Lecture 6b Flashcards
How do we obtain transgenic animals?
We inject the genes into fertilized eggs, allowing for the genes to integrate into the chromosome.
Once we have several independently derived transgenic animals, what do we need to do?
We have to “select out” the animals that express the gene in a way that is what we wanted.
What is the b-lactoglobulin promoter?
A promotor that is only functional in mammary cells (which produce breast milk) so any gene products will be secreted into the milk.
If we wanted to express a human protein in animal milk, what do we need to do to the plasmid vector?
We need to insert the human hormone gene behind the b-lactoglobulin promotor in the plasmid.
If we wanted to express a human protein in animal milk, what do we need to do with the plasmid vector once it has the human hormone gene in it?
We take the plasmid vector and inject it into a sheep oocyte. We then implant this oocyte into a female sheep, which will give birth to transgenic sheep offspring.
If we wanted to express a human protein in animal milk, what do we need to do when we have the transgenic sheep offspring?
We obtain milk from the female transgenic sheep. The milk will contain the human hormone. Then, we can purify the hormone from the milk.
Where is Insulin produced?
B-cells in the pancreas
What does Insulin do?
Regulates the uptake of glucose into fat and muscle cells.
Who needs Insulin?
People with insulin-dependent diabetes cannot synthesize enough insulin. This is Type 2 diabetes.
What are sources of Insulin?
Human cadavers (expensive) and cows (expensive + possible allergies)
After fertilization, do the sperm and egg nuclei fuse right away? Why is this important?
No. This is important because we can microinject zygotes with CRISP-Cas before the gametes have fused and produce mutant mice.
Why do we need to secrete proteins from the cell?
Some of them have to carry out their function outside of the cell.
In bacteria and archaea, where do proteins need to be targeted to for secretion?
The plasma membrane
In eukaryotes, where do proteins need to be targeted to for secretion?
Endoplasmic reticulum membrane
In eukaryotes, describe how a protein is secreted?
If a protein that is being synthesized has an endoplasmic reticulum (ER) signal sequence, an RNA-protein complex called the signal recognition particle (SRP) binds to it. The binding of the SRP causes translation to pause and the SRP binds to a protein in the ER membrane next to a channel. The SRP lines up the amino acid chain with the channel, then the SRP lets go of the chain for it to travel through the channel.
What was discovered by accident with short double stranded RNAs?
Short double stranded RNAs could reduce the expression of a gene more effectively than annealing a short single-stranded RNA.
What was the relationship of the double stranded RNA to the mRNA?
One of the strands was identical to the mRNA and other was complementary to the mRNA.
What do we call the short double stranded RNAs?
Short interfering RNAs (siRNAs)
