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BIOL 111 Exam 2
| Question | Answer |
|---|---|
| What is the central dogma of molecular biology? | DNA transcription-->RNA-->translation-->protein |
| Reverse transcription | RNA directs the production of DNA |
| Auxotroph | cannot make a certain nutrient |
| Beadle and Tatum's conclusion that each gene encoded a single enzyme pathway let to what discovery | One gene, one polypeptide |
| How many base codons are in an amino acid | 3 bases = 1 codon = 1 amino acid |
| There are 4 bases in DNA & 20 different amino acids. How can this specify all amino acids | 3 bases can encode 64 amino acids |
| What is a copolymer | More than one base |
| What was the first synthetic homopolymer | polyU; makes Phe-Phe-Phe so... UUU=Phe amino acid |
| What are the amino acids for codons (1) AAA & (2) CCC | Lysine; Proline |
| How is the genetic code redundent | The 3rd base; Generally more than 1 codon encodes for the same amino acid because changing the 3rd base doesn't always have an effect |
| What is the start codon | AUG (code) --> Met (amino acid) |
| What are the 3 stop codons and amino acids | UGA; UAG; UAA; don't code for any amino acids |
| What is the overall goal of transcription? | Preserves info in DNA to temporary copy of RNA |
| What is the overall goal of translation? | Protein synthesis: Converts info (codons) from RNA template to proteins |
| mRNA | messengerRNA; used to direct protein synthesis (template) |
| rRNA | ribosomalRNA; forms in each ribosomal subunit & interacts with proteins |
| tRNA | transferRNA;Multifunctional: (1) interacts with amino acids(carrying) & nucleaic acids (mRNA/rRNA) (2) has 3' acceptor stem (3)has anticodon loop to interact with mRNA |
| snRNA | small nuclear RNA; needed for splicing in euk./cleans up the message |
| miRNA | microRNA; base pairs match up with mRNA to 'silence' message by preventing translation (epigenetics) |
| *Memorize & review transcription/translation charts!!!!! * | |
| What is the purpose of RNA Polymerase and the difference between RNA Pol I,II,III? | used to make RNA: Pol I = rRNA Pol II = mRNA Pol III = tRNA *snRNA & miRNA can be done by Pol I or II |
| What is the result of the "wobble rules"? | There are fewer tRNA's than codons because of the redundancy of the 3rd base of the codon allowing 1 tRNA to read >1 codon |
| What's special about amioacyl-tRNA synthetase | There is a specific one for each amino acid used to charge tRNA (along with ATP) |
| What are the EPA sites? | E: exit; P: peptidyl - binds to tRNA with growing chain; A: amionacyl - binds tRNA with next amino acid to be added |
| What is epigenetics | Processes that change gene expression or function without changing the DNA sequence |
| Where do differences causing epigentics occur | transcriptional control - enhancer sequences and transcription factors |
| What is histone acetylation | Attachment of acetyl groups to lysine residues in the amino tail extending from the nucleosome core of the histones |
| What enzymes are necessary for histone acetylation | 1. Histone acetyl transferase (HAT) to acetylate lysine and promote transcription 2. Histone deacetylase (HDA) to reverse rxn and silence transcription |
| What is the purpose of histone acetylation | Gene regulation: (-) charges histones so no longer attracted to (-) charged DNA allowing DNA to be more accessible for transcription factors to recognize promoters & enhancer sequences |
| What is DNA methylation | Methyl group added to cytosine (C) in DNA to form 5-methylcytosinse |
| What does DNA methylation of CpG island do | repress gene expression |
| Where can DNA methylation occur | only in (5'-CG-3')CG-rich regions called CpG islands |
| Where can methylation changes in DNA occur | From parents or done individually |
| Genes paternally imprinted are expressed on ________________ chromosome | maternal |
| Genes____________ imprinted are expressed on paternal chromosome | maternally |
| In genomic imprinting how are genes expressed | As if you only have one copy because one is silences so gene is expressed no matter what |
| What's the difference between Prader-Willi syndrome and Angelman syndrome | PWS: deletion in paternal chromosome 15 AS: deletion in maternal 15 |
| Why is single strand chromosomal deletion in epigenetics considered a mutation | Deleted in one chromosome and silenced in the other because of methylated imprintation |
| How is imprinting correlated to parental care | Early life stress can cause imprinting resulting in increased reactivity of the hypothalamus-pituitary-adrinal axis |
| What are promoters and enhancers made of and what recognizes them? | Made of DNA; both recognized by transcription factors; promoters recognized by sigma factor |
| A single gene can produce: 1. A single transcript of the same sequence 2. A variety of transcripts of the same sequence 3. A single transcript of different sequences or 4. A variety of transcripts of different sequences | 4! |
| What is aminoacyl tRNA synthetase used for | to charge initiator tRNA |
| In protein synthesis the ________________ is translocated along the _______________, so and empty tRNA occupies the ____ site | ribosome; mRNA; E |
| What is peptidyl transferase used for | Elongation during translation |
| Which of the following require energy input: a. tRNA charging b. peptide bond formation c. translocation | A&C |
| When histones are acetylated, DNA loses its affinity for the histones because acetyl groups were added to ____________________, making them more negatively charged | lysine amino terminus tails |
| Parents can pass epigenetic changes in DNA to their offspring. How does this affect phenotype, genotype, mutation, and gene expression | Alters gene expression & phenotype; no change in genotype; no mutation |
Created by:
jkmccord11
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