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133 Cards in this Set
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What is genotype?
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An exact description of the genetic constitution of an individual, either with respect to a single trait or with respect to a larger set of traits.
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What is phenotype?
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The observable properties of an individual resulting from both genetic an environmental factors.
Can also be the final expression of a gene sequence. See: http://en.wikipedia.org/wiki/Phenotype |
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What are alleles?
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The alternate form of a genetic character found at a given locus on a chromosome.
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What is meant by "wild-type"?
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Geneticists' term for standard or reference type. Deviants from these standards, even if found in the wild, are referred to as mutant. Not usually applied to human genes.
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Define mutation
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A change in the genetic material not caused by recombination.
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Define mutagen.
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Any agent (e.g. chemicals or radiation) that increases the mutation rate.
pg. 292 |
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What is the "one-gene, one-enzyme" hypothesis?
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Proposed by Garrod that one specific gene coded for one specific enzyme.
Later confirmed by the bread mold (Neurospora) experiments by Beadle + Tatum. pg. 291-3 |
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What does "one-gene, one polypeptide" relationship mean?
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One gene codes, not for a whole enzyme, but rather just one polypeptide.
pg. 294 |
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What does the central dogma say?
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The direction of the flow of information is from DNA ⟹ RNA ⟹ Polypeptide
pg.294 |
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What is Transcription?
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The process by which the information in DNA sequences are copied into a complementary RNA sequence.
pg. 294, 296-7 |
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What is translation?
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The process in which mRNA sequences are used to create the amino acid sequence of a polypeptide.
pg. 294 |
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What is RNA?
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Ribonucleic Acid.
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What are the differences between RNA and DNA?
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RNA has ribose as sugar;DNA has dioxyribose. RNA has Uracil instead of Thymine. RNA is single stranded, DNA is double helix.
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What are nitrogenous bases?
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A nitrogen-containing molecule having the chemical properties of a base. It is an organic compound that owes its property as a base to the lone pair of electrons of a nitrogen atom. In biological sciences, nitrogenous bases are typically classified as the derivatives of two parent compounds, pyrimidine and purine
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List the nitrogenous bases used in both DNA and RNA.
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DNA - Adenine, Cytosine, Guanine, Thymine
RNA-Adenine, Cytosine, Guanine, Uracil |
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Name 3 types of RNA.
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Messenger RNA (mRNA)
Transfer RNA (tRNA) Ribosomal RNA (rRNA) pg. 294 |
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Explain the job of mRNA.
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It carries a copy of a gene sequence in DNA to the site of protein synthesis at the ribosome.
pg. 294 |
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Explain the job of tRNA.
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It carries amino acids to the ribosome for assembly into polypeptides.
pg.294 |
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Explain the job of rRNA
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It catalyzes peptide bond formation and provides a structural framework for the ribosome.
pg. 294 |
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What is a codon?
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3 nucleotides in messenger RNA that direct the placement of a particular amino acid into a polypeptide.
pg. 295 |
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What is an anticodon?
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3 nucleotides in transfer RNA that pair with a complementary triplet (a codon) in messenger RNA
pg.295 |
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What is a retrovirus?
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An RNA virus that contains reverse transcriptase. Its RNA serves as a template for cDNA production, and the cDNA is integrated into a chromosome of the host cell.
pg.296 |
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What does processive mean?
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Pertaining to an enzyme that catalyzes many reactions each time it binds to a substrate, as DNA polymerase does during DNA replication.
pg. 296 |
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What is a promoter?
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A DNA sequence to which RNA polymerase binds to initiate transcription.
pg.296 |
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What is a transcript?
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mRNA
(used to test for gene expression) pg. 295 |
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What is a RNA virus?
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Viruses that have RNA as their genetic material. Transcribe RNA to a complementary strand, which is then transcribed to multiple copies of the original.
pg.295-6 |
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What is reverse transcription?
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The production of DNA, using RNA as a template; essential to the reproduction of retroviruses. Uses the enzyme reverse transcriptase.
pg. 296 |
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What is a retrovirus?
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An RNA virus that contains reverse transcriptase. Its RNA serves as a template for cDNA production, and the cDNA is integrated into a chromosome of the host cell.
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What is RNA polymerase and what does it do?
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An enzyme that catalyzes the formation of RNA from a DNA template.
pg. G-25, 296 |
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What does processive mean?
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Pertaining to an enzyme that catalyzes many reactions each time it binds to a substrate, as DNA polymerase does during DNA replication.
pg. 296 |
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What is transcription initiation?
