BIOB11H3 Study Guide - Midterm Guide: Snrnp, Spliceosome, Intron

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greenherring451

28 Feb 2013

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Lecture 6 consensus sequence: the most common version of a conserved sequence. Suppress what is wrong without affecting anything else is called magic bullet sirna: small (21-23 nucleotide), double stranded fragments formed when double-stranded. Rna initiates the response during rna silencing. microrna: small rnas (20-23 nucleotides long) that are synthesized from many sites in the genome and involved in inhibiting translation or increasing degradation of complementary mrnas. (11. 5) What happens if things dont go according to plan. Consequences of mis splicing: accumulation of unspliced dna figure 11-2. If splicing is right then the rna should be exported to the cytoplasm where the interact with ribosomes to be translated. But if they are not exported then they are usually degraded. The second thing that can happen is called frameshift. And perhaps containing a protein sequence which is coded by an intron. During an aberrant splicing part of intron 1 still has not been spliced.

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Part B

Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why?

a) It could cause a frameshift nonsense or frameshift missense mutation because it would change the reading frame of the codon triplet.

b) It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one.

c) It could cause a nonsense mutation because the sequence would no longer be the same, so the protein would be shorter and non-functional.

d) It could cause a silent mutation because A and T are complementary to each other so it is not really a substitution mutation.

Part C

Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein?

a) A substitution missense mutation causes the protein to be shorter and thus non-functional.

b) A frameshift missense will cause the codons to be out of order, but a substitution missense does not change the order of the codons.

c) A frameshift missense mutation will cause an early Stop codon, but a substitution missense might be silent.

d) A substitution missense affects only one codon, but a frameshift missense affects all codons downstream of the frameshift.

Part D

Which of the following sequences shows a frameshift mutation compared to the wild-type mRNA sequence?

a) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUACAGAGUGA-3â

b) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUACGUUGGAGUGA-3â

c) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUACAUCUGGAGUGA-3â

d) wild-type	5â-AUGCAUACAUUGGAGUGA-3â
mutant	5â-AUGCAUGUGACAUUGGAGUGA-3â

Part F

Suppose that the triplet of nucleotides indicated in bold (AGC) spans two codons, that is, CTA and GCC. If the triplet AGC were deleted from this DNA coding sequence, what effect would it have on the resulting protein?

5â-ATGCTAGCCTATCGTAAC-3â

a) The two flanking codons would be altered, but the rest of the amino acid sequence would be the same because there would be no frameshift.

b) The entire amino acid sequence would be altered due to the frameshift.

c) All of the amino acids after the deletion would be altered due to the frameshift.

d) All of the amino acids up to the deletion would be altered due to the frameshift.

mauvetrout554

Types of Mutation
A sentence made of three-letter words can provide an analogy to the effect of mutations on a gene's DNA sequence.
Normal	THE ONE BIG FLY HAD ONE RED EYE
Missense	THQ ONE BIG FLY HAD ONE RED EYE
Nonsense	THE ONE BIG
Frameshift	THE ONE QBI GFL YHA DON ERE DEY
Deletion	THE ONE BIG HAD ONE RED EYE
Insertion	THE ONE BIG WET FLY HAD ONE RED EYE
Duplication	THE ONE BIG FLY FLY HAD ONE RED EYE
Expanding mutation
Generation 1	THE ONE BIG FLY HAD ONE RED EYE
Generation 2	THE ONE BIG FLY FLYFLY HAD ONE RED EYE
Generation 3	THE ONE BIG FLY FLYFLYFLYFLY HAD ONE RED EYE

Describe a genetic disorder resulting from one of the mutations listed in the table. What is the mode of inheritance of your chosen disorder? What does the affected gene sequence look like in comparison to the normal sequence? What is the change in the amino acid sequence as a result of the disorder?

Describe the DNA repair process in eukaryotes. Why do you think this process is absent in mitochondrial DNA? What properties of mitochondrial DNA prevent it from repairing itself?

Describe two purposes of performing a karyotype (other than detecting abnormal chromosome numbers). In your opinion, should karyotyping be performed in the early stages of pregnancy to look for genetic disorders? Why or why not?

Identify two types of chromosomal abnormalities that can result from addition, deletion, or duplication of genetic material and describe how it happens. Describe a genetic disorder that can result from one of the aberrations identified by you.

pearturtle71

One question, double check section as well.

Several genes code for enzymes that are responsible forhistidine biosynthesis in Escherichia coli. Part of theamino acid sequence for one of these enzymes is:

AUG CCU UGG GCC CAA AAA UGC

A series of mutants that have lost activity for this enzyme arerecovered. The mutant products are analyzed and found to have thefollowing amino acid sequences:

Mutant 1: Met-Pro-Trp-Pro-Glu-Lys-Cys
Mutant 2: Met-Pro
Mutant 3: Met-Pro-Cys-Gly-Pro-Lys-Met
Mutant 4: Met-Pro-Trp-Pro-Lys-Asp

Choose the correct type of mutation that occurred in the DNA toproduce each mutant type.
Nonsense :
Point :
Addition :
Deletion :

________________

Double check section:

A small section of Saccharomyces cerevisiae gene has the aminoacid sequence valine, histidine, cysteine, and lysine.

A mutation in the above section of the amino acid sequence resultedin the substitution of amino acid lysine with amino acidasparagine.

The mutation in the antisense strand DNA of Saccharomycescerevisiae gene described above involves

Select one:

a. the substitution of second adenine base from AAG

b. the substitution of cytosine base from TTC

c. the substitution of guanine base from AAG

d. the substitution of second thymine base from TTC

*** I picked c, is that correct?

A small section of a gene for a protein has the followingnucleotide sequence:

TAT AGG GAC CTA TGT

Which of the following mutations would cause a missense mutation inthe sequence shown above?

Select one:

a. Replacement of second guanine base with cytosine base

b. Replacement of first cytosine base with guanine base

c. Replacement of final thymine base with guanine base

d. Replacement of first thymine base with adenine base

** Picked A

Which of the following was not one of the first uses of modernbiotechnology?

Select one:

a. The insertion of a bacterial insulin gene into humancells.

b. The cloning of a mammal.

c. The insertion of an antifreeze gene into a fish.

d. The insertion of a human insulin gene into bacteria.

** I picked A

What are the sticky ends of the restriction fragments?

Select one:

a. The surfaces of sticky ends contain matching base pairs,allowing fragments to splice.

b. The surfaces of sticky ends have glue like substance thatallow fragments to splice.

c. The surfaces of sticky ends contain the exact samenucleotides, allowing fragments to bond.

d. The surfaces of sticky ends have velcro like structure,allowing fragments to bond.

** a

mauvetortoise304

BIOB11H3 Study Guide - Midterm Guide: Snrnp, Spliceosome, Intron

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