Role of membrane:
Mitochondria have inner and outer membranes which enclose and intermembranal space, membrane is impermeable to H+ ions. This allows accumulation of H+ to generate the proton gradient.
Membranes can be folded into cristae to increase surface area to accomodate numerous proteins such as electron carriers.
Electron transport chain is embedded in the inner mitochondrial membrane to allow for the oxidation of NADH in respiration and the process of chemiosmosis to occur so that the proton gradient can be set up for the synthesis of ATP.
Elementary stalk particles are found on the membrane consisting of ATP synthase,phosphorylation of ADP to ATP catalysed by ATP synthase.
Role of Oxygen:
Final Electron acceptor in the ETC
Combines with H+ to form water
involved in oxidative phosphorylation
Maintain electron flow in the ETC
Allows regenaration of coenzymes
Role of coenzymes:
NAP+ and FAD can be regenerated and recycled.
NAD+ and FAD are electron and H+ acceptors.
Allows for the transfer of high energy electrons to the ETC
Wednesday, September 26, 2007
Explain the economic justification for Singapore in the signing of Free Trade Agreement with other countries. [12 marks]
Free trade agreements are binding agreements between 2 or more countries to remove trade barriers and business restrictions. They typically include reducing tariffs on imports and relaxing restrictions on the level of participation in sectors like business and finance. FTA results in a free trade area.
Singapore has signed FTA with several countries like Japan,Australia,Jordan and US.
Improve price competitiveness
Singapore has small domestic market,FTAs open up markets and enable local firms to sell to larger market.
Cost savings derived from large scale production
FTAs increases volume of free trade,enabling trading countries to enjoy benefits according to comparative advantage.
FTAs lead to Trade creation,where consumption shifts from a high cost producer to a low cost producer within the Free Trade area
Attract investments from abroad
removal of barriers to capital flows make it easier in Singapore, MNCs with ready funds and advanced technology are encouraged to invest in Singapore.
Increased FDI leads to transfer of technology. Foreign firms provide greater competition and force local firms to be efficient.
Another benefit of FTA is the advantage of ready export markets.
conclusion:
FTAs are superhighways that connect Singapore to major economies and new markets. With FTAs, Singapore-based exporters and investors stand to enjoy a myriad of benefits like tariff concessions, preferential access to certain sectors, faster entry into markets and Intellectual Property (IP) protection.
As an integral part of Singapore’s trade architecture, Singapore's network of 13 FTAs is designed to position Singapore as an integrated manufacturing center in this region; promote research & development in our knowledge-based economy and drive the services hub.
Free trade agreements are binding agreements between 2 or more countries to remove trade barriers and business restrictions. They typically include reducing tariffs on imports and relaxing restrictions on the level of participation in sectors like business and finance. FTA results in a free trade area.
Singapore has signed FTA with several countries like Japan,Australia,Jordan and US.
Improve price competitiveness
The Trade in Goods Chapter will provide for comprehensive tariff elimination and reduction on products traded between member countries in an FTA. Tariff elimination, when measured in terms of tariff savings and concessions, will have the effect of reducing the cost burdens of businesses that are exporting to member countries. Savings from these preferential tariff concessions will make exports from Singapore more competitive vis-à-vis exports from non-member countries.
Intellectual Property Rights (IPR) Protection
- Stronger IPR protection set ground for knowledge-based industries
Singapore has small domestic market,FTAs open up markets and enable local firms to sell to larger market.
Cost savings derived from large scale production
FTAs increases volume of free trade,enabling trading countries to enjoy benefits according to comparative advantage.
FTAs lead to Trade creation,where consumption shifts from a high cost producer to a low cost producer within the Free Trade area
Attract investments from abroad
removal of barriers to capital flows make it easier in Singapore, MNCs with ready funds and advanced technology are encouraged to invest in Singapore.
Increased FDI leads to transfer of technology. Foreign firms provide greater competition and force local firms to be efficient.
Another benefit of FTA is the advantage of ready export markets.
conclusion:
FTAs are superhighways that connect Singapore to major economies and new markets. With FTAs, Singapore-based exporters and investors stand to enjoy a myriad of benefits like tariff concessions, preferential access to certain sectors, faster entry into markets and Intellectual Property (IP) protection.
