Food 6/11/17 Flashcards
What are carbohydrates made up of?
Simple sugar
What elements do carbohydrate molecules contain?
Carbon, Hydrogen, Oxygen
What does maltose form when it’s joined together?
Starch
What does glucose form when it’s joined together?
Glycogen
What are starch and glycogen?
Large complex carbohydrates
How is maltose drawn?
Pairs of the same shape joined up
How is glucose drawn?
Single shapes on there own
How is starch drawn?
A long chain of the same shapes
What are proteins made up of?
Long chains of Amino acids
What elements are in protein molecules?
Carbon, Hydrogen, Oxygen and Nitrogen
How are amino acids drawn?
Loads of different single shapes
How are proteins drawn?
Loads of different shapes joined together
What are lipids made up of?
Fatty acids and glycerol
What elements do lipids molecules contain?
Carbon, Hydrogen, Oxygen
How are glycerol and fatty acids drawn?
Glycerol-as a long oval
Fatty acids-3 long chains of shapes
How are lipids drawn?
Draw the large oval for glycerol then the three chains of fatty acids come from the long side of the oval
How do you prepare a food sample?
- get a piece food and break it up in a pestle no mortar
- put the ground up food in a beaker and add some distilled water
- stir with a glass rod to dissolve some of the food
- filter the solution with funnel to remove the solid bits of food
What’s the Benedict’s test for?
Glucose
What is the Benedict’s test?
1) prepare food sample and transfer 5cm3 to a test tube
2) prepare a 75°C water bath
3) add Benedict’s solution to test tube(about 10 drops)
4) place test tube in water bath for 5mins make sure it faces away from you
5) if glucose is present the solution will change from a blue to green or yellow in low concentrates and brick red in high concentrations
What’s iodine used to test for?
Starch
What is the iodine test?
1) make food sample and transfer 5cm3 into a test tube
2) then add a few drops of iodine solution and gently shake if starch is present the colour will change from browny-orange to black or blue-black
What’s the Biuret test for?
Proteins
What is the Biuret test?
1) prepare a sample of your food and put 2cm3 in a test tube
2) add 2cm3 of Biuret solution and gently shake
3) if protein is present the colour will change from blue to pink or purple
What is the emulsion test for?
Lipids
What is the emulsion test?
1)shake the test substance with ethanol for a minute to allow the ethanol to dissolve, then pour the solution into water
2)any lipid with show up as a cloudy emulsion
3)the more lipid there is the more noticeably milky white the colour will be
CLEAR->MILKY WHITE
What’s the Sudan III test for?
Lipids
What’s the Sudan III test ?
1) prepare a sample of your food(don’t need to filter) put 5cm3 Ina test tube
2) add 3 drops of Sudan III stain solution to the test tube and gently shake
3) Sudan III stain stains lipids if lipids are present the mixture will separate into two layers the top layer will be bright red
What are the 7 nutrients that you need?
Carbohydrates, Lipids, Proteins, Vitamins, Mineral ions, Water, Dietary fibre
What are carbohydrates found in and what is their function?
Found in-pasta, rice, sugar
Function-provides energy
What are lipids found in and what is their function?
Found in-butter, oily fish
Function-provide energy, act as an energy store, provide insulation
What are proteins found in and what is their function?
Found in-Meat, fish
Function-growth and repair of tissue, provide energy in emergencies
What is vitamin A found in and what is their function?
Found in-liver
Function-improve vision, keep skin and hair healthy
What is vitamin C found in and what is their function?
Found in-oranges
Function-prevent scurvy
What is vitamin D found in and what is their function?
Found in-Eggs
Function-needed for calcium absorption
What is mineral-calcium found in and what is their function?
Found in-Milk, cheese
Function-need to make healthy bones and teeth
What is mineral-iron found in and what is their function?
Found in-Red meat
Function-needed to make haemoglobin for healthy blood
What is water found in and what is their function?
Found in-food and drink
Function-just about every bodily function relies on water, we need a constant supply to replace the water we lose through urinating, sweating and breathing
What is dietary fibre found in and what is their function?
Found in-whole meal bread, fruit
Function-aids the movement of food through your gut
What does a balanced diet supply?
-gives you essential nutrients you need in the right amount
How can your activity level affect your energy requirement?
Active people need more energy than people who sit about all day
How does your age affect your energy requirement?
Children and teenagers need more energy than older people because they need to grow and are generally more active
How can pregnancy affect the energy requirements of a woman?
Pregnant women need more energy because they need energy to provide the energy their babies need to develop
Describe a practical where you can test the amount of energy there is in different types of food:
1) you need dry food that’ll burn easily
2) weigh a small amount of food and then skewer it on a mounted needle
3) add a set amount of water to a boiling tube held with a clamp this is to measure the amount of energy produced
4) measure the temperature of the water and light your food with a Bunsen burner, make sure the Bunsen burner isn’t near your tube so that it doesn’t affect your results
5) immediately hold the burning food under the boiling tube until it goes out, then relight th food and hold it under again do this until it won’t catch fire
6) then measure the temperature of the water again
What’s the equation for calculating the amount of energy in joules?
Energy in food(J)=mass of water in g X temperature change in water°C X 4.2
1g=1cm3
4.2 is the amount of energy needed to rise the temperature of water by 1°C
What’s the equation for calculating the amount of energy per gram?
Energy in food(J)
Energy per gram of food(J/g)=———————————
Mass of food(g)
Why do you need to calculate the amount of energy per gram?
