Monday, November 5, 2007
Mon-Day 1
Bio- we began our new unit, which shows the OTHER main function of DNA:
its coded information, in the form of nucleotide base sequences, is used to direct the synthesis of particular proteins that give an organism its specific characteristics/traits/features.
The coded information of the DNA molecules, which make up the chromosomes, cannot leave the nucleus; instead, the DNA sequence of bases is used as a template for the synthesis of RNA molecules, which CAN leave the nucleus without changing the number of chromosomes in the nucleus. This synthesis of RNA from DNA is called TRANSCRIPTION, which preserves the code and sequence of the DNA in a slightly different molecule, RNA. We saw how this process occurs.
There are several main differences between DNA and RNA. Today, we saw three of those differences: DNA is a double-helix of nucleotides whereas RNA is a single-helix of nucleotides;
DNA has Deoxyribose sugar as part of each nucleotide and RNA has Ribose as part of each nucleotide; DNA pairs A with T or G with C whereas RNA pairs A with U or G with C (U= uracil, which is VERY similar in shape and structure to thymine); there is NEVER NEVER NEVER any thymine in ANY RNA molecule!!!
There are three types of RNA that are transcribed from the DNA: we will see that these three types of RNA molecules work together (at the ribosomes outside of the nucleus) in the synthesis of each particular protein (a chain of amino acids) in a process called TRANSLATION.
The shape of the protein will cause the particular FUNCTION of the protein (which determines a particular trait); the shape of the protein is dictated by the particular SEQUENCE of amino acids that make up the protein; the particular sequence of amino acids of the protein are determined by the sequence of nitrogenous bases in the messenger RNA molecule; finally, the sequence of nitrogenous bases in the messenger RNA are determined by the sequence of nitrogenous bases in the DNA.
So, overall, we have the central dogma of molecular biology:
DNA codes for RNA via transcription. RNA codes for protein via translation. Proteins cause an organism to have particular traits/features.
We went over part of the DNA, mitosis, and asexual reproduction test; I was glad to see that many of you worked closer to your potential though, as we saw from test-skill review, almost all of you can do even better. As we progress and improve, this class can and should achieve a 90 or higher average on all future tests, as you have proven on this recent exam. Let's continue to improve our efforts and learn from our first quarter experiences so that we earn and produce excellent results in the next quarter.
Chem 7- we calculated and compared the densities of several different gases at STP. We saw that, given the same temperature and pressure conditions, the gas molecules with the greatest masses are the densest; this is related to the fact that, in a given volume, say 22.4 L, at the same T and P, there are the SAME number of each different type of gas molecules. So given the same number of molecules, naturally, the heaviest molecules will have the most mass in that same volume and, thus, be the densest.
We reviewed how to calculate the MOLAR MASS of a substance (the mass, in grams, of one mole of molecules of a substance) by adding up the gram atomic masses of the elements in the
We then finished our comparison and contrast of real gases vs. theoretical ideal gases and showed the conditions that would cause a real gas to behave ideally (high T and low P, KEEPING THE GAS IN THE GAS PHASE by heating and NOT squishing!) due to the overcoming of intermolecular attractions at high T and the insignificant molecular volumes at low P. We also showed, by contrast, that real gases can LIQUEFY or SOLIDIFY when they DEVIATE from ideal gas behavior at low T and high P (freeze and squish into a SOLID!).
Wednesday is our final review day for the unit exam on Thursday. We will also discuss both the can lab and the Charles lab, so bring those labs to class.
Chem 8/9- we calculated and compared the densities of several different gases at STP. We saw that, given the same temperature and pressure conditions, the gas molecules with the greatest masses are the densest; this is related to the fact that, in a given volume, say 22.4 L, at the same T and P, there are the SAME number of each different type of gas molecules. So given the same number of molecules, naturally, the heaviest molecules will have the most mass in that same volume and, thus, be the densest. We reviewed how to calculate the MOLAR MASS of a substance (the mass, in grams, of one mole of molecules of a substance) by adding up the gram atomic masses of the elements in the molecule, multiplied by each element's subscript within the molecular formula.
We then finished our comparison and contrast of real gases vs. theoretical ideal gases and showed the conditions that would cause a real gas to behave ideally (high T and low P, KEEPING THE GAS IN THE GAS PHASE by heating and NOT squishing!) due to the overcoming of intermolecular attractions at high T and the insignificant molecular volumes at low P. We also showed, by contrast, that real gases can LIQUEFY or SOLIDIFY when they DEVIATE from ideal gas behavior at low T and high P (freeze and squish into a SOLID!).
We discussed the Gay-Lussac lab (crush the can) and the Charles Law lab; the data for Table B of your lab will be posted on Blackboard tonight (Monday). Notice what happens to the RATIO of length (really volume) to Temperature when you use the Celsius data vs. when you use the converted Kelvin (absolute T) data! Can you see why the gas laws only "work" when the Kelvin temperatures are used because only Kelvin temperatures are DIRECT measures of average KE of the gas molecules (part of K-M Theory).
