Biological Molecules
-
Upload
kevyn-cobb -
Category
Documents
-
view
32 -
download
1
description
Transcript of Biological Molecules
![Page 1: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/1.jpg)
Biological Molecules
![Page 2: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/2.jpg)
Food Tests
Benedicts Test-(Reducing Sugars) Biuret Test-(Protein) Iodine test-(Starch) Emulsion test(Lipids) Non-reducing sugars test
![Page 3: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/3.jpg)
Benedict’s Test
Add 2cm3 of the sugar solution to a test-tube, and then an equal volume of Benedict’s solution. Bring to the boil in a water-bath.
Result: Turns green, then yellowish, then may form brick-red precipitate.
Basis: The Cu++ ions in the copper sulphate in Benedict’s are reduced by the sugar to insoluble Cu+ which precipitates out
![Page 4: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/4.jpg)
Biuret Test
Add equal quantities of test solution and potassium hydroxide and mix. Add two drops of copper sulphate, and mix
Result: Mauve or purple colour slowly develops
Basis: Nitrogen atoms in the peptide chain form a purple complex with the Cu++ ions
![Page 5: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/5.jpg)
Iodine Test
Add a few drops of potassium iodide solution to the test solution and mix
A blue/black colouration develops
A polyiodide complex forms with the starch molecules
![Page 6: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/6.jpg)
Emulsion test
Add equal quantities of the suspected lipid and absolute ethanol in a test tube. Shake vigorously to dissolve. Add an equal quantity of cold water.
Result: A cloudy white suspension
Lipids are insoluble in water, so adding water to a solution of the lipid in alcohol results in an emulsion of tiny lipid droplets in the water which look white as they reflect light.
![Page 7: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/7.jpg)
Non Reducing Sugars
Add 2cm3 sucrose solution to a test-tube. Add 1cm3 dilute sulphuric acid. Boil for one minute, and then carefully neutralize with sodium bicarbonate. (take care, as it will effervesce). Carry out Benedict’s test
The acid hydrolyses the sucrose (breaks the glycosidic bond) making two monomer molecules (glucose and fructose), which are reducing sugars
![Page 8: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/8.jpg)
Monomer – building blocks of biological molecules
Polymer - a chemical compound consisting of repeating structural units (monomers)
Macromolecules – another name for a polymer
![Page 9: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/9.jpg)
Carbohydrates
Made of C, H and O
Three types:
1. Monosaccharide
2. Disaccharide
3. Polysaccharide
![Page 10: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/10.jpg)
Monosaccharides
Simplest carbohydratesGlucose, fructose, galactose
![Page 11: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/11.jpg)
Glucose
Two types:
![Page 12: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/12.jpg)
Glycosidic Bonds
![Page 13: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/13.jpg)
![Page 14: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/14.jpg)
Condensation
![Page 15: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/15.jpg)
Hydrolysis
![Page 16: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/16.jpg)
![Page 17: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/17.jpg)
Polysaccharides
![Page 18: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/18.jpg)
Starch
Storage polysaccharide in plants Made of two substances:
1. Amylose
2. Amylopectin
![Page 19: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/19.jpg)
Amylose
α glucose molecules with 1-4 links
Coils into a spiral Held together with
hydrogen bonds
![Page 20: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/20.jpg)
Amylopectin
α glucose with 1-4 links and 1-6 links
Causes branching chains
![Page 21: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/21.jpg)
![Page 22: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/22.jpg)
Glycogen
Storage in animals and fungi
α glucose molecules with 1-4 links and 1-6 links
Forms a branching chain
Held together with hydrogen bonds
![Page 23: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/23.jpg)
Cellulose β glucose with 1-4 links Adjacent molecules in the chain are flipped 180
degrees Hydrogen bonds form between different chains
forming a bundle of microfibrils
![Page 24: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/24.jpg)
Proteins
![Page 25: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/25.jpg)
Primary Structure
Monomer – amino acid
Amino acids joined by peptide bonds Condensation reaction
![Page 26: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/26.jpg)
Secondary Structure
Two possible structures: α helix β pleated sheet
Held together by hydrogen bonds
![Page 27: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/27.jpg)
Tertiary Structure
Secondary structure folded and bonds form between the R chains
Different types of bonds: Hydrogen bonds Ionic bonds Disulphide bridges Hydrophobic interactions
![Page 28: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/28.jpg)
Tertiary Structure Bonds
![Page 29: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/29.jpg)
Quaternary structure
More than one tertiary structure joined together.
![Page 30: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/30.jpg)
Haemoglobin
Globular protein 4 tertiary structures joined together Two alpha chains (141 aa), and two beta
chains (146 aa) Each chain has a haem (containing an iron
atom) group attached This is used to bond the oxygen
![Page 31: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/31.jpg)
Some amino acids have hydrophobic side chains (repelling water), and some have hydrophilic side chains (attracting water)
The “R” groups on amino acids are sometimes referred to as side chains.
Haemoglobin
![Page 32: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/32.jpg)
Haemoglobin
Haem
![Page 33: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/33.jpg)
On the four polypeptide chains that make up the haemoglobin, amino acids with hydrophobic side chains point inwards, helping to hold the molecule together
Amino acids with hydrophilic side chains point outwards, making the haemoglobin molecule soluble.
Haemoglobin
![Page 34: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/34.jpg)
![Page 35: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/35.jpg)
Collagen
Fibrous protein Three strands plaited together Very strong
![Page 36: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/36.jpg)
![Page 37: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/37.jpg)
Lipids
Made of two parts: Glycerol Three fatty acid chains
High energy due to many hydrogen atoms
![Page 38: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/38.jpg)
Saturated and unsaturated
Saturated fats have no carbon to carbon double bonds, they are solid at room temperature
Unsaturated fats have one or more carbon to carbon double bonds. These form kinks in the fatty acid chains and so they are liquids at room temperature.
![Page 39: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/39.jpg)
Phospholipids
Polar region is the phosphate group and it allow it to be soluble in water – hydrophillic
The non-polar fatty acid chains are insoluble in water - hydrophobic
![Page 40: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/40.jpg)
Structure and function
Their insulating properties keep mammals warm.
They contain twice the stored energy of carbohydrates, gram for gram.
They are used in the formation of cell-surface membranes.
In aquatic mammals, the fat is less dense than water, so it acts as a buoyancy aid.
![Page 41: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/41.jpg)
Water
![Page 42: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/42.jpg)
Properties of water
High specific heat capacity High heat of vaporisation
both of which are a result of the extensive hydrogen bonding between its molecules.
These two unusual properties allow water to moderate Earth's climate by buffering large fluctuations in temperature.
![Page 43: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/43.jpg)
at approximately 4 °C pure water reaches its maximum density Protects aquatic environments
![Page 44: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/44.jpg)
Universal solvent Water molecules stay close to each other
(cohesion), due to the collective action of hydrogen bonds between water molecules. Leading to high surface tension.
Water also has high adhesion properties because of its polar nature.
![Page 45: Biological Molecules](https://reader036.fdocuments.in/reader036/viewer/2022062304/56812a67550346895d8dea4a/html5/thumbnails/45.jpg)
Essay
a) Describe the characteristics of water.
b) How do these characteristics enable living organisms to survive.