Chapter 7

Repressors

bind or do not bind to the operator depending on their shape (conformation) and are involved in negative control

A new field has emerged which employs the power of computers to store, retrieve, and analyze DNA sequence data called _____

bioinformatics

Negative control means a regulator molecule is

bound, and transcription is inhibited OR removed, and transcription starts

GCCCAAAG is a molecule of

cannot tell as written

The placement of the amino acid during translation is determined by the

complementarity of the codon-anticodon

Enzymes involved in essential metabolic pathways, such as glycolysis, are usually _____

constitutive

Translation occurs in the _____ of eukaryotic protozoa and bacterial cells

cytoplasm

In eukaryotes, which DNA sequences are spliced together to encode functional proteins?

exons

Bacteria use two-component regulatory systems to detect and react to changes in the _____

external environment

Adenine binds to thymine via three hydrogen bonds

false

During DNA replication, why are proteins necessary?

Primers provide DNA polymerase with the 3' end needed for synthesis

What enzyme binds to a DNA promoter region to initiate transcription?

RNA polymerase

During transcription, RNA polymerase synthesizes _____ from a _____

RNA; DNA

In transcription, _____ is synthesized, while in translation, _____ is synthesized

RNA; protein

What structure is indicated by: 10A, 15T, 3G, 7C

Single-stranded DNA

Catabolite protein (CAP) is needed for which of the following functions?

Transcription of the lac operon

During what process is the information in mRNA used to synthesize a protein?

Translation

_____ is the process of decoding the information carried by mRNA to synthesize a protein

Translation

Antisense RNA is the complement of the plus strand and may be useful in inhibiting translation

True

Quorum sensing allows bacteria to detect population density, facilitating coordinated activities such as biofilm formation

True

The lac operon is an inducible operon

True

The minus strand of DNA serves as the template for RNA production

True

several codons code for the same amino acid, which is called the redundancy of the code. Because of redundancy, the genetic code is said to be degenerate

True

The mechanism that cells use to detect and react to changes in the external environment is called _____

a two-component regulatory system

An _____ is a regulatory protein that facilitates transcription by enhancing the ability of RNA polymerase to initiate transcription

activator

During the elongation phase of translation, peptide bond form between _____

amino acids

A tRNA had an _____ which is complementary to the codon of the mRNA

anticodon

The two strands of the DNA helix are _____, meaning they are oriented in opposite directions

antiparallel

Activators

are involved in positive control AND are allosteric proteins.

The complete set of chromosomes and genes in an organism is referred to as the _____

genome

The simultaneous regulation of many bacterial genes is

global control

Repressor proteins block transcription. If the shape of the repressor is changed so that it cannot bind to the operator, _____ occurs and transcription progresses

induction

Some segments of the precursor mRNA in eukaryotes are non-coding and are called

introns

The P-site

is the peptidyl site on the ribosome

Signal transduction

is the relay of information about conditions outside a cell to inside the cell

Which is true about prokaryotic (bacteria) RNA polymerase

it is used during transcription

The lac operon only functions when _____ is present in the medium but _____ is absent from the medium

lactose; glucose

The DNA strand that is synthesized discontinuously during DNA replication, forming Okazaki fragments, is called the _____ strand

lagging

Cells can regulate the level of protein production by controlling the level of _____

mRNA

Which type of RNA is translated during protein synthesis?

mRNA

_____ is transcribed from a DNA template and translated during protein synhesis

mRNA

Identify the three different types of RNA use in gene expression

mRNA, tRNA, rRNA

The regulatory protein

may inhibit or enhance transcription

Proteins are synthesized by translating _____ RNA

messenger

A prokaryotes transcript that carries one genes is called _____ RNA while a transcript that carries multiple genes is called _____ RNA

monocistronic polycistronic

A single mRNA codon codes for _____ animo acid

one

A set of regulated genes transcribed as a single mRNA molecule, along with the sequence that control its expression, is called an _____

operon

The set of genes in bacteria that are linked together and transcribed as a single unit is referred to as an

operon

To initiate replication of a DNA molecule, specific proteins must bind to a specific DNA sequence called the _____

origin of replication

The _____ strand of DNA contains the same order of nucleotides as the corresponding RNA transcripts

plus (+)

Duplication of a chromosome before cell division is called DNA _____

replication

Which of the following initiates translation?

ribosomes assemble on the mRNA

DNA replication is

semiconservative

DNA replication is said to be _____, because they newly made double helices are composed of one strand from the original molecule and one newly synthesized strand

semiconservative

Two-component regulatory systems that microorganisms use to monitor their environment consists of which two proteins?

sensor protein and response regulator

Bacterial cells can control which genes are transcribed by producing various types of _____

sigma factors

A _____, which is a characteristic series of amino acids at one end of a protein, tags that protein for transport

signal sequence

Elongation of the polypeptide terminates when the ribosome reaches a _____ codon, which is a codon not recognized by a tRNA

stop

Microorganisms must adapt rapidly to changes in their environment in order to _____

survive

Which molecule carries an anticodon

tRNA

The region of DNA that signals the end of an RNA transcript is the _____ sequence

termination

The process of transcription stops when the RNA polymerase reaches a _____

terminator

Metagenomics is defined as _____

the analysis of the total microbial genomes in an environment

When E. coil is grown in medium containing both glucose and lactose

the cells grow fastest initially when glucose is available

In a carbon catabolite repression (CCR) regulatory mechanism called inducer exclusion, _____

the lactose transporter protein is locked in a non-functional protein, preventing the cell from taking up lactose

The two strands of DNA are complementary; this means that an adenine base (A) on one strand is paired with _____ on the other, and the cytosine (C) is paired with _____

thymine (T); guanine (G)

The genetic code is nearly universal

true

Select the enzymes that function in DNA replication.

