Gene Expression 1
What is X-chromosome inactivation and why does it occur?
Dosage compensation/Barr body; to ensure that there aren't too many genes being transcribed.
What is recombinant DNA?
A DNA molecule made from two difference sources.
What is a transgenic organism? What attribute of the genetic code allows us to create transgenic organisms?
An organism that contains DNA from a different species.
The universal code of DNA.
How are bacteria and plants used to clean up the environment? What is the general term for these processes?
They're used to break down/metabolize pollutants.
Bioremediation
What are the basic concerns regarding transgenic crops? Are any of them scientifically substantiated at this point?
Allergies*, movement of genes into wild relatives, loss of biodiversity, and acquisition of resistance by weedy species
*Not scientifically substantiated
What is the role of ubiquitin and proteasomes in the post-transcriptional degradation of proteins? How can mRNA be degraded?
Ubiquitin marks proteins for destruction and the proteasomes destroy them.
Removal of cap and tail
What is the role of alternative splicing in posttranscriptional regulation?
Different proteins can be made for different locations/functions; i.e. 1234 in kidneys, 1356 in liver
How are algae used to manufacture biofuels? Why are biofuels better for the environment?
Lipids are extracted from algae for fuel
They use carbon that is already in the atmosphere
How does reverse transcriptase work, and what is the final resulting molecule called?
DNA made from copying mRNA is called complementary DNA (cDNA).
What is glucose repression and how does it influence the overall function of the lac operon?
Glucose binds to the repressor of the lac operon so that lactase is not made.
What is the role of nuclear pores in regulating translation? How do translation repressor proteins work?
They mediate the exchange of proteins and RNA.
They bind to the start of mRNA so ribosomes can't bind.
How is human insulin produced by bacteria?
It's produced in E. coli; they use mRNA from humans and reverse transcriptase to make usable cDNA
What is RT-PCR? How does it work? what is quantitative RT-PCR? What is its main application?
PCR is performed on cDNA made from mRNA; allows creation of recombinant DNA containing only exons
Using PCR to amplify the cDNA made from RT-PCR; the amount of cDNA can be measured by the machine
What does the Cre-Lox system allow genetic researchers to do in the study of gene function?
It allows the study of genes essential in development and gene deletion at specific times/in specific tissues.
A Cre enzyme targets genes flanked by Lox sequences and cuts them out.
How do small RNAs work? What is the difference between siRNA and miRNA?
They control gene expression post-transcriptionally by cutting up mRNA or stopping ribosomes.
siRNA is specific and and miRNA is general.
What is DNA fingerprinting? What are its applications?
Using short tandem repeats (STRs) to identify people; can be used to identify criminals, paternity, bodies
What are the benefits and drawbacks of herbicide-resistant and Bt crops? What are the specific attributes of each of these genetic modifications?
Herbicide: Resistant to glyphosphate (an herbicide), doesn't have to be tilled, only one herbicide needs to be used in crop fields, glyphosphate breaks down in the environment
Weeds can become resistant, nearby plants can cross pollinate
Bt Crops: Bacillus thurigiensis toxin introduced, kills insects that eat the plant
Kills insects which is bad for ecosystem
What does FISH stand for and how is this process used in medical applications?
Fluorescent in situ hybridization
Used to find cancer; a labeled DNA probe is mixed with DNA to find large deletions, insertions, duplications, or translocations.
Briefly describe how the immunoassay process works.
Immunoassays allow detection of a molecule through use of an antibody.
A well plate is coated with an antibody, then a sample is added, then a second antibody with a fluorescent marker is added so that a specific molecule in the sample can be detected.
Describe the basic function of the trp operon; what are its component, and how does it work?
It encodes genes for making tryptophan; if tryptophan is absent in the cell, the operon is not repressed and tryptophan can be made.
Operator - Where the repressor binds
Promoter - Where RNA polymerase binds
Operon - A set of genes plus an operator and promoter
Co-Repressor - Binds to the repressor (i.e. tryptophan)
What does PCR stand for and what is it? What are the three stages of PCR?
Polymerase chain reaction; produces millions of copies of a DNA sequence.
1. Denaturation (high temp)
2. Annealing of primers (low temp)
3. DNA synthesis (intermediate temp)
What are restriction endonucleases and how do they cleave DNA? Which type of restriction endonuclease is the most accurate and what kind of sites does it usually find and cleave?
They're enzymes that cleave DNA at specific sites
Type 2; palindrome sites
What is a "knockout" mouse and how are they developed? What is a "knockin" mouse?
A mouse with a gene knocked out/removed; they're made by editing the gene, adding it to embryonic stem cells, inserting the embryonic stem cells into an embryo and implanting the embryo into a surrogate mother, then crossing the heterozygous offspring to create mice that are homozygous for the knocked out gene.
A mouse with a gene inserted
List and briefly describe the different techniques used to genetically modify plant cells.
Electroporation: Electricity creates temporary pores/openings for DNA.
Physical Bombardment: Coated nanoparticles are fired at plant tissue.
Chemical Treatment:
Bacterial Transfer: Ti plasmid with transgene integrates into plant DNA.