BIO 140 CH 1: Exam 1

Structure of DNA and Genomes

Which of the following is not a key characteristic of genetic material?

A: Immediate degradation after use

According to Chargaffs rules, in doubled stranded DNA:

A: A = T and G = C

The sugar component of DNA nucleotides is

A: Deoxyribose

Phosphodiester bonds in DNA connect:

A: Sugar to phosphate between adjacent nucleotides

Which component is NOT part of the lac operon structural genes?

trpA gene

The LCR(locus control region) in the beta globin locus:

Regulates temporal expression of multiple globin genes

The main difference between the lac and trp operons is that:

Lac is inducible (off → on), trp is repressible (on → off)

What happens when both glucose and lactose are present?

Glucose represses lac operon via low cAMP (catabolite repression)

The CAP-cAMP complex functions as:

A positive transcription factor that increases RNA polymerase binding

The lac repressor is coded by:

lacl

Which of the following correctly describes the trp operon when tryptophan is absent?

Repressor inactive, transcription on 

The function of the operator in the lac operon is to:

Bind repressor protein and block transcription 

What kind of molecule is allolactose?

An inducer

In the trp operon, tryptophan acts as a:

Corepressor

Which of the following is a similarity between lac and trp operons?

Both involve repressors that bind operator sequences

The lac operon is repressible system?

False

Allolactose binds to the operator to activate transcription

False

The trp operon is an inducible system

False

The lac repressor binds to the operator in the absence of lactose

True

The lac operon produces enzymes that metabolize lactose

True

The trp operon is normally ”on”

True

The lac operon is normally “on”

False

The CAP-cAMP complex is active when glucose is low

True

The lacl gene encodes a repressor protein

True

The trp repressor requires typtophan to bind DNA

True

The lac repressor requires lactose to bind DNA

False

Eukaryotic enhances can function thousands of base pairs away from promoters

True

The LCR is unique to bacteria

False

Mutations in enhancer sequences can cause disease

True

The lac operon an deukaryotic transcription factor systmes both rely on protein-DNA interactions

True