Bio 111 - Chapter 15 Assignment

In eukaryotic cells, the RNA is processed before it leaves the nucleus. This processing __________.

includes the addition of a cap and tail, which protect the mRNA molecule from enzymatic attack, and the removal of introns

Which of these indicates an enhancer region?

A

Your body is composed of a dazzling array of different cell types. Each cell type develops its own unique properties. How does this happen?

All cells (with very few exceptions) contain the same set of genes, but the process of gene expression determines which genes are active in each cell.

Which of the following events occurs during transcription?

A molecule of RNA is formed based on the sequence of nucleotides in DNA

In the accompanying image, a nucleotide is indicated by the letter _____.

B

Who formulated the one gene-one enzyme hypothesis?

Beadle and Tatum

The initiator tRNA attaches at the ribosome's _____ site.

P

Lipase is an enzyme (a type of protein) that breaks down fats.

The base sequence that codes for the lipase enzyme is duplicated during DNA replication. A specific sequence of bases in a DNA molecule codes for the lipase enzyme

Which of the following statements is false?

The start codon can be different depending on what kind of protein is to be translated.

Which of the following is NOT true about the genetic code?

The genetic code is ambiguous.

How do mutations affect an organism?

all of the above

An anticodon is __________.

a set of triplet bases on a tRNA that is complementary to a codon triplet on mRNA

Which of the following would indicate a base pairing mutation in DNA?

a G paired with a T

Can you correctly label various parts of a DNA molecule?

a. double helix b. phosphate group c. deoxyribose d. hydrogen bond e. base pair f. nucleotide g. nitrogenous base

Can you correctly label the structures in this diagram that summarizes chromosome packing?

a. histone b. nucleosome c. supercoil d. chromosome e. chromatin

The RNA segments spliced to one another during RNA processing are _____.

exons

The letter A indicates a _____.

phosphate group

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

sugar with two, and not three, oxygen atoms

In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.

1' ... 5'

Nucleic acids are assembled in the _____ direction.

5' to 3'

Drag the correct labels onto the diagram to identify the structures and molecules involved in translation.

A. mRNAB. Small subunit of ribosomeC. Large subunit of ribosomeD. Amino acidE. tRNAF. Anticodon

Which of these is a tRNA?

B

A nitrogenous base is indicated by the letter _____.

C

Which of these directly bind(s) to the promoter?

C and D

Which of these is(are) pyrimidines?

C, D, and E

What is the transcription product of the sequence GCTAGCGATGAC?

CGAUCGCUACUG

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.

CUG

Which of the following is true of tRNAs?

Each tRNA binds a particular amino acid.

Which of these nitrogenous bases is found in DNA but not in RNA?

Thymine

_____ bind(s) to DNA enhancer region

activators

RNA processing involves the addition of ________ to the ends of the RNA transcript.

extra nucleotides

A female that is planning to become pregnant is concerned about her exposure to environmental mutagens which may have caused DNA mutations. In order for these mutations to become heritable, they must affect the:

her egg cells

Shown below is a ribosome in the process of translation. The P site of a ribosome __________.

holds the growing polypeptide chain

Which of the following does not occur during RNA processing?

mRNA attaches to the small subunit of a ribosome.

The information carried by a DNA molecule is in _____.

the order of the nucleotides in the molecule

DNA replication occurs at an unbelievably fast rate. Once replication is complete, we can expect to find a _____ number of mistakes.

small

A terminator in mRNA synthesis is a(n) __________.

specific nucleotide sequence in DNA that signals the stop of transcription

A eukaryotic cell has a nuclear envelope that allows tRNA molecules, but not mRNA molecules, to leave the nucleus. Which of the following processes will not be able to take place in this cell?

tRNAs binding to codons

A gene is usually _____.

the information for making a polypeptide

Regulatory proteins bind to _____.

the operator

To begin the process of gene transcription, RNA polymerase attaches to _____.

the promoter associated with the target gene

If protein production were an assembly line, a ribosome would be _____.

the worker who puts all of the pieces together

Experiments have demonstrated that the "words" of the genetic code (the units that specify amino acids) are

three-nucleotide sequences.