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The process that begins transcription. Begins with RNA polymerase binding tightly to a promoter, a special sequence of DNA that "tells" the RNA polymerase where to start and which strand to transcribe.
pg. 296 |
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What is a template strand?
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In double-stranded DNA, the strand that is being transcribed to create RNA transcript that will be processed into a protein. Also refers to a strand of RNA that is used to create a complementary RNA.
G-29 |
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What is a promoter?
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A DNA sequence to which RNA polymerase binds to initiate transcription.
pg. 296 |
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Polymerase Chain Reaction
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An enzymatic technique for the rapid production of millions of copies of a particular stretch of DNA where only a small amount of the parent molecule is available.
G-22 http://www.youtube.com/watch?v=JRAA4C2OPwg&feature=related |
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What is the initiation site?
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The site of the promoter, a special sequence of DNA to which the RNA polymerase binds very tightly. This "tells" where to start transcription and which strand of DNA to transcribe.
pg. 296 |
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What is transcription elongation?
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The adding of nucleotides to the 3' end of the forming (antiparallel) strand by RNA polymerase.
pg 297-8 |
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What direction is the DNA template read?
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3' to 5'
pg. 298 |
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What direction is mRNA synthesized?
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5' to 3'
pg. 298 |
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What is transcription termination?
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The end of transcription indicated by a particular base sequence. Complex depending on the gene.
pg. 298 |
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What is the genetic code?
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It relates genes (DNA) to mRNA and mRNA to the amino acids that make up proteins.
pg 298 |
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What are the nucleotide triplets?
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A codon
pg. 298-9 Better explanation: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Codons.html |
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What is a codon?
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3 nucleotides in messenger RNA that direct the placement of a particular amino acid into a polypeptide chain.
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What is the start codon?
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AUG
codes for methionine, the initiation signal for translation. pg. 299 |
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What is methionine?
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Methionine is one of only two amino acids encoded by a single codon (AUG) in the standard genetic code (tryptophan, encoded by UGG, is the other). The codon AUG is also the "Start" message for a ribosome that signals the initiation of protein translation from mRNA. As a consequence, methionine is incorporated into the N-terminal position of all proteins in eukaryotes and archaea during translation, although it is usually removed by post-translational modification.
wikipedia |
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What is a "stop" codon?
What are the stop codons? |
A termination signal for translation.
pg. 298 |
UAA , UGA , UAG
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What is meant by redundant?
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For almost all the amino acids there is more than one codon. Methionine is an exception.
pg 299 |
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What is meant by unambiguous?
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If a codon could specify for more than one amino acid, it would lead to confusion as to which was needed.
pg 299 |
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What is meant by nearly universal?
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The same genetic code is used by all species on the planet. Exceptions only exist 1)mitochondria/chloroplasts slight differences in prokaryotes and in the nucleus of eukaryotes, 2) 1 group of protists UAA + UAG code for glutamine rather than stop.
pg 299 |
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What is a terminator?
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A specific sequence of bases that specify the termination of transcription.
pg 298 |
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What is an intron?
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Non-coding base sequences in eukaryote genes. (Intervening regions)
pg. 300 |
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What is an exon?
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The coding sequences in eukaryotic genes (expressing regions)
pg 300 |
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What is pre-RNA?
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Primary RNA, before the introns are removed. RNA that will NOT be translated.
pg 300 |
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What is mature RNA?
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RNA that has had the introns removed. RNA that will be translated.
pg 300 |
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What is nucleic acid hybridization?
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A method by which introns are located in a eukaryotic gene that involves:
1. a target DNA is denatured by heat to break the H+ bonds between the base pairs and separate the two strands. 2. A single-strand nucleic acid from another source (probe) is incubated with the denatured DNA If a probe-target double helix forms, it is a hybred. pg 300 |
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What are the differences between Prokaryote and Eukaryote gene expression?
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1) In Eukaryotes, transcription is done in the nucleus and translation is done in the cytoplasm. In Prokaryotes, both are done in the cytoplasm.
2) In Eukaryote genes there are non-coding portions that interrupt continuous reading of the Amino acid sequences, in prokaryotes the reading is in same order as the Amino Acid sequence. 3) In eukaryotes, there is modification of the mRNA after translation, but before translation (splicing out the introns; 5' cap; 3' poly A added). In prokaryotes there is none. 4)Eukaryotes, each gene has its own promoter. Prokaryote genes sometimes share. 5) Eukaryotes RNA polymerase does not recognize the promoter sequence by itself; it does in prokaryotes. pg 300-1 |
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What are the exceptions to the central dogma?
