Group I introns are remarkable because:
A: They are spliced by external RNA molecules without protein involvement.
B: They are spliced by protein molecules in the absence of external RNA molecules.
C: They are autocatalytic.
D: They are only present in mitochondrial and chloroplast genomes.
A: They are spliced by external RNA molecules without protein involvement.
B: They are spliced by protein molecules in the absence of external RNA molecules.
C: They are autocatalytic.
D: They are only present in mitochondrial and chloroplast genomes.
C
举一反三
- Regardless of its strength, the binding of a protein to other biological molecules always shows great _________: each protein molecule can bind to just one or a few molecules out of the many thousands of different molecules it encounters.
- Which of the following signaling molecules could be directly activated by Ca ion binding? A: cAMP B: Calmodulin C: Protein kinase A D: Protein kinase B E: Protein kinase G
- β-turns in protein molecules belong to the protein's hierarchical structure? A: Primary structure B: Secondary structure C: Tertiary structure D: Side chain conformation
- Each protein normally folds into a single stable conformation. This conformation, however, often changes dramastically when the protein interacts with other molecules in the cell.
- Moisture in food can be divided into "bound water" and "free water" according to different properties. Which of the following is not bound water? A: The first layer of water molecules adsorbed to glucose molecules B: Water molecules with unpaired electrons entering the outer empty orbits of sodium ions C: Water molecules adsorbed in capillaries in food tissue D: Water molecules bound to the negative ion of glutamic acid on the protein peptide chain
内容
- 0
Which of the following is NOT extracellular signaling molecules? A: Glucagon B: Epinephrine C: G protein D: Dopamine E: Angiotensin II
- 1
Many—if not most—protein molecules are _______: they can adopt two or more slightly different conformations, and their activity can be regulated by a shift from one to another.
- 2
tRNA molecules are synthesized without the need for intermediary mRNA.
- 3
According to the scientists, life came from ___________. A: combination of energy and biochemical materials B: combination of nucleic acid and amino molecules C: nucleic acid molecules D: amino acid molecules
- 4
Compounds composed of molecules (molecular compounds) usually contain only elements.