Enzymes and Digestion Flashcards
What is the function of glucose?
Short-term energy supply which is used for respiration.
What is starch?
Chains of glucose molecules, which get broken down into glucose for respiration.
What is the function of protein?
- Maintain cell function.
* Growth and repair of cells and tissues.
What is the function of lipids?
Long-term energy storage.
What is the function of fibre?
- In plants - make up cell walls.
* In humans - keep digestive system healthy and prevent constipation.
What is the function of minerals?
Make healthy bones and blood.
What is the function of vitamins?
Take part in important chemical reactions in the body.
What is the function of water?
Carry substances around the body and replace lost water.
How can you test for glucose?
By using Benedict’s reagent, which will turn from blue to brick red when heated if glucose is present.
How can you test for starch?
By using iodine, which will turn from brown/yellow to blue/black when if starch is present.
How can you test for protein?
By using Biuret reagent, which will turn from light blue to purple if protein is present.
What can a deficiency in Vitamin A cause?
Night blindness - degeneration of rod cells in the retina.
What can a deficiency in Vitamin C cause?
Scurvy - loss of teeth, gum bleeding, poor wound healing.
What can a deficiency in Vitamin D or calcium cause?
Rickets - brittle bones, bow legs, poor teeth.
What can a deficiency in iron cause?
Anaemia - low energy levels, dizziness.
What can a deficiency in protein cause?
Kwashiorkor - swollen belly, poor muscle growth, weight loss.
What can a deficiency in iodine cause?
Goitre - swollen lump in thyroid gland, slow metabolism.
How is energy in food used?
- Movement - kinetic energy.
- Body heat - heat energy.
- Growth and repair - chemical energy.
What is the structure of lipids?
1 part glycerol to 3 parts fatty acids.
Why can energy requirements differ with each person?
They very with activity levels, age, temperature, pregnancy, e.t.c.
What is the function of the mouth, teeth and tongue?
Starting point of digestion, where the teeth break up food particles mechanically and the tongue mix food with saliva.
What is the function of the oesophagus?
Transport of food to stomach.
What is the function of the stomach?
Storage and digestion of food.
What is the function of the duodenum?
Main digestion of food.
What is the function of the pancreas?
Secretes digestive juices and enzymes.
What is the function of the gall bladder?
Site of bile salt storage.
What is the function of the liver?
Site of bile salt production.
What is the function of the ileum (small intestine)?
Main absorption of nutrients.
What is the function of the large intestine?
Absorption of water.
How does food move along the digestive system?
Peristalsis -
• series of wave-like muscle contractions that moves food along the digestive system
How is absorption made efficient in the digestive system?
• Large surface area
- the ileum is lined by thousands of villi and there are thousands of microvilli on each cell of the villus wall.
• Short diffusion distance
- the villus wall is very thin (1 layer of cells thick)
- blood vessels are directly under the villus wall
• High concentration gradient
- continuous flow of blood which requires nutrients
- peristalsis brings along food constantly
What are enzymes?
Proteins that speed up chemical reactions (biological catalysts).
How do enzymes work?
- Each enzyme binds to its substrate at the active site.
- An enzyme-substrate complex forms.
- Reaction takes place.
- Product no longer fits into active site and is released.
- Enzyme can be used again.
Why are enzymes useful?
They speed up the breakdown of molecules.
What factors affect enzyme activity?
- Temperature - at around 40°C, after that the enzymes denature.
- pH.
How is starch digested?
- In the mouth, starch is digested into maltose by carbohydrase (produced in the salivary glands).
- In the duodenum, maltose is digested into glucose by carbohydrase (produced in the pancreas and duodenum).
How is protein digested?
- In the stomach, the enzyme protease (pepsin), made in the stomach lining, digests protein into amino acids.
- In the duodenum, the enzyme protease (trypsin), made in the pancreas, digests protein into amino acids.
How are lipids digested?
• In the duodenum, the enzyme lipase, made in the pancreas, digests lipids into glycerol and fatty acids.
What role does bile play in digestion?
- Bile neutralises the pH of food when it exits the stomach and enters the duodenum so that enzymes are not denatured and can digest the food.
- Bile emulsifies lipids into droplets to increase the surge area and help with lipase action.
Where is bile produced and stored.
Bile is produced by the liver and stored in the gall bladder.
What is the function of iron?
Iron is a component of haemoglobin (in red blood cells) and helps to transport oxygen. Iron is needed in order for your body to carry out respiration.
How are amino acids absorbed into the bloodstream?
They are absorbed into the blood by active transport against the concentration gradient using energy (from respiration).
What can happen to make someone’s faeces very separate hard lumps?
• Lack of water - lots of water is reabsorbed.
• Lack of fibre.
(constipation)
What can happen to make someone’s faces very watery with no solid pieces
•Food poisoning/infection.
• Too little water absorbed.
(diarrhoea)
What health problems can someone develop with too much fat in their diet?
- High blood pressure (clogged arteries).
- Increased risk of heart attack.
- Obesity.
- Diabetes.
- Stroke.
Why is snacking on crisps, chocolate and soft drinks an unsuitable diet for an inactive child?
Too many calories are consumed and all will not be burned/used up.
