Items 254-258

254. The elongate cellular projection labeled A is a

(A) flagellum
(B) nerve axon
(C) pseudopodium
(D) cilium
(E) microvillus

255. Structure labeled C is

(A) Golgi Apparatus
(B) pseudopodium
(C) cilium
(D) mcrovillus

256. Structures labelled C is

(A) Golgi Apparatus
(B) Perxisomes
(C) microtubules
(D) mitochondria
(E) secondary lyssomes

257. Organelles LEAST likely to found in the projection A are

(A) mitochondria
(B) intermediate filaments
(C) ribosomes
(D) microtubules
(E) membrane vesicles

258. Which of the following enzymes is LEAST likely to be present in projection A?

(A) protein kinase
(B) DNAase
(C) kinesin
(D) dynein
(E) protein phosphatase

ANSWERS AND TUTORIAL ON ITEMS 254-258

The answers are: 252-B; 255-D; 256-C; 257-C; 258-B. Tissue-culture microscope 3.7 is a transmission electron micrograph of neural tissue, showing a large axon (A) with its myelin sheath (B). The surrounding structures are axons and dendrites of other neurons, as well as portions supportive – or glial – cells. One of the most prominent membranous organelles are the mitochondria labelled (C) which produce the ATP required to power the various synthetic and motile events occurring in these cells. Nerve axons are long slender extensions reaching from the neuronal cell bodies (not shown) to the receptor cell (also not shown) receiving a signal from the nerve cell. The activation of a neuron cell body to the passage of a membrane depolarization that propagates along the nerve cell plasma membrane, as an action potential, to the axon terminus. Axons contain a variety of organelles, but – having no ribosomes (either free or bound to rough ER) – are unable to synthesize proteins. All proteins required for the establishment and maintenance of the axon are synthesized in the nerve cell body and carried to the nerve terminus by axoplasmic transport. Boom Mounted Microscopes Dual Arm type of microscope Boom Mounted Microscopes with Mobile Floor Stand Examine the transmission electron micrograph below (Tissue-culture microscope 3.8). It shows the apical aspect of an epithelial cell with certain structures labelled. For each numbered items, select the lettered structure that best corresponds.