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BIO205-CH8-MicGeneti
BIO205 - CH8 - Microbial Genetics - Tortora - Rio Salado - AZ
| Question | Answer |
|---|---|
| Genetic info in a cell | Genome - includes chromosomes & plasmids |
| DNA made of? | Nitrogenous base (A-T, G-C), deoxyribose (pentose sugar) & a phosphate group |
| Sugar-phosphate backbone | Alternating sugar & phosphate group |
| Where is base attached in DNA? | To each sugar in backbone |
| What constitutes phenotype in molecular terms? | Its collection of proteins - both enzymatic & structural |
| genotype | refers to the particular alleles individual carries |
| phenotype | refers to an individual's observable traits |
| semiconservative replication | Each DNA molecule - on strand is from the starting molecule, so it's said to be conserved, only the 2nd strand has been freshly synthesized. 1/2 new, 1/2 old |
| DNA polymerases | Enzymes that unwind DNA molecule, keep the 2 unwound, & assemble new strand on each one - link individual nucleotides on parent strand. |
| DNA ligases | Enzyme that seals new base-pairing during DNA replication - also used by recombinant DNA techs to seal base-pairings between DNA fragments & cut plasmid DNA. |
| Base pairs | 2 kinds in DNA = A-T & G-C |
| gene | sequence of nucleotides in DNA |
| DNA'S nucleotides are built of ___. | sequences of nucleotides in DNA |
| nucleotide | Building blocks of nucleic acids, composed of phosphate & nitrogen-containing base (A,G,T,or C) |
| thymine dimers | UV light causes two neighboring thymine bases to become linked (a dimer) - distorts affected DNA molecule & increases chance for replication errors. |
| RNA polymerases | Enzyme that catalyzes the assembly of RNA strands on DNA templates. |
| promoter | a sequence of bases that signals the start of a gene |
| 5' | Capped end where mRNA will bind to a ribosome when time comes for translation. Phosphate end attached to carbon |
| 3' | the trailing end of the forming RNA molecule - hydroxyl end attached to carbon |
| 5' ---> 3' | The direction of one DNA strand that runs counter to the other |
| Sequencing of molecular characterization of genomes. | Genomics |
| Supercoiling on DNA relaxed by? Unwound by? | Gyrase or topoisomerase, helicase |
| Enzyme that joins nucleotide to DNA strand. | DNA polymerase |
| Point at which replication occurs | replication fork |
| 1' | One prime = carbon atoms of sugar in each nucleotide |
| DNA polymerases can only add nucleotides to the __. | 3' end |
| DNA strands grow in different __. | directions |
| Where does energy come from to replicate DNA? | The nucleotides - 2 phosphate groups removed to add nucleotide to DNA - hydrolysis makes new bond. |
| Leading strand | The new DNA strand being synthesized in 5' -- 3' direction. |
| Which enzyme has proofreading capability? | DNA polymerase - evaluates if proper base-pairing structure. |
| DNA replication sequence - 6 steps | (1) helicase unwinds & rep fork form @ orig, (2) proteins stabilize, (3) Lead strand synth by DNA polymer. (5' -3'), (4) lag strand synth discontinously (RNA primer(5) RNA primer digest by DNA polymer. & replaced w/DNA, (6) DNA ligase joins new DNA fragm. |
| RNA | Ribonucleic acid - ribose (sugar), a phosphate group & base - A,C,G & U (uracil). |
| ribosomal RNA (rRNA) | Nuclic acid chain that combines w/certain proteins to form a ribosome, a structure on which a polypeptide chain is assembled. |
| messenger RNA (mRNA) | A linear sequence of nucleotides that carries protein-building instructions; this "code" is delivered to the ribosome for translation into a polypeptide chain. |
| transfer RNA (tRNA) | Another nucleic acid chain that can pick up a specific amino acid & pair with an mRNA code word for that amino acid. |
| Which comes 1st, translation or transcription? | Transcription - genetic info in DNA transcribed into RNA. |
| Synthesis of complementary RNA strand. | transcription |
| Which RNA carries coded info to ribosomes? | in RNA |
| Transcription requires what enzyme? | RNA polymerase |
| RNA polymerase binds to DNA where? | at promoter |
| Another name for protein synthesis | translation |
| language of mRNA | codons |
| Each codon codes for what? | A particular amino acid |
| __ refers to fact that most amino acids are signaled by several alternate codons. | degeneracy of the code |
| Start codon | methionine - AUG |
| Each tRNA has an __. | anticodon |
| Function of ribosome is to directly orderly binding of __ to __ & assemble __. | tRNA, codons, amino acids |
| Different locations of transcription between Prokaryote & Eukaryote | prok=cytoplasm, euk=nucleus |
| Eukaryote RNA molecule containing introns & exons. | RNA transcript |
| Products constantly produced at fixed rate. | constitutive |
| Name 2 genetic control mechanisms | repression & induction |
| How does repression work? | Inhibits gene expression by repressor (reg proteins) that block RNA polymerase's ability to initiate transcription |
| The process that turns on gene transcription. | induction |
