Cell Organisation, Enzymes And Digestion Flashcards
What are cells
The basic building blocks that make up all living organisms
What is a tissue, give examples
- A group of similar cells that work together to carry out a particular function
E.g. - Muscular tissue, which contracts to move whatever it’s attached to
- Glandular tissue, which makes and secretes chemicals like enzymes and hormones
- Epithelial tissue, which covers some parts of the body e.g. the inside of the gut
What is an organ, give examples
- a group of tissues that work together to perform a certain function
E.g. in the stomach you have these tissues: - Muscular tissue, which moves the stomach wall to churn up the food
- glandular tissue, which makes digestive juices to digest food
- Epithelial tissue, which covers the outside and inside of the stomach
What is an organ system, give an example
- A group of organs working together to perform a particular function
E.g. The digestive system which is made up of these organs - Glands (e.g. pancreas and salivary glands) which produce digestive juices
- The stomach and small intestine which digest food
- the liver, which produces bile
- The small intestine, which absorbs soluble food molecules
- The large intestine, which absorbs water from undigested food, leaving faeces
What do organ systems work together to make
Organisms
What is an enzyme
- Enzymes are biological catalysts produced by living things
- They are all large proteins and all proteins are made up of chains of amino acids
- These chains are folded into unique shapes, which enzymes need to do their jobs
What is a catalyst
A catalyst is a substance which increases the speed of a reaction, without being changes or used up in the reaction
Explain the ‘lock and key’ model
- Every enzyme has an active site with a unique shape that fits onto the substrate involved in the reaction
- Enzymes are specific.
- They only wok on the substrate that they “fit.”
- Just like a lock has a specific key to open it.
Why do enzymes need the right temps
- the higher the temp the faster the rate of reaction
- however it can get too hot for the enzyme and at a certain point, the enzyme will become denatured
- This means that some of the bonds holding the enzyme together break, changing the shape of the enzyme’s active site, and so the substrate won’t fit anymore
Why do enzymes need the right pH
- too high or too low can interfere with the bonds holding the enzyme together and denature it
- Often pH 7 is the optimum
With a few exceptions e.g. - pepsin = pH2 = because it is found in the stomach where it breaks down proteins
What do digestive enzymes break down
BIG MOLECULES such as:
- Starch
- proteins
- Fats
Why do the big molecules need to be broken down
- They are too big to pass through the walls of the digestive system, so digestive enzymes break them down into smaller ones
- These smaller, soluble molecules can pass easily through the walls of the digestive system, allowing them to be absorbed into the bloodstream
What breaks down starch
- Carbohydrases convert carbohydrates into simple sugars
- Amylase is an example of a carbohydrase. It breaks down starch
- Amylase is made in the Salivary glands, pancreas, small intestine
What breaks down proteins
- proteases convert proteins into Amino Acids
- made in: the stomach (pepsin), the pancreas, the small intestine
What breaks down lipids
- Lipases converts lipids into glycerol and fatty acids
- Lipase is made: in the pancreas, the small intestine
What can the products of digestion be used for
- make new carbohydrates, proteins and lipids
- some of the glucose (a carbohydrate) that’s made is uses in respiration
Where is bile produced
- produced in the liver
- stored in the gall bladder before it’s releases into the small intestine
Why is Bile good in the stomach
- The hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly
- Bile is alkaline —> it neutralises the acid and makes the conditions alkaline
- So the enzymes in the small intestine work best in these alkaline condition
What does bile do
- it emulsifies the fat
- This means that it breaks the fat into tiny droplets
- This gives a bigger SA of fat for the enzymes lipase to work on — which makes digestion faster
Where are enzymes produced
They are produced by specialised cells in the glands and in the gut lining
What do the salivary glands do in the breakdown of food
- produce amylase enzyme in the saliva
What does the stomach do in the breakdown of food
1) it pummels food with its muscular walls
2) It produces the protease enzyme, pepsin
3) It produces hydrochloric acid for 2 reasons:
- to kill bacteria
- to give the right pH for the protease enzyme to work (pH2 — acidic)
What does the pancreas do in the breakdown of food
- produces protease, amylase and lipase enzymes
- It releases these into the small intestine
What does the liver do in the breakdown of food
- where bile is produced
- blue neutralises stomach acid and emulsifies fats
What does the Gall bladder do in the breakdown of food
- where bile is stored, before it’s released into the small intestine
What does the large intestine do in the breakdown of food
- where excess water is absorbed from the food
What does the Rectum do in the breakdown of food
- where the faeces (made up mainly of indigestible food) are stored before they are excreted through the anus
What does the small intestine do in the breakdown of food
1) produces protease, amylase and lipase enzymes to complete digestion
2) This is also where the digested food is absorbed out of the digestive system into the blood
How do you test for sugars
- Add Benedict’s solution and place test tube in water bath for about 5 mins
- if there is sugar = blue —> green, yellow, brick red (depending on how much sugar is in the food)
How do you test for starch
- add a few drops of iodine solution and gently shake test tube
- if present = browny orange —> black or blue-black
How do you test for proteins
- add biuret solution to test tube and mix by gently shaking
- if present = blue —> purple
- if not = stay blue
How do you test for lipids
- add 3 drops of Sudan III stain solution using a pipettes
- if present = the mixture separates out into 2 layers. Top layer = bright red
- if not present = no separate red layer will form at the top of the liquid
