. Unlike carbohydrates and proteins, lipids do not form polymers. Two major types of lipids are triglycerides and phospholipids.

26 This group of lipids are the
Triglycerides This group of lipids are the fats and oils. They are formed from a glycerol molecule linked by ester bonds to three fatty acids. Ester bond:-This is formed from a condensation reaction where the carboxyl group of a fatty acid and an OH group from the glycerol join and water is lost so they share an oxygen atom. The formula for fatty acids is R-COOH, where the R, which is the hydrocarbon chain can be saturated or unsaturated.

27 Triglyceride Molecule
ester bond Glycerol 3 saturated fatty acids 3H2O

28 Phospholipids Fatty acid glycerol Fatty acid phosphate
The phosphate group is soluble in water, it is water loving, which is termed hydrophillic. The fatty acids are insoluble in water, they repel water, which is known as hydrophobic. fatty acids Due to these properties phospholipids form cell membranes when in water glycerol glycerol glycerol water phosphates

29 Phospholipid Bilayer formed in water
Simplified structure of a phospholipid molecule used in diagrams of membranes H2O H2O H2O Phospholipid Bilayer formed in water H2O H2O H2O H2O

30 Water Water is an inorganic substance.
It has many essential properties, it has these properties because of the way in which the molecules in water bond together. The biological importance of water is dependent on its physical properties.

31 Some Important Properties of Water
Solvent Properties Water is a polar molecule and it’s polarity makes it an excellent solvent for other polar molecules. There is a whole range of other polar molecules, which include small organic units such as glucose and amino acids, also ions like calcium,potassium and sodium. Non-polar substances do not dissolve in water.

32 Specific Heat Capacity
Water has a high specific heat capacity, which means it has temperature stability. It takes a large amount of heat (energy) to raise the temperature of water measurably. Due to this water containing organisms are stable thermally.

33 Latent Heat of Evaporation
Due to the high specific heat capacity, water resists evaporation into gas better than other liquids do. This is significant to humans and other animals as we rely on the evaporation of water from our body surface as a cooling device.

34 Questions and Answers This section is to test your knowledge on what has been covered in this package. You will need paper and a pen to help you answer some of the questions To get the answer click on the answer button Now go to the next page to start testing your knowledge.

35 Click here to see diagram
CARBOHYDRATES Question What is the name of this carbohydrate monomer ? Click here for answer Question 2 Draw a diagram to show how two of these monomers form a disaccharide and label the bond Click here to see diagram

36 Question 3 What is the name of the disaccharide formed ?
Click here for answer Question What are the two forms of the polysaccharide starch ? Click here for answer Question What are the differences between the two forms ? Click here for answer

37 Question 6 What three elements can be found in proteins but not in
carbohydrates and lipids ? Click here for answer Question 7 There are two subgroups of proteins, globular proteins and fibrous proteins. Which subgroup - a) is soluble in water ? b) has structural roles ? Click here for answers c) form long chains ? d) is spherical in shape ?

38 Question 8 What type of reaction occurs to join amino acids together?
Click here for answer Question What is the name of the bond formed between amino acids in a protein ? Click here for answer

39 Question 10 What are the two major types of lipids?
Click here for answer Question How is an ester bond formed in a triglyceride? Click here for answer

40 Question 12 The phosphate group of a phospholipid is soluble in water,
what is the term used for this type of molecule Click here for answer Question Fatty acids are insoluble in water, what is the term used for this type of molecule? Click here for answer

41 Question 14 Name two important properties of water.
Click here for answer Question Water is a polar molecule do Non-polar substances dissolve in water? Click here for answer

42 You have reached the end of this revision package
Choose an option Return to Carbohydrates Return to Proteins Return to Lipids Return to Water Return to Question and Answers Exit the package

43 Answer This carbohydrate monomer is glucose
Q1 Answer This carbohydrate monomer is glucose

44 Q2 Glycosidic Bond Answer H20

45 Answer The disaccharide formed is maltose
Q3 Answer The disaccharide formed is maltose

46 Answer The two forms of starch are amylose and amylopectin
Q4 Answer The two forms of starch are amylose and amylopectin

47 Q5 Answer Amylose consists of unbranched chains of  glucose and has a helical compact structure Amylopectin consists of branched chains of  glucose and has a branched compact structure

48 Answer Nitrogen, sulphur and phosphorous
Q6 Answer Nitrogen, sulphur and phosphorous

49 Answer Globular proteins a) soluble in water ? Fibrous proteins
Q7 Answer Globular proteins a) soluble in water ? Fibrous proteins b) structural roles ? Fibrous proteins c) form long chains ? Globular proteins d) spherical in shape ?

50 Answer A condensation reaction
Q8 Answer A condensation reaction

51 Q9 Answer A peptide bond

52 Triglycerides and phospholipids
Q10 Answer Triglycerides and phospholipids

53 Q11 Answer An Ester bond is formed from a condensation reaction where the carboxyl group of a fatty acid and an OH group from the glycerol join and water is lost so they share an oxygen atom.

54 Answer The phosphate is termed as a hydrophillic molecule
Q12 Answer The phosphate is termed as a hydrophillic molecule

55 hydrophobic molecules
Q13 Answer Fatty acids are hydrophobic molecules

56 - high specific heat capacity - high latent heat of evaporation
Q14 Answer Two from any of these - solvent properties - high specific heat capacity - high latent heat of evaporation

57 Q15 Answer No


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