Topic 4: Energy Transformations Flashcards
What is metabolism?
Metabolism is the sum total of all biochemical reactions that occur in cells.
What are the two main types of processes metabolism can be broken down into?
ENDERGONIC processes: result in a net input or use of energy
EXERGONIC processes: result in a net output or release of energy.
What is the difference between anabolic and catabolic reactions?
Chemical reactions in which atoms and molecules are brought together to make more complex molecules are called ANABOLIC reactions.
Reactions that break down complex molecules into simpler molecules are called CATABOLIC reactions.
What type of reaction is photosynthesis?
Photosynthesis is an example of an ENDERGONIC process and ANABOLIC reaction
What type of reaction is cellular respiration?
Cellular respiration is an example of an EXERGONIC process and a catabolic reaction.
What is an enzyme?
Enzymes are protein molecules that increase the rate of reactions that occur in living organisms or cells.
What is a substrate and product in relation to enzymes?
The compound being acted on by an enzyme is called a SUBSTRATE. The compound obtained as a result of enzyme action is called a product.
How do enzymes act on substrates to produce products?
Enzymes are highly specific in their action, each enzyme acts on only one kind of substance. Enzymes have an active site which can only bind to one specific substrate. When an enzyme controlled reaction takes place the enzyme and substrate molecule become joined together and for a short time form an enzyme substrate complex. Enzymes participate in reactions but they are not used up in the reaction and are available for reuse.
What is denaturisation?
When cells are exposed to high temperatures or in an environment that is more or less acidic than normal, they often cease to function. This is because proteins within the cell change their 3D shape - denaturisation. Enzymes are made of proteins and when they denature the shape of the active site changes and it can no longer bind to its substrate.
What happens to enzyme activity when there is an increase in temperature?
Enzyme substrates have increased in energy due to an increase in temperature, so collisions between the two will occur more frequently, therefore the substrate bonds to the active site more often which increases rate of reaction.
What is the optimum temperature?
The temperature that the enzyme shows maximum activity.
What happens to enzyme activity when the temperature surpasses the optimum?
The shape of the active site is changed so it can no longer bind to the substrate, therefore the rate of reaction slows.
What happens to enzyme activity at low temperatures?
At low temperatures the rate of enzyme reaction is very slow. The molecules have low kinetic energy and collisions between the enzyme and its substrate are less frequent. Thus the rate at which products form is very slow.
How does substrate concentration affect enzyme activity?
As substrate concentration increases, the rate of reaction increases as there is more substrate to bind with the enzymes active site. However, at saturation point, all the enzyme is being used. Therefore the rate of reaction cannot get higher no matter how much substrate present, and the rate plateaus.
How does enzyme concentration affect enzyme activity?
As enzyme concentration increases, rate of reaction increases as there is more enzyme for the substrate to bind to. However at saturation point, all the enzyme is being used. Therefore, the rate of reaction cannot get higher no matter how much enzyme present, and the rate plateaus.
How are autotrophs and heterotrophs distinguished between?
Organic molecules provide the chemical energy needed by cells to stay alive. How all organisms obtain these organic molecules separates them into two groups, heterotrophs and autotrophs.
What is a photosynthetic autotroph?
Transform sunlight energy into the chemical energy of sugars, such as glucose. Examples includes plants , algae and bacteria.
What is a chemosynthetic autotroph?
Live on other plant species and obtain preformed organic molecules from other organisms (hosts), parasites - archea
What is a heterotroph?
Organisms that obtain preformed organic molecules through feeding. Examples include, animals, fungi and some bacteria.
What is the difference between a heterotroph and an autotroph in terms of organic molecules?
Heterotrophs must obtain their organic molecules preformed, but autotrophs are organisms that can make their own organic molecules from simple organic molecules.
What is photosynthesis?
The process by which light energy is transformed into chemical energy in organic compounds, principally glucose, in autotrophs such as plants and algae.
