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bio22 test 3 -8
Chap 8
| Question | Answer |
|---|---|
| Regulation of Gene Expression? | Are expressed at fix rate.Regulate the way that the information in genes is turned into gene products |
| Induction | All ways off) the process that turns on the transcription on. The substance that acts to induce transcription of gene or genes is a inducer. |
| Repression | (All Ways On) would be to decrease the amount of that gene available and then thus decreasing that protein or enzyme available. |
| What is an operon? | It's a group of genes that work together to do one function. a) Promoter & Operator sites & structural genes that code for the protein. The operon is regulated by the product of the regulatory gene |
| How is it arranged? | It is made of three parts- Regulatory gene Control Region (Promoter & Operator) & Structure gene(ZYA) |
| Provide an example of an inducible and repressible operon. Explain how each one works. What are the default positions of each operon? | Induction Operon (allways off) (See Slides 1,2,3) |
| Provide an example of an inducible and repressible operon. Explain how each one works. What are the default positions of each operon? | Represson Operon is (Always On) (See Slides 4,5,6) |
| Define mutation? | a change in the gene material, which may be neutral, or beneficial or harmful to the gene. Describe the following types of mutations |
| Base substitution | (most common) in which single base pairs is base substation, in which a single base at one point in the DNA sequence is replaced with a different base. |
| Missense | if the base substitution results in an amino acid substitution in the synthesize protein this change in the DNA. |
| Nonsense (Part 1) | This is where it changes it into a stop codon and the protein will end prematurely. So in this case AUGAA here. This A gets changed because this DNA right here was changed from a T to an A. |
| Nonsense (Part 2) | To make the MRNA it resulted in a stop codon and you get your stop codon and terminated polypeptide. |
| Frameshift | In Which one or few nucleotide pairs are deleted or inserted in the DNA. This mutation can shift the “translation reading the frame.- that this the three by three grouping of nucleotides recognized as codons by the tRNAs during translation |
| What is a mutagen? | Spontaneous mutations –apparently occur in the absence of any mutation-causing agents. Agents in the environment such as certain chemicals and radiation that directly or indirectly bring about mutations. |
| Provide examples of mutagens? Chemical Mutagens (3 Examples) | Nitrous Acid Screws up the pairing with A- T, it changes the pairing to A-C It changes some of the pairs from Parents to AT then in the grand daughter as GC base pairs. |
| Provide examples of mutagens? Chemical Mutagens (1-2 Examples) | Chemical Mutagens- Nitrous Acid Screws up the pairing with A- T, it changes the pairing to A-C It changes some of the pairs from Parents to AT then in the grand daughter as GC base pairs. |
| Provide examples of mutagens? UV (2-2 Examples) | UV- causes Thymine dimers- which can cause skin cancer. |
| So there are ways your body can fix it? | One is called a photolyases. It will dissolve the bonds. Another way is excision repair that cuts on either side, removes it. |
| Describe laboratory tests that help in identifying mutagens? (1-3 Parts) | a)Positive (direct) Selection- involves the detection of the mutant cells by reception of the unmutated parent cells. – thus you have agar plate with PCN the Mutants will grow were the PCN is, the normal cells will not have any growth or colonies |
| Describe laboratory tests that help in identifying mutagens? (2-3 Parts) | b)Negative Selection (indirect) can be used, this process selects a cell that cannot perform certain functions, using the technique of replica plating Thus – the auxotrophic mutant can’t synthesize on histidine. |
| Describe laboratory tests that help in identifying mutagens? (3-3 Parts) | c)Ames test- that a mutant cell can revert to a normal cell in the presence of a mutagens are carcinogens. |
| What is recombination?- | refers to the exchange of genes between two DNA molecules. |
| Crossing over? (There 1-4 Parts) | 1)Dna from one cell aligns with DNA in the recipient cell. Notice that there is nick in the donor DNa. (Slide7) |
| Crossing over? (There 2-4 Parts) | 2)DNA from the donor aligns with complementary base parts in the recipient's chromosomes. This can involve 1000 of base pairs. |
| Crossing over? (There 3-4 Parts) | 3) RecA protein catalyzes the joining of the two strands. |
| Crossing over? (There 4-4 Parts) | 4)The result is that the recipients chromosome contains new DNA.Complementary base pairs btwn the 2 strands will be resolved by the DNA polymerase & Ligas. The donor DNA will be destroyed. The recipient may now one or more new genes. |
| Vertical gene transfer | occurs when genes are passed from an organism to its offspring. |
| Horizontal gene transfer | Bacteria can pass their genes not only to there offspring , but also laterally to other microbes of the same generation |
| Transformation | |
| Conjugation | This is done by sex pilus between two cells or by mating bridge. (One kind of plasmid, a circular piece of DNA that replicates indepently from the cells chromosomes |
| Transduction | |
| Transposons | Segments of DNA that can move from one region of DNA to another Contain insertion sequences for cutting and resealing DNA (transposase) Complex transposons carry other genes |
| Plasmids | Conjugative plasmid: Carries genes for sex pili and transfer of the plasmid Dissimilation plasmids: Encode enzymes for catabolism of unusual compounds R factors: Encode antibiotic resistance |
Created by:
zenink
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