Term
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Definition
| Process by which DNA directs the synthesis of proteins (or RNA) |
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Term
| What are the two stages for gene expression? |
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Definition
| Transcription and translation |
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Term
| What is Garrod's contribution to the early theories of gene expression? |
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Definition
| Garrod was the first to suggest that genes dictate phenotypes through enzymes that catalyze specific chemical reactions in the cell. |
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Term
| Explain Beadle's and Tatum's conclusions with the bread mold experiment. |
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Definition
| They formed the one gene - one enzyme hypothesis by essentially proving Garrod's initial theory. Beadle's and Tatum's hypothesis was later modified to the "one gene - one polypeptide" hypothesis. |
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Term
| List the three differences between RNA and DNA. |
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Definition
| Contains the sugar ribose, instead of deoxyribose; has uracil instead of thymine; usually consists of one strand |
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Term
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Definition
| Synthesis of RNA under the direction of DNA |
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Term
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Definition
| Synthesized in nucleus; carries messages from DNA to ribosomes for protein synthesis |
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Term
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Definition
| Synthesis of a polypeptide under the direction of mRNA |
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Term
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Definition
| Sites of translation that properly facilitate the orderly linking of amino acids into peptide chains; made of large and small subunits |
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Term
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Definition
| Initial RNA transcript from any gene, including those coding for RNA that is not translated into protein |
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Term
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Definition
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Term
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Definition
| Genetic instructions for amino acids are written in DNA as a series of nonoverlapping, three-nucleotide words |
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Term
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Definition
| One of the two DNA strands that is transcribed for each gene |
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Term
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Definition
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Term
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Definition
| Enzyme that pries the two strands of DNA apart and joins the RNA nucleotides as they base-pair along the DNA template |
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Term
| What is one similarity and one difference between RNA polymerase and DNA polymerase? |
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Definition
Similarity: both polymerases can only assemble in the 5' -> 3' direction
Difference: RNA pol doesn't need a primer |
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Term
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Definition
| DNA sequence where RNA pol attaches and initiates transcription; also determines which DNA strand is used as the template |
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Term
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Definition
| In bacteria only, the DNA sequence that signals the end of transcription |
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Term
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Definition
| Stretch of DNA that is transcribed into an RNA molecule |
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Term
| What are the three stages of transcription? |
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Definition
| Initiation, elongation, termination |
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Term
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Definition
| In eukaryotes, proteins that mediate the binding of RNA pol and the initiation of transcription |
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Term
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Definition
| Sequence of TATA that occurs about 25 nucleotides upstream from the transcription starting point |
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Term
| How does termination of transcription occur in eukaryotes? What is the product of initial transcription? |
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Definition
| RNA pol II transcribes a sequence on the DNA called a polyadenylation signal sequence (AAUAAA). Then, 30-35 nucleotides downstream, proteins cut the RNA transcript from the pol. This results in the product, pre-mRNA. |
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Term
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Definition
| After transcription, modification of pre-mRNA, which includes alteration of molecule ends and splicing |
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Term
| What are the two alterations that are made to pre-mRNA ends? |
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Definition
| The 5' receives a 5' cap, or sequence of guanine; the 3' end receives a poly-A tail, or sequence of adenine |
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Term
| What are the three benefits of altering the ends of pre-mRNA? |
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Definition
1. They facilitate the export of mature mRNA from the nucleus
2. The protect the mRNA
3. They help ribosomes attache to the 5' end once the mRNA reaches the cytoplasm |
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Term
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Definition
| Process of editing pre-mRNA by cutting and pasting segments of the molecule to form a continuous coding sequence (exons only) |
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Term
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Definition
| Coding segments of nucleic acid that are eventually expressed |
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Term
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Definition
| Noncoding segments of nucleic acid that are not expressed |
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Term
| snRNPs (small nuclear ribonucleoproteins) |
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Definition
| Particles that recognize splice sites; composed of snRNA |
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Term
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Definition
| Conglomeration of snRNPs and proteins |
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Term
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Definition
| RNA molecule that functions as an enzyme |
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Term
| What three properties of RNA allow it to function as an enzyme? |
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Definition
| 1. Structure: RNA is single-stranded and may base-pair with a complementary region elsewhere in the same molecule 2. Bases: may contain functional groups that can participate in catalysis 3. Hydrogen bonding: adds specificity to its catalytic activity |
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Term
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Definition
| When genes give rise to two or more different polypeptides depending on which segments are treated as exons |
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Term
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Definition
| When introns increase the probability of potentially beneficial crossing over between exons by providing more terrain for crossovers without interrupting coding sequences |
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Term
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Definition
| Synthesized in nucleus; transfers amino acids from cytoplasm to a ribosome to build a protein |
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Term
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Definition
| Nucleotide triplet on tRNA that is complementary for the codons on mRNA |
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Term
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Definition
| Enzyme that matches up tRNA with its correct amino acid |
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Term
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Definition
| Flexible base pairing of codons due to the presence of synonymous codons for a given amino acid |
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Term
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Definition
| Synthesized in nucleolus; form ribosomes; most abundant type of RNA |
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Term
| What are the three bindings sites for tRNA on ribosomes and their functions? |
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Definition
1. P site: holds tRNA carrying the growing polypeptide chain
2. A site: holds tRNA carrying the next amino acid to be added to the chain
3. E site: discharged tRNAs leave the ribosome here |
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Term
| What energy source is required for initiation and elongation during translation? |
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Definition
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Term
| What signals the start of translation? |
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Definition
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Term
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Definition
| Proteins that unite mRNA, tRNA, and the large and small ribosomal subunits during initiation |
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Term
| What signals the end of translation? |
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Definition
| Stop codon in mRNA reaches the A site of a ribosome |
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Term
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Definition
| Proteins that bind directly to the stop codon and cause the addition of a water molecule (instead of an amino acid) to the polypeptide chain |
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Term
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Definition
| Strings of ribosomes that translate mRNA at the same to time to make many copies of a polypeptide simultaneously |
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Term
| What are examples of post-translational modifications? |
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Definition
| Amino acids are chemically modified by attaching lipids, sugars, or phosphates; enzymes remove amino acids; enzymes join to polypeptides together |
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Term
| What is the difference between free and bound ribosomes? |
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Definition
| Free ribosomes are in the cytoplasm and synthesize proteins that remain in the cytoplasm; bound ribosomes are attached to the endoplasmic reticulum (ER) or nuclear envelope and make proteins for organelles |
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Term
| What determines whether a ribosome will be free or bound? |
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Definition
| Signal peptides target the ribosome for the ER |
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Term
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Definition
| Sequence of 20 amino acids at the leading end of a polypeptide that is recognized by a signal-recognition particle (SRP) |
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Term
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Definition
| Chemical changes in a single base pair of a gene |
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Term
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Definition
| Replacement of one nucleotide and its partner with another pair of nucleotides |
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Term
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Definition
| Have no effect on encoded protein |
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Term
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Definition
| Change one amino acid to another; have little effect on the protein |
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Term
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Definition
| Change a codon for an amino acid into a stop codon; lead to nonfunctional proteins as they cause translation to end prematurely |
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Term
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Definition
| An insertion or deletion type mutation where the number of nucleotides inserted or deleted is not a multiple of three; have serious effect on protein encoding |
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