To be able to compare the foods fairly
How can the accuracy of the testing energy in food experiment be increased?
- experiment isn’t perfect quite a lot of heat is lost to the surroundings
- insulating the boiling tube e.g. With foil, would minimise heat loss and keep more energy in the water making your results more accurate
What do digestive enzymes break down?
Larger molecules into smaller ones
What are examples of big molecules and why do they need to be broken down?
Starch, protein and lipids
Too big to pass through the wall of the digestive system and they’re insoluble
What are examples of smaller molecules and why are they better than larger ones?
Sugar, amino acids, glycerol, fatty acids
They’re soluble and pass through the walls of the digestive system easily
What does the amylase enzyme break down?
Breaks down long chains of starch into couples of maltose
What does the maltase enzyme break down?
Brakes down couples of maltose into single glucose
What does the protease enzyme break down?
Protein which is a long chain of amino acids into single amino acids
What does the lipase enzyme break down?
Breaks down lipids into glycerol and fatty acid chains
What does bile do and where is it produced stored and released?
- bile is produced in the liver, stored in the gall bladder, released in the small intestine
- acid in the stomach the pH is too high for enzymes in the small intestine,bile is alkaline so it neutralises the stomach acid and creates conditions to be alkaline(best pH for enzymes in small intestine)
- bile emulsified fat, it breaks fat into small droplets this gives a bigger surface area for the lipase to work on which makes digestion faster
By what process is food moved through the gut?
Peristalsis
What and how does peristalsis work?
1) there’s muscular tissue down the alimentary canal
2) it’s job is to squeeze balls of food(boluses) throughyour but otherwise your gut would get clogged up with old food
3) the squeezing action which is waves of circular muscle contractions is called peristalsis
What is another name for your alimentary canal?
Gut
What role does your mouth play in digestion?
1) salivary glands in the mouth produce amylase enzymes in the saliva
2) teeth break down food
What role does your oesophagus play in digestion?
The muscular tube that connects the mouth and the stomach
What role does your stomach play in digestion?
1) pummels the food with its muscular walls
2) produces the protease enzyme, pepsin
3) produces hydrochloric acid
- to kill bacteria
- gives the optimum pH for the protease enzyme to work
What role does your liver play in digestion?
Where bile is produced
What role does your gall bladder play in digestion?
Where bile is stored
What role does your pancreas play in digestion?
Creates protease, amylase and lipase enzymes and releases them into the small intestine
What role does your large intestine play in digestion?
Also called colon
Where excess water is absorbed from food
What role does your small intestine play in digestion?
1) produces protease, lipase and amylase enzymes to complete digestion.
2) where nutrients is absorbed out of the alimentary canal into the body
3) first part is the duodenum and the last part is the ileum
What role does your rectum play in digestion?
Last part of the large intestine
Here the faeces are stored before they leave through the anus
How do villi in the small intestine help with digestion?
- small intestine is adapted for the absorption of food
- small intestine very long so has time to absorb all nutrients
- big surface area for absorbsion because the walls of the small intestine are covered with villi
- each cell on the surface of villi has a microvilli on which increase the surface area even more
- villi have a single permeable layer of surface cell and a good blood supply to assist quick absorbsion
What is a catalyst?
A catalyst is a substance which increases the speed of a reaction without being used up or changed in the reaction.
How do you speed up a reaction other than raising the temperature?
- There’s a limit to how far you can raise the temperature before your cells start getting damaged
- Enzymes reduce the need for high temperatures, we only have enzymes to speed up the rate of reaction(metabolic reaction)
What are enzymes?
Enzymes are proteins, made up of chains of amino acids, chains of folded into unique shapes
What’s a substrate?
A molecule that is changed in a reaction
What’s an active site?
Every enzyme has an active site
An active site is where substrate ions join onto an enzyme
In what way are enzymes specific?
Enzymes only work with specific substrates because of the shape of the active site
What’s a lock and key model?
When it is shown how a substrate fits in an active site to form enzyme/substrate complex and then the enzyme is used again
How does temperature affect an enzyme?
-changing the temperature affects the rate of an enzyme-catalysed reaction
-higher temperature increases the rate of reaction at first(more heat, more energy-means higher collision rates between enzymes and substrates)
-lower temperature-lower collision rate-slower reaction
-if it’s too hot an enzyme will denature so the active site shape doesn’t fit the substrate anymore
Each enzyme has an optimum temperature when the reaction goes fastest
What two ways can you measure the effect of temperature on enzyme activity?
Measure how fast a product appears or how fast a substrate disappears
Experiment: How can you measure how fast a product appears?
- You can use the enzyme catalyse which catalyses the breakdown of hydrogen peroxide into water and oxygen
- collect the oxygen in a measuring cylinder and measure how much is given off over a certain amount of time
- run a series of experiments with different temperature water baths at different temperatures to see how temperature affects the reaction
- control variables-enzyme concentration, pH,volume of solution
Experiment: How do you measure how fast a substrate disappears?
- enzyme amylase catalyses the breakdown of starch to maltose
- detect starch by using iodine on a spotting tile if starch is present the solution will change from browny-orange to blue-black
- you can time how long it takes for starch to disappear by regularly sampling the starch solution and use the times to compare rates between different tests
- by adjust the water bath temperature you can see how temperature affects the amylase
In what way does pH affect enzymes?
- if the pH is too high or low the pH interferes with the bonds holding the enzymes together and this denatures the enzyme
- all enzymes have an optimum pH
