BIOL 208 Lecture : Approaches to studying biology at molecular level

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rubygoose486

16 Oct 2011

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Module 1 summary: approaches to studying biology at molecular level. Three approaches commonly used to address biological questions: genetics. Determine normal for the trait of interest. Expose organisms to mutagens and screen for mutants. Have an organism to express that gene abnormally to learn about resulting phenotypic traits (gene silencing: biochemical. Isolate protein of interest (using column chromatography or any other method) Helps identify gene responsible for specific protein. Determine amino acid sequence (may compare with database) Screen genomic library and sequence isolate gene: bioinformatics. Once we have sequenced a gene we can check the database to find the following: Identify site of mutation relative to normal" sequence.

Related Questions

A small amount of a rare protein has been isolated and treated with proteases to cleave the protein into peptide fragments, which were separated by chromatography and subjected to mass spectrometry to determine their amino acid sequence. Unfortunately, as is often the case when only small amounts of protein are available, only the following three short stretches of amino acid sequence from the protein were obtained:

Peptide #1: Ala-Gln-His-Leu-Met-Lys Peptide

#2: Arg-Arg-Asn-Ile-Val-Ala Peptide

#3: Val-Asn-Ser-Thr-Ala-Pro A.

Using the genetic code (see Figure 7.24), design a collection of DNA probes specific for each peptide that could be used to detect the gene in a cDNA library by hybridization. (2 points) B. Which of the three collections of oligonucleotide probes would be preferable to use first. Explain your answer. (Hint, since the genetic code is redundant, each peptide has multiple potential coding sequences).

A UQ PhD student discovered a mutant in maize called roundcob1 (rc1). She was only able to find one recessive allele of rc1, which she called rc1-1. Your honours project is to identify new recessive mutant alleles of rc1 (e.g rc1-2, rc1-3...) using a mutant screen.

a) Describe a forward genetics approach youâd take to identify the new rc1 alleles using EMS mutagenesis, and by screening the cob phenotype of the M1 plants. Make sure you specify the genotypes (genetic background) of the parental line(s) you will use in your screen and briefly outline your screen design

b) Specify how you would use a genetic test to prove that your M1 plants carry new recessive mutations in rc1.

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You perform a forward genetic screen to look for Arabidopsisthaliana mutants that are altered in cold stressresponses. You find two mutants with oppositephenotypes. Mutant #1 is extremely resistant to coldstress (compared to the wild-type plant), and you identify the genethat has been mutated. It turns out that there is asingle base pair mutation that changes a Lysine to an Arginine inthe protein. Interestingly, this is the only lysine in this proteinwhich contains 400 amino acids.
The other mutant is less tolerant to cold stress than a wild typeplant. This mutant contains a different single base pairmutation in the same gene as mutant #1. This mutationchanges a codon encoding Glycine that is 10 amino acids from theNterminal end of the protein, to a Stop codon.Explain why thesespecific point mutations in the same gene can cause radicallydifferent mutant phenotypes. In your answer, please discus the rolethis gene plays in the cold response.

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BIOL 208 Lecture : Approaches to studying biology at molecular level

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