Biology Chapter 17: From Gene to Protein

1. Amino acid removal from the end of the polypeptide chain 2. Chain enzymatically cleaved into pieces 3. Cut out central & reattach other parts (insulin) 4. Attach two or more separate polypeptides (hemoglobin) 5. Add sugars, phosphates, lipids, etc.

Changes to the genetic information of a cell or virus.

Chemical changes in a single base pair of a gene.

<p>Insertions or deletions of base pairs that cause the whole later sequence to be off, shifted by one or more.</p> Signup and view all the answers

<ol> <li>Polypeptide synthesis begins on a free ribosome in the cytosol. 2. SRP binds to signal peptide, halting synthesis. 3. SRP binds to a receptor protein in the ER membrane. 4. SRP leaves and synthesis resumes, translocating across the ER membrane. 5. Signal-cleaving enzyme cuts off the signal peptide. 6. The completed polypeptide leaves the ribosome and is processed in the ER.</li> </ol> Signup and view all the answers

<p>Always in the cytosol unless it has a signal peptide.</p> Signup and view all the answers

<p>Nonsense mutations cause translation to be terminated too early, resulting in non-functional proteins, while missense mutations lead to the incorporation of the wrong amino acid.</p> Signup and view all the answers

<p>Insertion and deletion.</p> Signup and view all the answers

<p>If CCG mutated to CCA, the corresponding anticodon would change but still attach the same amino acid, leaving the organism unaffected.</p> Signup and view all the answers

<p>Physical and chemical agents that interact with DNA.</p> Signup and view all the answers

<ol> <li>Initiation &amp; termination of translation is different. 2. Bacteria have no compartmental organization, enabling simultaneous transcription and translation.</li> </ol> Signup and view all the answers

<p>A gene is a region of DNA that can be expressed to produce a final functional product that is either an RNA or a polypeptide.</p> Signup and view all the answers

<ol> <li>RNA is transcribed from DNA. 2. Pre-mRNA is spliced to produce mRNA. 3. mRNA leaves the nucleus and attaches to a ribosome. 4. Each amino acid attaches to its tRNA with enzyme attachment. 5. tRNAs add their amino acids to the chain as the mRNA moves through the ribosome. 6. Polypeptide is released for modification or as a finished product.</li> </ol> Signup and view all the answers

<p>The process by which DNA directs the synthesis of proteins (or sometimes just RNAs).</p> Signup and view all the answers

<p>That some people are unable to make a particular enzyme to metabolize certain things.</p> Signup and view all the answers

<p>Alkaptonuria: most people have an enzyme to metabolize alkapton, but people who have inherited an inability to do so have black urine because of the presence of alkapton.</p> Signup and view all the answers

<p>Each of the various mutations affecting eye color blocks pigment synthesis at a specific step, by preventing the production of the enzyme that catalyzes that step.</p> Signup and view all the answers

<p>They experimented on Neurospora, which only need a minimal food supply. After mutating some of them with X-rays, some couldn't survive on minimal since their enzymes couldn't synthesize needed molecules from that food.</p> Signup and view all the answers

<p>If several identical mutants were put in different solutions, and one of these was Arginine and that was the only one that survived, the mutant must have been defective in making arginine since that's the one that survived.</p> Signup and view all the answers

<ol> <li>The function of a gene is to dictate the production of a specific enzyme. 2. Not all proteins are enzymes.</li> </ol> Signup and view all the answers

<p>One gene -&gt; one polypeptide. Many eukaryotic genes can code for a set of related proteins though, called alternative splicing. And many genes code for RNAs that don't become proteins.</p> Signup and view all the answers

<ol> <li>It contains ribose instead of deoxyribose. 2. It has uracil instead of thymine. 3. It's usually single-stranded instead of double-stranded.</li> </ol> Signup and view all the answers

<p>DNA + RNA = the 4 types of nucleotides (U or T). Proteins = amino acids.</p> Signup and view all the answers

<p>DNA is used as a template to make a complementary sequence of mRNA.</p> Signup and view all the answers

<p>Synthesis of a polypeptide under the direction of mRNA. Translates codons to amino acids at ribosomes.</p> Signup and view all the answers

<p>In the cytoplasm.</p> Signup and view all the answers

<p>The primary transcript. It's only called this in the nucleus, before modification.</p> Signup and view all the answers

<p>DNA -&gt; RNA -&gt; Protein.</p> Signup and view all the answers

<p>4, 20.</p> Signup and view all the answers

<p>4, in triplet arrangements (4^3 = 64 unique triplets).</p> Signup and view all the answers

<p>4^3 = 64. 300 codons in an mRNA -&gt; 100 polypeptides in the amino acid.</p> Signup and view all the answers

<p>The template strand, since it gives the pattern/template for the sequence of nucleotides in an RNA transcript.</p> Signup and view all the answers

<p>The mRNA base triplets.</p> Signup and view all the answers

<p>He synthesized an artificial mRNA by linking identical RNA nucleotides containing uracil at their base: one codon in repetition: UUU.</p> Signup and view all the answers