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RNA viruses
pg295 |
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How do RNA viruses replicate their genetic material?
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They transcribe RNA to RNA. The complementary strand is then used to make multiple copies of the viral genome by transcription.
pg. 295 |
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What is a retrovirus and how does it replicate?
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Retroviruses are viruses that infect a host cell, and makes a DNA copy of its genome which becomes incorporated in the host's genome. The host cell makes RNA that the virus can either translate to produce viral proteins or can be incorporated as the viral genome into new viral particles.
pg 296 |
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What are the 3 steps of Transcription?
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Initiation, Elongation, Termination
pg. 296-8 |
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What is a probe?
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A single-strand nucleic acid that is used in nucleic acid hybridization.
pg 301 |
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What are domains?
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Functional regions of a protein encoded by separate exons.
pg. 301 |
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What is a 5' G cap?
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Consists of guanosine triphosphate. Added to the 5' end of a pre-mRNA to facilitate the binding of mRNA to the ribosome for translation and protection against being digested by ribonucleases that break down RNAs.
pg. 302 |
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What is a 3' poly A tail?
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100-300 adenine nucleotides added to a pre-mRNA that adds stability and may assist in its export to the cytoplasm.
pg 302 |
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What is meant by RNA splicing and what are the key components and the process?
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Removal of the introns and joining of the exons in a pre-mRNA.
snRNPs, spiceosomes, consensus sequeces, pre-mRNA 1) several small nuclear ribonucleoprotein particles (snRNPs) bind at the ends of the the pre-mRNA. 2) The RNA in the snRNPs are complementary to the "consensus" sequences located between the introns and exons (short stretches of DNA that don't vary much at boundaries in many genes). 3) ATP us used to form a large RNA-protein complex called a spliceosome. 4) The spliceosome cuts the pre-mRNA, releases the introns, and joins the ends of the exons together to produce mature mRNA. pg 303 |
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What are snRNPs?
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small nuclear ribonucleoproteins. Used in splicing introns/exons in pre-mRNA
pg 303 |
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What is a consensus sequence?
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Short stretches of DNA that appear with little variation in many genes. Located in boundaries between introns and exons.
pg 303 |
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What is a spliceosome?
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A RNA-protein complex used in splicing. Cuts the pre-mRNA, releases the introns, and joins the ends of the exons together to produce mature mRNA.
pg 303 |
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What is a charged tRNA?
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pg
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What is a ribosome? Small sub-unit? Large sub-unit?
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pg
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What are rRNA molecules and what do they do?
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pg
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Where is the A site and what happens there?
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amino acid site. One of 3 "slots" in the ribosome pg
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Where is the P site and what happens there?
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Polypeptide site
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Where is the E site and what happens there?
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Exit site
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What is translation initiation?
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pg
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What is an initiation complex?
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pg
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What are the initiation factors?
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pg
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What is translation elongation?
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pg
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What is translation termination?
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pg
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What are the translation elongation factors?
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pg
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What is peptidyl transferase and what does it do?
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pg
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What direction is mRNA translated?
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5' to 3'
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What are protein release factors?
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pg
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What are polyribosome (polyosome)?
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pg
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What is a signal sequence?
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pg
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What are docking proteins?
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pg
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What is a signal recognition particle?
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pg
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What is post-translational modification?
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pg
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What is proteolysis?
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pg
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What is glycoslyation?
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pg
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What are glycoproteins?
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pg
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What is phosphorylation?
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pg
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How does the sequence of bases in DNA lead to observable, physical characteristics?
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The sequence of bases in DNA determine the expression of polypeptides that are made in the body which are the building blocks for enzymes and tissue.
pg 292 |
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How did experiments utilizing bread mold lead to the one-gene, one-enzyme hypothesis?
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It was discovered by analyzing the pathway to convert nutrients to Arginine and discovering that mutations in a gene prevented certain steps in the conversion depending on what mutations were in the gene (s). pg. 293
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How has the one-gene, one-enzyme hypothesis been modified and why?
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It was modified to one gene, one-polypeptide. Many enzymes are composed of more than one polypeptide subunit.
pg 294 |
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How does RNA differ from DNA?
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1. Ribose instead of deoxyribose as the sugar.
2. Uracil instead of thymine as a base. 3. One strand instead of a double stranded helix. pg. 294 |
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What types of RNA participate in protein synthesis?