-Helicase -DNA polymerase -Primase -Ligase

Which is the correct order of events in transcription?

-Initiation -Elongation -Termination

The subunits of the 70S ribosome are _____

50S and 30S

What are the roles of ribosomes in tranlation?

-aligning amino acids and catalyzing formation of peptide bonds between them -ribosomes detect sequences that indicate where translation should start and finish

How does RNA differ from DNA?

-in RNA, uracil replaces thymine -RNA is usually singe-stranded

The two type of RNA used in RNA interference (RNAi) are _____

-microRNA (miRNA) -short interfering RNA (siRNA)

Gene regulation may entail

-turning on genes only when needed -turning off genes when not needed -turning on or off entire groups of genes

Which of the following are nucleobases found in DNA

-Guanine -Adenine -Cytosine -Thymine

Which of the following statements about RNA interference are TRUE

-Binding of RNA in the RISC to complementary mRNA leads to enzymatic destruction of that mRNA -A short strand of RNA within a RISC unit hybridizes to a complementary sequence of mRNA

RNA polymerase can only add nucleotides to the _____ end of a growing strand

3'

The eukaryotic ribosome is 80S, and its subunits are _____

40S and 60S

RNA polymerase synthesizes a strand of RNA in the _____ direction

5' to 3'

When analyzing a DNA sequence, the sequence _____ on the plus strand indicated the possible start codon AUG in an RNA transcript

ATG

The report that genes direct the synthesis of proteins was first made by

Beadle and Tatum

_____ is a regulatory mechanism in which a carbon compound prevents the production of inducible enzyme needed for the metabolism of a different carbon source

Carbon Catabolite Repression (CCR)

The molecule that contains all the instructions needed to produce a cell's components is _____

DNA

AUG always functions as a start codon, no matter where it occurs in a transcript

False

DNA-binding proteins that bind to DNA always inhibit transcription

False

Repressible enzymes are constantly synthesized and are involved in processes such as glucose

False

What is the number of tRNA molecules that may be associated with translation?

Fewer than 64

What is the outcome if translation begins at the wrong reading frame?

Generally, a non-functional protein is made

Why is it a good idea for a bacterial cell to be able to use glucose FIRST as an energy source (until it is depleted), THEN switch lactose

Glucose is an easier compound to break down and obtain energy from the lactose AND for conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown?

Which of the following are involved in breaking and unwinding the DNA helix at the origin of replication?

Helicase and DNA gyrase

Which proteins are involved in the initiation of DNA replication?

Helicase and DNA gyrase

Which of the following breaks the hydrogen bonds between tow strands of DNA, causing them to denature (separate)

High temperature

_____ enzymes are usually not synthesized but are made when they are needed by a cell

Inducible

Why is the position of the first AUG after the ribosome binding site critical?

It establishes the reading frame

Which pair is incorrect?

Splicing-removal of introns from prokaryote mRNA following transcription

Cells are often ground up with abrasive to get to their internal enzymes/molecules, followed by removal of the abrasives. Here are two situations and two outcomes. What is the correct interpretation of the results? In situation #1, radioactive amino acids are mixed with ground-up cell material. Radioactive proteins are produced. In situation #2, radioactive amino acids AND the enzyme RNAse (an enzyme that degrades RNA) are mixed with ground-up cell material. No radioactive proteins are produced.

The mRNA from the cell can be used to make proteins with the radioactive amino acids in the first situation. In the second situation, the mRNA is destroyed by the RNAse before it can be translated into protein containing the radioactive proteins with the radioactive amino acids

All DNA nucleotides contain which of the following?

The same sugar, deoxyribose ,and phosphate group, but different nucleobases

Carbon catabolites is a regulatory mechanism that ensures that a cell _____

imports and uses the sugar that allows fastest cell growth

An _____ is a molecule that can bind to a repressor protein, changing its shape and preventing it from binding to the operator

inducer

The lac operon

positively regulated by the presence of lactose

RNA _____ produced by primase provide DNA polymerase with the 3' end needed for synthesis during DNA replication

primers

An open reading frames (ORF) potentially encodes which of the following?

protein

During protein synthesis, many copies of a specific _____ can be synthesized from a single transcript

protein

mRNA is produced when a region of DNA is known as the template is copied. The newly synthesized strand of mRNA is called the _____

transcript

Alternative sigma factors allow cells to directly control _____

transcription

Which of the following is incorrect

transcription is the conversion of DNA into RNA

Information is passed from the environment into the cell by a process known as signal _____

transduction

A drug that inhibits the activity of bacterial DNA gyrase _____ be a good antibiotic because _____

would; it would selectively inhibit bacterial DNA synthesis due to differences between bacterial/human gyrase