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106 Cards in this Set
- Front
- Back
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How does the T2 virus infect E.coli? What is left behind on the exterior of the cell?
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- injects its genes into the cell and directs the production of new virus particles
- protein coat of original parent virus ("ghost") |
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Which experiment supported that DNA, not protein is the genetic material? Explain it.
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- Hershey-Chase experiment
- virus' DNA labelled with radioactive P, protein with S - radioactive protein found in ghosts and radioactive DNA found in cells |
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Which experiment confirmed that DNA replication is a semi-conservative process?
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Meselson-Stahl
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What is the central dogma?
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DNA --> RNA --> Protein
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Which method can be used to observe oxygen levels in the brain?
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Positron Emission Tomography
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Describe the experiment that discovered how many bases act as a codon and specify an amino acid.
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- 1, 2, and 3 base deletions
- only 3 base deletion produced a functional protein - 1 and 2 base deletions caused a shift in the reading frame |
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How many codons are there and how many amino acids do they code for?
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64, 20
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What is the start codon? Which amino acid does it code for?
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AUG, methionine
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What are the 3 stop codons?
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UGA, UAA, UAG
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The genetic code is redundant. What does this mean?
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More than one codon codes for each of the 20 amino acids. Helps to prevent mutation.
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The genetic code is unambiguous. What does this mean?
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one codon never codes for more than one amino acid
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DNA replication is very accurate. What is the average rate of error?
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less than one mistake per billion bases
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Which enzyme can proofread after synthesis is complete and how can it do this?
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DNA polymerase III. Acts as an exonuclease that removes deoxyribonucleotides from DNA
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How can UV light cause a kink in the DNA strand?
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excites bonds, covalent bonds switch and bind, can cause thymine dimers
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How can you repair dimers?
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nuclear excision repair
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What are some medical implications of cross-linking agents?
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- fight cancer by preventing replication
- can treat psioriasis |
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Explain nucleotide excision repair.
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- system recognizes damage
- enzymes remove single-stranded DNA - complimentary DNA strands acts as template for resynthesis - DNA polymerase fills in gaps in 5'-3' direction - DNA ligase links new and old nucleotides |
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Name the rare autosomal recessive disease characterized by the development of skin lesions.
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XP (Xeroderma pigmentosum)
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What causes XP?
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- mutations of one of several nucleotide excision repair systems
- cells cannot repair DNA damagect by UV radiation |
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How many times could the DNA from all the cells of your body stretch from McMaster to the moon and back if it were lined up end to end?
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1000s of times
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How much exposure does an Airport Body Scanner deliver? What is this dose equal to?
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- 0.05 uSv
- 2 mins of flying at 30 000 ft/ half a banana |
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What are introns?
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Non-coding regions of RNA
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What occurs during RNA processing?
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- introns removed
- ends receive a cap and a poly A tail |
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Inside ribosomes, mRNAs are translated to proteins via which intermediary molecules?
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tRNAs
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During transcription in bacteria, mRNA is synthesized by _________ which synthesizes the _________ strand.
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RNA polymerase, template strand
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What are the three phases of transcription in bacteria?
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initiation, elongation, termination
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What is a holoenzyme? Give an example.
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- composed of a core enzyme and other required proteins
- synthesizes first step of transcription (initiation) in bacteria Ex. prokaryotic RNA polymerase |
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What tells RNA polymerase where to bind and when to start synthesizing RNA for the initiation phase of transcription in bacteria?
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sigma subunit
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In which direction does RNA polymerase move along the template strand during elongation of transcription?
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5'-3'
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How is the end of transcription signaled?
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termination phase: RNA polymerase encounters transcription termination signal on template, signal causes hairpin to form which causes RNA polymerase to release
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Which specific sections of DNA iniate transcription of bacterial genes and where are they found? What recognizes them?
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- promoters
- 10 and 35 bases upstream on non-template strand - sigma |
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What opens up the double helix in bacteria?
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sigma
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The template strand in bacteria is threaded through _________
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the RNA polymerase active site
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How does RNA polymerization begin?
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ribonucleoside triphosphate (NTP) pairs with a complementary base on DNA template strand
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How is a Philadelphia chromosome created?
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Translocation between 9 and 22
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What does FISH stand for?
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Fluorescence In Situ Hybridization
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What does BCR stand for? What chromosome is it on?
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Breakpoint Cluster Region, 22
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What does ABL stand for? What chromosome is it on?
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Abelson Tyrosine Kinase, 9
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How does Gleevec help CML patients?
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prevents phosphorylation by tyrosine kinases (BCR & ABL)
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What is a G banding karyotype?
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GC rich regions are darker
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How is transcription in eukaryotes initiated?
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- by basal transcription factors which math RNA polymerase with appropriate promoter region
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What are the 3 types of RNA polymerase found in eukaryotic cells and what does each transcribe/code for?
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- RNA pol I = rRNA
- RNA pol II = proteins - RNA pol III = tRNA |
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How are introns removed?
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by splicing
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How is a spliceosome formed and what is its function?
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- by small nuclear ribonucleoproteins (snRNPS)
- catalyzes splicing reaction of introns from primary RNA transcript |
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What is the purpose of adding a 5' cap to RNA transcripts?
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recognition signal for translation machinery
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How is the amount of protein made maximized in prokaryotes?
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- transcription and translation tightly coupled due to lack of compartmentalization
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What does the P site in a ribosome hold?
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the tRNA with the growing polypeptide chain attached
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Which site holds a tRNA that is about to exit the ribosome?
