One of the ways smooth endoplasmic reticulum (ER) differs from rough endoplasmic reticulum is that rough ER is covered by
a. the extracellular matrix.
b. the Golgi apparatus.
c. ribosomes.
d. the cytoskeleton.
e. mitochondria.
Ans: c. ribosomes.
You might also like to view...
Angiosperm tracheids move water more rapidly from roots to shoots than gymnosperm tracheids
Indicate whether the statement is true or false.
Several rings of bone matrix in osteon cylinder. Contain collagen fibers that run in different directions in adjacent rings, withstands stress and resist twisting. Bone salts are found between collagen fibers.
What will be an ideal response?
A microbiologist is working with two genera of bacteria, A and B, to determine if cells are competent. Strains are grown under optimal conditions, and DNA fragments that carry the gene for green fluorescent protein are added to each culture at 20-minute intervals. Samples from each treatment are plated to nutrient agar and incubated, after which the plates are examined under an ultraviolet lamp. The microbiologist observes that all plates of bacteria B contain colonies that are fluorescent, while for bacteria A only the plates from stationary phase demonstrate fluorescent colonies. What can be concluded from these results?
A. Both bacteria A and bacteria B cells are competent. B. Competence in bacteria B is dependent on the phase of growth. C. Competence in bacteria A is constitutively expressed. D. Neither bacteria A nor bacteria B cells are competent.
Which of the following is true of transmembrane proteins?
a. The signal sequences are always cleaved off. b. They are always inserted with the amino terminus on the lumenal side and the carboxyl terminus in the cytosol. c. They cross the membrane only once. d. They usually have one or more helices spanning the membrane bilayer.