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine ... cytosine

Which of the following occurs when RNA polymerase attaches to the promoter DNA?

initiation of a new RNA molecule

During the transcription of a given portion of a DNA molecule, __________.

mRNA is synthesized from only one of the strands

Which of the following is a correct statement about mRNA?

mRNA moves from the nucleus to the cytoplasm following RNA processing.

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

In the presence of a regulatory protein the lac operon is _____.

not transcribed

This is an image of a(n) _____.

nucleotide

Operons are a standard method for gene regulation in _____.

prokaryotes but not eukaryotes

Which of these is NOT a component of the lac operon?

regulatory gene only

The site of translation is

ribosomes in the cell cytoplasm.

Can you match each term related to the genetic basis of cancer with its description? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

1. A normal gene that, if mutated, can lead to cancer is called a(n) proto-oncogene. 2. A gene that causes a cell to become cancerous is called a(n) oncogene. 3. A(n) tumor-suppressor gene is a gene that encodes proteins that inhibit cell division. Such proteins normally help prevent cells from becoming cancerous. 4. A(n) growth factor is a protein that promotes cell division. In excess, such a protein may lead to cancer.

After reading the paragraphs below, answer the questions that follow. Diabetes mellitus is a metabolic disease that is characterized by the buildup of glucose in the blood, or hyperglycemia. Diabetes results either from the pancreas not being able to produce the hormone insulin (type 1 diabetes) or if the body's cells become resistant to insulin (type 2 diabetes). Insulin is a protein that binds to receptors on cell surfaces to allow glucose to enter the cell. In order to manage the disease, type 1 diabetics require frequent insulin injections. Until the 1970s, insulin was obtained from processing the pancreases of large mammals such as cows and pigs; it was then purified for medicinal use. This all changed in the 1970s with the advent of recombinant DNA technology, which allows scientists to insert genes from other species into bacterial plasmids and have bacteria produce proteins from these other species' genes. In 1978, the gene that codes for human insulin was added to a bacterial plasmid and bacteria were used to produce human insulin. These bacteria acted as mini-factories that produced human insulin for type 1 diabetes patients. Today, the production of human insulin from bacteria is commonplace and is a multibillion dollar market for pharmaceutical companies. In order for bacterial cells to be able to produce the human insulin protein, which of the following is not required?

Bacteria have to have a gene for a bacterial form of insulin.

DNA is a double helix composed of nucleotides. Suppose that a portion of one of the two strands of a DNA molecule has the sequence GCAGTAG.

CGTCATC

You are interested in designing an experiment to test the hypothesis that frogs use the same genetic code as humans. Which of the following experiments would not give you useful data to test this hypothesis?

Compare nucleotide sequences of promoters from similar frog and human genes.

Which of these is a regulatory gene?

D

Which one of the following does not play a role in translation?

DNA

A gene made of __________ is transcribed into __________ and then translated to form a __________.

DNA ... RNA ... protein

Which of these is a difference between a DNA and an RNA molecule?

DNA is double-stranded, whereas RNA is single-stranded.

DNA is considered to be the molecule of life.

DNA produces more of itself.DNA directs the production of proteins

Can you match the terms to their definitions? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

DNA serves as the molecular basis for life. DNA copies itself via the process of replication. RNA is produced from DNA via the process of transcription. Proteins are produced from RNA via the process of translation. There are five examples of a base: A, G, C, T, and U. One way that RNA is different from DNA is that it contains Us instead of Ts.

The nucleotide sequence of a DNA codon is GTA. A messenger RNA molecule with a complementary codon is transcribed from the DNA. In the process of protein synthesis, a tRNA pairs with the mRNA codon. What is the nucleotide sequence of the tRNA anticodon?

GUA

What is the name of the process shown in the diagram?

Initiation (of translation)

Which of the following statements correctly describes mRNA processing in eukaryotes?