Those two labs are due on Wednesday. Email me if you have further questions about those labs.
its coded information, in the form of nucleotide base sequences, is used to direct the synthesis of particular proteins that give an organism its specific characteristics/traits/features.
The coded information of the DNA molecules, which make up the chromosomes, cannot leave the nucleus; instead, the DNA sequence of bases is used as a template for the synthesis of RNA molecules, which CAN leave the nucleus without changing the number of chromosomes in the nucleus. This synthesis of RNA from DNA is called TRANSCRIPTION, which preserves the code and sequence of the DNA in a slightly different molecule, RNA. We saw how this process occurs.
There are several main differences between DNA and RNA. Today, we saw three of those differences: DNA is a double-helix of nucleotides whereas RNA is a single-helix of nucleotides;
DNA has Deoxyribose sugar as part of each nucleotide and RNA has Ribose as part of each nucleotide; DNA pairs A with T or G with C whereas RNA pairs A with U or G with C (U= uracil, which is VERY similar in shape and structure to thymine); there is NEVER NEVER NEVER any thymine in ANY RNA molecule!!!
There are three types of RNA that are transcribed from the DNA: we will see that these three types of RNA molecules work together (at the ribosomes outside of the nucleus) in the synthesis of each particular protein (a chain of amino acids) in a process called TRANSLATION.
The shape of the protein will cause the particular FUNCTION of the protein (which determines a particular trait); the shape of the protein is dictated by the particular SEQUENCE of amino acids that make up the protein; the particular sequence of amino acids of the protein are determined by the sequence of nitrogenous bases in the messenger RNA molecule; finally, the sequence of nitrogenous bases in the messenger RNA are determined by the sequence of nitrogenous bases in the DNA.
So, overall, we have the central dogma of molecular biology:
DNA codes for RNA via transcription. RNA codes for protein via translation. Proteins cause an organism to have particular traits/features.
We went over part of the DNA, mitosis, and asexual reproduction test; I was glad to see that many of you worked closer to your potential though, as we saw from test-skill review, almost all of you can do even better. As we progress and improve, this class can and should achieve a 90 or higher average on all future tests, as you have proven on this recent exam. Let's continue to improve our efforts and learn from our first quarter experiences so that we earn and produce excellent results in the next quarter.
Chem 7- we calculated and compared the densities of several different gases at STP. We saw that, given the same temperature and pressure conditions, the gas molecules with the greatest masses are the densest; this is related to the fact that, in a given volume, say 22.4 L, at the same T and P, there are the SAME number of each different type of gas molecules. So given the same number of molecules, naturally, the heaviest molecules will have the most mass in that same volume and, thus, be the densest.
We reviewed how to calculate the MOLAR MASS of a substance (the mass, in grams, of one mole of molecules of a substance) by adding up the gram atomic masses of the elements in the
We then finished our comparison and contrast of real gases vs. theoretical ideal gases and showed the conditions that would cause a real gas to behave ideally (high T and low P, KEEPING THE GAS IN THE GAS PHASE by heating and NOT squishing!) due to the overcoming of intermolecular attractions at high T and the insignificant molecular volumes at low P. We also showed, by contrast, that real gases can LIQUEFY or SOLIDIFY when they DEVIATE from ideal gas behavior at low T and high P (freeze and squish into a SOLID!).
Wednesday is our final review day for the unit exam on Thursday. We will also discuss both the can lab and the Charles lab, so bring those labs to class.
Chem 8/9- we calculated and compared the densities of several different gases at STP. We saw that, given the same temperature and pressure conditions, the gas molecules with the greatest masses are the densest; this is related to the fact that, in a given volume, say 22.4 L, at the same T and P, there are the SAME number of each different type of gas molecules. So given the same number of molecules, naturally, the heaviest molecules will have the most mass in that same volume and, thus, be the densest. We reviewed how to calculate the MOLAR MASS of a substance (the mass, in grams, of one mole of molecules of a substance) by adding up the gram atomic masses of the elements in the molecule, multiplied by each element's subscript within the molecular formula.
We then finished our comparison and contrast of real gases vs. theoretical ideal gases and showed the conditions that would cause a real gas to behave ideally (high T and low P, KEEPING THE GAS IN THE GAS PHASE by heating and NOT squishing!) due to the overcoming of intermolecular attractions at high T and the insignificant molecular volumes at low P. We also showed, by contrast, that real gases can LIQUEFY or SOLIDIFY when they DEVIATE from ideal gas behavior at low T and high P (freeze and squish into a SOLID!).
We discussed the Gay-Lussac lab (crush the can) and the Charles Law lab; the data for Table B of your lab will be posted on Blackboard tonight (Monday). Notice what happens to the RATIO of length (really volume) to Temperature when you use the Celsius data vs. when you use the converted Kelvin (absolute T) data! Can you see why the gas laws only "work" when the Kelvin temperatures are used because only Kelvin temperatures are DIRECT measures of average KE of the gas molecules (part of K-M Theory).
Those two labs are due on Wednesday. Email me if you have further questions about those labs.
# posted by C @ 12:35 PM 
