Term
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Definition
| a sequence of DNA that codes fora specific polypeptide or RNA molecule |
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Term
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Definition
| the process by which gene products are synthesized by a cell |
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Term
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Definition
| specific sequences of nucleotide bases in mRNA, arranged in codons that correspond to each of the 20 different amino acids |
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Term
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Definition
| one of the two strands of DNA that provides the instructions for building a polypeptide chain; also called the anti-sense strand or non coding strand. always the same strand for a given gene |
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Term
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Definition
| the sequence of DNA analogous to the mRNA produced from the template strand; also called the sense strand |
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Term
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Definition
| a sequence of three nucleotides in mRNA that codes for a particular amino acid |
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Term
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Definition
| the property of the genetic code that allows for a single amino acid to be coded for by multiple codons; the code is unambiguous such that any particular codon will never code for different amino acids |
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Term
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Definition
| a sequence of nucleotides in tRNA complementary to a codon in mRNA |
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Term
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Definition
| an enzyme that catalyzes the synthesis of RNA using DNA as a template |
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Term
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Definition
| a nucleotide sequence found in the template strand of DNA that includes the site where transcription by RNA polymerase will begin |
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Term
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Definition
| a sequence of nucleotides found in the promoter region of eukaryotic genes that is recognized by transcription factors |
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Term
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Definition
| a sequence of nucleotides in DNA that signals the end of transcription |
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Term
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Definition
| in eukaryotic organisms, proteins that facilitate the binding of RNA polymerase to the promoter sequence |
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Term
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Definition
| the first step of gene expression during which a complementary mRNA molecule is produced from the DNA template strand |
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Term
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Definition
| the correct grouping of codons in mRNA that produces the intended polypeptide sequence; determined by the start codon and can be shifted by the addition or deletion of nucleotides in DNA |
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Term
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Definition
| in eukaryotic organisms, the product of transcription before any RNA processing has occurred; also called the primary transcript |
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Term
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Definition
| a type of RNA that carries genetic information from the nucleus to the cytosol |
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Term
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Definition
| in eurkaryotic organisms pre-RNA is modified before it leaves the nucleus: introns are removed, exons are spliced together, and a 5' cap and poly-A-tail are added |
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Term
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Definition
| a chemically-modified guanosine triphosphate that is added to the 5' end of pre-mRNA to facilitat binding by ribosomes and to provide protection from enzymes that break down RNA |
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Term
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Definition
| a sequence of 100 to 300 adenine nucleotides added to the 3' end of pre-mRNA to assist in the export of mRNA from the nucleus |
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Term
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Definition
| introns are removed from pre-mRNA and exons are joined together during this process, creating a continuous coding sequence |
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Term
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Definition
| a RNA-protein complex consisting of proteins and snRNPs that cuts out introns and joins together exons during pre-mRNA processing |
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Term
| small nuclear ribonucleoprotein particles (snRNP) |
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Definition
| RNA-protein molecules that bind to other proteins to form a splicosome |
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Term
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Definition
| nucleotide sequences in eukaryotic genes that code for amino acids |
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Term
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Definition
| non-coding nucleotide sequences in eukaryotic genes that are removed during RNA processing |
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Term
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Definition
| variation in the splicing of exons for ag iven mRNA that produces two or more different polypeptide sequences from the same gene |
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Term
| aminoacyl t-RNA synthetases |
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Definition
| enzymes that catalyze the addition of an amino acid to a corresponding tRNA molecule |
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Term
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Definition
| the second step of gene expression during which a polypeptide chain is produced from an mRNA molecule |
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Term
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Definition
| cellular structures that bind to mRNA and provide the location for the assembly of the corresponding polypeptide chain by facilitating the specific coupling of tRNA anticodons with mRNA codons |
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Term
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Definition
| a type of RNA that carries genetic information from the nucleus to the cytosol |
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Term
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Definition
| a type of RNA found in ribosomes that catalyzes teh formation of peptide bonds between amino acids during the process of translation |
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Term
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Definition
| a type of RNA that carries amino acids to the ribosome during the process of translation. many different structures and functions, each carry a specific amino acid on one end and an anticodon on the other end which base-pairs with mRNA |
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Term
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Definition
| several ribosomes simultaneously translating the same mRNA |
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Term
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Definition
| a sequence of nucleotides in mRNA (AUG) that provides the code for the first amino acid (methionine)during translation |
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Term
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Definition
| a swquence of nucleotides in mRNA (UAA, UAG, or UGA), which signals the termination of translation |
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Term
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Definition
| a sequence of DNA that codes fora specific polypeptide or RNA molecule |
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Term
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Definition
| the process by which gene products are synthesized by a cell |
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Term
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Definition
