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Flashcards in cellular and molecular Deck (51)
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1

DNA is made up of 4 deoxyribonucleotides containing the purine bases _______ and ________, and the pyrimidine bases _________ and ________.

The bond between the bases is a ________ bond.

adenine and guanine
cytosine and thiamine

Adenine binds to thymine and cytosine binds to guanine.

hydrogen

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2. The central dogma of molecular biology is that DNA can be copied to DNA and to messenger RNA (process is called _________), and that proteins can be synthesized using the information in mRNA as a template (called _______), but that the information can’t be transferred back from protein to nucleic acid, or from RNA to DNA.

transcription, translation

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3. How is the structure of RNA different from DNA?

-Thymine is replaced with uracil
-The base pairs are linked by ribose rather than 2’ deoxyribose
-RNA is usually single stranded
-RNA is much more susceptible than DNA to degradation by nucleases

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4. What are/were the benefits of sequencing the genome?

-The expectation that knowledge of the sequence of position of all genes would produce tangible improvements in medical care
-Tools could be developed for storing and analyzing the large amount of information produced
-The work would produce a biotechnology industry to stimulate the development of new medical applications from the data

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5. A Boxer was chosen for the canine genome sequencing project because this breed was described as having the lowest rate of _________, in other words, the lowest rate of variation in sequence, when compared to other breeds.

heterozygosity

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6. The feline genome has also been sequenced. What is of particular interest?

-The large numbers of endogenous retrovirus-like sequences identified, accounting for about 4% of the feline genome.

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7. Only approximately __% of the genome codes for mRNA, rRNA, tRNA, small nuclear RNA, and small nucleolar RNA.

10

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8. Transcription is mediated by a DNA-directed what? Where in the cell does it occur?

-RNA polymerase
-Primarily in the nucleus, but also in the mitochondria

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9. The length of genes is often many times greater than that of the transcribed mRNA molecule due to the presence of _______ which are noncoding nucleic acids, that separate the exons, or the coding sequence. The base triplets of three nucleotides are termed codons and code for individual amino acids.

introns

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10. Translation of mRNA molecules to a polypeptide occurs in the _________.

ribosomes

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The presence of intronic sequence permits alternative splicing of the exons and thus variation in the sequence, which is translated to protein from a single gene and is called a ____ ______. An important example is the increased expression of a splice variant in breast cancer causing a reduced survival time due to shorter time to tumor mets.

splice varient

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12. The majority of genomic DNA present within mammalian cells is not _______, with less than 2% of the haploid human genome coding for genes.

transcribed

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13. Areas of noncoding elements, which are highly conserved between mammalian species, are often associated with genes that code for ____________________

regulation of development.

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14. The one way flow of genetic information is not always the case. What is the enzyme that can generate a DNA sequence from and RNA template? What is the best described reverse transcriptase in mammalian cells and why is it thought to be important?

-Reverse transcriptase
-Telomerase, implicated in aging and oncogenesis b/c it is responsible for preventing the shortening of the telomere length and its expression is a near universal marker of malignancy

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15. Segments of DNA sequence that are transcribed into mRNA are termed _______. Its position and the start of the gene are identified by a sequence upstream termed the _______.

transcription units
promoter

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16. Genes such as ribosomal proteins and histones have a common function between different cells and thus are constitutively expressed between different cell types and are called ______ genes.

housekeeper

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17. What is epigenetics? What are some of the mechanisms by which it occurs? Give an example in dogs.

-Methods other than DNA sequence that control differential expression in different cell types within an individual
-Via DNA methylation and histone acetylation
-Hypomethylation is associated with transcriptional activity and has been implicated in the neoplastic transformation of cells and has been identified in canine neoplasia such as lymphoma

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18. What are mutations called that don’t affect the fitness of an individual?

-Neutral mutations

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19. What is a haplotype?

-When a set of alleles that are closely linked at a particular locus and they are inherited together, each different set is termed a haplotype

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20. What is the most common type of mutation? What are other examples.

-Most common is a single nucleotide polymorphism, or a point mutation
If it changes a protein sequence or length it is called a nonsynonymous mutation
-A missense mutation results in a change to an amino acid codon, which may alter the protein structure
-A nonsense mutation is when the mutation may replace the normal amino acid codon with a stop codon leading to termination of the protein sequence
-A synonymous mutation changes the sequence but not the amino acid
-The deletion or addition of a single or multiple base pair sequence will change the frame in which the sequence is read by RNA polymerase and is termed a frame shift mutation

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21. What is genetic linkage?

-The tendency to inherit together two or more alleles at different loci on the same chromosome more frequently than would be expected by independent assortment.

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22. What is linkage disequilibrium?

-The association of alleles at different loci, but not necessarily on the same chromosome, at greater frequency than would be expected by random chance.

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23. What are some ways of detecting mutations?

-Use of restriction nucleases which are bacterial enzymes that cut the DNA double helix at restriction sites and identify mutations resulting in loss or gain of a restriction site.
-DNA sequencing

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24. What is the purpose of a gene knockout experiment?

-They involve the insertion of a mutated (nonfunctioning) gene into a vector, which is then inserted into embryonic stem cells, leading to offspring with the gene knockout. This is the gold standard for determination of the effect of the loss of a single or both copies of a gene, or the mutation of a gene on an organism.

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25. What enzymes are responsible for the posttranslational modification of a protein by the addition of a phosphate group? What does this phosphorylation do functionally?

-Kinases
-Causes the protein to interact with other proteins recognizing the phosphorylated domain and is commonly associated with cell signaling

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26. What are examples of tests utilizing proteomics in veterinary medicine?

-Western blot, immunohistochemical staining, ELISA, mass spectrometer

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27. What is pharmacogenomics?

-The study of the interaction of genetic variation with response to a drug, be that efficacy or toxicity

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1.) What is a biomarker, according to the NIH?

a. Characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to therapeutic intervention

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2.) Where is the greatest proportion of cartilage in the body (which makes specific OA biomarker development difficult)?

a. Spine and respiratory system

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3.) What does the Dimethylmethylene Blue (DMMB) assay measure and how does it work?

a. Measures intact GAG chains via colorimetric assay to the insoluble precipitate formed by DMMB and intact GAG chains