Ch 7 micro

Eukaryotic mRNA usually specifies multiple proteins

False

The most difficult aspect of the new field of metagenomics is generating sequence data reliably and cost-effectively.

False

The purpose of RNA synthesis is to provide a new copy of DNA as the original deteriorates over time.

False

Translation occurs on ribosomes only in prokaryotes

False

Translation of eukaryotic mRNA can occur in the nucleus after exons are spliced together

False

Synthesis of mRNA is

in the 5' to 3' direction with new nucleotides being added to the 3' end of the mRNA molecule

The molecules that bind to a repressor and cause it to no longer bind to the operator are called

inducers

The lac operon is _______

inducible

Eukaryotic mRNA contains non-coding regions called ___________

introns

The lac operon

is an example of negative control

The E-site

is responsible for the release of the tRNA

When a repressor binds to the operator site on DNA,

it blocks RNA polymerase binding and mRNA synthesis

After mRNA is made, what generally occurs?

it is translated to protein

When bacterium is grown on glucose only,

it must synthesize all the amino acids it needs

In an inducible operon, when a substrate or inducer is present,

it reacts with the pressor and inactivates it

What role does the sigma factor of RNA polymerase have in transcription?

it recognizes and binds to the promoter region of the template RNA

RNA is a chain of ______

nucleotides

One bacterial chromosome replicates to become 2 chromosomes with

each made of one strand of DNA from the original chromosome and one newly synthesized strand

Binding of an activator to an activator binding site on DNA

enhances the ability of RNA polymerase to bind to the promoter site

One advantage of having genetic control mechanisms is

enzymes are only produced when they are needed

RNA interference (RNAi) is a mechanisms by which

eukaryotic cells destroy RNA transcripts in a selective and specific manner to control gene expression

The plus (+) strand of DNA acts as a template during transcription

false

What is an isotope?

forms of the same element that contain equal numbers of protons but different numbers of neutrons

A segment of DNA encoding a protein or an RNA molecule is a

gene

early in the process of DNA replication, the enzyme _________ separates the two strands

helicase

the 2 strands of dna are joined to each other or held together by

hydrogen bonding

What happens when a hairpin loop forms in mRNA?

the RNA polymerase and the mRNA dissociate from the DNA

In some degradative pathways, in the absence of an inducer (such as arabinose),

the activator protein can't bind to DNA, and RNA polymerase can't bind to the promoter site

Unlike DNA, RNA is usually single-stranded

true

rRNA

type of RNA molecule present in ribosomes

tRNA

type of RNA molecule that carries amino acids to the growing peptide chain during translation

mRNA

type of RNA molecule that contains the genetic information decoded during translation

A mechanism that blocks transcription

will block the production of mRNA

Which of the following occurs in both prokaryotes as well as eukaryotes

- transcription - translation - DNA replication

gene regulation may entail

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

Organize the steps that are involved in the mechanism of RNA interference (RNAi)

1. cell produces short single-stranded RNA 2. and RNA-induced silencing complex (RISC) assembles 3. Binding of the RNA in the RISC to mRNA tags the mRNA for destruction 4. Enzymes cut mRNA; RISC can then bind to another mRNA molecule

How many nucleotides are in a codon?

3

Which of the following shows the direction genetic information flows?

DNA → RNA → protein

On one of the strands of bacterial DNA, the new complementary strand is synthesized discontinuously into small pieces of DNA called _______

Okazaki fragments

The initial transfer RNA occupies the _______ site on the ribosome

P site

The processes of transcription and translation differ between prokaryotes and eukaryotes in the following way:

Prokaryotes transcribe and translate simultaneously

Why did scientists originally believe that genetic material was protein rather than DNA?

Proteins are more complex in structure than DNA; they though DNA was too simple in structure to have such an important cellular role

What component of RNA is different from one person (or bacterium) to the next?

The order or nitrogenous bases

Why is translation needed?

The subunits of nucleic acids are nucleotides, while those of proteins are amino acids

Which nucleotide is not found in RNA?

Thymine

If the codon CCU is positioned in the A site of the ribosome, which of the following will occur?

a tRNA with the anticodon CCA will deliver its amino acid to the site

If you know the sequence of nucleotides in mRNA, you can deduce the DNA sequence it was transcribed from

True

In prokaryotes, the mRNA transcript encounters ribosomal subunits immediately as it leaves the DNA

True

Only eukaryotic mRNA is processed before translation

True

Prokaryotes lack membrane-enclosed organelles

True

Replication, transcription and translation take place in the bacterial cytoplasm

True

The sequence of DNA bases ultimately determines the sequence of amino acids in a polypeptide

True

If one strand of DNA contains the bases ACAGT, what would be the complementary bases on the mRNA strand?

UGUCA

In the absence of lactose

a repressor protein binds to the operator

If an organism lost the ability to make primase, what would it be unable to do?

add a short sequence of complementary RNA to the existing DNA strand

Ribozymes

are self-catalytic RNA AND suggest that nucleic acids evolved before proteins

Repressible operons (such as the arg operon)

are usually in the "on" mode

Introns are removed and exons are spliced together

before translation

DNA Polymerase

can only add nucleotides in a certain direction

Which world in the description tells us that Hershey and Chase used high speed spinning to separate 2 things?

centrifugation

__________ are groups of three bases in mRNA that specify one amino acid in the amino acid chain

codons

DNA is characterized by which of the following features

deoxyribose & thymine

A _______ is a cluster of genes that perform related functions, found in ____________

operon, prokaryotes

Coordinated sets of genes that are regulated as a single unit are referred to as

operons

the specific point on the dna molecule where replication begins is the

origin of replication

The bond connecting amino acids is a ______ bond

peptide

A __________ is the physical expression of the genes present and can change depending upon what genes are turned "on"

phenotype

3 basic parts of a DNA nucleotide are

phosphate deoxyribose sugar nitrogenous base

What 3 components make up RNA subunits?

phosphate nitrogenous base ribose sugar

What usually terminates the process of translation?

presence of a stop codon on mRNA

Translation of mRNA into protein begins before transcription is complete in _________.

prokaryotes only

Transcription begins when RNA polymerase binds to the

promoter on DNA

DNA polymerase

requires a template for the synthesis of DNA

Protein synthesis occurs on the ________

ribosomes

When an amino acid such as arginine binds to a repressor,

the repressor binds to the operator site

global control

the simultaneous regulation of many bacterial genes

Two different mechanisms for copying the DNA strands are used because

the strands are oriented in opposite directions

Translation is needed because

the subunits of DNA and RNA are nucleotides while those of protein are amino acids

The process of transcription is similar to

the synthesis of the leading strand during DNA replication

What does the word "transcribe" mean?

to make a copy