Chapter 13: Translation and Proteins Flashcards
Biological polymerization of
amino acids into polypeptide chains.
Translation
This class of molecules adapts specific triplet codons in mRNA to their correct amino acids. (Adaptor hypothesis)
transfer RNA
Three consecutive ribonucleotides complementary to the
codon of the mRNA.
Anticodon
True or False. Electron microcopy reveals that the bacterial ribosome is about 40 nm at its largest dimension and consists of two subunits, one large and one small.
True
Composition of ribosome subunit.
- one or more molecules of RNA
2. ribosomal proteins
When the two subunits are associated with each other in a single ribosome, the structure is sometimes called?
Monosome
Reflection of the density, mass, and shape of ribosome subunits (RNA components and ribosomal proteins).
Svedberg coefficient (S)
Size of prokaryotic monosome.
70S particle (50S large subunit and 30S small subunit)
Size of eukaryotic monosome.
80S (60S large subunit and 40S small subunit)
True or False. Sedimentation coefficients, which reflect the variable rate of migration of different-sized particles and molecules, are additive.
False
Are part of the moderately repetitive DNA fraction and are present in clusters at various chromosomal sites. Part of the DNA that transcribes RNA.
rRNA gene (rDNA)
True or False. In humans, these gene (rDNA)
clusters have been localized near the ends of chromosomes
13, 14, 15, 21, and 22.
True
True or False. In humans, a gene cluster encoding 5S rRNA has been located on chromosome 1.
True
True or False. In pro and eukaryotic organisms, tRNAs are transcribed as larger precursors, which are cleaved into mature 4S tRNA molecules.
True
A number of nucleotides are unique to tRNA. These bases are called?
Modified base
True or False. Modified structures of tRNA are created after transcription of tRNA. (posttranscriptional modification)
True
True or False. The presence of modified bases enhances hydrogen bonding efficiency during translation.
True
This arrangement created a series of paired stems and unpaired loops resembling the shape of a clover-
leaf.
cloverleaf model of tRNA
The end of the tRNA molecule where the
amino acid is covalently joined to the terminal adenosine residue. All tRNA molecules possess this sequence.
CCA-3’
True or False. Shapes of the intervening loops may be recognized by the specific enzymes responsible for adding amino acids to tRNAs.
True
The tRNA molecules must be chemically linked to their respective amino acids. This process of called?
Charging
Charging of amino acid to the tRNA is mediated by what enzyme?
Aminoacyl tRNA synthetases.
True or False. Because of the ability of the third member of a triplet code to “wobble,” it is now thought that there are only 31 different tRNAs.
True
True or False. It is also believed that there are only
20 synthetases, one for each amino acid, regardless of the greater number of corresponding tRNAs.
True