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mRNA - carries a copy of gene sequence in DNA to site of protein synthesis on ribosome.
tRNA - carries an amino acid to the ribosome for assembly into polypeptides. rRNA- catalyzes peptide bond formation and provides a structural framework for the ribosome. pg 294 |
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What are the necessary components required for transcription to begin?
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1. DNA template
2. Nucleoside triphosphates (ATP, GTP, CTP, and UTP) 3. An RNA polymerase Remember, RNA polymerase does NOT need a primer. pg 296 |
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What are the differences in location of translation and transcription in prokaryotes and eukaryotes?
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prokaryotes- both happen in cytoplasm.
eukaryotes - transcription in nucleus Translation in the cytoplams |
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What are the differences in gene structure in prokaryotes verses eukaryotes?
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Prokaryotes- DNA sequence is read in the same order and the amino acid sequence.
Eukaryotes- have introns within the coding sequence that need to be spliced out. |
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What modifications of mRNA after transcription but prior to translation need to occur?
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prokaryotes - none
eukaryotes - introns spliced out, 5' cap, 3' poly A tail added. |
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How does RNA differ from DNA?
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1. Ribose instead of deoxyribose as the sugar.
2. Uracil instead of thymine as a base. 3. One strand instead of a double stranded helix. pg. 294 |
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What types of RNA participate in protein synthesis?
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mRNA - carries a copy of gene sequence in DNA to site of protein synthesis on ribosome.
tRNA - carries an amino acid to the ribosome for assembly into polypeptides. rRNA- catalyzes peptide bond formation and provides a structural framework for the ribosome. pg 294 |
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What are the necessary components required for transcription to begin?
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1. DNA template
2. Nucleoside triphosphates (ATP, GTP, CTP, and UTP) 3. An RNA polymerase Remember, RNA polymerase does NOT need a primer. pg 296 |
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What is the sequence produced if the mRNA is GAU?
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?
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What is the sequence if the anticodon is CUG?
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?
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What is the sequence produced if the DNA complementary strand is CUU?
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?
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What is the sequence if the DNA template strand is GAA?
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?
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What are the differences in location of translation and transcription in prokaryotes and eukaryotes?
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prokaryotes- both happen in cytoplasm.
eukaryotes - transcription in nucleus Translation in the cytoplams |
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What are the differences in gene structure in prokaryotes verses eukaryotes?
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Prokaryotes- DNA sequence is read in the same order and the amino acid sequence.
Eukaryotes- have introns within the coding sequence that need to be spliced out. |
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What modifications of mRNA after transcription but prior to translation need to occur?
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prokaryotes - none
eukaryotes - introns spliced out, 5' cap, 3' poly A tail added. |
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How are RNA molecules produced?
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RNA is made by transcribing DNA sequences, cutting out the introns, splicing together the exons, adding a G-cap to the 5' end and a poly A tail to the 3' end.
pg 294 +296 |
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What hypotheses were proposed to explain the flow of information from DNA to RNA to protein?
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1) Messenger hypothesis and transcription - RNA forms as a complementary copy of 1 DNA strand in a gene (mRNA) and travels to the cytoplasm to serve as information sequences of codons. Each codon = 3 consecutive nucleotides.
2) Adapter Hypothesis and translation - There is an adapter molecule that can bind a specific Amino Acid sequence and recognize a specific sequence of nucleotide. pg 295 |
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Are there any exceptions to the central dogma?
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Yes RNA viruses and retroviruses
pg 295 |
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What determines the strand of DNA that will be transcribed?
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A promoter - a special sequence of DNA to which the RNA polymerase tightly binds. Wukaryotes usually have 1 promoter per gene. Prokaryotes can have 1 promoter form multiple genes.
Promoters tell the RNA polymerase where to start transcription and which strand to transcribe. pg 296 |
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What are the steps in the process of transcription?
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1. Initiation - A promoter orients a RNA polymerase as to which direction to read and what strand to transcribe.
2. Elongation - RNA begins at the 3' end and begins to add nucleotides to elongate the polypeptide. 3. Termination - a termination sequence is read and the polypeptide is freed. pg 297-298 |
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What experiments led to deciphering the genetic code?
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1. Nirenberg + Matthaei - test tube protein synthesis determing amino acids specified by synthetic mRNA of known codon compositions.
2. Discovery that simple artificial mRNAs only are 3 nucleotides long could bind to a ribosome, which could bind to corresponding tRNA with specific amino acids. pg 298 |
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What is the genetic code and how does it work?
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The genetic code is the set of instructions in the form of nucleotide triplets, that translate a linear sequence of nucleotides in mRNA into a linear sequence of amino acids in a protein.
