Enzymes Flashcards
What is metabolism?
It’s the sum of all the chemical reactions that take place within an organism
What reactions are involved in metabolism?
Growth, movement, repair, response to stimuli and reproduction
What do all changes/reactions require?
Energy to be released or absorbed
Why is metabolism necessary?
To control the chemical and energy requirements of a cell, by doing this it maintains a balanced internal state [homeostasis] within an organism
What is the most important controllers of cellular reactions?
Enzymes
Solar energy
The primary source of energy is sunlight. Some of the energy in sunlight is trapped by organisms that contain pigments which can absorb light [chlorophyll]. Green plants use solar energy to form chemical bonds of carbohydrates and other biomolecules = form of energy conversion is known as photosynthesis
Cellular energy
If refers to sources of energy that are capable of being released by reactions within a cell [energy stored in bonds of biomolecules]
Each organism breaks down energy-rich biomolecules in the process of respiration. This releases energy, some of which is used by cells and the rest is released into the environment as heat
What is a catalyst?
It is a substance that speeds up chemical reactions without being used up in the reaction
What are enzymes?
Proteins that speed up a reaction without being used up in the reaction
What does the shape of an enzyme mean?
The 3D shape of an enzyme [globular folding] means it will fit neatly and react only with a substance of a shape that matches the enzyme
What happens if the shape of an enzyme is changed?
It will reduce the efficiency of the enzyme to speed up a reaction
What will change the shape of enzymes?
Changing the PH or temperature of a reaction will change the shape of enzymes
What would occur at normal cell temperature in the absence of enzymes?
Reactions would occur too slowly for the cell to stay alive
What is the substrate?
It’s the substance with which an enzyme acts on [reacts]
What is the product?
It’s the substance the enzyme forms
Features of enzymes
Made of protein
Enzymes have a complex, three dimensional shape in order to fit with a substrate
Enzyme reactions are reversible = can cause a reaction to proceed in either direction. Any enzyme can be anabolic or catabolic
Enzymes are named by adding the ending ase to the name of their substrate
What is the role of enzymes?
Control metabolic reactions
Give an example of a catabolic enzyme?
Amylase - it converts starch into maltose. It breaks down a substance into simpler parts
Give an example of amylase in plants and animals
Animals - produced by salivary glands in mouth and pancreas. Converts starch to maltose
Plants - seeds contain starch and when seeds germinate the enzyme amylase converts the starch to maltose
Give an example of an anabolic enzyme
DNA polymerase which forms and repairs DNA. It converts simpler molecules into more complex from.
Enzymes that control photosynthesis = convert water and c02 into glucose
What affects enzyme activity
Temperature
PH
Enzyme concentration
Substrate concentration
How does temperature affect enzyme activity?
At low temps, ice forms and the cell contents become solid + enzymes cannot work
As temperature increase, the molecular movement increases so the substrate molecules and enzymes bump into eachother more often and therefore the rate of reaction increase
Above a certain temperature, enzymes begin to lose 3D shape so the rate of reaction falls
When will an enzyme denature?
When the shape of enzyme is fully lost
What is a denatured enzyme?
A denatured enzyme has lost its shape and can long carry out its function
