BIOSC 0160 Lecture Notes - Lecture 4: Missense Mutation, Frameshift Mutation, Nonsense Mutation

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5 Apr 2018

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Mutation: nucleotide sequence of dna that can be passed on from one cell, or organism , to another. Somatic mutaitons: occur in somatic (nongamete) cells. Passed on to daughter cells in mitosis, but only within one person, not passed on heriditarly to kids. Germ line mutaitons: occur in cells of germ line (the cells that create gametes). A mutate gamete passes it on to new organism at fertilization, every cell in this new organism is mutant, so it will pass it on to offspring. Not all mutation types have a phenotypic effect. Usually a mutation in a region of the. Dna that does not encode a protein, or if coded doesn"t change aa sequence. Silent mutations are common and just create genetic diversity, not phenotypic differences. Loss-of-function mutation: affects protein function, can cause a gene to not be expressed, or be altered to not fit enzyme. These mutations show recessive inheritance in diploid organisms.

Related Questions

Scientists have been studying the effects of Starkagaren Disease, which is regulated by the stgn gene, in cultured normal and breast cancer cell lines. They have fused a yellow fluorescent probe to the end of the stgn gene to study the disease more closely. By adding a probe, it will create a hybrid protein that emits a yellow color under a blue laser. This hybrid protein is known as a fluorescentâtagged protein, meaning that the protein itself will function and fold normally but it will be tagged with a yellow fluorescent probe (YFP) at the end. This allows the scientists to follow the protein through the cell cycle. They find that the stgn protein normally binds to centromeres in normal cells. After looking at cells at various stages of the cell cycle, they find that compared to normal cells, the breast cancer cells that express the Starkagaren Disease display abnormal nuclei, some appear very large, some have tiny nuclei, and some cells do not have a nucleus at all.

Scientists have figured out that Starkagaren Disease is passed on through a mutation in the germ cells. The mutation is found on the chromosome 12 so either the mother or father can pass on the gene. But in order for the disease to express, both parents need to have the mutation. You are a genetic counselor talking to two individuals that have familial history of either a grandparent or aunt or uncle with the disease, they would like you to explain their chances of having a child that could possible inherit the disease.

a) Would the defect be found in homologous chromosomes or sister chromatids, or both? Explain.

b) If the location of the gene with the defect is found near the tip of the chromosome, how likely would that defect transfer to a homologous chromosome? Explain how it may or may no occur.

viridiansardine993

please solve this:

Cancer Biology (Oncogenic Pathways)

The majority of malignant cells rely on dysregulation of a handful of oncogenes and their associated signaling pathways to support their abnormal proliferation and survival. The list below indicates the proteins that have become the âname sakeâ for these key dysregulated pathways. Note that sometimes the protein listed is mutated and drives the pathway (ex. Ras), but other times it is rarely mutated (ex. Akt where PI3K and PTEN mutations predominate).

Working together in your groups, please create a portfolio of âprofilesâ for the pathways shown below. For each pathway, include a map that links together the main proteins or molecules involved- ligands, receptors, transcription factors, etc... but always end with the ultimate effect on the cell! These pathway maps must be your own creation- do not copy other image files. For each protein or molecule you list in the map, please provide a âkeyâ that describes what it is, its specific function in the pathway, and detail where the most common pathogenic mutations occur in at least three proteins in the pathway (see below for details). Since these pathways can be extremely complex, you need not include more than three proteins or molecules at any one level in the pathway.

For information on the pathogenic mutations, use the COSMIC (catalogue of somatic muations in cancer) resource at http://cancer.sanger.ac.uk/cosmic . Enter the gene/protein name Ã click on the gene name in table below Ã under âMutation Impactâ select Pathogenic Ã Apply. A bar graph depicting the various mutations will be shown, provide the number of confirmed mutations and the changes (DNA and amino acids) it causes at that site. For example, in the BRAF gene: 24,291 mutations have been confirmed that involve a T to A mutation at base 1799 which leads to a Valine (V) to Glutamic acid (E) amino acid substitution at position 600 (note this mutation constitutively activates the BRaf kinase).

Key Oncogenic Pathways to Profile:

Ras

Akt

Wnt

TGFB

Notch

Hedgehog

Grading will be based on aesthetic clarity, thoroughness and accuracy of the information.

