B3 Organisation and the Digestive system

What is a tissue?

group of cells with a similar structure and function

What are cells?

The basic building blocks of all living organisms

What are organs?

Organs are groups of tissues that work together to perform certain functions

What is metabolism?

rate of chemical reactions in the body

What is an enzyme?

a protein molecule which acts as a biological catalyst

What is the active site?

the region on the enzyme where the substrate binds

What is the lock and key hypothesis? ( Enzyme specificity)

- The shape of the active site is complementary to the reactant
- An enzyme reactant complex can form and the products can be released, leaving the enzyme unchanged

What do digestive enzymes do?

convert food into small soluble molecules that can be absorbed into the bloodstream

What do carbohydrase's do?

break down carbohydrates to simple sugars

What is amylase and what does it do?

a carbohydrase which breaks down starch into glucose

What do protease do?

break down proteins to amino acids.

What do lipase do?

break down lipids (fats) to glycerol and fatty acids.

What are the products of digestion used to do?

used to build new carbohydrates, lipids and proteins. Some glucose is used in respiration

Where is bile made and stored?

made in the liver and stored in the gallbladder

What is bile used for?

It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area.

What do alkaline conditions/ large SA in bile help with?

increasing the rate of fat breakdown by lipase

What is the main function of the digestive system?

To digest food and absorb the nutrients obtained from digestion.

What is the role of the pancreas and salivary glands in the digestive system?

produce digestive juices containing enzymes

What is the role of the stomach in the digestive system?

Produces hydrochloric acid - kills any bacteria present and provides optimum acidic pH for protease enzyme to function

What is the role of the small intestine in the digestive system?

site where soluble food molecules absorbed into bloodstream

What is the role of the large intestine in digestion?

absorbs water from undigested food, producing faeces

How does temperature affect enzyme action?

Up to a certain point, increasing temperature increases enzyme action, as molecules have a higher kinetic energy. Above a certain temperature, the enzyme becomes denatured, so it can no longer catalyse the reaction. The optimum temperature is around 37°.

How does pH affect enzyme function?

The optimum pH for most enzymes is 7 (apart from proteases in the stomach). If the pH is too extreme, the shape of the active site may be altered and the enzyme may no longer work.