Biology Chapter 10

*Describe one of three emergence factors that can cause a virus to spread

1. The increased amount of modern travel has caused previously isolated human populations' viruses to spread across the world. 2. Close contact among different species can allow viruses access to new species. 3. Mutations in viruses can allow them to attach to human cells and enter the cells.

The directions for each amino acid in a polypeptide are indicated by a codon that consists of ________ nucleotides in an RNA molecule.

3

When one DNA molecule is copied to make two new DNA molecules, the resulting DNA molecules contain -100% of the parent DNA -none of the parent DNA. -75% of the parent DNA. -50% of the parent DNA.

50% of the parent DNA.

________ marks the end of a gene and causes transcription to stop. -RNA ligase -Methionine -A terminator -A stop codon

A terminator

Which of the following diseases is NOT caused by a prion? -AIDS -mad cow disease -Creutzfeldt-Jacob disease in humans -kuru in humans

AIDS

What is the transcription product of the sequence GCTAGCGATGAC? -CGTUCGCUTCUG -CGUTCGCUTCUG -CAGTAGCGATCG -CGAUCGCUACUG

CGAUCGCUACUG

A gene made of __________ is transcribed into __________ and then translated to form a __________. -DNA ... protein ... RNA -DNA ... RNA ... protein -protein ... RNA ... DNA -RNA ... DNA ... protein

DNA ... RNA ... protein

Which enzyme catalyzes the elongation of a new DNA strand? -DNA ligase -DNA polymerase -RNA polymerase -reverse transcriptase

DNA polymerase

Which of the following is true of tRNAs? -tRNAs are extremely small molecules, only slightly larger than water. -Each tRNA binds a particular amino acid. -There are four types of tRNA. -Transfer tRNAs carry special sequences known as codons.

Each tRNA binds a particular amino acid.

Which statement about herpesviruses is false? -Herpesviruses may cause cold sores or genital sores to appear during times of physical or emotional stress. -Herpesviruses acquire their envelopes from the host cell nuclear membrane. -Herpesviruses reproduce inside the host cell's mitochondria. -Herpesviruses may remain dormant for long periods of time while inside the host cell nucleus.

Herpesviruses reproduce inside the host cell's mitochondria.

Which of the following statements correctly describes mRNA processing in eukaryotes? -Introns are cut out, and the resulting exons are spliced together. -Exons are cut out and transported to the smooth endoplasmic reticulum. -Exons are cut out, and the introns are spliced together. -Introns are cut out and spliced together at the end of the mRNA.

Introns are cut out, and the resulting exons are spliced together.

In many bacteria, genes that confer resistance to antibiotics are carried on -F factors. -exons. -introns. -R plasmids.

R plasmids.

Which statement regarding RNA is false? -One RNA molecule can include four different nucleotides in its structure. -RNA contains the nitrogenous base uracil. -RNA molecules have a sugar-phosphate backbone. -RNA contains the sugar dextrose.

RNA contains the sugar dextrose.

How would the shape of a DNA molecule change if adenine paired with guanine and cytosine paired with thymine? -The DNA molecule would be shorter. -The DNA molecule would be longer. -The DNA molecule would be circular. -The DNA molecule would have irregular widths along its length.

The DNA molecule would have irregular widths along its length.

*What happens when bacteria that are infected with lysogenic viral DNA experience environmental stress? -The viral DNA becomes a phage that circularizes and then becomes another prophage. -The environmental stress causes the viral DNA to leave the bacterial DNA and then leave the bacterial cell to then find another host. -The environmental stress causes the viral DNA to leave the bacterial DNA and go into a lytic cycle. -The virus causes the bacterial host cell to divide and multiply.

The environmental stress causes the viral DNA to leave the bacterial DNA and go into a lytic cycle.

An error in DNA replication produces a single base mutation in a gene that codes for a protein. Which outcome is not possible? -The mutation results in a human disease such as sickle-cell disease. -The mutation results in mRNA being made from the protein. -The mutation results in changed protein function. -The mutation results in a longer or shorter protein or a protein of the same length.

The mutation results in mRNA being made from the protein.

*How does a phage replicate in a lysogenic cycle? -The viral DNA becomes a circle of DNA that can then replicate inside the host cell until the host cell is broken open. -The virus causes the host cell to divide uncontrollably, causing more viral DNA to be replicated in the host cells. -The phage takes over the reproduction tools of the host cell (tRNA, ribosomes, ATP, etc.) to produce more viral DNA and viral proteins. -The viral DNA embeds into the host cell DNA and gets replicated as the host cell reproduces.

The viral DNA embeds into the host cell DNA and gets replicated as the host cell reproduces.

How do retroviruses such as HIV differ from other viruses? -They contain DNA that is used as a template to make RNA. -They have much simpler reproductive cycles than other RNA viruses. -They can reproduce only inside living cells. -They contain the enzyme reverse transcriptase.

They contain the enzyme reverse transcriptase.

Which statement regarding the flow of genetic information is false? -Eukaryotic mRNA is processed in several ways before export out of the nucleus. -Polypeptides form proteins that determine the appearance and function of the cell and organism. -Ribosomes function as factories that coordinate the functioning of mRNA and tRNA. -Transcription occurs in the cytoplasm of eukaryotic cells.