Grading Rubric: 75 points total

Visuals: Aesthetic clarity 30 points

Pathways are well organized, easy to follow

activating and inhibitory relationships are readily apparent

Creative layout

Content: Thoroughness and Accuracy 30 points

All pathways completed

Essential level of detail in key

1. In Humans, many types of cancers have been linked to?

A. Duplications
B. Inversions
C. translocations
D. deletions
E all of these

2. 5- bromoouracil is mutagenic because it is a(n)

a. base-modifying agent
b. base analog
c. intercalating agent
d. alkylating agent.

3.Ultraviolet radiation creates __________ in DNA

A. 5-methyl cytosine residues
B. breakages
C point mutations
D. mutational hot spots
E thymine dimers

4. The telomeres of chromosomes is composed of

A. heterochromatin
b. nucleosome
c. histone
d. achromatic

5. In eukaryotes, a replicon is

a. the distance between the origin of replication and thetermination of replication
b. a single chromosome
c. the entire genome
d. one DNA strand of a single chromosome

6. In a nonreciprocal interchomosomal translocation, a segment of achromosome is

a. exchanged with an identical segment on a differentchromosome
b. exchanged with an identical segment on a sister chromatid
c. transferred to a different chromosome without a reciprocalexchange of genetic material
d. transferred to a new location on the same chromosome without areciprocal exchange of genetic material

7. Somatic mutations are always.

a. spontaneous
b. carcinogenic
c. heritable
d. lethal
e. none of these

8. A woman with an XO genotype is

a. aneuploid
b. euploid
c. diploid
d. poluploid

9. Spontaneous mutations may occur as a result of

a. all of these
b. errors in DNA replication
c. transposition
d. none of these
e. normal cell biochemistry

10. In the semi conservative model of DNA replication, progenydouble helices consist of

a. one parental DNA strand and one new strand
b. one parental DNA strand and one new RNA strand
c. two new RNA strands
d. two parental DNA strands
e. two new DNA strands

11. A mutation in a gene may alter a cellâs

a. phenotype
b. genotype and phenotype
c. genotype

12. During replication, the direction of synthesis of new DNA fromthe leading strand is

a. both 5â to 3â and 3â to 5â
b. none of these
c. 3â to 5â
d. from left to right only
e. 5â to 3â only

13. A mutation that results in a switch from a purine-pyramidingbase pair to a pyramiding-purine base pair is a _________mutation.

a. neutral
b. transition
c. missense
d. transversion
e. nonsense

14. A trisomic human cell would contain how many chromosomes?

a. 45
b. 46,
c. 47.
d. 48

15. In a strand of DNA, a _____________ bond connects the phosphategroup of one nucleotide to the sugar of the adjacentnucleotide

a. hydrogen
b. ester
c. phosphodiester
d. phosphate
e. disulfide

16. Cri-du-chat syndrome is caused by which type of chromosomalmutation?

a. deletion
b. duplication
c. translocation
d. transversion
e. inversion

17. During replication, the role of DNA primase is to

a. add nucleotide to the growing DNA chain
b. synthesize a short chain for RNA
c. untwist the double helix at the origin of replication
d. relax the super coiling of the double helix
e. synthesize the primo some

18. A(n) ____________ inversion involves the Centro mere

a. chromocentric
b. paracentric
c. epicentric
d. percentric
e. concentric

19. Which of the following substances mutates DNA by intercalatingbetween adjacent base pairs?

a. methyl methane sulfonate
b. all of these
c. nitrous acid
d. 2-amino urine
e. acridine orange

20. A molecule of RNA is always

a. double stranded
b. helical
c. nonparallel
d. all of these
e. none of these

21. Mutagenesis of cells using radiation or a chemicalintercalating agent could be used to create __________ mutations ina region of DNA.

a. random
b. both random and site-specific
c. site-specific

22. In Griffithsâs tranformation experiments, the mice died whenthey were injected with

a. living, no virulent bacteria
b. living, virulent bacteria
c. heat-killed, no virulent bacteria
d. living, nonvirulent bacteria
e. both B and D

23. A monoploid human cells

a. shows only the excessive phenotype of all these genes
b. would be functionally impaired
c. is normal
d. would not survive

24. Gametes containing an abnormal number of chromosomes may occuras a result of

a. paracentric inversion
b. reciprocal translocation
c. disjunction of chromosomes
d. unequal crossing over

25. DNA may be altered as a result of _____________ events thatoccur normally in cells

a. depurination
b. deamination
c. depyrimidation
d. all of the above
e. none of the above