| specific sequences of nucleotide bases in mRNA, arranged in codons that correspond to each of the 20 different amino acids |
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Term
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Definition
| one of the two strands of DNA that provides the instructions for building a polypeptide chain; also called the anti-sense strand or non coding strand |
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Term
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Definition
| the sequence of DNA analogous to the mRNA produced from the template strand; also called the sense strand |
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Term
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Definition
| a sequence of three nucleotides in mRNA that codes for a particular amino acid |
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Term
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Definition
| the property of the genetic code that allows for a single amino acid to be coded for by multiple codons; the code is unambiguous such that any particular codon will never code for different amino acids |
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Term
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Definition
| a sequence of nucleotides in tRNA complementary to a codon in mRNA |
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Term
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Definition
| an enzyme that catalyzes the synthesis of RNA using DNA as a template |
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Term
|
Definition
| a nucleotide sequence found in the template strand of DNA that includes the site where transcription by RNA polymerase will begin |
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Term
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Definition
| a sequence of nucleotides found in the promoter region of eukaryotic genes that is recognized by transcription factors |
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Term
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Definition
| a sequence of nucleotides in DNA that signals the end of transcription |
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Term
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Definition
| in eukaryotic organisms, proteins that facilitate the binding of RNA polymerase to the promoter sequence |
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Term
| What was Garrod's suggested concerning the synthesis of genes? |
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Definition
| Garrod suggested that genes dictate phenotypes through enzymes and that inherited disease reflected an inability to synthesize a certain enzyme. This suggestion implied that cells synthesize and degrade molecules in a series of steps, a metabolic pathway. |
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Term
| What did Beadle and Tatum do and what was the conclusion? |
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Definition
| They created mold mutants and then identified three classes of mutants based on differences in their inability to synthesize arginine due to a lack of an enzyme. This lead them to develop a one gene-one enzyme hypothesis, which states that each gene dictates production of a specific enzyme |
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Term
| one gene-one enzyme hypothesis |
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Definition
| developed by Beadle and Tatum, states that each gene dictates the production of a specific enzyme |
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Term
| what is the central dogma? |
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Definition
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Term
| what are some differences between prokaryotic and eukaryotic transcription and translation |
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Definition
1. Euks create pre-mRNA from transcription, Proks create mRNA
2. Euks perform RNA processing to change pre-mRNA to mRNA
3. Euks have to export mRNA from the nucleus to the cytoplasm for translation, in Proks everything takes place in the cytoplasm |
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Term
| what happens during transcription and translation (basic) |
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Definition
| the triplet codes of genes are transcribed into complementary nonoverlapping mRNA triplet codes, which are then translated into an amino acid chain, forming a polypeptide |
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Term
| what direction are the mRNA base triplets READ in during TRANSLATION |
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Definition
| during translation, the mRNA codons are read in the 5' to 3' direction |
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Term
| what is meant by "the genetic code is redundant, but not ambiguous |
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Definition
| more than one codon may spedify a particular amino acid, but no codon specifies more than one amino acid |
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Term
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Definition
| promoters signal the transcriptional start point and usually extend several dozen nucleotide pairs upstream of the start point |
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Term
| transcription initiation complex |
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Definition
| the complete assembly of transcription factors and RNA polymerase II bound to a promoter |
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Term
| what occurs during initiation? |
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Definition
| during initiation, promoters signal a start point which transcription factors then mediate the binding of RNA polmerase, creating the transcription initiation complex. |
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Term
| what occurs doing elongation |
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Definition
| the RNA polymerase II splits the DNA helix and uses the DNA template strand to synthesize a RNA transcript in the 5'-->3' direction. a gene can be transcribed simultaneously by several RNA polymerases |
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Term
| what occurs during termination for proks? |
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Definition
| in proks, transcription is stopped at the end of the terminator sequence because the sequence signals for RNA polymerase to dissociate and stop synthesizing |
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Term
| what occurs during termination for euks? |
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Definition
| in euks, polymerase II transcribes a polyadenylation signal. once this sequence is exposed, other proteins associate with it causing the RNA transcript to released 10-35 nucleotides later. |
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Term
| what happens during RNA processing? |
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Definition
| occurs in euks to transform pre-mRNA to mRNA. during RNA processing, 5' caps are added to the 5' end, a poly A tail is added to the 3' end, and splicing occurs. |
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Term
| why does RNA processing occur? |
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Definition
1. protect against degeneration
2. facilitate export from the nucleus
3. association with ribosomes |
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Term
| what occurs during splicing? |
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Definition
| cuts introns out by binding snRNPs to the pre-mRNA strand to the consensus sequence with complemntary base pair sequences. the snRNPs then come together and form a splicosome, looping the intron out. then they cut the pre-mRNA at a exon-intron boundry, exposing OH which is used to remove the Intron at the other end and attach to the other exon. |
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Term
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Definition
| a change in the nucleotide sequence of a segment of DNA that codes for a gene product |
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Term
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Definition
| a physical or chemical agent such as X rays, ultraviolet radiation, and carcinocgetns (e.g. benzene), that causes mutations in DNA |
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Term
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Definition
| the replacing of one base pair with another in DNA |
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Term
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Definition
a mutation in DNA caused by chemical changes in just one base pair that results in the replacement of one amino acid by another.
