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CH.10 Sec.1,2 & 3
Question | Answer |
---|---|
What are the main functions of DNA? | Stores and transmits genetic information |
Identify the types and locations of covalent bonds and hydrogen bonds in a DNA molecule. | Covalent bonds exist between the deoxyribose sugar and phosphate molecules. Hydrogen bonds join the nitrogen bases. |
List the base-pairing rules. | Adenine-Thymine (RNA-Uracil), Cytosine-Guanine |
What roles do enzymes play in DNA replication? | Helicase enzymes separate the two nucleotide chains starting at the replication fork. Then DNA polymerase moves along the separated chains of DNA; new chains of DNA are assembled using nucleotides in the surrounding medium. |
How would the deoxyribose sugar-phosphate backbone of nucleotide chains look if purines paired only with purines and pyrimidines paired only with pyrimidines? | The backbone would appear uneven, similar to the appearance of a roller coaster. |
Define transcription. List the main steps involved in this process. | The process by which genetic information is copied from DNA to RNA. RNA polymerase binds to the promoter of a specific gene, then a complementary copy of that gene's DNA base sequence is made using RNA nucleotides, thus forming the mRNA strand. |
In what ways does the structure of RNA differ from that of DNA? | RNA usually consists of a single chain of nucleotides, has ribose instead of deoxyribose as its sugar, and contains uracil rather than thymine. |
mRNA. | Consists of RNA nucleotides in the form of a single uncoiled chain; carries genetic information from the DNA in the nucleus to the cytosol of a eukaryotic cell |
List three roles of RNA polymerase in transcription. | 1. Initiates transcription by binding to promoter, DNA molecule in region splits. 2. Attaches to first DNA nucleotide of template chain. Begins adding complementary RNA nucleotides to new molecule. 3. Termination signal-RNA polymerase releases DNA & RNA |
What basic principle ensures that the transcribed RNA molecule is carrying the right genetic message? | Accuracy of the genetic message is assured by complementary base pairing. |
Transcription. | The process of producing RNA and DNA. |
Translation. | The process by which polypeptides are assembled from the information encoded in mRNA. |
Codon. | A series of three nucleotides in mRNA that code for a specific amino acid. |
Anticodon. | A set of three bases complementary to the codon. |
rRNA. | Consists of RNA nucleotides in globular form; joined by proteins, it makes up the ribosomes where proteins are made; most abundant form of RNA |
Anticodon | Consists of a single chain of about 80 RNA nucleotides folded into a hairpin shape that binds to specific amino acids |
Significance of the start codon and the stop codons. | To engage a ribosome to start translating an mRNA molecule and to cause the ribosome to stop translating an mRNA |
Do all polypeptides begin with the amino acid coded for by the start codon? | serine-glycine-proline-valine |
How does the structure of tRNA relate to its function in translation? | Allows an amino acid at one end to be positioned in a polypeptide when the anticodon at the other end of the tRNA pairs with a codon. |