molecular and cellular neurobio exam 1

Which observation was central to Ramón y Cajal's neuron doctrine?

Neurons are independent cells that make specialized contacts with other cells

Which neuronal compartment is considered the principal receptive pole of most neurons?

Soma and dendritic tree

Where are sodium action potentials typically initiated in a neuron?

Axon initial segment

Which feature most clearly distinguishes a typical dendrite from an axon?

Dendrites often taper and may contain numerous spines

Which statement about neuronal microtubule organization is correct?

Axonal microtubules are uniformly oriented with their plus ends toward the terminals

Why can dendrites synthesize some proteins locally?

They contain ribosomes, selected mRNAs, and translational machinery

What is the proposed function of “zip-code” sequences in neuronal mRNAs?

They target specific mRNAs to particular subcellular locations

Why may activity-dependent local protein synthesis near a dendritic spine be functionally important?

It permits individual synapses to modify their molecular composition and strength

What is a major advantage of Patch-sequencing for neuronal classification?

It relates gene-expression profiles to electrophysiological and morphological properties of individual neurons

Why is transcriptomic information alone considered insufficient for defining every neuronal cell type?

Neuronal identity also involves morphology, physiology, connectivity, spatial context, and other molecular features

A vesicle carrying newly synthesized membrane proteins from the soma toward an axon terminal would primarily undergo:

Fast anterograde transport

Which molecular motor is most strongly associated with plus-end-directed anterograde transport in axons?

Kinesin

Which cargo would most likely undergo retrograde axonal transport toward the soma?

Internalized neurotrophin–receptor complex

Why can cytoskeletal proteins exhibit a low average rate of “slow” axonal transport even though molecular motors themselves move rapidly?

They repeatedly undergo rapid movements separated by long pauses

Why are mitochondria preferentially retained at axon initial segments, nodes of Ranvier, and synapses?

These sites have particularly high metabolic demands

During the withdrawal reflex produced by a painful stimulus to the right foot, what occurs on the stimulated side?

Flexor motoneurons are activated and extensor motoneurons are inhibited

A motoneuron sends a recurrent axon collateral to an inhibitory interneuron, which then inhibits that same motoneuron. This arrangement is an example of:

Recurrent inhibition

In the spinothalamic pathway, neurons projecting from the spinal cord toward the thalamus:

Cross the midline and ascend in the anterolateral white matter

Selective ablation of Mrgprd+ nociceptive neurons in the experiments described in Chapter 1 produced the strongest deficit in behavioral responses to:

Noxious mechanical stimuli

Which observation provides strong evidence that a population of neurons functions as an engram?

Silencing neurons active during memory encoding impairs later memory expression