| How does induction work? | Inducer (enzyme) encourages cell to synthesize more enzymes. |
| Repressible gene is default __ while inducible gene is default __. | on, off |
| Structural genes | Determine the structures of proteins - amino acid sequence |
| operon | Operator & promoter sites & the structural genes they control. |
| operator | Region of DNA adjacent to structural genes that control their transcription. |
| Promoter | Starting site on DNA strand for transcription of RNA by RNA polymerase |
| Details of the control of gene expression by induction & repression are described by __. | operon model |
| What combines to form lac operon? | 3 lac structural genes & adjoining control regions. |
| I gene codes for what in bacterial DNA? | Repressor protein - blocks ability of RNA polymerase to initiate transcription. |
| Repressor protein binds & prevents RNA polymerase when __. | the necessary substance - like lactose - is absent. |
| Why are enzymes produced in presence of lactose? | Some lactose is transported into cell & is converted into an inducer, which binds to repressor protein & alters it, allowing operator site to be open. |
| Corepressor do what? | Bind to repressor protein & allow it to bind to operator to repress synthesis. |
| Transcription of the lac operon requires? | Presence of lactose & absence of glucose. |
| Catabolite repression (glucose effect) | INhibition of alternate carbon sources for metabolism due to availability of glucose. |
| Base substitution that results in amino acid substitution in synthesized protein. | Missense mutation - change in DNA due to base substitution. |
| Sickle cell disease due to __ mutation. | missense |
| Mutation in base substitution that causes a stop codon to be in wrong place. | Nonsense mutation - only a fragment of the protein is made. |
| What does nitrous acid do to DNA? | Chemical mutagen - makes base-pair changes and alters DNA. |
| Nucleoside analog | Chemical that is structurally similar to normal nucleosides in nucleic acids, but with altered base-pairing properties. |
| Frameshift mutagens are often __. | potent carcinogens |
| Why are X rays & gamma rays potent mutigens? | They have rays of ionizing radiation that cause electrons to pop out of their shells & become ions & free radicals. |
| Mutagens increase rate of? | Spontaneous mutation by 10 - 1000 times. |
| Positive (direct) selection | Identifying mutant cells by culturing them. |
| Negative (indirect) selection | Identifying mutant cells by selecting cells that don't grow using replica plating. |
| replica plating | Inoculating a number of solid minimal culture media from an original plate to produce same pattern of colonies on each plate. |
| What is an auxotroph? | A mutant microbe having a nutritional requirement that is absent in parent - enzyme lacking, etc. |
| An Ames test is used to screen? | For potential carcinogens - uses bacteria. |
| Plants & animals transmit their genes by __ gene transfer. | vertical - passing genes to offspring. |
| Bacteria can pass thier genes __. | horizontally - to other microbes of same generation. |
| In horzontal gene transfer, who is the recombinant? | The recipient cell that incorporates donor DNA into its own DNA. |
| What is transformation in bacteria? | Genes are transferred from one bacteria to another as "naked" DNA. |
| Competence results from __. | alterations in cell wall that make it permeable to large DNA molecules. |
| Conjugation | Plasmid replicates independently from cell's chromosome. |
| Conjugation requires __. | direct cell-to-cell contact. |
| F factor | Fertility factor - a plasmid found in donor cell in bacterial conjugation. |
| Hfr cell | F+ factor integrates into chromosome & creates - high frequency of recombination. |
| __ is used to map location of genes on bacterial chromosomes. | conjugation |
| Transduction | Bacterial DNA transferred from donor to recipient cell inside a virus that infects bacteria. Bacteriophage, or phage. |
| What mechanism of genetic transfer creates phage? | Transduction |
| Name 4 ways bacteria can acquire new genotypes. | Mutation, transformation, conjugation, & transduction. |
| The F factor is a __. | conjugate plasmid - carries gene for sex pili. |
| __ plasmids code for enzymes that trigger catabolism of unusual sugars & hydrocarbins. | dissimilation |
| Dissimilation plasmids help bacteria to __. | survive in very diverse & challenging environments |
| Bacteriocins | toxic proteins that kill other bacteria. |
| Resistance factors (R factors) | Carry genes that confer resistance to antibiotics, heavy metals, toxins. |
| transposons | Small DNA segments that move around on a DNA molecule. |
| Insertion sequences (IS) | Contain a gene that codes for an enzyme which catalyzes cutting & resealing of DNA during transposition. |
| Plasmids like R factors are frequently made up of __. | a collection of transposons |
| Transposons can spread from __. | one organism - or even speces - to another. |
| A powerful mediator of evolution in an organism. | transposons. |
Created by:
Ladystorm
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