CSB349H1 Lecture Notes - Lecture 1: Alternative Splicing, Dscam, Classical Genetics

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amethystfly536

28 Aug 2019

School

UTSG

Department

Cell and Systems Biology

Course

CSB349H1

Professor

Alan Moses Wolfgang Moeder

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Document Summary

In classical genetics, a gene was a unit of inheritance that transmitted a single characteristic from parent to offspring: biochemistry revealed that the inherited characteristics were associated with enzymes and other proteins, one for each gene. Each gene coded for each protein which created one phenotype: but sometimes, genes were not expressed and sometimes a protein could not be found even though we know. Enzymes were expressed and other time they weren"t. This was also controlled by other genes? humans would have it. In early 1960s jacob and monod figured out how this was possible and molecular biology was born biochemistry controlled by genetics. Proteins made by some genes will be controlling the expression of proteins made by other genes: monod said what is true of e. coli is true of the elephant (but turns out it is not true) Eukaryotic gene expression is more complex than those of bacteria.

Related Questions

In the October 2011 issue of PLoS Genetics, Pierson et al. used whole-exome sequencing to identify the mutations responsible for a rare spastic ataxia-neuropathy syndrome. The paper and supporting information can be found at http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1002325, and you will need to access the paper to answer these questions. The paper is focused primarily on the phenotype and the particular gene, but our attention will be primarily on the methods used for the exome-sequencing approach, which is found in the Methods and in the Supporting Information.

a. Figure 1A shows a pedigree of the family with two affected sons, who are not identical twins.

i. Recalling pedigree analysis from your introductory genetics course, what is the most likely mode of inheritance for this syndrome?

ii. What is the probability that the next child born to this couple will be disease-free?

b. Summarize the experimental strategy that yielded the results shown in Supplemental Table S2, as found under Supporting Information. Your summary should define the abbreviations used in the column headings and what the numbers mean. You should also include an explanation of why the numbers decrease as one reads from left to right from columns 2 through 6 (not including Total Protein Coding Exons Sequenced). c. The numbers of candidate genes in Supplemental Table S3 are 71 and 7, but these numbers do not appear anywhere in Supplemental Table S2. What inference from the data was made that allowed the investigators to arrive at the numbers in Table S3 based on the numbers in Table S2?

d. What further inferences led the investigators to conclude that AFG3L2 is the gene most likely responsible for this syndrome?

e. In the analysis of Miller Syndrome described in the chapter, the affected children did not have the same mutation on each homologous chromosome, and were in fact heteroallelic for the mutations. In this example, the children have the same mutation on each homologous chromosome. Why did the authors expect that the affected children would be homozygous for the same mutation?

f. What is the postulated mechanism by which this mutation results in this phenotype?

g. In this chapter, genes can be cloned and identified based on the following five properties: map position, mutations and allelic differences, expression patterns, complementation testing, and homology with genes in other organisms. Using a flow chart, diagram how these five properties led to the identification of the gene for this syndrome.

crimsonrabbit286

13. The arms of a human and the wing of a bat are _________________ structures, composed of the same bones that have been modified for different functions.

analogous

vestigial

c.	homologous

d.	convergent

14. Xeroderma pigmentosum is an autosomal recessive genetic disorder. People who are homozygous for the disease-causing allele have skin that is damaged by exposure to ultraviolet radiation; this can lead to skin cancer at an early age. The mutation that causes this disorder is in a gene that functions:

a.	to repair DNA by excising (removing) nucleotides damaged by UV light.

b.	in lysosomes, to break down lipids that otherwise accumulate in the nervous system.

c.	to produce the UV blocking pigment melanin in the skin cells

d.	in red blood cells to carry oxygen to the skin.

15. The Amish are a religious sect descended from a small group of colonists who came to the United States over 200 years ago. Their religious beliefs have kept them isolated from society. The Amish have a much higher than average incidence of both polydactyly (extra fingers and toes) and dwarfism in their communities. This is most likely explained by:

a.	inheritance of acquired characters.

b.	the founder effect.

c.	disruptive selection.

d.	natural selection.

16. In the structure of DNA that Watson and Crick proposed, the sides of the "ladder" of the DNA molecule are always the same distance apart, making the molecule a constant width. This occurs because when the bases hydrogen bond to form the rungs of the "ladder", a:

a.	purine always pairs with a pyrimidine.

b.	purine always pairs with a purine.

c.	pyrimidine always pairs with a pyrmidine.

d.	The structure of the double helix is not determined by how the bases pair.

17. The RNA transcript of DNA that travels to the cytoplasm, carrying the instructions to make a protein, is called:

rRNA.

tRNA.

mRNA.

d.	RNA polymerase.

18. When DNA is replicated, the error rate is approximately one error for every 10,000 nucleotides copied. However, that error rate is reduced to only 1 error for every 1 billion nucleotides. The DNA sequence is "corrected" by:

a.	repeating S phase to see if the error rate is lower the second time around.

b.	enzymes that proofread the DNA and repair errors.

c.	messenger RNA during the process of transcription.

d.	Any errors made during DNA replication cannot be corrected. If errors are detected after S phase, the cell is destroyed.

19. Mendel's principle of segregation says that:

a.	when gametes are formed, each gamete receives only one allele for a particular gene.

b.	some genes are dominant to others.

c.	a testcross must be used to determine the genotype of an organism with a dominant phenotype.

d.	all of the above

20. Tay-Sachs disease is lethal before reproductive age, but the allele persists in Louisiana French Canadians because:

a.	it is a dominant allele.

b.	new mutations causing this disease are common in that population.

c.	it is not expressed in the phenotype of heterozygous individuals.

d.	the disease is contagious and can be transmitted by nonheritable means.

21. Physical features that are similar in organisms which are not closely related to each other are most likely a result of ____________. A good example of this is the similarities seen between some marsupial and placental mammals.

a.	natural selection.

b.	adaptation to similar environments

c.	convergent evolution

d.	All of the above phrases can be used to correctly fill this blank.

22. In humans, which of the following sex chromosome compliments could be found in males?

23. The proteins that are associated with eukaryotic chromosomes:

a.	help to package the DNA within the nucleus.

b.	are involved in gene expression, through binding with the DNA.

c.	may be replicating or transcribing the DNA.

d.	All of these are true of proteins that are associated with eukaryotic chromosomes.

24. A sequence of DNA nucleotides that contains the information to produce a single protein is a(n):

codon.

gene.

c.	polypeptide.

d.	anticodon.

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CSB349H1 Lecture Notes - Lecture 1: Alternative Splicing, Dscam, Classical Genetics

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