Human Nutrition - Unit 2 Flashcards
What are the 3 elements carbohydrates contain?
- oxygen
- carbon
- hydrogen
what is starch?
it is a long and insoluble molecule made up of glucose molecules in a long chain.
what are the 3 elements lipids contain?
- oxygen
- carbon
- hydrogen
lipids are made from 3 fatty acids chain and glycerol.
:)
YOU GOT THIS
what are the 4 elements proteins contain?
- oxygen
- carbon
- hydrogen
- nitrogen
(they are built from amino acids)
what is a balanced diet?
a diet that has the correct proportion of carbohydrates, proteins, vitamins, minerals and lipids. These are known as nutrients.
what is the function and source of carbohydrates?(starch and sugars)
function: provides energy
source: pasta, rice, fruit
what is the function and source of lipids? (fats and oils)
function: energy store, insulation
source: butter, dairy
what is the function and source of proteins?
function: growth and repair
source: meat and fish
what is the function and source of vitamins and minerals?
function: for overall health
source: various foods (fruit and veg)
what is the function and source of fibre?
function: aid peristalsis to keep food moving through gut (overall health)
source: wholemeal foods such as brown bread
what is the function and source water?
function: overall health
source: food and drinks
what does vitamin C (found in oranges) do?
prevents scurvy (a deficiency disease caused when a nutrient is lacking from a diet)
why is vitamin A (found in liver) needed?
needed for vision
why is vitamin vitamin D (found in eggs) needed?
needed for calcium absorption
why is mineral calcium (found in milk) needed?
needed to make bones and teeth
why is mineral iron (found in red meat) needed?
needed to make haemoglobin
what is the energy requirement on activity level
more activity = more energy required for muscle contraction
why is energy required for children
children need energy to grow
what is the energy requirement on pregnancy
need to eat more to provide energy for the baby to grow and develop
how do you test for starch?
using iodine solution . Positive result will cause the iodine to turn from yellow-black to blue-black
how do you test for glucose
using benedict’s solution, this needs it to be heated in a water bath. If positive (glucose is present) it will turn from clear blue to cloudy orange brick color (brick red).
the amount of sugar can also be determined with benedict’s solution. It will change different colors depending on the amount of sugar present.
how do you test for protein
using biuret’s solution. If protein present, it will turn from blue to purple.
how do you test for lipids
lipids are insoluble in water but soluble in ethanol. You can shake a tube with oil and ethanol to dissolve the oil, then add this to water. The lipids will precipitate out, forming an emulsion.
what is ingestion?
food enter the mouth
what is digestion?
the break down of large soluble molecules into small, soluble molecules
what is absorption?
small molecules move from small intestine into the blood
what is assimilation / synthesis?
small food molecules are used to build large food molecules
what is egestion?
removal from undigested food (faeces)
Name the 9 parts (or functions) of the alimentary canal
- chewing
- salivary glands
- oesophagus
- liver
- gallbladder
- stomach
- pancreas
- small intestine
- large intestine
What does chewing do?
chewing breaks down food into smaller particles, increasing their surface are.
what does the salivary glands do?
salivary glands secrete amylase, an enzyme.
what does the oesophagus do?
it transports food from the mouth to the stomach
what does the liver do?
it makes a digestive juice called bile.
what is stored in the gallbladder?
bile
what happens in the stomach?
in the stomach, muscles contract to chum up the food. Protease enzymes break down proteins to amino acids.
What does the pancreas do?
it produces digestive enzymes, and releases them to the small intestine.
what are the small intestines?
It is where digestion ends (more enzymes to break food down) and products of digestion are absorbed into the blood.
what is the large intestine?
it is where water is absorbed into the blood. Any remaining food, such as fibre, and waste products are stored in the rectum as faeces, then removed from the body through the anus.
What is the stomach acid?
the Ph of the stomach is about Ph 2 (acidic). this is due to the hydrochloric acid there.
what are the 2 main functions of the stomach acid?