As an integral part of Singapore’s trade architecture, Singapore's network of 13 FTAs is designed to position Singapore as an integrated manufacturing center in this region; promote research & development in our knowledge-based economy and drive the services hub.
Friday, September 14, 2007
Denaturation of Proteins
Denaturation refers to the breaking of weak bonds holding the secondary,tertiary and quartenary structure but not the covalent bonds within the primary structure
5 ways to denature proteins: Heating
pH changes
Mechanical agitation
add metal ions
add 8mol/dm^3 of urea
Heating:
Most globular proteins undergo denaturation when heated above 60 degree celcius
Effect: Disrupt the weaker Van der Waal's forces and hydrogen bonding to a lesser extent
Irreversible at high heat
Coagulation of egg white on heating
pH changes:
Protonates or deprotonates the ionic R groups, thus disrupting the electrostatic attractions involved in securing the tertiary and quarternary structure in place.
irreversible at extreme pH changes
coagulation of sour milk
Add metal ions
Disrupts the electrostatic attraction between the charged R groups of the amino acids by forming similar bonds with these groups.
Disrupt the formation of disulphide S-S bridges by forming bonds with -SH group of cysteine residue.
making of salted eggs by adding sodium chloride
Add urea:
Urea acts by competing for the intra molecular hydrogen bnds that stabilizes the structure
Reversible denaturation.
5 ways to denature proteins: Heating
pH changes
Mechanical agitation
add metal ions
add 8mol/dm^3 of urea
Heating:
Most globular proteins undergo denaturation when heated above 60 degree celcius
Effect: Disrupt the weaker Van der Waal's forces and hydrogen bonding to a lesser extent
Irreversible at high heat
Coagulation of egg white on heating
pH changes:
Protonates or deprotonates the ionic R groups, thus disrupting the electrostatic attractions involved in securing the tertiary and quarternary structure in place.
irreversible at extreme pH changes
coagulation of sour milk
Add metal ions
Disrupts the electrostatic attraction between the charged R groups of the amino acids by forming similar bonds with these groups.
Disrupt the formation of disulphide S-S bridges by forming bonds with -SH group of cysteine residue.
making of salted eggs by adding sodium chloride
Add urea:
Urea acts by competing for the intra molecular hydrogen bnds that stabilizes the structure
Reversible denaturation.
Wednesday, September 12, 2007
Gene therapy
Explain what is meant by gene therapy:
Gene therapy is a technique or correcting defective genes responsible for disease development which involves altering a patient's natural genotype
Gene therapy's purpose is also to kill the cells involved.
There are 2 approaches which include Germ cell therapy of sperm,egg or early embryo , and somatic cell therapy.
The technique of gene therapy is to insert a normal gene into the genome to replace the abnormal disease-causing gene.
This requires a vector to deliver the therapeutic gene into the patient's target cells which could be viral or non-viral method.
Viral delivery system includes use of retrovirus
Non-viral delivery system includes use of electroporation.
Examples if diseases that can be treated using gene therapy inculde severe combined immunodeficiency disease.
Gene therapy is a technique or correcting defective genes responsible for disease development which involves altering a patient's natural genotype
Gene therapy's purpose is also to kill the cells involved.
There are 2 approaches which include Germ cell therapy of sperm,egg or early embryo , and somatic cell therapy.
The technique of gene therapy is to insert a normal gene into the genome to replace the abnormal disease-causing gene.
This requires a vector to deliver the therapeutic gene into the patient's target cells which could be viral or non-viral method.
Viral delivery system includes use of retrovirus
Non-viral delivery system includes use of electroporation.
Examples if diseases that can be treated using gene therapy inculde severe combined immunodeficiency disease.
Sunday, September 9, 2007
Tyrosine Kinase receptors
A tyrosine kinase receptor can trigger more than 1 signal transduction pathway at once, helping the cell regulate and coordinate many aspects of cell growth and cell reproduction.
A kinase is an enzyme that catalyzes transfer of phosphate groups.
1)Tyrosine Kinase receptor consist of extracellular signal-binding site, an alpha helix spanning the membrane, and intracellular tail containing multiple tyrosines.
