Cell Biology Revision (Part 2) Flashcards
Enzymes
An enzyme is a biological catalyst which speeds up a biochemical reactions and remains unchanged following the reaction.Properties of an enzyme are:
- Speeds up chemical reactions
- Less energy (ATP) is needed in a chemical reaction when it is present- lowers activation energy
- It is unchanged at the end of the reaction
Enzymes are specific which means they work on only one substrate molecule. Shape of the active site is complementary to the shape of the substrate which means it fits together exactly. When a substrate enters the active site of an enzyme it’s shape changes slightly to fit on tightly around the substrate molecule. This close contact increases the chance of a chemical reaction taking place.Degradation enzymes connect with their specific substrate through the active site. Then they split the substrate in 2 and releases the 2 new products. 3 degradation enzyme reactions are:
- SAM = Amylase
Starch ————-> Maltose
-PPP = Pepsin
Protein ————-> Polypeptides ( Amino acids)
-HPCOW = Catalase
Hydrogen Peroxide ————-> Oxygen + Water
Synthesis enzymes build up the substrate molecules to form larger products. Here is a synthesis enzyme reaction:
G1PPS = Potato Phosphorylase
Glucose-1-phosphate —————————-> Starch
Enzymes have 2 limiting factors:
- temperature
- pH
Protein
Proteins are composed of chains of amino acids. A typical protein is about 400 amino acids long. As there are 20 different types of naturally occurring amino acids, many different proteins can be made. Different proteins are made of different combinations of amino acids.One protein is an enzyme and it is a catalyst of chemical reactions.
Genetic Engineering
Genetic engineering is when scientists take a gene containing a certain trait from a cell and put it in a different cell and then breed it until there are lots.
Advantages
- Large quantities of the desired product are formed
- Genetic engineering has made possible a wide range of substances for medical and commercial value
Disadvantages
- Genetic engineering is very expensive to set up
- Genetically engineered bacteria could be formed that May have a harmful effect on the ecosystem
An example of a GM product is the insulin producing bacteria.
Respiration
Respiration is the process of releasing energy from food. Aerobic Respiration is respiration with oxygen. Here is its equation:
Glucose + Oxygen ———–> 38ATP + CO2 + Water
Aerobic respiration is split into two stages, in the 1st stage the Glucose is split into 2 Pyruvate + 2 ATP. This happens in the cytoplasm and then the Pyruvate diffuses into the mitochondria. In the 2nd stage the Pyruvate is broken down into CO2 + Water + 18ATP ( each Pyruvate ). Aerobic respiration is controlled by a series of enzyme controlled reactions.
Aerobic respiration
Aerobic Respiration is respiration with oxygen. Here is its equation:
Glucose + Oxygen ———–> 38ATP + CO2 + Water
Aerobic respiration is split into two stages, in the 1st stage the Glucose is split into 2 Pyruvate + 2 ATP. This happens in the cytoplasm and then the Pyruvate diffuses into the mitochondria. In the 2nd stage the Pyruvate is broken down into CO2 + Water + 18ATP ( each Pyruvate ). Aerobic respiration is controlled by a series of enzyme controlled reactions.
Anaerobic Respiration
Anaerobic respiration in animals is different to plants. When you are exercising vigorously you are unable to breath fast enough to meet your oxygen demand! So without oxygen, your muscle cells start to carry out anaerobic respiration.Here is the equation:
Glucose ————->Pyruvate ————–> Lactic Acid
^ ^
2 ATP produced Causes muscle fatigue
This process is reversible so when your body gets some recovery time the build up of lactic acid disappears.
Anaerobic respiration in Plants
Glucose ————> Pyruvate ———–> Ethanol + CO2
^ ^
Only 2 ATP produced No ATP produced
No oxygen required No oxygen required
Anaerobic respiration in plants and yeast is irreversible because after the reaction the CO2 is lost to the environment. This form of respiration is inefficient because only 2 ATP are produced.
Differences between aerobic and anaerobic respiration
Aerobic Anaerobic
Need for oxygen - always required Never required
Energy yield - 38ATP molecules 2ATP molecules
Glucose
breakdown - Completely Partially
End products - CO2 + water Animal cell - lactic acid
Plant cell - CO2 + Ethanol
ATP
ATP is an immediate source of energy for cells particularly muscles that need it when they are contracting. ATP is made of 1 adenosine and 3 inorganic phosphate groups called Pi for short. When ATP has been used it turns back into ADP + Pi and then it goes back to the start. ATP is used for:
- Muscle contraction
- Nerve impulses
- Cell division ( growth )
- Building up ( synthesis ) of proteins
Photosynthesis
Photosynthesis is the process where green plants create their own food. Chlorophyll traps the energy from the sun and the plant also takes in CO2 + water from the environment.
CO2 + Water ——- Light + Chlorophyll ———–> Glucose + Oxygen
Raw materials Essential requirements Products
Photosynthesis is split into 2 stages Photolysis and Carbon Fixation. Limiting factors of photosynthesis are:
- Light intensity
- CO2 concentration
- Temperature
Photolysis
Photolysis is the first stage of photosynthesis and is sometimes also called the water splitting stage. It is called this because light splits water into Hydrogen + Oxygen.
Hydrogen Oxygen
|
ATP
The Oxygen diffuses out the plant and Hydrogen and ATP are passed onto stage 2.
Carbon Fixation
Carbon Fixation is the second stage of photosynthesis and it uses the ATP produced from the first stage. This stage is controlled by enzymes.
Hydrogen + CO2 ———-> Glucose
Glucose
Glucose is a sugar and it can also be turned into 2 different carbohydrates:
- Starch - a storage carbohydrate
- Concentrated energy source
- Insoluble in water
- Coiled in shape - Cellulose - a structural carbohydrate
- Tough material which makes up plant cell walls
- Insoluble in water
- Linear in shape