Transcription occurs in the cytoplasm of eukaryotic cells.

*When a mutation causes an insertion of an extra nucleotide in a gene sequence, it causes ______ mutation. -a temporary -a viral -a frameshift -a prion

a frameshift

The shape of a DNA molecule is most like -beads on a string. -a twisted rope ladder. -a set of railroad tracks. -a wooden ladder.

a twisted rope ladder.

Emerging viruses that infect human cells can originate from __________. -poor hygiene -lambda viruses that were previously confined to bacterial populations that can now spread due to technological changes -a virus spreading from one host species to humans -a rapidly mutating lytic phage

a virus spreading from one host species to humans

The four bases contained in DNA are _____.

adenine, guanine, cytosine, thymine

A phage is a virus that infects -humans. -plants. -bacteria. -animals.

bacteria.

Why does a DNA strand grow only in the 5' to 3' direction? -because DNA polymerase requires the addition of a starter nucleotide at the 5' end -because the DNA molecule only unwinds in the 5' to 3' direction -because DNA polymerases can only add nucleotides to the 5' end of the growing molecule -because DNA polymerases can only add nucleotides to the 3' end of the growing molecule

because DNA polymerases can only add nucleotides to the 3' end of the growing molecule

Bacteria can quickly acquire new genes in a single generation through __________. -conjugation, transformation, and transduction -mutations -rapid cell division -transformation only

conjugation, transformation, and transduction

The 2009 H1N1 flu virus -killed over 50 million people worldwide. -was spread by mosquitoes. -evolved through the genetic reshuffling of viruses that infect humans, birds, and pigs. -was an avian flu virus.

evolved through the genetic reshuffling of viruses that infect humans, birds, and pigs.

Which human activity has contributed to an increase in the number of bacteria having R plasmids? -nitrogen fixation by genetically engineered plants -improper use of restriction enzymes in research and medical facilities -increased carcinogen exposure from excessive fossil fuel burning -heavy use of antibiotics in medicine and in agriculture

heavy use of antibiotics in medicine and in agriculture

The drug AZT was one of the first drugs used to treat HIV. Which of the following drug actions would prevent the spread of HIV without harming the host cell? -inhibition of reverse transcriptase -prevention of the formation of glycoproteins -destruction of amino acids that are vital to viral protein synthesis -inhibition of all DNA polymerase enzymes

inhibition of reverse transcriptase

Conjugation -is the result of cell division. -occurs when a phage transfers bacterial DNA from one bacterium to another. -is the direct transfer of DNA from one bacterium to another. -occurs when a bacterium acquires DNA from the surrounding environment.

is the direct transfer of DNA from one bacterium to another.

The phage reproductive cycle that kills the bacterial host cell is known as a _____ cycle.

lytic

During the transcription of a given portion of a DNA molecule, __________. -mRNA is synthesized from both strands of the DNA molecule, but first on one side and then the other -half of the mRNA is synthesized on half of one chain, then the other half of the mRNA is made on the other half of the DNA -mRNA is synthesized from both strands of the DNA molecule at once -mRNA is synthesized from only one of the strands

mRNA is synthesized from only one of the strands

A virus infects a cell and randomly inserts many short segments of DNA containing a stop codon throughout the organism's chromosomes. This will probably cause _____. -manufactured proteins to be short and defective -incorrect pairing between mRNA codons and amino acids -no deleterious effects, as long as the stop codons are not also inserted into tRNA -the DNA to break up into thousands of short segments

manufactured proteins to be short and defective

The first amino acid inserted into a new polypeptide chain in eukaryotic cells is always __________.

methionine

Any change in the nucleotide sequence of DNA is called a

mutation.

Monomers for the synthesis of DNA are called __________.

nucleotides

Viral DNA incorporated into host cell DNA is known as a(n)

prophage.

*A virus is a small amount of genetic material that is surrounded by a capsid. The capsid is made of _____. -nucleic acids -protein -phospholipids -ribosomes

protein

In an important experiment, radioactively labeled bacteriophages were allowed to infect bacteria. In the first trial, the phages contained radioactive DNA, and radioactivity was detected in the bacteria. Next, other phages containing radioactive protein were allowed to infect bacteria, and radioactivity was not detected in the bacteria. These experiments led to the conclusion that __________. -the genes of this phage were made of DNA -DNA is made of nucleotides -bacteriophages can infect bacteria -genes carry information for making proteins

the genes of this phage were made of DNA

A gene is usually _____. -made of RNA -made by a ribosome -the same thing as a chromosome -the information for making a polypeptide

the information for making a polypeptide

If you analyzed the nucleotide content of DNA, you would expect to find that __________. -A + T = G + C -the ratio of A to G is close to 1:1 and the ratio of T to C is close to 1:1 -the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1 -the ratio of A to C is close to 1:1 and the ratio of G to T is close to 1:1

the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1

If protein production were an assembly line, a ribosome would be _____. -a loose piece that needs to be put together -the worker who puts all of the pieces together -the machines that move pieces to their appropriate locations -the foreman who barks out instructions

the worker who puts all of the pieces together

The transfer of genetic information from DNA to RNA is called -initiation. -transcription. -translation. -elongation.

transcription.