1. Chapter 5:Sources of Energy
Higher Human Biology
Unit 1: Cell Function and Inheritance
Chapter 5:Sources of Energy
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Mrs Smith: Ch5 Sources of Energy.

2. Mrs Smith: Ch5 Sources of Energy.
Learning intentions.
To compare the differences between mono-, di- and poly-saccharides
To examine the structure of lipids and their various roles in cells and organisms
To study protein degradation and their use as an alternative respiratory substrate
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Mrs Smith: Ch5 Sources of Energy.

3. Mrs Smith: Ch5 Sources of Energy.
Carbohydrates.
Carbohydrates (e.g. Sugar, starch and glycogen) are compounds whose molecules all contain the chemical elements CARBON (C), HYDROGEN (H) and OXYGEN (O).
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Mrs Smith: Ch5 Sources of Energy.

4. Monosaccharides (single-sugar)
This is a simple sugar.
Made up of six-sided unit, galactose, glucose and fructose are examples of these
Monosaccharide's are soluble in water.
Described as reducing sugars.
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Mrs Smith: Ch5 Sources of Energy.

5. Disaccharides (double-sugar)
Made of two monosaccharides joined together.
Maltose and sucrose are
examples of disaccharides.
Disaccharides are soluble in water.
Maltose has reducing properties.
Sucrose is a non-reducing sugar.
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Mrs Smith: Ch5 Sources of Energy.

6. Mrs Smith: Ch5 Sources of Energy.
Polysaccharides
A polysaccharide is a carbohydrate composed of many monosaccharide molecules joined together.
These molecules are all very large and insoluble in water.
ALL CARBOHYDRATES ARE RICH SOURCES OF ENERGY
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Mrs Smith: Ch5 Sources of Energy.

7. Mrs Smith: Ch5 Sources of Energy.
Starch
This polysaccharide consists of a long chain of glucose (>1000 monosaccharide units).
These molecules are all very large and insoluble in water.
Starch is the form in which plants store carbohydrate.
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Mrs Smith: Ch5 Sources of Energy.

8. Mrs Smith: Ch5 Sources of Energy.
Glycogen
This polysaccharide is very similar to a branched form of starch.
These molecules are also very large and insoluble in water.
This means glycogen cannot diffuse out of the cell and they do not affect the cells osmotic balance
This makes it an ideal storage material, particularly abundant in liver and muscle cells.
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Mrs Smith: Ch5 Sources of Energy.

9. Mrs Smith: Ch5 Sources of Energy.
ALL CARBOHYDRATES are a rich source of ENERGY.
Monosaccharide's can be used to release energy. (e.g. glucose can undergo glycolysis during respiration)
However disaccharides and polysaccharides must be broken down by enzymes before they can release their energy.
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Mrs Smith: Ch5 Sources of Energy.

10. Identifying unknown carbohydrates
TEST
Solubility
Benedict’s
Barfored’s
Clinistix
Iodine
Glucose
Soluble
Brick-red
Brick-red rapidly
Purple-blue -
Fructose
rapidly
Maltose
Faint Brick-red slowly
Lactose
Sucrose
Brick-red after acid hydrolysis
Starch
Insoluble
Blue-black
Glycogen
Purple-red
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Mrs Smith: Ch5 Sources of Energy.

11. Mrs Smith: Ch5 Sources of Energy.
TASK
Testing your knowledge: Please complete Torrance pg38 Qu’s 1-3.
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Mrs Smith: Ch5 Sources of Energy.

12. Mrs Smith: Ch5 Sources of Energy.
Lipids
This is a diverse group of organic compounds including fats, oils, phospholipids and steroids.
Lipids contain the elements C, H and O. (but the proportion of oxygen in lipids is smaller than in carbohydrates).
LIPIDS ARE INSOLUBLE IN WATER
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Mrs Smith: Ch5 Sources of Energy.

13. Triglyceride (Simple lipid)
Fat (solid at rm temp) and oil (Liquid at rm temp) are examples of triglycerides.
Their molecular structure consists of a glycerol and 3 fatty acids.
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Mrs Smith: Ch5 Sources of Energy.

14. Mrs Smith: Ch5 Sources of Energy.
Phospholipids
A typical phospholipid contains two molecules of fatty acids linked to one glycerol, in addition it has one phosphate on the third position of the glycerol
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Mrs Smith: Ch5 Sources of Energy.

15. Phospholipids- different properties at each end!
The phosphate (‘head’) end of the molecule is hydrophilic (water loving) and is therefore soluble in water.
The fatty acid (‘tail’) end of the molecule is hydrophobic (water-hating) and is therefore insoluble in water.
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Mrs Smith: Ch5 Sources of Energy.

16. Mrs Smith: Ch5 Sources of Energy.
Phospholipid example.
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17. Mrs Smith: Ch5 Sources of Energy.
Steroids
Steroids are lipids, however their structure varies from simple and phospholipids.
Each molecule of a steroid has a basic structure composed of 3 6-carbon rings joined to a 5-carbon ring.
Cholesterol is an example of a steroid. It provides the basic molecular structure from which other steroids are formed (bile and sex hormones).
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Mrs Smith: Ch5 Sources of Energy.

18. Mrs Smith: Ch5 Sources of Energy.
Steroids
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19. Mrs Smith: Ch5 Sources of Energy.
Roles of Lipids
Energy store
Thermal and nerve insulation
Fat pads
Vitamin transport
Hormones
Major components of the plasma membrane
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Mrs Smith: Ch5 Sources of Energy.

20. Roles of Lipids: Energy store
Fat is deposited in fatty (adipose) tissue.
It is insoluble and compact making it an ideal form in which to store energy.
When energy is required, a fat molecule is broken down into glycerol and fatty acids which become available for use in aerobic respiration.
Fat liberates more than double the quantity of energy than the same mass of carbohydrate.
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Mrs Smith: Ch5 Sources of Energy.

21. Roles of Lipids: Thermal and nerve insulation.
The fat beneath the skin also serves as a INSULATOR to help conserve body heat.
The sheath around each nerve fibre consists of a fatty material called myelin, this insulated the nerve and increased the speed of the impulses.
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Mrs Smith: Ch5 Sources of Energy.

22. Roles of Lipids: Fat Pads
Pads of fat in the palms of the hands and soles of the feet protect the underlying structures by acting as cushions.
The kidneys are also protected by fat pads.
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Mrs Smith: Ch5 Sources of Energy.

23. Roles of Lipids: Plasma membrane
Phospholipids are one of the basic building blocks of cell membranes.
The steroid cholesterol is also an important components of membranes.
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Mrs Smith: Ch5 Sources of Energy.

24. Mrs Smith: Ch5 Sources of Energy.
Proteins
Proteins broken down into amino acids.
Excess amino acids cannot be stored in the body.
They are deaminated into urea and organic compounds.
These organic acids enter the respiratory pathway to produce some ATP
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Mrs Smith: Ch5 Sources of Energy.

25. Mrs Smith: Ch5 Sources of Energy.
Starvation
Tissue protein is used as a source of energy only during prolonged starvation when the reserves of glycogen and fat have become exhausted.
Skeletal muscle and other tissues rich in protein are used up to produce energy during the crisis.
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Mrs Smith: Ch5 Sources of Energy.

26. Mrs Smith: Ch5 Sources of Energy.
Marathon Running
In the first few minutes the body uses glucose from muscle glycogen.
Blood glucose mainly from liver glycogen is used for the next 30 minutes
As glucose supplies decrease fatty acids become the energy supply.
Farrah Olympic gold 2012 – long distance
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Mrs Smith: Ch5 Sources of Energy.