Please enable JavaScript.
Coggle requires JavaScript to display documents.
biological molecules and human nutrition - Coggle Diagram
biological molecules and human nutrition
structure of carbohydrates, lipids and proteins
carbohydrates
made up of simple sugars
contain carbon, hydrogen and oxygen
starch and glycogen are large complex carbohydrates which are made up of smaller units like glucose and maltose
proteins
made up of amino acids
long chains of amino acids
all contain carbon, oxygen, nitrogen, hydrogen and oxygen
lipids
made up of fatty acids and glycerol
contain carbon hydrogen and oxygen
functions of nutrients
carbohydrates provide energy
lipids provide energy, act as energy store and provide insulation
proteins are needed for growth and repair of tissue and to provide energy in emergenices
vitamins
A
helps to improve vision and keep your skin and hair healthy
B
needed to prevent scurvy
C
need for calcium absorbtion
mineral ions
Calcium
needed to make bones and teeth
Iron
needed to make haemoglobin for healthy blood
water
most bodily functions rely on water, we need a constant supply to replace water lost through urinating, breathing and sweating
dietary fibre
aids the movement of food through the gut
energy requirements vary in different people
activity level-active people need more energy than people who sit around all day
children and teenagers need more energy than older people-they need to grow and tend to be more active
pregnancy-pregnant women need more energy than other women as they have to provide for their babies as well as themselves
food tests
benedicts test for glucose
prepare a food sample and transfer 5cm^3 to a test tube
prepare a water bath so its set to 75 degrees
add some benedict's solution to the test tube-about 10 drops
put the test tube in the water bath for five minutes
if the food sample contains glucose then the solution will change from blue to brick red
iodine test for starch
add 5cm^3 of the sample to a test tube
add a few drops of iodine and if starch is present the solution will change from brown/orange to blue black
biurets test for proteins
a 2cm^3 of the food sample to a test tube
add 2cm^3 for biurets solution and gently shake
if the food sample contains protein, the solution will turn from blue to pink/purple
emulsion test for lipids
add 2cm^3 of ethanol to the substance
add the same amount of distilled water
shake and if a cloudy white emulsion forms then lipids are formed
enzymes and digestion
breaking down big molecules
starch proteins and fats are too big to pass through the walls of the digestive system. they are also insoluble
sugars, amino acids, glycerol and fatty acids are much smaller and are soluble so they can diffuse across the walls of the digestive system
the digestive enzymes break down the big molecules into smaller ones
reaction chains
amylase converts starch to maltose and maltase converts maltose to glucose
proteases convert proteins into amino acids
lipases converts lipids into glycerol and fatty acids
bile neutralises the stomach acids and emulsifies fat
bile is produced in the liver
its stored in the gall bladder
they HCl in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. Bile is an alkali that neutralises the acid and makes the condition alkaline. the enzymes in the small intestine work best in alkaline conditions
Bile also emulsifies fats. in other words, it breaks down fats into tiny droplets. this gives a much larger SA of fat for the enzyme lipase to work on. this makes digestion faster
food is moved through the gut by peristalsis
there is muscular tissue all the way down the alimentary canal
its job is to squeeze balls of food through your gut, otherwise it would get clogged up
this squeezing action, which is waves of circular muscle contractions is called peristalsis
a balanced diet supplies all your essential nutrients
the six essential nutrients are carbohydrates, proteins, lipids, vitamins, minerals and water
these need to be in the right proportions
you also need fibre
energy from food
food can be burnt to see how much energy it contains
this can be done using a calorimeter
you need dry food, water and a flame
you need food that will burn easily
weigh a small amount of food and skewer it on a mounted needle
add a set volume of water to a boiling tube. this will be used to measure the amount of energy that's released
measure the temperature of the water then set fire to the food using a bunsen burner
immediately hold the burning food under the boiling tube until it goes out. relight the food and repeat until the food won't light any more
measure the temperature of the water again
calculating the amount of energy in food
use the equation: energy in food (J) = mass of water (g) x temperature change of water (degrees C) x 4.2
1cm^3 of water has a mass of 1g
4.2 in the formula is the amount of energy needed to raise the temperature of 1g of water by 1 degree C
the accuracy of the experiment can be increased
the experiment isn't perfect, quite a lot of the energy released from burning the food is lost to the surroundings. this is why the energy value on a packet of food is likely to be much higher than they value in the experiment
insulating the boiling tube will help to minimalize the heat loss in the water, making the results more accurate
the alimentary canal
the alimentary canal run through your body
mouth
salivary glands in the mouth produce amylase enzyme in the saliva
teeth break down food
oesophagus
the muscular tube that connects the mouth and stomach
liver
where bile is produced
gall bladder
where bile is stored
stomach
it pummels the food with is muscular walls
it produces the proteases enzyme pepsin
it produces HCl for two reasons
to kill bacteria
to give the optimal pH for the protease enzyme to work
pancreas
produces protease, amylase and lipase enzymes. it releases them in the small intestine
small intestine
produces protease, amylase and lipase enzymes to complete digestion
this is also where the nutrients are absorbed out of the alimentary canal
the first part is the duodenum and the last part is the ileum
large intestine
also called the colon. where excess water is absorbed from food
rectum
the last part of the large intestine
were the faeces are stored before the are pooed out of the anus
villi in the small intestine help with absorbtion
the small intestine is adapted for absorption of food
its very long so there's time to break down food before it reaches the end
there a really big surface area for absorption, because the walls are lined with millions of tiny projections called villi
each cell on the surface of a villus also has its own microvilli, little projections that increase the SA even more
Villi have a single permeable layer of surface cells and a very good blood supply that make absorption by diffusion very easy and fast