Term
| Describe the key steps of transcription. |
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Definition
Initiation: Transcription factors bind to promoter, facilitating binding of RNA polymerase II. R.P. separates DNA strands and synthesis begins.
Elongation: R.P. moves along DNA strand, connecting RNA nucleotides that have paired to the DNA template to the 3' end of the growing RNA strand.
Termination: After polymerase transcribes to a stop codon, the pre-mRNA is cut and released |
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Term
| What happens between pre-mRNA and mature mRNA? |
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Definition
| Pre-mRNA gets spliced; introns are removed and exons are spliced together. Also, a 5' cap consisting of a modified guanine nucleotide is added to the 5' end. A poly-A tail is attached to the 3' end. |
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Term
| What is alternative RNA splicing? |
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Definition
| It allows different polypeptides/proteins to be produced from the same gene, depending on which exons are combined during processing. |
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Term
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Definition
| A large protein complex that holds the small RNAs that remove introns out of the RNA transcript and connect the exons |
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Term
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Definition
| RNA molecules that act as enzymes in spliceosomes. |
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Term
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Definition
| Amino acids are carried by tRNA to ribosomes, where they are added to a growing polypeptide. |
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Term
| What is the "wobble" phenomenon? |
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Definition
| During translation, it allows the third nucleotide of some tRNA anticodons to pair with more than one kind of nucleotide in the codon. This way, a tRNA can recognize more than one mRNA codon that code for the same amino acid. |
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Term
| What are transcription factors? |
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Definition
Transcription factors can come in the form of an activator or a repressor. Activators bind to the enhancer region, facilitating RNA polymerase's binding to the promoter, increasing transcription.
Repressors can bind in a myriad of ways and decrease transcription. |
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Term
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Definition
| binding site for tRNA holding the growing polypeptide chain |
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Term
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Definition
| binding site for tRNA holding amino acid to be added next |
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Term
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Definition
| exit site from which discharged tRNAs leave the ribosome |
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Term
| What are post-translational modifications? |
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Definition
| Amino acids may be chemically modified, one or more may be removed, segments of the polypeptide may be excised, or several polypeptides may associate into a protein with a quaternary structure. |
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Term
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Definition
| affects just one nucleotide pair |
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Term
| nucleotide-pair substitution mutation |
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Definition
| one nucleotide and its complementary partner is replaced with another pair of nucleotides |
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Term
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Definition
| substitutions that do not change the amino acid translation |
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Term
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Definition
| insertion of a different amino acid |
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Term
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Definition
| when a point mutation changes an amino acid codon into a stop codon, stopping translation early |
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Term
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Definition
| alter the reading frame, pushing everything past it into the wrong codon |
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Term
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Definition
| physical agents and chemical agents that cause mutations |
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Term
| translation initiation complex |
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Definition
| the small ribosomal subunit, mRNA, initiator tRNA, and large ribosomal subunits that combine to begin translation |
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Term
| What happens in the initiation stage of translation? |
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Definition
| A special initiation tRNA carries mRNA to a small ribosomal subunit, which scans the mRNA until it hits the start codon. This is when the large ribosomal subunit connects and translation begins. |
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Term
| Elongation phase of translation |
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Definition
| mRNA moves through ribosome 5' end first, and the ribosome's A, P, and E sites ensure the polypeptide chain is put together properly. |
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Term
| Termination phase of translation |
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Definition
| translation continues until a stop codon is read |
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Term
| Describe the structure and function of ribosomes. |
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Definition
| A ribosome is made up of two subunits, one small and one large, that are linked together through interactions of proteins in one subunit with the ribosomal RNAs of the other subunit. This allows translation to occur, and therefore protein synthesis. |
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Term
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Definition
| One gene causing a lot of effects, like cystic fibrosis. |
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Term
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Definition
| When the presence of a gene masks the effect of the other, such as albinism. |
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