<p>UUU -&gt; Phe.</p> Signup and view all the answers

<ol start="61"> <li>UAA, UAG, and UGA are stop signals.</li> </ol> Signup and view all the answers

<p>AUG -&gt; Met.</p> Signup and view all the answers

<p>Both GAA and GAG specify glutamic acid (redundancy for less harmful mutations), neither specifies any other amino acid (no ambiguity for no mix-ups).</p> Signup and view all the answers

<p>Reading symbols of a language in the correct groupings.</p> Signup and view all the answers

<p>RNA polymerase, assembles RNA in 5' -&gt; 3'.</p> Signup and view all the answers

<p>RNA polymerase doesn't need a primer.</p> Signup and view all the answers

<p>The stretch of DNA that's transcribed into an RNA (from promoter to terminator sequence).</p> Signup and view all the answers

<ol> <li>Initiation: After RNA pol binds to the promoter, the DNA strands unwind, and the pol initiates RNA synthesis at the start point on the template strand. 2. Elongation: The polymerase moves downstream, unwinding the DNA and elongating the RNA transcript 5' -&gt; 3'. In the wake of transcription, the DNA strands re-form a double helix. 3. Termination: Eventually, the RNA transcript is released, and the polymerase detaches from the DNA.</li> </ol> Signup and view all the answers

<p>Bacteria = 1, Eukaryotes = 3.</p> Signup and view all the answers

<ol> <li>The transcription start point (the nucleotide where RNA synthesis begins) is included in the promoter. 2. Determines which of the two strands are used as the template. 3. Needs transcription factors (in eukaryotes) to mediate the binding of RNA pol + initiation of transcription.</li> </ol> Signup and view all the answers

<ol> <li>The eukaryotic promoter includes a nucleotide sequence containing TATA about 25 nucleotides upstream from the start point. 2. One or a few transcription factors recognize the TATA box and bind to the DNA so that RNA polymerase II can do so. 3. Additional transcription factors bind to the DNA along with RNA polymerase II, forming the transcription initiation complex. The DNA double helix then unwinds, and RNA synthesis begins at the start point on the template strand.</li> </ol> Signup and view all the answers

<p>A crucial promoter DNA sequence.</p> Signup and view all the answers

<p>The complex of transcription factors and RNA polymerase II bound to the promoter.</p> Signup and view all the answers

<p>Eukaryotic cells. The primary transcript is altered at both ends and sections in the middle are removed.</p> Signup and view all the answers

<p>It receives a 5' cap, where a form of guanine modified to have 3 phosphates on it is added after the first 20-40 nucleotides.</p> Signup and view all the answers

<p>An enzyme adds 50-250 adenine nucleotides, forming a poly-A tail.</p> Signup and view all the answers

<ol> <li>They seem to help facilitate the export of the mature mRNA from the nucleus. 2. They protect the mRNA from degradation by hydrolytic enzymes. 3. They help ribosomes attach to the 5' end of the mRNA once it reaches the cytoplasm.</li> </ol> Signup and view all the answers

<p>Untranslated regions: parts of mRNA that won't be translated to protein but have functions like ribosome binding, located at the 5' and 3' ends.</p> Signup and view all the answers

<p>Introns are noncoding segments of nucleic acid between coding regions. Exons are expressed regions that exit the nucleus.</p> Signup and view all the answers

<p>RNA polymerase II transcribes the polyadenylation (PD) signal sequence, which codes for a PD signal in the pre-mRNA. Then 10-35 nucleotides downstream, associated proteins with the growing RNA cut it free from the polymerase. The polymerase continues transcribing though for hundreds of nucleotides past termination. This extra RNA is then digested by an enzyme that moves along the pre-mRNA until it reaches the polymerase, then the polymerase falls off and transcription is terminated.</p> Signup and view all the answers

<p>Small nuclear ribonucleoproteins are proteins in the nucleus that recognize the splice sites at each end of an intron (short nucleotide sequences). Made up of RNA and protein molecules.</p> Signup and view all the answers

<p>Small nuclear RNA about 150 nucleotides long.</p> Signup and view all the answers

<p>Spliceosomes interact with certain sites along an intron, releasing it and joining the exons that were around it.</p> Signup and view all the answers

<ol> <li>snRNPs and other proteins together form a spliceosome on a pre-mRNA molecule containing introns and exons. 2. Within the spliceosome, snRNPs base pair with nucleotides at specific sites along the intron. 3. The spliceosome cuts out the intron and at the same time splices the exons together. The spliceosome then comes apart itself and releases the only-exon mRNA.</li> </ol> Signup and view all the answers

<p>The RNA parts of snRNP base-pair to specific sites along an intron.</p> Signup and view all the answers

<p>RNA molecules that function as enzymes. In some organisms, RNA splicing can occur without any other proteins or RNAs: the intron acts as its own excisor.</p> Signup and view all the answers

