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Genetics Ch 9
Microbiology Ch 9 Study
| Question | Answer |
|---|---|
| Genetics | Broad: Science that studies the inheritance of biological characteristics by living things. |
| Deoxyribonucleic acid (DNA) | is a nucleic acid containing genetic instructions used in dev and functioning of living org's(except RNA viruses). Genes carry genetic info but other DNA seq's have structural purpose or are inv in regulating gene expression. |
| DNA Structure | nucleotide: ~phosphate ~deoxyribose sugar ~nitrogenous base DOUBLE HELIX |
| Genome | sum total of genetic material carried within a cell |
| Plasmids | A DNA molecule that is separate from and can replicate independently of the chromosomal DNA. Mainly DS and circular. USU occur in bacteria but are sometimes found in eukaryotes. |
| Chromosome | discrete cellular structure composed of a neatly packaged DNA molecule |
| Gene | a specific segment of DNA that contains the necessary codes to produce proteins or an RNA molecule |
| Genotype | sum of all types of genes in an organisms genetic make-up (only some expressed) |
| Phenotype | Expression of genotype creating traits--changes depending on which genes are "turned on" or expressed. |
| Purine | A nitrogen base that is an important encoding component of DNA and RNA. The 2 most common: Adenine & Guanine |
| Pyrimidine | Nitrogen bases that help form the genetic code on DNA and RNA. Uracil, thymine, and cytosine are the most prevalent. |
| Pyrimidine dimer | The union of 2 adjacent pyrimidines on the same DNA strand, brought about by exposure to UV light. It is a form of mutation. |
| Paired bases | The pairing of purine bases in one DNA strand to pyrimidine bases in another DNA/RNA strand. Held together by weak hydrogen bonds. |
| Adenine : Thymine pairing | Forms 2 hydrogen bonds and is the site for DNA "unzipping" to begin synthesis. |
| Guanine : Cytosine pairing | Forms 3 hydrogen bonds |
| antiparallel arrangement | Term used to describe the asymmetrical orientation of paired helixes in opposite directions. One side runs 3' to 5' and the other side 5' to 3' |
| DNA replication | The process of duplication of DNA coding in high fidelity to pass genetics through generations of organisms. |
| Helicase | Fx: Unzipping the DNA helix |
| Primase | Fx: Synthesizing an RNA primer |
| DNA polymerase III | FX: Adding basses to the new DNA chain; proofreading the chain for mistakes |
| DNA polymerase I | Fx: Removing RNA primer, closing gaps, repairing mismatches |
| Ligase | Fx: Final binding of nicks in DNA during synthesis and repair |
| Gyrase | Supercoiling |
| Semiconservative replication | Produces two copies that each contained one of the original parent strands of DNA and one new strand |
| DNA Polymerase III Constrictions | *cannot add nucleotides to a DNA strand w/o a preexisting unbound nucleotide *RNA primer must be inserted at the origin of replication *Can add nucleotides only in 5' to 3' |
| Replication forks | Due to the circular shape of a bacterial DNA molecule, opening of the circle forms a Y shaped point of DNA synthesis on both ends of DNA synthesis process |
| Leading Strand | The newly forming 39' DNA strand that is replicated in a continuous fashion without segments |
| Lagging strand | The newly forming 59' DNA strand that is discontinuously replicated in segments (Okazaki fragments). |
| Transcription | mRNA synthesis; the process by which a strand of RNA is produced against a DNA template. |
| Translation | Protein synthesis; the process of decoding the mRNA code into a polypeptide. |
| triplets (aka codon) | A specific sequence of 3 nucleotides in mRNA (or the sense strand in DNA) that constitutes the genetic code for a particular amino acid |
| ribonucleic acid (RNA) | The nucleic acid responsible for carrying out the hereditary program transmitted by an organism's DNA |
| anticodon | The trinucleotide sequence of tRNA that is complimentary to the trinucleotide |
| RNA Polymerase | Large enzyme complex responsible for DNA code synthesis of RNA during transcription. *Works without the need of helicase (unlike DNA), it can bind to DNA, unwind it and synthesize the RNA. |
| promoter region | The site composed of a short signaling DNA sequence that RNA polymerase recognizes and combines to commence transcription. |
