Flashcards in Biology Chapter 8 Deck (22):
Metabolic rate varies between
Different species: temperature and size main factor
Breaking down large molecules to small molecules (usually releases energy)
Building up large molecules from small ones (usually requires energy)
Types of energy:
Chemical (eg in food),
Kinetic (energy of movement).
ATP (Adenosine Tri Phosphate)
Stores Chemical energy.
Has 3 phosphate groups attached to adenine and ribose.
Mainly produced in mitochondria.
First law of thermodynamics
Energy can be changed from one form to another, it cannot be created or destroyed
Second law of thermodynamics
Entropy (disorder) is always increasing. So things fall apart and break down, because the general trend is towards disaster.
In living things, chemical energy (ATP) is used for:
Mechanical work. Eg muscles.
Chemical work. Eg anabolism.
Active transport. Eg sodium/potassium pump.
Control chemical reactions in the cell.
Act as catalysts. (Speed up chemical reactions by lowering the activation energy)
Enzymes are specific
Each affects a particular substrate.
They have an active site that the substrate molecule fits.
Work very rapidly (up to 100,000 Chemical reactions per min) so are only needed in tiny quantities.
The speed of enzymes can be affected by
Environmental conditions (temp, pH)
What temperature do human enzymes work best at?
37 degrees Celsius
Above 40 degrees C enzymes become denatured. Cold temps slow enzymes.
By cooling down a patient's body, surgeons can do heart surgery without a heart/lung machine
What pH do most human enzymes work best at?
Close to pH 7
Trypsin in the intestines works best around pH 8.
Pepsin in the stomach works best around pH 2.
Acids act as preservatives, as they slow or stop enzymes
Vitamins are needed in small amounts. Large amounts can be toxic. Vitamin E supplements may increase death risk.
Some vitamins are antioxidants that protect cells from damage. Coffee contains antioxidants
During pregnancy, what deficiency increases the risk of birth defects?
Attach to the active site of the enzyme
Attach away from the active site
Enzyme inhibitors are important in pesticides
Some medications, such as HIV drugs and aspirin, are inhibitors
All of the chemical reactions in an organism