Derek Lee
Mr. Hillegas
Ap Biology
7 March 2011
Chapters 13 & 14 Work
II. Connections
1. 5’ & electronegativity- 5’ refers to DNA polymerase enzymes joining the phosphate group at 5’ carbon. In this sense bonds between atoms are based on charges in which the electronegativity between two types of atoms determines what types of bonds they will form. For example prior to this step 5’, helicases must unzip and break off weak hydrogen bonds.
2. Start codon & incomplete dominance – Start codons or chain initation codons, AUG or GUG, signal the initiation of translation and the first amino acid in a polypeptide chain. Genes code for the proteins which express traits. In the case of codominance, two phenotypes are expressed equally, in which the proteins must be both signaled for translation and thus expression.
3. Semiconservative & barr body- Semiconservative replication is the normal process of DNA synthesis, in which the two original strands of molecule separate, and each acts as a template on which a new complementary strand is laid down. In females, on of these two strands of chromosomes, DNA, through process of x-inactivation will become unread and thus a bar body. This prevents females from having such a difference of DNA in comparison to males.
4. RNA Polymerase & nucleolous- RNA polymerase is a catalyzes the synthesis of a complementary strade of RNA from a DNA template. At the nucleolous RNA, specifically mRNA help translate the words in protein-building messages- they are the translators which give words that orginiated in the DNA their meaning. The nucleolous uses this information to make proteins.
5. DNA Polymerase & Glycosidic linkage- DNA polymerase refers to anyi of various enzymes that function in the replication and repair of DNA by catalyzing the linking dATP, dCTP, dGTP, and dTTP, in a specific order using single-straded DNA as a template. These bonds it makes are sugar/ glycosidic linkages.
6. Helicase & G2 Karyotype- A G2 Karyotype shows the chromosomes like a normal karyotype after Synthesis phase, meaning it will show the duplicated or double the normal amount of chromosomes. Helicase, or enzymes will unwind the deoxyribonucleic acid double helix at a replication fork in the process of DNA replication to form two new strands of DNA.
III. Essentials
1. 2 DNA strands are anti parallel, yet DNA polymerase can only synthesize new DNA in the 5’ to 3’ direction. This poses special problems for replicating double-stranded DNA. To begin replication, unwinding enzymes called DNA helicases cause two parent DNA strands to unwind and separate from on another at the origin of replication. Helix destabilizing proteins bind to the single-stranded regions so the two strands do not rejoin. Enzymes called topoisimerases produce breaks in the DNA and then rejoin them in order to relieve the stress in the helical molecule during replication. As the strands continue to unwind and separate in both directions around the entire DNA molecule, new complementary strands are produced by the hydrogen bonding of free DNA nucleotides with those on each parent strand.
2. DNA is double stranded, contains deoxyribose sugar, and contains thymine base.
RNA is single stranded, has ribose sugar, and has a uracil base.
3. tRNA – information adapter molecule. IT is the direct interface between amino-acid sequences of a protein and the information in DNA.
mRNA- A copy of the information carried by a gene on the DNA. It functions to move the information contained in DNA to the translation machinery.
rRNA- A component of ribosomes, the protein synthetic factories in the cell.
4. A.- In transcription, only one part of one DNA strand, not the whole molecule, is unwound and used as the template strand.
-The enzyme RNA polymerase, not DNA polymerase, adds ribonucleotides one at a time to the end of a growing strand of RNA.
-Each DNA protein-coding region has its own start and stop signal.
-A promoter is the start signal, a base sequence in DNA to which RNA polymerases bind and prepare for transcription.
-Using the gene’s base sequence as the template for covalently bonding free ribonucleotides together in a complementary sequence, the end result is a new GNA released as a free transcript.
B. RNA Splicing – process which removes intros and joins exons in a primary transcript. -An intro usually contains a clear signal for splicing.
-In some cases, a splicing signal may be masked by a regulatory protein, resulting in alternative splicing.
-In rare cases, a pre-mRNA may contain several ambiguous splicing signals, resulting in a few alternatively spliced mRNAs.
-It is the process by which base pairs that interrupt the continuity of genetic information in deoxyribonucleic acid are removed from the precursors of messenger ribonucleic acid.
C. Translation – Is the process of converting the mRNA codon sequences into an animo acid polypeptide chain.
-Each tRNA has a molecular “hook,” an attachment site for an amino acid. It has an anticodon, a ribonucleotide base triplet that can base-pair with a complementary codon in an mRNA transcript.
-This process has 3 steps beginning with initiation, or when a ribosome attaches to the mRNA and starts to code at the FMet codon – AUG, GUG, or UUG.
-Second, in elongation, tRNA brings the corresponding amino acid to each codon as the ribosome moves down the mRNA strand.
-And last, termination, or the reading of the final mRNA codon – the STOP codon – which ends the synthesis of the peptide chain and releases it.
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