ex- sickle cell |
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Term
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Definition
| a mutation in DNA that results in the early termination of translation, almost always leads to a nonfunctional protein |
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Term
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Definition
| a mutation in DNA that results in the replacement of one amino acid by another |
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Term
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Definition
| a mutation that alters the reading frame of the mRNA molecule |
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Term
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Definition
| a mutation in DNA that does not alter the amino acid sequence of the polypeptide chain |
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Term
| what accounts for tRNA's shape? |
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Definition
| tRNA's clover-leaf shape is created by hydrogen bonds |
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Term
| what two steps are required for acurate translation? |
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Definition
1. a correct match between a tRNA and an amino acid, done by the enzyme aminoacyl-tRNA synthetase
2. a correct match between tRNA anticodon and an mRNA codon |
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Term
| aminoacyl-tRNA synthestase |
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Definition
| an enzyme that assists in the matching of tRNA and an amino acid |
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Term
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Definition
| flexible pairing at the third base of a codon. allows some tRNAs to bind to more than one codon |
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Term
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Definition
| tRNA is charged when it is attached to an amino acid, |
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Term
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Definition
| aminoacyt-tRNA binding site, holds the tRNA that carries the next amino acid to be added to the chain |
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Term
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Definition
| peptidyl-tRNA binding site, holds the tRNA that carries the growing polypeptide chain |
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Term
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Definition
| exit site, where discharged tRNAs leave the ribosome |
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Term
| describe the initiation of translation |
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Definition
| assembly of translation initiation by a small ribosomal unit binding with mRNA and an initaitor tRNA and moves down the mRNA until it hits the AUG start codon, finally initiation factors bring in the large subunit to complete the complex. requires GTP hydrolysis |
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Term
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Definition
| binds with AUG codon, carries the MET amion acid |
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Term
| describe the elongation stage of translation |
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Definition
1. tRNA moves to the A site and binds through GTP hydrolysis
2. tRNA in P site gives growing chain to A site w/ a peptide bond
3. ribosome moves down mRNA using translocation fuled by GTP hydrolysis, pushing A-->P, P-->E, E--> expulsion of ribosome
4. A site is now ready for another tRNA
5. continues until a stop codon is reached |
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Term
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Definition
trigger the stopage of translation
UAG, UAA, UGA |
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Term
| what direction does translation proceed in? |
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Definition
| translation proceeds along mRNA in a 5' to 3' direction |
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Term
| describe the termination of translation |
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Definition
1. triggered when a stop codon reaches the A site
2. water is added to the polypeptide instead of an amino acid
3. polypeptide is released, translation complex breaks down with the hydrolysis of 2 GTP |
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Term
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Definition
| a number of ribosomes can translate a signel mRNA simultaneously, forming a polysome/polyribosome. they enable a cell to make many copies of a polypeptide very quickly |
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Term
| how does rough ER become rough? |
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Definition
1. signal recognition particle binds to a signal sequence on the growing pep. chain
2. translation temporarily stops elongation
3. SRP binds to a translocation complex in the ER membrane
4. signal sequence is cleved
5. elongation resumes until termination and peptide is then fed through the membrane
6. proteins may then be further modfied |
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Term
| what happens to polypeptides after translation? |
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Definition
| they fold into three demensional shapes |
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Term
| how are polypeptides further modified |
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Definition
| proteins are further modified through activation by enzymes that cleave them, add on to them. others come together to become the subunits of a protein |
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Term
| whats the difference between free and bound ribosomes? |
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Definition
| free ribs make proteins that function in the cytosol while bound ribs make proteins for the endomembrane system and proteins that are secreted from the cell |
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Term
| golgi prottein modification |
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Definition
1. proteins go to the golgi apparatus
2. glycosylation adds sugar and modifies protin to prepare it for the golgi apparatus
3. once in the trans golgi cistenae, signal is completed and binds to recptor protein
4. receptor binds to wall and transports protein to transport vesicle
5. proteins released and signal sequence is cleaved |
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Term
| types of small scale mutations |
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Definition
point mutations with in a gene can either be:
1. nucleotide-pair substitutions
2. one or more nucleotide-pair insertions or deletions |
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Term
| nucleotide-pair substitutions |
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Definition
| replaces one nucleotide and it's partner with another pair of nucleotides |
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Term
| effects of insertions and deleations |
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Definition
| additions or losses of nucleotide pairs in a gene and are much more disastrous to the resulting protein than substitution mutations because they're likely to cause frameshifts |
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