BIO 102 Test 1

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The LAC operon of E.Coli consists of

1. A segment of DNA 2. A promoter 3. An operator 4. Three structural genes

When can gene expression be regulated?

1. Before transcription 2. During transcription and before translation 3. During translation 4. After translation

A prokaryotic cell can control the amount of enzymes it produces by

1. Blocking transcription 2. Hydrolyzing the mRNA after its made 3. Preventing translation of mRNA 4. Hydrolyzing the protein after translation

The genetic information of viruses can be

1. DNA 2. RNA 3. Single Stranded 2.Double Stranded

Alternative splicing helps to explain

1. The great variety in proteins 2. The differences in complexity among organisms 3. Why there are more mRNAs than human genes 4. The small number of genes in the human genome

Prokaryotes and Eukaryotes differ in transcription in that

1. There are 3 RNA polymerase in eukaryotes 2. Initiation of transcription is simpler in prokaryotes 3. Structural genes for a pathway are more likely to be clustered in operons in prokaryotes 4. Eukaryotic promoters may bind to several transcription factors

A point mutation is

A change in a single nucleotide of DNA

The type of mutation that stops translation of a protein results in a shortened protein because translation does not proceed beyond the mutation. This type of point mutation is

A nonsense mutation

An Operon is a what?

A promoter, operator, and a group of linked structural genes

Which of the following is a transcription factor?

A regulatory protein

Viruses are

Acellular

Which of the following mechanisms of post transcriptional regulation of gene expression can produce several different proteins from a single gene ?

Alternative splicing

The Anticodon is

Always present on a tRNA and is located in the middle

Mutations

Can arise from errors in DNA replication

Epigenetic changes

Can involve DNA methylation

The CRP-cAMP complex binds to the ____ of the operon

Close to the RNA polymerase binding site

A promoter is the region of ?

DNA that binds RNA polymerase

The Central dogma of molecular biology states that ________ is transcribed into ______ is translated into _______

DNA: RNA; Protein

In Eukaryotes, a DNA sequence, which can be distant from the gene, stimulates transcription when bound by an activator protein. This sequence is called a what?

Enhancer

Research on E.Coli indicates that

Glucose is the preferred energy source

Mutations are

Heritable changes in the nucleotide sequence of DNA that are passed on from one organism to another

How are inducible and repressible systems similar?

In both systems, the regulator molecules function by binding to the operator

When the operator is unbound by the repressor by its biding to the inducer, the binding of the CRP-cAMP complex _____ the binding of RNA polymerase at the promoter

Increases

In DNA, 5-methylcytosine

Is related to transcriptional silencing of genes

What effect does the presence of ample glucose have on the amount of lac operon transcription ?

It decreases the rate of transcription

In sickle-cell disease, one amino acid is substituted for another. This type of mutation is referred to as a _______ mutation

Missense

DNA is _____ charged due to the presence of a ______ group

Negatively; phosphate

What is the name of the type of mutation that results in a stop codon

Nonsense mutation

Bacteriophages are composed of what?

Nucleic acids and proteins

DNA is wound around histones to form structures that block both the invitation and the elongation steps of transcription. These structures are

Nucleosomes

The region of DNA in prokaryotes to which RNA polymerase binds to most tightly is the

Promoter

The genes that encode repressor proteins are

Regulatory genes

What structure of molecules brings tRNA and mRNA together?

Ribosomes

The most efficient means of regulating protein synthesis is by

Selective blocking of transcription

When an enhancer (a DNA consensus sequence) is bound, it

Stimulates transcription of a specific gene

The lytic life cycle of a phages results in

The bursting of a bacterium by a bacteriophage

In gel electrophoresis of DNA fragments

The fragments are separated on the basis of their sizes due to their differential ability to sieve through the pores of the gel

Which of the following statements about the lytic cycle is true

The host cell lysis

Ubiquitin forms a complex with proteins and then binds with ______, forming a sort of "molecular chamber of doom," where proteins are digested into small peptides and amino acids

The proteasome

A mutation of a sigma factor in a bacterium would most likely affect what?

The rate at which transcription is initiated

What happens during lysogengy?

The viral genome is integrated into the host's genome creating a prophage

Which of the following is the truth of both positive and negative gene regulation?

They involve regulatory proteins binding to DNA

RNA polymerase II by itself cannot bind to the chromosome and initiate transcription. It can bind to the chromosome and initiate transcription. It can bind and act only after regulator proteins called _______ factors have been assembled

Transcription

The process by which some phages may transfer DNA fragments from on bacterium to another is called what?

Transduction

Exons are

Translated

Why are most genetic disease rare?

Two parents probably do not carry the same recessive alleles

Damage to DNA can be caused by _________ absorbed by the thymine in DNA, causing interpose covalent bonds

Ultraviolet radiation in sunlight

Frame-shift mutations occur

With all insertions and deletions whose sizes are not multiples of three nucleotides

Nucleosomes disaggregate to allow transcription and then reaggregate

by the acetylation and deacetylation

To be activated, the CRP, an allosteric protein must first bind to what?

cAMP

The expression of the LAC structural gene is ____ when lactose is absent from the culture medium and is_____ when lactose is added because lactose binds to the ____ and inactivates it

low; high; lac repressor

Transcription factors are

proteins that bind to the DNA promoter sequence

The promoter in the LAC operon is

the region that binds to RNA polymerase


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