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Genetics
Genetics Exam # 3
| Question | Answer |
|---|---|
| What is a plasmid? | Small loops of extra chromosomal (outside) DNA in bacteria (1-5% size of main bacterial chromosomes; can replicate independently. |
| What is the significance of plasmids? | Often carry genes for virulence factors (toxins, enzymes, and capsules), drug resistance and or recombinant factors (fertility factors). |
| What are genes? | Is a portion of the nucleic acid molecule. |
| What is the function of a gene? | Carries the genetic code for synthesis of one protein. All of the types of genes present in an organism is its genotype. The physical expression of those genes is the organism’s phenotype. |
| What is the structure of a nucleotide? | Each nucleotide has 3 parts: 1) a 5 carbon sugar: ribose in RNA, deoxyribose in DNA; 2) a phosphate; 3) a nitrogenous base: either a purine (2 rings), adenine and guanine; or pyrimidine (1 ring), cytosine and thymine |
| What is the structure of DNA? | Usually a double stranded chain of nucleotides (may be single in a virus). |
| What is the structure of RNA? | Usually a single chain of nucleotides (may be double stranded in a virus). |
| How does the genetic code work? | Within a gene of a nucleic acid molecule, each 3 consecutive nucleotides is a codon. |
| What are codons? | The genetic code for one amino acid. |
| What is DNA replication? | The copying of the DNA formula |
| How are new DNA molecules made? | DNA replication:1)Involves DNA molecule, “unzipping” along the hydrogen bonds between paired bases;2)Each half “attracts” the nucleotides needed to recreate the other half;3)If successful, both new molecules are identical to the original and to each other |
| What is transcription? | The production or copying of RNA from DNA. |
| How does the process of transcription proceed? | 1)Only one half of the DNA (one side) is used to make the gene copy; 2) RNA nucleotides are added according to the base-pairing rules of the partially unzipped portion of DNA (the gene); 3) End result is a gene copy in the form of RNA (mRNA). |
| What is translation? | Protein synthesis; translating the genetic code into a specific protein |
| What molecules are involved in the translation process? | mRNA carries the genetic code for a protein out from the chromosome to the ribosome. Transfer RNA (tRNA) carries individual amino acids to the mRNA which aligns them into the proper sequence. Ribosomal RNA (rRNA) links up the amino acids to form a protein |
| What are mutations? | Any change in nucleic acids (inheritable ones most importantly) can involve more than one nucleotide; are the sources of new genes (such as those for virulence or drug resistance) meaning NOT ALL MUTATIONS ARE BAD |
| What causes mutations? | Errors in DNA replication, radiation, mutagenic chemicals. |
| What type of mutations are possible? | Silent neutral, base substitution (point), frame shift mutation |
| What is recombination? | Any process that produces new combinations of existing genes in an individual cell (horizontal gene transfer). |
| What are the 4 modes of recombination in bacteria? | Conjugation, Transformation, Transduction, & Transposition |
| Conjugation | pieces of DNA are transferred through a mating type of process involving direct contact between bacteria that are joined by a sex pilus. |
| Transformation | DNA fragments (from dead cells) can be picked up by living cells and incorporated into their genomes (all the genes they possess). |
| Transduction | host DNA carried from host to host by a virus (bacteriophage). |
| Transposition | when certain gene sequences have the ability to be moved from one location in the genome to another. |
| What is genetic engineering? | Human manipulation of the genome of organisms (from microorganisms to humans); the objective is to get the organism (whom you implanted genes into) to produce some chemical/ molecule. |
| Know the applications of the genetic engineering process. | • Can produce; Improved crop varieties (resistant to pests or drought); Vaccines; Potential for over coming human genetic defects (ex. Human insulin or human growth hormones). |
| How is a gene from one species of an organism put into a different species of organism? (Part 1) | 1) Cut gene you are interested in out of the DNA. |
| How is a gene from one species of an organism put into a different species of organism? (Part 2) | 2) Put gene into a bacterial plasmid that accepts it (not 100% of the time) |
| How is a gene from one species of an organism put into a different species of organism? (Part 3) | 3) When bacteria translates the “implanted” gene along with its genes, the products of that gene will be produced, or the bacteria server to replicate many, many copies of the gene, which are eventually removed and placed in another organism |
| Silent Neutral Mutation | Result in no change to the protein (once translated) change in DNA not protein. |
| Base Substitution Mutation | a change in a single nucleotide base can result in missense mutation and nonsense mutation |
| Missense Mutation | changes the amino acid when gene is translated |
| Nonsense Mutation | creates a stop codon in the middle of mRNA leading to only a protein fragment being made during translation. |
| Frameshift Mutation | is the addition or deletion of one or more nucleotide; shifts reading frame of codons. |
Created by:
lisaanne11