Chapter 16 Multiple choice questions

What is the difference between forward and reverse genetics? Select all correct answers.

In forward genetics we examine mutant phenotypes and try to identify the causative variant

In reverse genetics we create a mutant and examine its effect on a phenotype

Reverse genetics means going from genotype to phenotype while forward genetics goes from phenotype to genotype

Reverse genetics starts from the assumption that genetic effects cannot be reversed

Why are embryonic stem cells needed for genetic engineering? Select all correct answers.

They provide an endless supply of genetic material

They can develop into an entire organism

Homologous recombination is so inefficient thousands of cells are needed to obtain the correct targeting

Unlike other cells they will accept exogenous genetic material and can thus be engineered

What is the difference between homologous and non-homologous recombination? Select all correct answers.

Homologous recombination results in the introduction of genetic material at a specific DNA locus, whereas non-homologous recombination occurs anywhere in the genome

Homologous recombination can happen when the sequence of the exogenous DNA matches the sequence of the target. That is not necessary for non-homologous recombination

Homologous recombination refers to the recombination between a pair of identical chromosomes, and non-homologous recombination to recombination between non-homologous chromosomes

Homologous recombination occurs during reproduction, but non homologous recombination can occur at any time during development

What is the function of CRISPR? Select all correct answers.

It functions to prevent phage attack

It is part of an immune system for bacteria

It is a system molecular biologists designed to engineer changes in DNA

Its function is to mutate the DNA of infected cells

Why use CRISPR rather than homologous recombination to engineer mutations? Select all correct answers.

CRISPR works in any organism

CRISPR is a quicker way to introduce mutations

CRISPR can efficiently and quickly engineer allow you to precisely rewrite a long piece of DNA sequence

CRISPR is far more efficient in cutting DNA than homologous recombination

What are the possible outcomes if you knock out a gene in a mouse? Select all correct answers.

A dead mouse

Nothing much wrong with the mouse

A specific effect on behavior

A very sick animal

What are the effects of constitutive mutations on mouse behavior? Select all correct answers.

The effects of a genetic knockout on behavior are quantitative

The phenotype depends on the mouse strain in which it is measured

The effects are pleiotropic

The effect sizes are relatively small

What makes a neuron special? Select correct answer.

Neurons join together to form a seamless network of protoplasm which conducts electricity throughout the nervous system

Neurons have a specialized nucleus to generate the proteins needed for synaptic function

Neurons possess synapses and dendrites

Neurons have a transcriptional apparatus that is specially designed to generate neurotransmitter receptors

How do neurons convey information through the nervous system? Select all correct answers.

They conduct electricity

Information is transmitted through a neuronal code

They exchange information at specialised structures called synapses

The neuron's nucleus transmits information via RNA

What is long term potentiation (LTP)? Select all correct answers.

LTP is a way for the cell to encode memory in a digital format

LTP stores memories in an analogue format

LTP is a cellular phenomenon that explains how cells that wire together fire together

LTP is a sustained increase in synaptic transmission following electrical stimulation to a neuronal pathway

What does the NMDA receptor do? Select correct answer.

The receptor responds to GABA to inhibit neuronal depolarization

The receptor opens a channel to allow magnesium into the cell and hence initiate a cellular signalling pathway

The receptor is a molecular coincidence detector

The receptor is where memories are stored

What evidence supports the hypothesis that LTP is involved in spatial memory? Select all correct answers.

Genetic knockout of CAMKII impairs spatial memory in the water maze

Pharmacological inhibition of the NMDA receptor impairs spatial memory in the water maze

Mutations of many components of the postsynaptic density impair both spatial memory and LTP

Any mutation that disrupts neurotransmission disrupts both LTP and spatial memory

What does CREB do? Select all correct answers.

CREB mutations disrupt short term memory

CREB is a transcription factor that regulates the expression of many other genes

CREB acts on the synapse to alter neurotransmission, and thus provides an explanation for synaptic plasticity

CREB is a memory gene in mice, flies and sea slugs

How does the CRE-LOX system for making inducible mutations work? Select correct answer.

Injection of an antibiotic in CRE-LOX mice creates a mutation in a specific gene

Over-expression of the CRE recombinase will generate a mutation in a gene of interest

LoxP sites flanking a gene of interest are the target of the Cre recombinase, which is only expressed in a subset of cells

A LOXP enzyme combines with a Cre recombinase to generate knockouts of genes in tissues of interest

What are genetically encoded reagents? Select all correct answers.

They include designer receptors exclusively activated by designer drugs, or DREADD for short

They are genetically engineered reagents that have the power to turn cell activity on or off

They refer to reagents that synthesize genes

They include channelrhodopsins that can be used render neuronal depolarization and repolarization sensitive to light

How does the chromosomal rearrangement on chromosome 16p cause autism? Select correct answer.

Its action is due to the disruption of the serotoninergic transmission throughout to the brain

The mutation interferes with oxytocin receptors in the nucleus accumbens

It influences social activity by altering the function of a subset of serotoninergic neurons active in the nucleus accumbens

The mutation has a specific effect on midbrain inhibitory activity

Are there examples of genes that are master regulators of behavior? Select all correct answers.

No gene acts in isolation so it makes no sense to talk about a master regulator behavior

Some protein hormones can modulate neuronal circuits and thus come close to acting as genes whose function is to regulate behavior

Serotonin, glutamate and dopamine are all good examples of neuropeptides that regulate behavior

Galanin is an example of a master regulator of behavior

Can genetic strategies identify key molecules involved in the regulation of behavior? Select correct answer.

Behavior is highly polygenic and therefore it is impossible to identify key regulators

Optogenetic regulation of behavior in awake freely-behaving mice demonstrates that there are genes that regulate behavior

Experiments with inducible mutations and genetically encoded reagents have begun to uncover specific effects of genes on behavior

Only when we have complete control over cellular activity in the brain will we be able to understand how genes control behavior

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