26. Which enzyme prevents DNA from tangling up as the replicationfork migrates during replication?

a. DNA polymerase I
b. DNA helicase
c. topoisonmerase
d. DNA polymerase III
e. DNA gyrase

27. Which of the following enzymes play an important role in DNAreplication?

a. DNA helicase
b. DNA ligase
c. DNA primase
d. all of them
e. DNA polymerase III

28. A mutation gene sustains a mutation that restores the originalphenotype, This is a

a. frame shift mutation
b. transversion
c. reversion
d. transition
e. forward mutation

29. A dicentric chromosome has two

a. telomeres
b. mutations
c. arms
d. centromeres

30. Which type of chromosomal mutation cannot revert to thewild-type state

a. duplication
b. deletion
c. translocation
d. both A and C
e. all of them

31. Translation of histone mRNAs occurs during which phase of theeukaryotic cell cycle?

a. M
b. G1
c. G2
d. S
e. all of these

32. After removal of the RNA primers, Okazaki fragments are joinedthrough a reaction that involves which enzyme?

a. RNA polymerase
b. DNA helicase
c. DNA polymerase
d. DNA primase
e. DNA ligase

33. Which of the following is required for the synthesis of DNAduring replication?

a. DNA polymerase
b. magnesium ions
c. all of them
d. template DNA
e. dNTPs

34. Most of the genome of an active cell consists of

a. heterochromatin
b. histochromatin
c. poluchromatin
d. euchromatin

35. In eukaryotes, DNA replication begins,

a. a single origin of replication on each chromosome
b. a single origin of replication on each chromosome
c. multiple origins of replication on each chromosome
d. all of the above
e. none of the above

36. A human cell contains 2 sets of 24 chromosomes is

a. euploid
b. haploid
c. polyploid
d. aneuploid

37. Pseudodominance occurs as a result of which type ofmutation?

a. translocation
b. duppolication
c. all of these
d. point mutation
e. deletion

38. The enzymatic activity of a telomerase is best described asa

a. none of these
b. polymerase
c. ligase
d. reverse transcriptase
e. topoisomerase

39. A Barr body is an example of

a. constitutive heterochromatin
b. facultative heterochromatin
c. facultative euchromatin
d. constitutive euchromatin

40. An addition or deletion of one or two base pairs in a genecauses a ____________ mutation

a. Transition
b. frameshift
c. nonsense
d. transversion
e. neutral

41. A heterozygous chromosomal inversion can be detected

a. by cytogenetic observation of loops in chromosomes
b. through genetic studies indicating a decrease in the frequencyof recombination between genes
c. by observing a decrease in the number of viable progenyfollowing genetic crosses
d. all of the above

42. The mutagen 5-bromouracil is an analog of which base?

a. adenine
b. threonine
c. thymine
d. cystosine
e. uracil

43. A mutation that changes a codon from one that represents anamino acid to one that signals a chain termination is a______________ mutation.

a. neutral
b. missense
c. frame shift
d. nonsense

44. A chromosomal mutation that results in an increase in theamount of DNA is a(n)

a. duplication
b. inversion
c. deletion
d. both A and C
e. all of the above

45. Prior to replication, the DNA double helix must be untwisted bywhich type of enzyme?

a. topoisomerase
b. ligase
c. polymerase
d. helicase
e. primase

46. In his transformation experiments, Griffiths used cultures ofwhich bacterium?

a. Sacchromyces cerevisiae
b. Escherichia coli
c. Streptococcus pneumoniae.
d. Bacillus cereus
e. Eneterococcus faecalis

47. A mutation changes a codon from a UCG to a UAG. This is a____________ mutation?

a. point
b. nonsense
c. silent
d. both A and B
e. all of the above

48. In eukaryotes, DNA replication

a. is initiated at several sites on chromosomes
b. occurs bidirectional
c. is semidiscontinuous
d. all of the above
e. none of the above

49. Which of the following bacteria are used in the Amestest?

a. Pseudomonas aeruginosa
b. Escherichia coli
c. Vibrio cholera
d. Salmonella typhimurium
e. Rickettsia rickettsii

50. Which of the following changes represents a missensemutation?

a. UGA (stop) to UAG (stop)
b. AAA (lysine) to AGA (arginine)
c. UUU (phenylalanine) to UAA (stop)
d. AUG (methionine) to UGA (stop)
e. AAA (lysine) to AAG (lysine)

BIOSC 0160 Lecture Notes - Lecture 4: Missense Mutation, Frameshift Mutation, Nonsense Mutation

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