Transcription and Translation: From DNA to Protein, Quizzes of Biology

Download Transcription and Translation: From DNA to Protein and more Quizzes Biology in PDF only on Docsity! TERM 1 Central Dogma of Molecular DEFINITION 1 DNA --> RNA --> Protein transcription translation TERM 2 Transcription DEFINITION 2 Synthesis of RNA under the direction of DNA For a protein- coding gene, this RNA is referred to as a messenger RNA (mRNA) because it carries a genetic message from the DNA to the protein synthesizing machinery of the cell. > occurs in nucleus TERM 3 Translation DEFINITION 3 Synthesis of a polypeptide by a ribosome under the direction of a mRNA > occurs in the cytoplasm TERM 4 RNA polymerase DEFINITION 4 >separates or melts the DNA strands >links the RNA nucleotides as they base-pair along the DNA template. >adds nucleotides only to the 3 end of the growing polymer >gene (template strand) is read 3->5, creating a 5->3 RNA molecule >in eukaryotes ,three RNA polymerases (I, II, and III) > in eukaryotes RNA Pol II is used for mRNA synthesis. TERM 5 Promoter DEFINITION 5 >RNA polymerase binds and initiates transcription >upstream of the information contained in the gene, the transcription unit TERM 6 Terminator DEFINITION 6 -signals the end of transcription TERM 7 three stages of transcription DEFINITION 7 - initiation - elongation - termination TERM 8 Transcription Initiation DEFINITION 8 > After RNA polymerase binds to the promoter, the DNA strands unwind, and the polymerase initiates RNA synthesis at the start point on the template strand TERM 9 tata box DEFINITION 9 transcription factors recognize this, where the promoter binds TERM 10 transcription elongation DEFINITION 10 > During elongation, the polymerase moves downstream, unwinding DNA and elongating the RNA transcript 5-to-3. >Polymerase unwinds helix Adds nucleotides that are complementary to bases in template strand >Helix rewinds after RNA polymerase passes > Many polymerase molecules can transcribe a single gene at the same time. TERM 21 codons DEFINITION 21 mRNA is read in group of 3 nucleotides TERM 22 start codon DEFINITION 22 AUG (methionine) TERM 23 Stop Codons DEFINITION 23 UAA, UAG, or UGA TERM 24 open reading frame DEFINITION 24 string of codons TERM 25 characteristics of the Genetic Code DEFINITION 25 >Universal -Essentially all organisms use the same genetic code dictionary >Degenerate -As many as six codons may specify the same amino acid - See Ser, Leu, Arg >Unambigous -A codon specifies only one amino acid TERM 26 Transfer RNA (tRNA) DEFINITION 26 - transfers amino acids from the cytoplasms pool to a ribosome. - Each tRNA carries a specific amino acid at one end - Other end has a specific nucleotide triplet - anticodon that basepairs with codons in mRNA TERM 27 anticodon DEFINITION 27 - a nucleotide triplet that basepairs with codons in mRNA TERM 28 Wobble Hypothesis DEFINITION 28 -Affects basepairing of the 3rd base of codon, only -1st and 2nd base of codon follow Watson-Crick base pairing A=U, G=C TERM 29 The anatomy of a Ribosome DEFINITION 29 >Each ribosome has a binding site for mRNA and three binding sites for tRNA molecules > Both subunits (large and small) are composed of proteins and ribosomal RNAs (rRNAs) TERM 30 the P site DEFINITION 30 The P site holds the tRNA carrying the growing polypeptide chain TERM 31 The A site DEFINITION 31 carries the tRNA with the next amino acid TERM 32 initiation of translation DEFINITION 32 - Start codon is AUG specifying the amino acid Methionine or Met (M) TERM 33 The E site DEFINITION 33 Discharged tRNAs leave the ribosome at the E site. TERM 34 translation elongation DEFINITION 34 >Translocation -Ribosome moves the tRNA with the attached polypeptide from the A site to the P site (3 nucleotides or one codon) -Requires hydrolysis of GTP -tRNA still base-paired to mRNA, so mRNA also moves -tRNA in P site moves to the E site and then leaves the ribosome TERM 35 termination of translation DEFINITION 35 1. Termination occurs when a Stop codon reaches A site and a release factor binds to the stop codon (UAG, UAA, or UGA). 2. The release factor hydrolyzes the bond between the polypeptide and the tRNA in the P site. 3. The translation complex machinery (release factor, mRNA, and the large and small ribosomal subunits) disassembles. TERM 46 Insertions/Deletions DEFINITION 46 -Additions or losses of one or more nucleotide pairs -May causes a frameshift in the open reading frame (ORF) - Nucleotides read in new combinations of triplets - new codons TERM 47 silent mutation DEFINITION 47 point mutation that has no effect on protein sequence (generally in 3rd base of codon) TERM 48 missense mutation DEFINITION 48 point mutation that changes the amino acid UGU (Cys) --> UGG (Trp) TERM 49 nonsense mutation DEFINITION 49 amino acid codon altered to a stop codon UGU (Cys) --> UGA (Stop) TERM 50 mutagens DEFINITION 50 In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level. TERM 51 frameshift mutation DEFINITION 51 A frameshift mutation (also called a framing error or a reading frame shift) is a genetic mutation caused by indels (insertions or deletions) of a number of nucleotides that is not evenly divisible by three from a DNA sequence. TERM 52 (snRNPs) DEFINITION 52 small nuclear ribonucleoproteins TERM 53 signal recognition particle DEFINITION 53 SRP binds to the signal peptide directing ribosomes to the ER TERM 54 aminoacyl-tRNA synthetase DEFINITION 54 joining of specific amino acid to a tRNA TERM 55 signals for protein secretion DEFINITION 55 Signal peptide at start of coding region of a polypeptide targets the ribosome and the mRNA to the rER.