We will be starting at 4.30pm. - PowerPoint Presentation

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We will be starting at 4.30pm.

In the meantime, please check the following:

Ensure your computer speakers are on and the volume is upEnsure you have your camera on and your microphone switched offClick the Q&A button to ask us any questionsEnsure you have any accompanying Masterclass documents in front of you for referenceIf you are having any issues, please send us a message through the chat feed

Chemistry Masterclass

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Carbohydrates and Fats

Chemistry MasterclassWith Steve Kuruc

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VCAA

carbohydrates: mono, di and polysaccharides,complex carbohydrates, starch/ cellulose glycosidic linkagesglycogencomparison of glucose, fructose, sucrose aspartame –structure & energy contentfats and oils (triglycerides): common structural features - ester links distinction between fats and oils with reference to melting pointsexplanation of different melting points of triglycerides with reference to the structures of their fatty acid tails and the strength of intermolecular forceschemical structures of saturated and unsaturated fatty acidsdistinction between essential and nonessential fatty acidsstructural differences between omega-3 fatty acids and omega-6 fatty acids

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Learning Intentions

PMI about AspartameKnowing the purpose/importance of carbohydrates and fats in the dietStructural, chemical and physical differences between these biomoleculesSpecific details about digestion * hydrolysis reactions

‘Visually’ identify these molecules and infer chemical and physical properties

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Success Criteria

I know what AspartameIs… as well as its pro’s and con’s.I know the purpose/importance of carbohydrates and fats in the dietI know structural, chemical and physical differences between carbs/fats

I can draw or predict outcomes of hydrolysis reactionsI can ‘visually’ identify carbs/fats from images or structures and infer chemical and physical properties

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Carbohydrates are the sugars, starches and fibre found in fruits, grains,

vegetables, including milk products. Carbohydrates are important to a healthy diet as they provide us with energy.

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FACTS

Carbohydrates fuel our brain, central nervous system and muscles.

They also prevent protein from being used as an energy source and enable fat metabolism

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Mood swings & irritability.

Without enough carbohydrates, your blood sugar will drop, leaving you feeling moody and most likely irritable as well  Carbohydrates help create mood boosting chemicals such as serotonin.

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Carbohydrates are classified as

simple or complex, the difference between the two forms is their

chemical structure and how quickly the ‘sugar’ is absorbed into blood. HINT : think glycemic index

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Disaccharides

contain two sugar units for example, Sucrose (table sugar)Lactose (from dairy) Maltose (found in beer and some vegetables).

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Complex carbohydrates

Are called

polysaccharides

They can be considered as polymers of smaller ‘sugar’ units.

Starch

Glycogen

Cellulose

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Monosaccharides

Glucose, Fructose and Galactose – are all isomers

 of C6H12O6Glucose is also known as DEXTROSE and is usually a product of DIGESTION of complex carbohydrates.Amylase in saliva starts breaking starch down into simpler carbohydrates in the mouth.

Hydrolysis

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Structure of Glucose

Glucose exists as a colourless crystalline solid

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Disaccharides

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Carbohydrate digestion continues in the small intestine where maltase acts on maltose to form glucose units that can be absorbed directly into the blood stream

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Carbohydrate digestion beyond the stomach…

Oligosaccharides

*3 - 10 monosaccharides in length

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Cellulose

Also known as FIBRE

Makes up 50% of the words carbon and is bound up in trees and plants.Main constituent of paper, wood, cotton, linen...Odourless, tasteless and insoluble.Essential in our diet but cannot be digested.

Exists as a large polymer molecule that can be broken down in the presence of strong acids/high temperatures.

Can have a huge molar mass…

ie

2.5x10

6

g/mol

POLYSACCHARIDES

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Starch

Plants use starch as an

GLUCOSE storage moleculePlants use starch as a source of energy at night as photosynthesis can only occur in sunlight.Starch is soluble and comes in 2 forms – branched and linear forms.Starch is present in many foods we eat and can be digested by AMYLASE in the mouth and small intestine.

*Iodine turns dark blue in the presence of starch

POLYSACCHARIDES

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More about

AmyloseAmylose comprises about 20% of starch and consists of 50–300𝛼-glucose units in length.Glycosidic linkages exist at C1 and C4.

This bonding arrangement results in long chain molecules that form spirals due to hydrogen bonding along its length. As hydrogen bonding occurs within the coil, steric hindrance causes amylose to be insoluble in water.

Can’t bond with me… really?

I can do better…

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Glycogen

‘Animal starch’ as it is

a GLUCOSE storage moleculeIs stored in muscles and the liver and allows the body immediate access to ‘fuel’ for energyGlycogen is hydrolysed to form glucose for energyCellular Respiration converts glucose into water and carbon dioxide plus ATP for our energy needs.

POLYSACCHARIDES

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Digestion of polysaccharides

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Did you know - the

sweet

taste associated with glucose and sucrose arises from their molecular shapes! For a molecule to ‘taste’ sweet it must form bonds with our taste buds in order for the brain to recognise sweetness.

Three bonds are needed to combine with a taste bud…two H-bonds and one non-polar site…

Apparently there is a

triangle

of sweetness that be present in a molecule for this to occur!

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‘such a sweetie…’

There are substances 1000’s of times sweeter than glucose.

Sucrose is twice as sweet as glucose. Can you think of a reason for this?Artificial sweeteners such as ASPARTAME are 200 times sweeter than sucrose…(but contain the same energy content per gram)

We can keep ‘taste’ and reduce calorific content of food without the guilt

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