| Transcription Stages | initiation, elongation, and termination |
| nontemplate DNA | in RNA synthesis - does not carry a message that can be translated to a protein |
| Start codon | as ribosomes begin scanning the mRNA by moving 5' to 3' direction--translation begins when "AUG" codon is encountered |
| STOP CODONS | UAA, UAG, UGA |
| Degeneracy (aka Redundancy) | The property of the genetic code that allows an amino acid to be specified by several different codons. |
| Nonsense / Stop Codons | Termination codons UAA, UAG, UGA for where there is no corresponding anticodon--stop synthesis |
| Polyribosomal Complex | Length of mRNA allots feeding through more than 1 ribosome simultaneously; permits synthesis of 100's protein mol's. |
| Introns | The segments on split genes of eukaryotes that do not code for polypeptide. They can have regulatory function (see exon). |
| Exon | A stretch of eukaryotic DNA coding for a corresponding portion of mRNA that is not translated into peptides. During transcription, exons are separated from introns & spliced together-continuous mRNA transcript. |
| Operons | Prokaryotic form of gene regulation: section of DNA that contains one or more structural genes along w/corresponding operator gene that controls transcription. |
| Inducible (Operon) | "OFF" norm - catabolic operon turned on (when needed) by the substrate of the enzyme for which the structural genes code. (e.g. lactose) |
| Respressible (Operon) | "ON norm" -anabolic operon turned off only when the product of the pathway is no longer required (arginine) |
| corepressor | excess product within a cell that slows down the transcription of an operon |
| Mutation | A phenotypic change due to an alteration in genotype - an alteration of the nitrogen base sequences of DNA. |
| Wild Type | Original, nonmutated sequencing of genomes. |
| Mutant Strain (mutation) | Show variance in morphology, nutritional characteristics, genetic control mech, resistance to chemicals, temperature preference, & almost any type of enzymatic fx. |
| Spontaneous mutation | a random change in DNA arising from errors in replication that occur without a known cause |
| Induced mutations | mutations resulting from exposure to known mutagens |
| mutagens | primarily physical or chemical agents that damage DNA and interfere with its functioning |
| Point mutations | small mutations that affect only a single base on a gene- involve addition, deletion, or substitution of SINGLE bases |
| Missense mutation | ANY change in the DNA code and copied to mRNA that leads to placement of different amino acid... 1)create a faulty, nonfx protein 2)prod a protein that fx in a different way or 3)cause no significalt alt to protein fx |
| Nonsense mutation | Changes a normal codon into a STOP codon = stops the production of protein (almost ALWAYS results in a nonfx protein) |
| Silent mutation | alters the base but does not change the amino acid and has no effect on synthesis |
| Back-mutation | Occurs when a gene that has mutated reverts back to its original base composition |
| Frameshift (mutation) | One or more bases insterted into or deleted from a newly synthesized DNA strand thus changing reading of every aa = nonfx protein |
| Ames test | Method for detecting mutagenic agents based upon alteration of nutritionally defective bacteria |
| histidine (His or H) | essential amino acid containing a positively charged imidazole functional group. |
| Conjugation | attachment of 2 related species and the formation of a pilus to transport DNA |
| Transformation | Lysed donor cell releases naked DNA fragments to any competent receptor cell |
| Transduction | transfer by means of bacteriophage vector from donor lysed bacterial cell - live receptor cell of the same species |
| Competent (via transduction) | cells capable of receiving genetic material by the use of special DNA Binding proteins located on the cell wall |
| transposons | A DNA segment with an insertion sequence at each end, enabling it to migrate to another plasmid, to the bacterial chromosome, or to a bacteriophage |
| Bacteriophage | A virus that specifically attacks bacteria |
Created by:
JaeLaw23
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