NEUR 3044 TEST 2 QUESTION AND ANSWERS

Which of the following are true about animal research?

> animals are very similar to humans and share a lot of DNA sequences

> federal laws in the U.S. require animal research prior to human research

> animals are susceptible to many of the same diseases as humans

Which of the following are examples of stem cells in the nervous system

> radial glia

> neural progenitors

The following cells are found exclusively in the central nervous system:

> oligodendrocytes

> ependymal cells

> astrocytes

> microglia

Which two cell types share the basic function of creating myelin?

> oligodendrocytes

> schwann cells

Chromosomes (DNA) are duplicated during which phase of the cell cycle?

> s phase

Why are restriction points necessary in the cell cycle?

> restriction points check for favorable conditions. DNA damage or unduplicated DNA throughout different parts of the cell cycle to ensure complete and appropriate duplication of DNA prior to mitosis

The important features of stem cells are:

> stem cells are unspecialized, self-renewing, and able to differentiate into more specialized cells

What is the purpose of voltage-gated sodium channel inactivation?

> prevents back propagation of voltage-gated sodium channel inactivation

How do ion exchangers work?

> they do not use ATP, but instead use electrochemical gradients of other ions as an energy source

DNA methylation occurs on which of the following?

> cytosine

What is the main advantage of using a conditional knockout mouse instead of a constitutive knockout?

> conditional knockouts allow researcher to select the specific cell type the knockout occurs in, which may be necessary for the organism to survive and develop normally

Transgenic animals are defined as:

> an organism or cell of one species in which one or more genes of another species have been incorporated

What is gene editing and what is its approved purpose?

> the use of biotechnology to insert, delete, modify, or replace DNA in the genome of a living organism for the purpose of improving a crop/farm animal or correcting a genetic disorder

How is homology directed repair (HDR) useful in gene editing?

> researchers can use HDR to knock in a gene by target a specific sequence with Cas9 and provide a specially designed small DNA template for use in repair, which allows a specific sequence of DNA (transgene, edited, or repaired sequence) to be inserted as part of the double stranded break repair

Why might a protein function knockout (functional knockout) be a better choice than a constitutive knockout if you're studying a human disease?

> functional knockouts can have point mutations that closely resemble human disease allele variants, rather than removing the entire protein

Why aren't transmembrane proteins translated in the cytoplasm?

> transmembrane proteins have hydrophobic domains that but be translated directly into a phospholipid bilayer to fold correctly

> a signal sequence is translated at the beginning of a protein, to allow binding of the SRP, which ten moves the ribosome and mRNA complex to the ER for co-translational translocation

What is Cre recombinase?

> it is an enzyme from the P1 bacteriophage that catalyzes the recombination between two of its recognition sites (loxP)

According to this diagram, what is the resulting genotype of this mouse? Important information: MMTV is a promotor specific to the mammary glands.

> KrasG12D will be expressed only in cells of the mammary glands (conditional knock-in)

A protein that is co-translationally translocated at the ER could be destined for which of the following locations?

> secretion from the cell

> lysosome

Which of the following statements are TRUE about the plasma membrane?

> the plasma membrane is fluid

> the plasma membrane is composed of the same phospholipids found in the ER and golgi

> it's composed of amphiphilic phospholipids that create a bilayer

PCR requires cycling through several different stages. Which of the following are accurate descriptions of the stages of PCR?

> denaturing: heat to 95C to melt DNA strands

> extension: heat to 72C where taq polymerase is most active

Which of the following statements are true according to the central dogma of molecular biology?

> genetic information is converted into RNA through transcription

> RNA information is converted into protein by translation

> genetic information encoded in DNA is duplicated by DNA replication

How can viral vectors be useful in science?

> to insert foreign DNA or RNA into a host cell for research purposes

If you want to test a set of neurons in a specific region of the brain to see if they're necessary for a certain behavior, which optogenetic tool would be the best choice?

> halorhodopsin targeted to the neurons of interest

What happens to the acid hydrolases in the Golgi?

> they are bound to the M6P receptor in the trans golgi membrane

> they are post-translationally modified with the addition of mannose

> they are post-translationally modified by phosphorylation

Which of the following are true of targeted nucleases?

> can be used for gene silencing, deletion, insertion or correction

> they're enzymes that have restriction endonuclease activity

> include TALENs, CRISPR/Cas9 and Zinc finger nucleases

> specifically target selected sequences of DNA

The following statements about CRISPR/Cas9 are TRUE:

> it allows bacteria to identify prior infections by viruses to disarm it immediately in subsequent infections with the same virus

> Cas9 is an endonuclease that works like genetic scissors to cut specifically around the inserted viral genetic material

> it is the natural immune system of bacteria

Which of the following are key properties of ion channels, as described by Hodgkin and Huxley?

> ions move across the membrane at high rates

> ion channels must be selective

> ion channels must have a voltage sensor

How do voltage gated potassium channels select for K+ instead of Na+?

> the selectivity pore only stabilizes K+

> K+ is dehydrated, but amino acids in the selectivity pore are arranged to stabilize dehydrated K+

Explain how an error in the targeting of a specific acid hydrolase can result in human disease.

> an error in the targeting of a specific acid hydrolase can cause the function of the lysosome to be altered. typically, the lysosome is responsible for carrying out certain degradation functions such as autophagy, phagocytosis, etc. if someone has this type of error, lysosomal storage disease can develop, causing a toxic build up of materials inside the lysosome and ultimately harming the individual

A physician has an infant patient who is suffering from epilepsy. Genetic testing reveals a mutation in the DNA sequence for a voltage-gated potassium channel. This mutation appears to result in the VGKC opening later in the AP (at higher membrane voltage) than normal. Where specifically in the protein would you expect to see this mutation appear> What would you suggest has happened to the function of the protein? Why?

> i would expect the mutation to appear in the voltage sensor, which occurs in helix 4 of the protein. also, i would suggest that the mutation has caused a conformational shape change in the protein, causing the function to be altered as well. the shape change has led to the voltage sensor of the VGKC opening at higher membrane voltage, instead of the normal voltage.