Letters on left of chart corresponds to the 1st letter of the codon. Letters on top correspond to 2nd letter in the codon, Letters down right side correspond to 3rd letter of codon. pg 299 |
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What is the connection between non-hybridized loops of DNA and eukaryotes?
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They indicate intron sequences in eukaryote DNA.
pg 302 |
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What are the functions of a tRNA?
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Transfer RNA links the information in mRNA codons with specific amino acids in proteins.
pg 304 |
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What 2 key events must happen to ensure that the protein made in translation is the one specified by the mRNA?
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1 the tRNA must read the mRNA codons correctly.
2. the tRNAs must deliver the amino acids that correspond to each mRNA codon pg 304 |
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How are RNA molecules produced?
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RNA is made by transcribing DNA sequences, cutting out the introns, splicing together the exons, adding a G-cap to the 5' end and a poly A tail to the 3' end.
pg 294 +296 |
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What hypotheses were proposed to explain the flow of information from DNA to RNA to protein?
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1) Messenger hypothesis and transcription - RNA forms as a complementary copy of 1 DNA strand in a gene (mRNA) and travels to the cytoplasm to serve as information sequences of codons. Each codon = 3 consecutive nucleotides.
2) Adapter Hypothesis and translation - There is an adapter molecule that can bind a specific Amino Acid sequence and recognize a specific sequence of nucleotide. pg 295 |
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Are there any exceptions to the central dogma?
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Yes RNA viruses and retroviruses
pg 295 |
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What determines the strand of DNA that will be transcribed?
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A promoter - a special sequence of DNA to which the RNA polymerase tightly binds. Wukaryotes usually have 1 promoter per gene. Prokaryotes can have 1 promoter form multiple genes.
Promoters tell the RNA polymerase where to start transcription and which strand to transcribe. pg 296 |
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What are the steps in the process of transcription?
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1. Initiation - A promoter orients a RNA polymerase as to which direction to read and what strand to transcribe.
2. Elongation - RNA begins at the 3' end and begins to add nucleotides to elongate the polypeptide. 3. Termination - a termination sequence is read and the polypeptide is freed. pg 297-298 |
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What experiments led to deciphering the genetic code?
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1. Nirenberg + Matthaei - test tube protein synthesis determing amino acids specified by synthetic mRNA of known codon compositions.
2. Discovery that simple artificial mRNAs only are 3 nucleotides long could bind to a ribosome, which could bind to corresponding tRNA with specific amino acids. pg 298 |
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What is the genetic code and how does it work?
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The genetic code is the set of instructions in the form of nucleotide triplets, that translate a linear sequence of nucleotides in mRNA into a linear sequence of amino acids in a protein.
Letters on left of chart corresponds to the 1st letter of the codon. Letters on top correspond to 2nd letter in the codon, Letters down right side correspond to 3rd letter of codon. pg 299 |
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What is the connection between non-hybridized loops of DNA and eukaryotes?
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They indicate intron sequences in eukaryote DNA.
pg 302 |
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What are the functions of a tRNA?
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Transfer RNA links the information in mRNA codons with specific amino acids in proteins.
1. It binds to a particular amino acid 2. It associates with mRNA 3. It interacts with ribosomes pg 304 |
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What 2 key events must happen to ensure that the protein made in translation is the one specified by the mRNA?
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1 the tRNA must read the mRNA codons correctly.
2. the tRNAs must deliver the amino acids that correspond to each mRNA codon pg 304 |
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What structural attributes in tRNA facilitate its functions?
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3D confirmation of tRNA suited for interaction with the binding site on ribosomes
The 3' end is the amino acid attachment site It contains an anticodon - a site of complementary base pairing with the codon in mRNA that corresponds to the amino acid it is carrying. pg 305 |
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What is wobble?
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A phenomenon that allows the codons for some amino acids to be recognized by the same tRNA. ex. Alanine codons, GCA, GCC, and GCU can all be recognized by one tRNA.
pg. 305 |
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How does a tRNA get "charged"?
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1. Aminoacyl-tRNA synthase, an enzyme, activates the amino acid, catalyzing a reaction with ATP to form high energy AMP-amino acid and a pyrophosphate ion.
2. the enzyme then catalyzes a reaction of the activation amino acid with the correct tRNA. 3. The specificity of the enzyme ensures that the correct amino acid and tRNA are paired. 4. The charged tRNA is released and able to join with an elongating polypeptide product. pg 305 |
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