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E site
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Which experiment lead to the discovery that there are 3 RNA polymerases?
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alpha-amanitin from death cap mushrooms at high and low concentrations
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What is a point mutation?
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single base change
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What is a missense mutation?
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- change in amino acid sequence of the protein has occured
- deleterious: reduce fitness |
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What are silent mutations?
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- do not change amino acid sequence
- neutral: do not affect fitness |
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What is the benefit of carrying the sickle trait?
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malaria resistance
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What is polyploidy?
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change in # of each type of chromosome present
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What is aneuploidy?
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addition or deletion of a chromosome
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How big is an X chromosome?
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- slightly smaller than blood cell
- larger than bacteria - larger than mitochondria |
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What is inversion?
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- chromosome level mutation
- chromosomal segment detaches, flips and reattaches to chromosome |
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What is translocation?
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chromosomal segment detaches and becomes attached to a different chromosome
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Which type of inversion does not involve the centromere?
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paracentric (as opposed to pericentric)
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What is a dicentric chromosome?
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- has two centromeres
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How can a dicentric chromosome assay be useful?
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To determine how much radiation you got.
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What causes an XX male?
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SRY (sex determining Y gene) translocated to X chromosome
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How can GFP (Green Fluorescent Protein) help us learn more about radiation-induced cancer?
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DNA instructs cell to produce the GFP attached to the RAD51 protein
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Name and describe the three mechanisms of gene expression regulation.
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- transcriptional control: slow but efficient
- translational control: allows a cell to quickly change when proteins are produced - post-translational control: most rapid response but energetically expensive |
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Which population is more likely to abort a child missing two fingers?
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public
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Which population is more likely to abort a with Down's Syndrome?
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doctors
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Which population is more likely to abort a child that will develop cancer in their early 30s?
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public
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Which population is more likely to abort a child with low IQ?
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about equal (between public, doctors and ethicists)
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Would the majority of people rather know or mnot know if they will develop a disease later in life?
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about equal
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PCR requires primers. Differentiate between the two primers.
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- one is complementary to a sequence on one strand, upstream of target
- other is complementary to a sequence on the other strand downstream of target - they both bind to a single-strand target |
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During PCR, the primers bind and allow which enzyme to work?
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DNA polymerase
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What are the three steps of PCR?
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denaturation, annealing, extension
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Describe the steps of PCR, including temperatures.
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- denaturation occurs at 95, bonds break, strands separate
- at ~60, primers form H bonds with single strands - 72 = optimal temp for taq polymerase to synthesize the complementary DNA strand using dNTPs - primers provide 3' OH end - amout of DNA doubles each time |
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What percentage of people are hypersensitive to radiation?
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5-10 %
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What are some adverse effects of radiotherapy?
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- erythema
- fibrosis - loss of organ function |
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What was the cobalt bomb?
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grand-daddy of all the radiation therapy machines found in modern cancer facilities
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What is stereotactic surgery?
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lienar accelerator, brain tumour treatment
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How many grey can the average person withstand?
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1/2 a grey
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How many grey are required to kill tissue?
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2
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What percentage of men over 85 have some degree of prostate cancer?
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100%
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What is a PSA test? What are normal and high levels?
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- measures the level of PSA in the bloodstream
- normal: 0-4 ng/ml - high: 20+ ng/ml |
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What did the study involving radiation-induced apoptosis as a tool to predict radiation sensitivity find?
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- small intravariation
- large intervariation |
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What is the normal size of a prostate?
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walnut/squash ball
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What is the benefit of Intensity Modulated Radiation Therapy (IMRT)?
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you can avoid radiating places you don't want to treat
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What are STRs? What types are there?
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- simple tandem repeats
- small sequences repeated down the length of a chromosome - microsatellites/simple sequence repeats: repeat 1-5 bases - minisatellites/VNTRs: about 6-500 bases |
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Why are micro and minisatellites used as markers for DNA fingerprinting?
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high variation among individuals
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What percetage of forensic DNA case work consists of direct indentification?
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>75%
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What are the three main types of forensic DNA markers?
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autosomal, mitochondrial, Y-chromosome
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What are the autosomal DNA markers?
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- VNTRs
- SNPs - STRs |
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Describe the process used when VNTRs are being analyzed?
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- DNA digested
- analyzed by Southern hybridization |
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Which process is used when STRs are being analyzed?
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PCR
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Which genes are analyzed by codis?
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3 4 5 7 8 13 18 21
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What does CODIS stand for?
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Combined DNA Index System
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What does COI stand for?
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convicted offender index
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What does CSI stand for?
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Crime Scene Index
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What percentage of conceptions have serious genetic errors?
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>70%
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Who makes more errors, mother or father? Who more molecular errors?
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mother, father
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What percentage of eggs have a chromosomal error/sperm are abnormal?
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~ 20%
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What are 3 significant changes affecting human reproduction due to medical advances?
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- increased reproductive fitness
- increase in genetic disease treatment - prenatal identification and replacement of affected conceptions |
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Name 5 methods of prenatal diagosis.
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serum screening, ultrasonography, chorionic villus sampling (CVS), amniocentesis, cordoncentesis
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What percentage of pregnancies are lost?
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over 60%
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How are Belgian Blue cows created?
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myostatin gene modification
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What are the 3 types of DNA repair?
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error free, apoptosis, error prone
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How does information flow in a cell?
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DNA-->mRNA--> Proteins
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Which proteins regulate apoptosis?
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BcH2 and BAX
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What causes an XY female?
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SRY gene is missing
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