Term
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Definition
| a DNA segment that includes the clustered genes, the promoter, and the operator |
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Definition
| a segment of DNA within or near the promoter that controls the access of RNA polymerase to the genes |
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Term
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Definition
| a protein that binds to a specific operator, blocking attachment of RNA polymerase and turning an operon off |
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Term
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Definition
| transmission of traits by mechanisms that don't involve changes in DNA, like chromatin modifications |
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Term
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Definition
| noncoding sequences that help regulate txn by serving as binding sites for txn factors |
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Term
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Definition
| distal control elements located far from a gene or within an intron |
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Term
| What are microRNAs (miRNAs)? |
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Definition
| Small RNA molecules that bind with mRNA molecules that have a complementary sequence, blocking translation or degrading the mRNA |
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Term
| What are small interfering RNAs (siRNAs)? |
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Definition
| inhibit the expression of genes the same way as miRNAs |
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Term
| What are microarray assays? |
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Definition
| Reverse transcriptase enzyme is used to make complementary copies of DNA from mRNAs. The complementary DNA (cDNA) is used in microarray assays and scientists can test fragments of DNA segments from thousands of genes arrayed on a grid (DNA chip). This is how we have identified genes being expressed. |
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Term
| What is the adaptive advantage of grouping bacterial genes into an operon? |
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Definition
| It allows protein synthesis to be controlled coordinately in response to the needs of the cell. |
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Term
| What are the three major events that generate genetic variation during sexual reproduction? |
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Definition
| Independent assortment of chromosomes, crossing over, and random fertilization |
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Term
| Define independent assortment. |
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Definition
| The first meiotic division separates parent chromosomes into daughter cells independent of each other--there's no way to guarantee how it's going to divide. |
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Term
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Definition
| Crossing over is a phenomenon that occurs during Prophase I of meiosis, in which maternal and paternal chromosomes are merged in some parts in order to pass on traits to daughter cells, resulting in recombinant chromosomes. |
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Term
| Explain the importance of metaphase I and compare it to metaphase of mitosis and metaphase II. |
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Definition
| All three versions of metaphase have the chromosomes lined up in the middle of the cell in preparation of division. However, in metaphase I homologous chromosomes are together. In mitosis' metaphase, the replicated chromosomes are together. In metaphase II, the homologous chromosomes have finished crossing over and are separated into four genetically varied haploid daughter cells. |
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Term
| What does it mean to say the genetic code is redundant and unambiguous? |
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Definition
| Each codon specifies one amino acid; however, several codons may code for the same one. |
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Term
| Compare transcription and translation in bacteria and eukaryotes. |
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Definition
| In eukaryotes, transcription occurs in the nucleus, while it occurs in the cytosol in bacteria. Also, in eukaryotes the original product of transcription is pre-mRNA which has to go through RNA processing prior to beginning translation. RNA processing is just the splicing of introns from exons by ribozymes found in spliceosomes, and the fusion of exons together to express a specific gene. There is also a poly-A tail added to the 3' side and a 5' modified guanine cap. Now the RNA is mature and ready for translation. In bacteria, the RNA is mature as soon as transcription ends. In bacteria, translation and transcription can occur simultaneously. This isn't possible in eukaryotes. |
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