B3 Organisation And The Digestive System Flashcards
What is a tissue?
A group of cells with similar structure and function working together
What are organs?
Collections of tissues that work together to perform a specific function
What are organ systems?
Groups of organs that all work together to perform specific functions
Role of the salivary glands in digestion
Produce amylase enzymes in the saliva
Role of the liver in digestion
Where bile is produced
Function of bile
Neutralises stomach acids and emulsifies fats
Role of the Gall Bladder in digestion
Stores bile before it is released into the small intestine
Role of the stomach in digestion
1) Pummels the food with its muscular walls
2) Produces the protease enzyme pepsin
3) Produces hydrochloric acid to kill bacteria and produce the right pH for the protease enzyme to work
Why does the stomach produce hydrochloric acid?
1) To kill bacteria
2) To produce the optimal pH for the protease enzymes to work
Role of the pancreas in digestion
Produces protease, amylase and lipase enzymes and releases these into the small intestine
Role of the small intestine in digestion
1) Produces protease, amylase and lipase enzymes to complete digestion
2) Where the digested food is absorbed into the blood
Role of the large intestine in digestion
Where excess water if absorbed from the food
Role of the rectum
Where the faeces are stored before they are passed out through the anus
Adaptations of the small intestine
1) Very large surface area as it is covered in villi
2) Has a good blood supply and short diffusion distances to the blood vessels
What elements are carbohydrates made up of?
Carbon, hydrogen and oxygen
What are carbohydrates used for?
Most are broken down to glucose, which is used in cellular respiration to provide energy for metabolic reactions in your cells
What are simple sugars?
Sugars made up of one or two sugar units
Examples of simple sugars
Glucose and Sucrose
What are complex carbohydrates?
Long chains of simple sugar units bonded together
Examples of complex carbohydrates
Starch and Cellulose
What elements are lipids made up of?
Carbon, hydrogen, and oxygen
Uses of lipids
1) Energy reserves
2) Regulate hormones
3) Transmit nerve impulses
What are lipids made up of?
Three molecules of fatty acid joined to a molecule of glycerol
Are lipids soluble in water?
No, all lipids are insoluble in water
What determines whether the lipid is a liquid oil or a solid fat?
The different combinations of fatty acids
What elements are proteins made up of?
Carbon, hydrogen, oxygen, and nitrogen
What is a protein molecule made up of?
Long chains of amino acids
What determines what a protein is?
The different arrangements of the various amino acids
Roughly how many different amino acids are there?
20
What are proteins used for in the body?
-Structural components of tissues such as muscles and tendons
-Hormones such as insulin
-Antibodies
-Enzymes
What is a catalyst?
A substance that speeds up a chemical reaction without being used up in the reaction
What controls the rate of chemical reactions in the body?
Enzymes
What is the active site?
The part of the enzyme that directly binds to a substrate with a specific shape
What binds to the active site?
The substrate
How is the active site made?
The long chains of amino acids are folded to produce a molecule with an active site that has a unique shape so it can bind to a specific substrate molecule
What can enzymes do?
-Join small molecules together
-Break up larger molecules
-Change one molecule into another
Explain how enzymes work using the lock and key theory
The substrate of the reaction to be catalysed fits into the active site of the enzyme in the same way that a key would fit into a lock
What is a good theory for explaining how enzymes work?
The lock and key theory
What is the metabolism?
The sum of all the reactions in a cell or in the body
Give 3 examples of enzyme controlled metabolic reactions
-Building glycogen from glucose
-Conveting one amino acid into another
-Breaking down glucose in cellular respiration
How does the rate of enzyme-controlled reactions change with temperature?
It increases up to around 40 degrees C
Why do enzymes not work after 40 degrees C?
The amino acid chains begin to unravel, and as a result, the shape of the active site changes. The substrate no longer fits in the active site
What does it mean for an enzyme to be denatured?
The shape of the active site changes so the substrate no longer fits into it
What is the optimal temperature for most enzymes?
37 degrees C
What two factors affect enzyme activity?
-Temperature
-pH
What is the optimal pH for enzymes?
Different enzymes work best at different pH levels
Why does the pH affect enzyme action?
A change in pH affects the forces holding together the folded chains of the enzyme, and as a result, the specific shape of the active site is lost
What do you call enzymes that break down carbohydrates?
Carbohydrases
Which enzyme breaks down starch?
Amylase
Whaat does amylase break down?
Carbohydrates
Where is amylase produced?
-Salivary glands
-Pancreas
Does any enzyme digestion take place in the pancreas?
No, all the enzymes made there flow into the small intestine
What do you call enzymes that break down proteins into amino acids?
Protease enzymes
Where are protease enzymes produced?
-Stomach
-Pancreas
-Small intestine
Where is pepsin produced?
Stomach
What are lipids broken down into?
Fatty acids and glycerol
Where are lipids broken down?
Small intestine
What do you call enzymes that break down lipids?
Lipase enzymes
Where are lipase enzymes made?
-Pancreas
-Small intestine
What is the optimal pH for amylase enzymes?
7
What is the optimal pH for pepsin enzymes?
2
What is the optimal pH for lipas enzymes?
7.5
What is the iodine test for starch?
Iodine goes from yellow-red to blue-black
What is the Benedict’s test for sugars?
Blue Benedict’s solution turns brick red on heating
What is the test for protein?
Blue Biuret reagent turns purple
What is the test for lipids?
Ethanol added to a solution gives a cloudy white layer
How can you investigate the effect of pH on enzyme activity?
Create different pH solutions of amylase, starch and buffer. Add iodine in the wells of a spotting tile. Add a drop of the solution into the iodine well. Put a drop into a well every 30 seconds. When the iodine solution remains browny-orange, starch is no longer present
