Test
DNA In Protein Synthesis -The Genetic Code
Preguntas del test (32)
1In stage one of the process by which the information of the gene is used to determine how the protein molecule is constructed, a copy of the code is made by building a molecule of mRNA which is catalysed by RNA polymerase, involving complementary base paring with the antisense strand as a template. The mRNA strand then leaves the nucleus through pores in the nuclear membrane and passes to the ribosomes in the cytoplasm to be 'read'.
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2The second stage of protein synthesis occurs in the ribosomes in the cytoplasm, and AAs are activated for protein synthesis by combining with short lengths of tRNA, with a different tRNA for each of the 20 AAs. One end of each tRNA molecule is a site where a particular AA can attach and at the other end there is an anticodon.
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3Anticodons are made up of a sequence of 3 bases which are complementary to the the codon of mRNA that codes for the specific AA.
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4Translation is stage 3 and occurs in the ribosomes in the cytoplasm, where a protein is assembled one AA residue at a time as a ribosome moves along the mRNA reading the codons.
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5Complementary anticodons of the AA-tRNA slot into place and are temporarily held in position by hydrogen bonds. While there the AAs of neighbour AA-tRNAs are joined by peptide linkages.
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6Genes function (are expressed) only in cells they relate to, when they are needed.
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7In eukaryotes, genes are only transcribed if an RNA polymerase enzyme binds to a region of DNA situated close to the gene known as a ___ .
- Apromoter
- Bexpressor
- Ctranscriber
8What are the special features of promoters in eukaryotic chromosomes?
- Asome permit repeated, unrestricted binding of RNA polymerase, resulting in continuous expression of a gene
- Bsome require a regulatory protein to be present and bound, prior to binding of RNA polymerase & gene expression
- Csome regulatory proteins must first be activated by reaction with a steroid hormone or some other metabolite, before binding of RNA polymerase & gene expression
- Dsome do not permit binding of RNA polymerase, resulting in no expression of specific genes.
9The steps of the expression of a gene begin when the genetic informaiton in DNA is transcribed into a molecule of mRNA by complementary base paring. The RNA polymerase binds to a promoter region (the 'start' signal for transcription) located immediately before the gene.
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10Highlight the characteristics that apply to the sense strand and leave the once that apply to the antisense strand blank.
- ACarriers the promoter sequence of bases to which RNA polymerase binds and begins transcription.
- BHas the same base sequence as the mRNA.
- CCarries the terminator sequence of bases at the termination of each gene that causes RNA polymerase to stop transcription.
- DIs the template sequence for transcription by complementary base paring by RNA polymerase.
- EHas the same base sequence as the tRNA.
- FIs read in the '5 -> 3' direction and mRNA synthesis occurs in the opposite direction.
11RNA polymerase draws on a pool of free nucleotides.
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12As the RNA trand is formed, it falls away from the antisense strand and hydrogen bonds re-form between the two DNA strands. The process continues until a base sequence known as the inhibitor is reached, causing both RNA polymerase and the completed mRNA strand to be freed from the site of the gene.
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13The sections of DNA that carry meaningful information are called introns and the intervening lengths f DNA are called exons.
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14When a split gene is transcribed into mRNA, the sequence of introns continues to exist exactly as it occurred in the DNA, and so an enzyme catalysed reaction known as ___ removes the introns to shorten the length of mRNA which is now described as mature before it moves out into the cytoplasm.
- Apost-transcriptional modification
- Bpre-transcriptional modification
- Cpost-prescribed modification
15The AA activation process by ehich AA are combined with tRNA occurs in the cytoplasm and requires ATP.
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16It is this tRNA, once attached to its AA, which facilitates the translation of the three-base sequences of each codon of mRNA into a sequence of AAs in a protein.
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17The codon located on one end of the tRNA is complementary to the codon of mRNA that codes for that specific AA.
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18An AA is attached to its tRNA by enzyme action specific to that AA, which allows recognition by a specific tRNA activating enzyme which attaches a specific AA to the tRNA and ensure they'r ein the right sequence.
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19Translation occurs in the ribosomes which are organelles made up of a large and small subunit which are both composed of ___ and protein. During translation, the mRNAs bind with the ___ subunit where also occur the three sites where the tRNA's interact.
- ArRNA | small
- BmRNA | big
- CtRNA | small
20At the 1st site, codons of the incoming tRNA bind to specific tRNA AAs through their anticodons by complementary base paring.
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21At the 2nd site, the tRNA leaves the ribosome following transfer of its AA to the growing protein chain.
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22At the 3rd site, the AA attached to its tRNA is condensed with the growing polypeptide chain by formation of a peptide linkage.
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23The structure of mRNA, ribosomes and their growing protein chain, is called a polyphosphome.
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24Other ribosomes that synthesis proteins to be excreted from the cell or packages in lysosomes are located where?
- Abound to the membranes of the rER.
- Bbound to the membranes of the sER.
25post-transcriptional modifications refer to processing steps that some proteins (inactive precursors) needs to go through in order to be activated.
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26post-transcriptional modifications refer to processing steps that some proteins (inactive precursors) needs to go through in order to be activated.
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27The central dogma of molecular biology refers to the one-way flow of coded information from the nucleus to the cytoplasm.
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28An exception to the central dogma of molecular biology is the enzyme secreted by the HIV nucleic acid -reverse transcriptase, which catalyses the copying of the RNA strand to form a DNA double helix which enters the host nucleus and becomes attached to a hsot chromosome.
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29Reverse-transcriptase can be extracted from retroviruses and used in genetic modification for the synthesis of a DNA strand, complementary to an existing RNA strand.
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30DNA ligase occurs with nucleic acid in the nucleus of all organisms and is used for..
- Ajoining together DNA molecules during replication of DNA.
- Bbreaking DNA into shorter lengths.
31Polymerase occurs in the same place as ligase and is used for..
- Asynthesising nucleic acid strands, guided by an antisense strand of nucleic acid.
- Bsynthesising DNA strands complementary to an existing RNA strand.
32Restriction enzymes found in the cytoplasm of bacteria can be used for breaking DNA molecules into shorter lengths at specific nucleotide sequences.
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Información
- Descripción
- IBD (Unit 8 : Nucleic Acids & Proteins) Biology Test sobre DNA In Protein Synthesis -The Genetic Code, creado por cloud.berry el 07/05/2014.
- Autor
- cloud.berry
- Idioma
- English
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