2)the binding of a signal molecule(such as a growth factor) causes 2 receptor polypeptides to form a dimer
3)Dimerization activates the tyrosine-kinase region of each polypeptide, each tyrosine-kinase adds phsophate from an ATP molecue. The phosphorylated tyrosine-kinase receptor proteins activate a variety of specific relay proteins which trigger different transduction pathways.
G-Protein Linked receptors
A G-protein Linked receptor is a plasma membrane receptor that works with the help of a G protein.
When GDP is bound to a G protein, G protein is inactive.
When an appropriate signal molecule binds to the extracellular side of the receptor, the receptor is activated and changes shape. It's intracellular cytoplasmic side then binds to an inactive G protein, causing a GTP to displace a GDP. This activates a G protein.
The activated G protein dissociates from the receptor and binds to an enzyme and activates it.
G protein also functions as GTPase enzyme and hydrolyzes the bound GTP to GDP. inactive G protein dissociates from enzyme and is available for reuse.
The GTPase function of G protein allows the pathway to shut down rapidly when signal molecule is no longer present.
A kinase is an enzyme that catalyzes transfer of phosphate groups.
1)Tyrosine Kinase receptor consist of extracellular signal-binding site, an alpha helix spanning the membrane, and intracellular tail containing multiple tyrosines.
2)the binding of a signal molecule(such as a growth factor) causes 2 receptor polypeptides to form a dimer
3)Dimerization activates the tyrosine-kinase region of each polypeptide, each tyrosine-kinase adds phsophate from an ATP molecue. The phosphorylated tyrosine-kinase receptor proteins activate a variety of specific relay proteins which trigger different transduction pathways.
G-Protein Linked receptors
A G-protein Linked receptor is a plasma membrane receptor that works with the help of a G protein.
When GDP is bound to a G protein, G protein is inactive.
When an appropriate signal molecule binds to the extracellular side of the receptor, the receptor is activated and changes shape. It's intracellular cytoplasmic side then binds to an inactive G protein, causing a GTP to displace a GDP. This activates a G protein.
The activated G protein dissociates from the receptor and binds to an enzyme and activates it.
G protein also functions as GTPase enzyme and hydrolyzes the bound GTP to GDP. inactive G protein dissociates from enzyme and is available for reuse.
The GTPase function of G protein allows the pathway to shut down rapidly when signal molecule is no longer present.
Friday, September 7, 2007
Describe the main differences in structure between plant and animal cells
Plasmodesmata is present in plants but not animal cells
(Plasmodesmata are narrow channels that act as intercellular cytoplasmic bridges to facilitate communication and transport of materials between plant cells. The plasmodesmata serve to connect the symplastic space in the plant and are extremely specialized channels that allow for intercellular movement of water, various nutrients, and other molecules (including signalling molecules) . Plasmodesmata are located in narrow areas of cell walls called primary pit fields, and they are so dense in these areas (up to one million per square millimeter) that they make up one percent of the entire area of the cell wall :
Centrioles are absent in higher plants but are present in animal cells
Large central vacuole filled with cell sap in plant cells whereas small and numerous digestive vacuoles in animal cells.
Plant cells lacks lysosomes while animal cells contain lysosomes.
Presence of tonoplast in plant cells but not in animal cells.
tonoplast
Presence of cellulose cell wall in plant cell but not in animal cell.
Explain how lysosomes differ from ribosomes:
Lysosomes are 0.1 to 0.5 micrometre in diameter while ribosomes are 20 nanometres in diameter
Lysosomes are sacs formed from Golgi apparatus while ribosomes are made up of protein and RNA.
Lysosomes are not bound to endoplasmic reticulum while ribosomes may be attached to endoplasmic reticulum.
Lysosomes are involved in autolysis while ribosomes are involved in protein synthesis.
Lysosomes are membrane bound while ribosomes lack membrane
Ribosomes are made up of large and small subunits while lysosomes do not contain any subunits.
Enzymes in lysosome are hydrolytic while enzymes in ribosomes are used for peptide bond formation. Lysosome enzymes such as protease and ribosome contains peptidyl transferase.
Outline the structure and function of the Golgi body in cells:
Made up of flattened membrane sacs
Consists of cis and trans side
formed from vesicles from rough edoplasmic reticulum
Involved in chemical modification of protein,forming glycoproteins.