- it provides optimum conditions for protease enzymes in the stomach. They work at optimum in acid conditions.
- kills bacteria
what is the peristalsis?
The peristalsis describes the movement of muscles to move food along the gut.
Circular muscles contract causing the gut to get narrower, squeezing food along.
What are the 4 facts about the Bile?
- NOT AN ENZYME
- Produced in liver
- Stored in gallbladder
- Works in small intestine
what are the 2 (main) functions of the Bile?
- It breaks down fats into fatty acids, which can be taken into the body by the digestive tract.
- helps with digestion
where does absorption of food take place?
absorption of food take place in the small intestine. Digestion also ends there
what are the 2 facts about the small intestine? (what does it have and its length)
- it has a villi (it increases the surface area of the intestine)
- it is long (to provide more space for absorption.
what does each villi have that will increase further surface area (so that there is more space for absorption)?
a microvilli
how thick are the walls in the small intestine? why?
The walls are 1 cell thick (very thin) - shorter distance for products of digestion to be absorbed through.
how many capillaries in the small intestine? why?
Lots of capillaries - a good blood supply to maintain concentration gradient.
what is the lacteal in the small intestine for?
it is to absorb products of fat digestion.
what are the 4 parts of the small intestine?
- surface area
- capillaries
- lacteal
- blood vessel
what are enzymes? what do they do and how do they do it?
enzymes are biological catalysts. They speed up the rate of chemical reactions in living organisms, without being changed or used up. They do that by lowering the temperature needed for the reaction to occur.
what are enzymes in digestion responsible for?
They are responsible for the breakdown of large, insoluble molecules into small, soluble molecules.
what are enzymes made up of?
proteins.
what does amylase do?
it breaks down starch into maltose.
what does maltase do?
it breaks maltose into glucose
what does protease do?
it breaks down proteins into amino acids.
what does lipase do?
it breaks down lipids into fatty acids and glycerol
what are the specific conditions that enzymes require to work?
- optimum temperature (37º C)
- optimum pHs (varies depending on where, in stomach for protease, acidic, slightly alkaline in small intestines)
how fast do enzymes reactions occur at low temperature?
too slow
In what temperature do enzymes denature?
in high temperatures (and extreme pHs)
what are the 2 reactions that happen to enzymes in low temperature?
- move slower
- collide less - slow reaction rate
what are the 3 reactions that happen to enzymes in high temperature?
- activity site changes shape
- enzymes denature
- substrate can no longer fit
How do you investigate how enzyme activity can be affected by changes in temperature?
- set up water bath at 20º C.
- Add 5cm3 of amylase to one boiling tube, and 5cm3 of starch to another.
- Place these in the water bath.
- Leave it for 5 minutes
- While waiting, add a drop of iodine to each dip in the spotting tile.
- Add the amylase to the starch, and leave in the water bath.
- Immediately, use a pipette to transfer a small sample of the mixture to the first drop of iodine in the spotting tile.
- Record the colour.
- Repeat this step every 30s, until the iodine solution remains yellow.
- Record the time it took for the solution to remain yellow. (Max 10 mins)
- Repeat the experiment again at 30ºC, 40ºC, 50ºC and 60ºC
what to do for safety in the investigation of how enzyme activity can be affected by changes in temperature?
- eye protection (amylase is very dangerous for the eye)
- avoid skin contact
what colour will the iodine turn in low temp. ?(investigation of how enzyme activity can be affected by changes in temperature)
iodine keeps turning blue black - rate of iodine is too slow so starch remains since it is not broken down.
what colour will the iodine turn in optimum temp. ?(investigation of how enzyme activity can be affected by changes in temperature)
iodine remains orange - starch broken down to glucose so not present.
what colour will the iodine turn in high temp. ?(investigation of how enzyme activity can be affected by changes in temperature)
remains blue black - enzymes denatured so starch is not broken down.
