Study notes, UNIT 2

Protein synthesis:
1. - The first step in protein sysnthesis is transcription , here the MRNA is created from a DNA template which occurs in the nucleas.First the Dna molecule unwinds and unzips using an enzyme called DNA helicase. Then the DNA polymerase pairs the complamentary bases and the MRNA strand leaves the DNA to form a ribosome and then the DNA winds up again using an enzyme called DNA ligase.
-The second step is called translation , this happens in the ribosome which is either attached to ER or in the cytoplasm.First the MRNA strand attaches to the ribosome ( each group has three pairs called codon), and the complimentary transfer RNA(anti codon) pairs up with a specific codon pair with their amino acid and then leaves the chain. This process continues until a peptide bond is formed between the amino acid which is now the protien.

2. For the codon GAA , the anti codon is CUU
                            AGA                             UCU

3.The two enviornmental mutagens that can cause mutations are exposure to radiation and DNA damaging chemicals.  
  
4. Mutations in DNA can change the order of a amino acid to create black eyes and instead the protein may make green eyes. Another example is that the mutation can also make six fingers instead of five because the protein sysnthesis was changed.

Transport Across Cell Membrane:

1. The fluid mosaic model helps to move things across the cell membrane. It is made up of a phospholipid bilayer that gives it shape and has hydrophobic and hydrophyllic heads. It has vesicles to transport things and add membrane to their own. The proteins form different pattern in different area wihtin the same mebrane. Glucolipds help to recognize and the cholestrol makes the membrane less permeable to water soluble ions and molecules.

2, Cell membranes are selectively permeable because it only allows some molecules to cross based on size and charge of the molecule.

3. Diffusion , facilitatice transport and osmosis are all passive transport, they do not tequire energy. diffusion help s to moves molecules across membrane from a high to low concentration, faciliatative diffusion helps to move particles using a carrier protien in membrane , osmosis is the diffusion of water from high to low concentration.While active trasport uses energy and moves molecule form low to high concentration and during this process the ATP is broken down into ADP molecule and phosphate ion.

4. The factors are;
-  Size of moleclues; smaller molecules diffuse faster than big molecules.
-Temperature; higher temperature increases rate of diffusion.
-CGradient;a greater difference in concentration gradient causes faster diffusion.
-Number of protien pores or carries within the cell membrane; more pores means faster rate of diffusion.

5.When molecules are too big to be actively transported , endocytosis occurs. In this process the moleclues are engulfed through folding of plasma membrane throught he vesicle and forming lysosome when the embrane pinches off. There are two methods of endocytosis; phagocutosis which menas cell eating that engulfs solid materials and pinocytosis which means cell drinking that engulfs liquid. Whereas, exocytosis means release of vesicle contenets outside of cell by fusion of vesicle with plasma membrane.

6.In a hypertonic enviornment, the water molecules move out of the cell (high to low concentration) and thus the cell shrinks.In a hypotonic enviornment the water moleclues move into the cell and thus the cell swells up. In an isotonic enviornment the water molecule do not move and stay in the same area thus the cell size stays the same.

7.As the surface area of the cell increases so does the volume of the cell and vice versa. So the larger the size of the cell the better to transport nutrients and diffuse in the cell.

Enzymes:

1. Enzymes are biological catalysts that speed up a chemical reaction without being used itself or altered.They help to increase the metabolism rate. Active site is the region where the chemical reaction takes place and the reactant that binds loosely is called a substrate forming a enzyme substrate complex.but to start a reaction an intial enrgy is required which is called the activation energy.  There are also non protien molecules that are called co enzymes which the enzymes and these complete the actice site.

2. The thyroxin is found in the thyroid gland found in the neck and this helps to increase the rate of metabolism by stimulatiing the body cells.

3.The lock and key model of enzymatic action means when an enzyme and a substrate fit together from the beginning.

4. In a biochemical reaction , vitamins helps to synthesize coenzymes , which are very large molecules but they have to ingested first.

5. Enzymes are organic moleclues that help to increase the rate of chemical reaction without being used itself. Coenzymes are non protein that bind to enzymes and carry out chemical reactions in the active site.

6.
PH level- Enzymes mostly prefer the PH level between 6-8 except pepsin and trypsin. If the PH level os too high the enzyme denatures and cannot form enzyme substrate cimplex.

Temperature-If the temperature speeds up around 45 degrees or more the enzyme denature and cannot function but if it decreases from the regular body temperature(36.9 celcius) then usually it doesnt denature.

Concentration of substrate- The rate of chemical reaction increases if the substrate increaes until the enzyme becomes saturated after that a constane production happens,

Concentration of enzyme-If the amount of enzyme increases the rate also increases and vice cersa but the production will only level off if there are no more substrate left.

Competitive inhibitors- This bind with the enzyme and decrease the rate of the substrate binding instead.

Heavy metals- These are a type of non- competitive inhibitors that reduce the rate of reaction because they are irreversible and also denature the enzyme.