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Why are muscle cells able to contract
As they control special protein fibres that can change their length
What is a tissue
A Tissue is a group of cells with a similar structure and function
What is an Organ
A group of tissues working together for a specific function
What does the stomach contain
Muscle tissues and glandular tissues which releases enzymes
What is an organ system
Organs which work together to form organisms
What 3 main nutrients does food contain
Proteins, Carbs, Lipids
Why do these molecules have to be digested
As the molecules are too large to be absorbed into the bloodstream
What happens during digestion
Large food molecules are broken down into small molecules by enzymes. The small molecules can then be absorbed into the bloodstream.
What are the steps in digestion
Food is chewed in the mouth. Enzymes in the saliva break down starch into smaller sugar molecules
Food passes down the Oesophagus into the stomach.
In the stomach enzymes begin to digest proteins
The stomach contains Hydrochloric acid which helps the enzymes digest the proteins
The Churning Action of the stomach muscles turns the food into a fluid increasing the surface area for enzymes to digest.
What do the enzymes the pancreas release do
Continue the digestion of starch and protein and start the digestion of lipids
What does the liver produce
Bile
What does Bile do
Speeds up digestion of lipids and neutralises the acid released from the stomach
What happens after digestion in the stomach
The food passes into the small intestine where chemicals are released from the liver and pancreas
In the small intestine the small food molecules are absorbed into the bloodstream by either diffusion or by active transport
The fluid makes its way into the large intestine where water is absorbed into the bloodstream
The Faeces is released from the body
What are the products of digestion used for
Used by the body to build new carbohydrates, Lipids and Proteins
What is some of the glucose used for
Respiration
What do enzymes do
Catalyse chemical reactions
What are enzymes
Large protein molecules with a groove on their surface called the active site
What is the active site
Where the substrate attaches too
What are the enzymes that break down proteins called
Proteases
Where are proteases found
The stomach, Pancreas and small intestine
What happens when we digest proteins
The protease enzymes convert the protein back into individual amino acids
What happens when the amino acids are absorbed back into the body cells
Joined in a different order to make human proteins
What are carbohydrates broken down into
Carbohydrase’s
In the case of starch what is this called
Amylase
What does a lipid molecule consist of
Molecule of glycerol attached to three molecules of fatty acids
What does lipid molecules get digested by
The enzyme lipase
What does this produce
Glycerol and fatty acids
Where do we find lipase
In the pancreatic fluid and in the small intestine
Where is Bile Stored
In the Gull Bladder
What does Bile do to large lipid droplets
Changes them into smaller droplets
Is Bile Alkaline or acidic
Alkaline
What does it being Alkaline mean
It neutralises stomach acid
What is the lock and key theory
The theory that enzymes are specific and the substrate must fit perfectly into the active site
What is the optimum temp
37 Degrees (Human Body Temp)
What happens if the temp goes past the optimum
The enzyme molecule vibrates and the shape of the active site changes
What happens if the pH is too alkaline or too acidic
The active site denatures
What colour does iodine turn if starch is present
Blue-Black
Explain the steps for the Effect of pH on Amylase Required Practical
Add 2cm3 of starch solution to a test tube
Add 2cm3 of Amylase solution to a test tube
Add 2cm3 pH 5 buffer solution to a test tube
Place all 3 test tubes in a water bath at 30oc and leave for 10 mins
Combine the 3 solutions in one test tube and mix with a stirring rod. Return to the water bath and start a stopwatch
After 30 seconds use the stirring rod to transfer a drop of solution into the iodine spotting tile
The iodine should be Blue-Black
Continue every 30 seconds until iodine remains orange
