17 notecards = 5 pages (4 cards per page)
What makes up the protein component of a nucleosome?
Two tetramers of histone proteins
What is the first order of chromatin packing?
Coiling around nucleosomes
The second order of chromatin packing occurs when nucleosomes coil
together to form a fiber that is 300 nm in diameter.
Eukaryotic chromosomes contain two general domains that relate to the
degree of condensation. These two regions are ________.
called heterochromatin and euchromatin
Chromatin of eukaryotes is organized into repeating interactions with
protein octomers called nucleosomes. Nucleosomes are composed of which
class of molecules?
In contrast with euchromatin, heterochromatin contains more genes and
is earlier replicating.
Telomerase is an enzyme involved in the replication of the ends of
The genetic code is degenerate, meaning that a codon can specify more
than one amino acid.
A DNA sequence produces a mutant protein in which several amino acids
in the middle of the protein differ from the normal protein. What kind
of mutation could have occurred?
An addition and a deletion mutation
Which of the following statements about eukaryotic transcription is
A polycistronic mRNA may be transcribed if the gene products are used
in the same pathway or needed at the same time.
What is the initiator triplet in both prokaryotes and eukaryotes?
What amino acid is recruited by this triplet?
Introns are known to contain termination codons (UAA, UGA, or UAG),
yet these codons do not interrupt the coding of a particular protein.
Introns are removed from mRNA before translation.
When considering the initiation of transcription, one often finds
consensus sequences located in the region of the DNA where RNA
polymerase(s) binds. Which of the following is a common consensus
RNA polymerase is a holoenzyme composed of a five-subunit core enzyme and a sigma (σ) subunit. Different types of σ subunits aid in the recognition of different forms of bacterial promoters. The bacterial promoter is located immediately upstream of the starting point of transcription (identified as the +1 nucleotide of the gene). The promoter includes two short sequences, the –10 and –35 consensus sequences, which are recognized by the σ subunit.
The RNA polymerase holoenzyme first binds loosely to the promoter sequence and then binds tightly to it to form the closed promoter complex. An open promoter complex is formed once approximately 18 bp of DNA around the –10 consensus sequence are unwound. The holoenzyme then initiates RNA synthesis at the +1 nucleotide of the template strand.
The RNA-coding region is the portion of the gene that is transcribed into RNA. RNA polymerase synthesizes RNA in the 5′ → 3′ direction as it moves along the template strand of DNA. The nucleotide sequence of the RNA transcript is complementary to that of the template strand and the same as that of the coding (nontemplate) strand, except that the transcript contains U instead of T.
Most bacterial genes have a pair of inverted repeats and a polyadenine sequence located downstream of the RNA-coding region. Transcription of the inverted repeats produces an RNA transcript that folds into a stem-loop structure. Transcription of the polyadenine sequence produces a poly-U sequence in the RNA transcript, which facilitates release of the transcript from the DNA.