BIOL-3301

What forms the backbone of a polynucleotide chain?

Alternating sugar and phosphate groups

What types of bonds are formed between complementary DNA bases?

Hydrogen bonds

What enzyme lays down the RNA primer during DNA replication?

Primase

DNA polymerase can only add nucleotides to which end of a growing strand?

3' end

What are the short fragments formed on the lagging strand during replication called?

Okazaki fragments

What is the function of the sigma subunit in bacterial RNA polymerase?

Promoter recognition and binding

What DNA sequence is commonly found in eukaryotic promoters?

TATA box

In bacteria

intrinsic termination of transcription involves what?

What sequences are removed from pre-mRNA during RNA splicing?

Introns

Exon/intron boundaries are typically characterized by which sequences?

5' GU and 3' AG

What modification is added to the 5' end of eukaryotic mRNA?

5' methyl guanine cap

What modification is added to the 3' end of eukaryotic mRNA?

Poly-A tail

What is the start codon in translation?

AUG (methionine)

What are the three stop codons in translation?

UAA

What site on the ribosome holds the growing peptide chain?

P site

What type of mutation is most severe?

Frameshift mutation

What effect does histone acetylation have on transcription?

Loosens chromatin and increases transcription

What effect does histone methylation usually have on transcription?

Tightens chromatin and decreases transcription

What molecule does miRNA target for destruction?

mRNA

How many Barr bodies are present in a cell with three X chromosomes?

Two

What RNA is translated within the cell?

mRNA

Which enzyme relieves supercoiling during DNA replication?

Topoisomerase

How many nucleotides code for one amino acid?

Three

What kind of mutation adds or removes a base pair and shifts the reading frame?

Frameshift mutation

Which end of the protein corresponds to the start of the gene?

Amino (N-terminal) end

Where does translation of secreted proteins occur?

On ribosomes bound to the rough endoplasmic reticulum

What type of sequence can be tens of kilobases away from the transcription start site but still regulate transcription?

Enhancer sequence

What does acetylation of histones lead to?

Relaxed chromatin and increased transcription

When is DNA replication carried out?

During S phase of the cell cycle

Which of the lac and trp operons are controlled by repressors modified by other molecules?

Both

When is the lac operon transcribed at the lowest levels?

When lactose is absent

When tryptophan is present

which regions of the trp operon leader form a stem-loop to terminate transcription?

What is required for DNA polymerase to start synthesis?

An RNA primer made by primase

What happens during RNA splicing in eukaryotes?

Introns are removed and exons joined by spliceosome

Which part of an mRNA sequence is not translated?

5' UTR and 3' UTR

What sequence in prokaryotes helps ribosomes recognize the start codon?

Shine-Dalgarno sequence

Which of the following modifies the lac repressor to allow transcription?

Lactose (allolactose)

Which of the following modifies the trp repressor to stop transcription?

Tryptophan

Which molecule coats and inactivates one X chromosome in females?

Xist RNA