Section 2 - Human Nutrition Flashcards
Protein Structure
- made up of amino acid chains
- they all contain Carbon Hydrogen Oxygen and Nitrogen (CHON) atoms
amino acids -> proteins
Lipids structure
- built from fatty acids and glycerol
- contain Carbon, Hydrogen and Oxygen (CHO) atoms
glycerol&fatty acids -> lipids
carbohydrates structure
- carbohydrates are made up of simple sugars
- contain Carbon, Hydrogen and Oxygen (CHO) atoms
- starch and glycogen are long complex carbohydrates made up of simple sugars such as maltose or glucose joined together in a long chain
maltose -> starch
glucose -> glycogen
Make a food sample
- break piece of food with pestle and mortar
- transfer to beaker and add distilled water
- stir with glass rod to dissolve food
- filter with funnel to get rid of solid bits of food
What is the glucose test?
Benedict’s Test
What is the Starch test?
Iodine Solution
What is the Protein Test
Biuret Test
What is the Lipid test
Sudan III Test
Benedict’s Test
GLUCOSE
- prepare food sample and transfer 5cm³ to a test tube
- prepare water bath at 75º
- add benedicts solution to test tube (10 drops) using a pippet
- place test tube in water bath and leave for 5 minutes (tube pointing away from you)
- if food sample contains glucose then solution will change from BLUE to GREEN or YELLOW in low concentrations or BRICK-RED in high concentrations
Iodine solution
- make food sample and transfer 5cm³ to test tube
- add iodine solution and gently shake
- if it contains starch it will change from BROWNY-ORANGE to BLACK or BLUE-BLACK
Biuret Test
- prepare food sample and transfer 2cm³ to a test tube
- add 2cm³ of biuret solution and mix by gently shaking
- if protein is present solution will turn from BLUE to PINK or PURPLE
Sudan III Test
- prepare food sample (without filtering it) and transfer 5cm³ to a test tube
- use pipette to add three drops of Sudan III stain solution to test tube and gently shake
- if sample contains lipids the mixture will separate out into TWO LAYERS. the top layer will be bright RED
Carbohydrates
found in - pasta, rice, sugar…
function - provide energy
Lipids
found in - Butter, oil, fish…
function - provide energy and act as energy store and provide insulation
Proteins
found in - meat, fish
function - needed for growth and repair of tissue and to provide energy in emergencies
Vitamin A
found in - Liver
function - improve vision and keep skin and hair healthy
Vitamin C
found in - Fruit
function - prevent scurvy
Vitamin D
found in - Eggs, sunlight
function - Needed for calcium absorption
Mineral ion (calcium)
found in - milk, cheese
function - to make bones and teeth
mineral ion (iron)
found in - red meat
function - make haemoglobin for healthy blood
water
found in - food and drink
function - every bodily function relies on water - constant suppply needed to replace urinating sweating and breathing
dietary fibre
found in - wholemeal bread, fruit
function - aids movement of food through gut
Balanced diet - the six essential nutrients
carbohydrates
proteins
lipids
vitamins
minerals
water
+ fibre
energy requirement variations
amount of energy you need depends on
1) activity level (active need more energy)
2) Age (children and teens need more than old people, to grow and more active)
3) Pregnancy (need extra energy for baby to develop)
what do digestive enzymes do?
They break down big, insoluble molecules (starch, proteins and fats) that can’t pass through the walls of the digestive system into much smaller, soluble molecules (sugars, amino acids, flycerol and fatty acids) that can easily pass throygh digestice system walls
Amylase
converts starch into maltose
maltase
converts maltose into glucose
protease
converts protein into amino acids
lipase
converts lipids into glycerol and fatty acids
Bile function
neutralises stomach acid and emulsifies fats
(the hydrochloric acid in stomach makes pH to acidic for enzymes in small intesine. bile is alkaline so it neuralises the acid and makes conditions alkaline so the enzymes can work best)
(bile also emulsifies (breaks down fat into tiny droplets) giving a bigger surface area for the enzyme lipase to work on - making digestion faster)
where does bile come from
produced in liver
stored in gall bladder
released in small intestine
peristalisis
the waves of muscular contractions that aid boluses through the gut (covered by muscle tissue)
alimentary canal: mouth
- salivary glands in mouth produce amylase enzyme in the saliva
- teeth break down food
alimentary canal: oesophagus
muscular tube that connects mouth and stomach
GUT
another word for alimentary cannal
alimentary canal: liver
where bile is produced
alimentary canal: gall bladder
where bile is stored
alimentary canal: large intestine
also called colon
- where excess water is absorbed from the food
alimentary canal: rectum
- last part of the large intestine
- where the feaces (made up mainly of indigestible food) are stored before they are excreted through the anus
alimentary canal: stomach
- it pummels food with muscular walls
- produces protease enzyme, pepsin
- produces hydrochloric acid to:
a) kill bacteria
b) optimum pH for protease enzyme to work (pH 2)
alimentary canal: pancreas
- produces protease, amylase and lipase enzymes which it releases in the small intestine
alimentary canal: small intestine
- produces protease, amylase and lipase enzymes to complete digestion
- this is where nutrients are absorbed out of alimentary canal and into body
- first part is the duodenum and the last part is the ileum
Villi in the small intestine
help with absorption
small intestine adapted:
- it is very long so there is time to break down and absorb all the food before it reaches the end
- big surface area for absorption because walls are covered in millions and millions of little villi
- each cell on surface of a villus has its own microvilli - that further increases teh surface area
- villi have a single permeable layer of surface cells and a good blood supply to assist quick absorption