<p>That all biological enzymes were proteins. Actually, RNA can be enzymes/catalysts too.</p> Signup and view all the answers

<ol> <li>Since RNA is single-stranded, a region of an RNA molecule may base-pair with a complementary region in the same molecule, giving it a 3D shape that's specific. 2. Like amino acids in an enzymatic protein, some of the bases in RNA contain functional groups that may participate in catalysis. 3. It's able to H bond with other nucleic acids (RNA/DNA), which adds specificity to its catalytic activity.</li> </ol> Signup and view all the answers

<p>A single gene can encode more than one kind of polypeptide, depending on which segments are treated as exons during RNA processing.</p> Signup and view all the answers

<p>A nucleotide triplet at the bottom of the tRNA that base pairs to the codon of the mRNA so the amino acid can detach.</p> Signup and view all the answers

<p>Messenger RNA: modified single-strand chain of nucleotides that are complementary to DNA. Carries the message of genes, of what proteins to make.</p> Signup and view all the answers

<p>A tRNA has an anticodon on one end and an amino acid on the other end. Functions to transfer amino acids from the cytoplasm to the mRNA, at the ribosome.</p> Signup and view all the answers

<p>Ribosomal RNA: molecules that make up a ribosome, where mRNA's message is translated to amino acids.</p> Signup and view all the answers

<p>Introns increase the probability of beneficial cross-overs between the exons of alleles by not interrupting coding sequences. Either allelic or nonallelic shuffling can lead to new proteins with new functions.</p> Signup and view all the answers

<p>tRNA is made in the nucleus and forms hydrogen bonds between base pairs of itself (in the T) and hydrogen bonds from anticodon to codon.</p> Signup and view all the answers

<p>20, one for each amino acid. They are a group of related enzymes that facilitate the correct matching up of tRNA and amino acids.</p> Signup and view all the answers

<p>Wobble explains why the synonymous codons for a given amino acid can differ in their third base, but usually not in their other bases.</p> Signup and view all the answers

<ol> <li>Active site of aminoacyl-tRNA synthetase binds the amino acid and ATP. 2. ATP loses two P groups and joins amino acid to AMP. 3. Appropriate tRNA covalently bonds to an amino acid, displacing AMP. 4. The tRNA charged with amino acid is released by the enzyme.</li> </ol> Signup and view all the answers

<p>In the nucleus, rRNA genes on the chromosomal DNA are transcribed, and the RNA is processed and assembled with proteins from the cytoplasm. The resulting ribosomal subunits are then exported to the cytoplasm.</p> Signup and view all the answers

<p>Prokaryotic ribosomes are smaller and have 3 rRNA molecules. Eukaryotic ribosomes are larger and have 4 rRNA molecules. Certain antibiotic drugs can inactivate bacterial ribosomes without inhibiting the ability of eukaryotic ribosomes to make proteins.</p> Signup and view all the answers

<p>A site holds the tRNA carrying the next amino acid to be added to the chain. P site (start site) holds the tRNA carrying the growing polypeptide chain. E site is where discharged tRNAs exit the ribosome.</p> Signup and view all the answers

<ol> <li>Initiation: Initiation factors bring together mRNA and tRNA carrying the first amino acid met. 2. Elongation: Amino acids are added one by one to the preceding amino acid, stimulated by elongation factors. 3. Termination: UAG, UAA, or UGA codes for a stop signal and release factor binds.</li> </ol> Signup and view all the answers

<ol> <li>Small ribosomal subunit binds to mRNA, and initiator tRNA with the anticodon UAC base pairs with the start codon AUG, carrying the amino acid met. 2. Large ribosomal subunit binds to complete the complex, using GTP. Initiation factor proteins bring all the components together.</li> </ol> Signup and view all the answers

<p>True</p> Signup and view all the answers

<ol> <li>Codon recognition: The tRNA anticodon base-pairs with the mRNA codon in the A site. Hydrolysis of GTP here increases efficiency and accuracy. 2. Peptide bond formation: The large ribosomal subunit catalyzes the formation of a peptide bond between the new amino acid in the A site and the growing polypeptide in the P site. 3. Translocation: The ribosome moves the tRNA in the A site to the P site.</li> </ol> Signup and view all the answers

<p>A protein that binds directly to the stop codon in the A site. It causes the addition of a molecule of H2O instead of an amino acid. This hydrolyzes the bond between the completed polypeptide and the tRNA on the P site, releasing the polypeptide through the E site of the ribosome.</p> Signup and view all the answers

<p>String of ribosomes all translating the same mRNA at the same time allowing many copies of the polypeptide to be made more quickly.</p> Signup and view all the answers

<p>Protein folding due to primary structure and amino acid interactions, which sometimes occur in chaperonins, determine shape and function. Post-translational modifications: attachments (sugars, phosphates) or removal (of 1 or more amino acids) have to occur sometimes for the protein to function in the cell.</p> Signup and view all the answers