B2 - Organiation Flashcards
What are tissues
A tissue is a group of similar cells that work together to carry out a particular function. It can include more than one type of cell
What is an organ
An organ is a group of different tissues that work together to peform a certain function.
What is an organ system
The organ system is a group of organs that work together to peform a particular function
What do multiple organ systems work together to form
The organism e.g the body
The most obvious way to increase the rate of reaction would be to Increase the Temperature.
What problems or offputs could this have.
-Would Require alot of energy.
-Limit to how far you can raise temp before cells can get damaged.
-May also speed up non useful unwanted reaction
What is a catalyst
A catalyst is a substance that increases the speed of reaction without being changed or used up in the reaction
What is the active site
The active site is a part of the Enzyme that has a unique shape that is complimentary to the substrates of the reaction.
Why might a reaction not be catalysed
The substrate dosent fit the active site of the enzyme - this allows the enzymes to be really specific about which reactions they speed up
What were the 2 models of enzyme action
The first is the Lock And Key model (the original) when scientists thought the substrate had to fit perfectly into the active site.
The Induced fit model (more realistic) is what we now know that the enzyme actually changes shape slightly as it binds to the substrate so they can fit together more perfectly. The active site is complimentary to the substrates.
Explain why enzymes have an optimum pH. (2)
IF the pH is to high or too low, the pH inteferes with the bonds holding the enzyme together. This changes the shape of the active site and denatures the enzyme.
Changing the temperature of an enzyme changes the rate of an enzyme-catalysed reaction.
An enzyme needs the right temperature why is this.
A higher temperature increases the rate at first but if it gets to Hot some of the bonds holding the enzyme together break. This changed the shape of the active site and causes the shape of the enzyme to denature.
All enzymes have a an optimum pH they work best at. Its often neutral pH 7, but not always - give 1 example where its not.
One example is pepsin - an enzyme used to break proteins In the stomach, it works best at pH 2, which means it’s well suited to the acidic conditions there.
How can we investigate the effect of pH on enzyme Activity (Amylase)
● Put a drop of iodine solution into each well of a spotting tile.
● Then take 3 test tubes with 2cm³ starch solution in the first tube, 2cm³ of amylase solution in the second tube and in the third 2cm³ of pH buffer solution.
● Then place all 3 test tubes in a water bath at 30°. Leave then for 10 minutes to allow the solutions to reach the correct temperature.
●Now combine the 3 solutions into one test tube and mix with a stirring rod. Return to the waterbath and start a stopwatch.
●After thirty seconds use a stirring rod to transfer one drop of solution to a well in the spotting tile containing iodine.
●We now take a sample every thirty seconds and we continue till until the iodine remains orange. When the iodine remains orange this tells us that starch is no longer present and the reaction is completed.
●We now repeat the whole experiment several times using different pH buffers e.g pH 6 & 7
For the effect or pH on enzyme activity practical: ●Why might it take so long for the starch to be broken down at pH 5?
●How might the practical be made more accurate
Because the enzyme has been denatured meaning the active site no longer binds to the starch properly so the reaction will take alot longer.
●By taking more examples for example testing every 10 secomd instead of 30.
What enzyme breaks down