Involved in synthesis and transport of lipids
Plays a role in cell wall formaton in plant cells
Plasmodesmata is present in plants but not animal cells
(Plasmodesmata are narrow channels that act as intercellular cytoplasmic bridges to facilitate communication and transport of materials between plant cells. The plasmodesmata serve to connect the symplastic space in the plant and are extremely specialized channels that allow for intercellular movement of water, various nutrients, and other molecules (including signalling molecules) . Plasmodesmata are located in narrow areas of cell walls called primary pit fields, and they are so dense in these areas (up to one million per square millimeter) that they make up one percent of the entire area of the cell wall :
Centrioles are absent in higher plants but are present in animal cells
Large central vacuole filled with cell sap in plant cells whereas small and numerous digestive vacuoles in animal cells.
Plant cells lacks lysosomes while animal cells contain lysosomes.
Presence of tonoplast in plant cells but not in animal cells.
tonoplast
(Science: plant biology) membrane that surrounds the vacuole in a plant cell. The cell membrane of plants surrounding the vacuole which is selectively permeable, and regulates the movements of ions around the cell.
Presence of chloroplast in plant cell but not in animal cell.Presence of cellulose cell wall in plant cell but not in animal cell.
Explain how lysosomes differ from ribosomes:
Lysosomes are 0.1 to 0.5 micrometre in diameter while ribosomes are 20 nanometres in diameter
Lysosomes are sacs formed from Golgi apparatus while ribosomes are made up of protein and RNA.
Lysosomes are not bound to endoplasmic reticulum while ribosomes may be attached to endoplasmic reticulum.
Lysosomes are involved in autolysis while ribosomes are involved in protein synthesis.
Lysosomes are membrane bound while ribosomes lack membrane
Ribosomes are made up of large and small subunits while lysosomes do not contain any subunits.
Enzymes in lysosome are hydrolytic while enzymes in ribosomes are used for peptide bond formation. Lysosome enzymes such as protease and ribosome contains peptidyl transferase.
Outline the structure and function of the Golgi body in cells:
Made up of flattened membrane sacs
Consists of cis and trans side
formed from vesicles from rough edoplasmic reticulum
Involved in chemical modification of protein,forming glycoproteins.
Involved in synthesis and transport of lipids
Plays a role in cell wall formaton in plant cells
Factor Vlll
Factor Vlll is a glycoprotein synthesized in liver cells. Many haemophiliacs, who are deficient in Factor Vlll, are now treated by regular injections of genetically engineered Factor Vlll.
Outline how the isolated gene for human Factor Vlll is obtained and inserted into a host cell
Use restriction enzymes to cut the human gene and mammalian cell chromosome
Isolate the human Factor Vlll and mammalian cell and insert the DNA encoding the human factor Vlll into mammallian cells grown in culture.
Human Factor Vlll gene is coupled to the promoter for the ovine(sheep) milk protein beta-lactoglobulin.
State 1 advantage of using recombinant Factor Vlll instead of blood derived Factor Vlll.
Recombinant Factor Vlll does not require injection and thus no risk of infections such as HIV.
Suggest why the host cell used to produce genetically engineered Factor Vlll must be a mammalian cell and not a bacteria cell.
E coli cannot be used as it lacks the machinery to attach carbohydrate properly.
(Human Factor Vlll is a glycoprotein)
Electrical pulse used to introduce activated mammallian cell int enucleated cell.
Outline how the isolated gene for human Factor Vlll is obtained and inserted into a host cell
Use restriction enzymes to cut the human gene and mammalian cell chromosome
Isolate the human Factor Vlll and mammalian cell and insert the DNA encoding the human factor Vlll into mammallian cells grown in culture.
Human Factor Vlll gene is coupled to the promoter for the ovine(sheep) milk protein beta-lactoglobulin.
State 1 advantage of using recombinant Factor Vlll instead of blood derived Factor Vlll.
Recombinant Factor Vlll does not require injection and thus no risk of infections such as HIV.
Suggest why the host cell used to produce genetically engineered Factor Vlll must be a mammalian cell and not a bacteria cell.
E coli cannot be used as it lacks the machinery to attach carbohydrate properly.
(Human Factor Vlll is a glycoprotein)
Electrical pulse used to introduce activated mammallian cell int enucleated cell.
Subscribe to:
Posts (Atom)
