This sugar in RNA has one extra hydroxyl group compared to DNA’s sugar. 
What is ribose?
This enzyme synthesizes RNA from a DNA template.
What is RNA polymerase?
This RNA molecule carries amino acids to the ribosome during translation.
What is tRNA (transfer RNA)?
A cluster of genes under the control of a single promoter in prokaryotes is called a(n) ___.
What is an operon?
DNA wraps around these positively charged proteins to form nucleosomes, the first level of chromatin organization.
What are histones?
These bases pair via hydrogen bonds in DNA: adenine pairs with ___, and cytosine pairs with ___.
What are thymine and guanine?
The region of DNA where RNA polymerase binds to initiate transcription is called the ___.
What is the promoter?
Translation proceeds in this direction on the mRNA (from ___ to ___).
What is 5′ to 3′?
In the lac operon, when lactose is present, it acts as an ___ to remove the repressor from the operator.
What is inducer?
Proteins that bind to enhancers or silencers to affect transcription are called ___.
What are transcription factors?
In a DNA double helix, the two strands run in opposite directions. What term describes that orientation?
What is antiparallel?
After transcription in eukaryotes, this modification is added to the 5′ end of the mRNA.
What is the 5′ cap (a methylated guanine cap)?
This codon is the “start” codon for nearly all proteins.
What is AUG?
The trp operon is an example of a ___ operon (i.e. normally “on” but can be turned off).
What is a repressible operon?
The addition of methyl groups to DNA tends to ___ gene expression.
What is repress (or reduce)?
RNA differs from DNA in three main ways; state two of them.
What are
(i) RNA is single-stranded,
(ii) RNA has ribose (not deoxyribose),
(iii) RNA uses uracil instead of thymine?
These are noncoding sequences removed from pre-mRNA before translation.
What are introns?
Multiple codons can code for the same amino acid. This property is called ___.
What is redundancy of the genetic code?
This regulatory protein binds to a specific DNA sequence and blocks RNA polymerase when no inducer is present, preventing transcription of structural genes.
What is a repressor protein?
In eukaryotes, the presence of ___ is required for initiation of transcription.
What are transcription factors?
A purine base always pairs with a pyrimidine. Name one purine and one pyrimidine.
What are Adenine/Guanine (purine) and Cytosine/Thymine/Uracil (pyrimidine)?
Name the complex (or unit) that carries out the splicing of introns out of pre-mRNA.
What is the spliceosome?
A mutation that changes one amino acid to another is called a ___ mutation; one that introduces a stop codon prematurely is a ___ mutation.
What is a missense mutation; and what is a nonsense mutation?
In the lac operon, what are the roles of the genes lacZ, lacY, and lacA?
What is encode for the lactase enzyme?
This process can produce different proteins from the same gene by splicing the exons in different combinations?
What is alternative splicing?