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

The lac operon controls expression of three genes that produce lactose-digesting enzymes. What role does lactose play in regulating the lac operon?

It binds to and disables the repressor protein, thereby allowing production of the three enzymes.

The operon model of the regulation of gene expression in bacteria was proposed by _____.

Jacob and Monod

Can you identify the molecules and processes involved in the flow of genetic information through a cell? Drag the labels to the appropriate locations in the diagram.

Left to right: dna, transcription, rna, translation, protein

Which of the following enzymes catalyzes the production of a strand of RNA from DNA?

RNA polymerase

After reading the paragraphs below, answer the questions that follow. Diabetes mellitus is a metabolic disease that is characterized by the buildup of glucose in the blood, or hyperglycemia. Diabetes results either from the pancreas not being able to produce the hormone insulin (type 1 diabetes) or if the body's cells become resistant to insulin (type 2 diabetes). Insulin is a protein that binds to receptors on cell surfaces to allow glucose to enter the cell. In order to manage the disease, type 1 diabetics require frequent insulin injections. Until the 1970s, insulin was obtained from processing the pancreases of large mammals such as cows and pigs; it was then purified for medicinal use. This all changed in the 1970s with the advent of recombinant DNA technology, which allows scientists to insert genes from other species into bacterial plasmids and have bacteria produce proteins from these other species' genes. In 1978, the gene that codes for human insulin was added to a bacterial plasmid and bacteria were used to produce human insulin. These bacteria acted as mini-factories that produced human insulin for type 1 diabetes patients. Today, the production of human insulin from bacteria is commonplace and is a multibillion dollar market for pharmaceutical companies. In order to add the gene for human insulin to a bacterial plasmid, the DNA molecules have to be "cut" with enzymes called restriction endonucleases and then pasted back together with enzymes called DNA ligases. Imagine that during this process, the first five nucleotides of the human insulin gene were accidentally cut out before it was pasted into the bacterial plasmid. What is the most likely outcome if this plasmid was added to bacterial cells?

The human insulin protein would not be produced because transcription would not take place since the RNA polymerase would not recognize the promoter.

Which of the following statements regarding the flow of genetic information is false?

Transcription occurs in the cytoplasm of eukaryotic cells.

In eukaryotes, translation is initiated only after transcription is completed. However, prokaryotes can initiate translation before a gene is completely transcribed. Which choice is the best explanation for this observation?

Translation in eukaryotes cannot occur until the RNA leaves the nucleus, whereas in prokaryotes both transcription and translation occur in the cytoplasm.

Using the figure, can you complete the sentences about the structures and processes involved with the flow of information through the cell?

Translation is the process in which mRNA codons are converted into an amino acid sequence. The principal role of RNA is to act as a messenger carrying instructions from DNA out of the nucleus for the synthesis of proteins. Transcription is the first step of gene expression, during which a particular segment of DNA is converted into RNA. DNA is a long linear polymer found in the nucleus of a cell, shaped like a double helix, and associated with the transmission of genetic information. A ribosome serves as the site of protein synthesis in the cytoplasm. A protein is made up of hundreds or thousands of smaller units called amino acids, attached to one another in long chains.

When messenger RNA (mRNA) is being transcribed, the RNA base _____ always pairs with the base _____ in DNA.

U ... A

Drag the correct labels onto the nucleotides in the RNA transcript. Not all labels will be used.

U, C, G, A

Can you correctly identify the processes by which genetic information flows and where those processes occur in the cell?

a. replication b. transcription c. translation d. nucleus e. nucleus f. ribosomes

Within an operon, repressors _____.

block gene transcription to RNA by attaching to the operator

Translation occurs in the _____.

cytoplasm

he function of tRNA during protein synthesis is to _____.

deliver amino acids to their proper site during protein synthesis

Considering only the steps that take place during translation, which of the following is not needed in order for translation to occur?

dna template

The transfer of genetic information from DNA to RNA is called

transcription

What is the proper order of the following events in the expression of a eukaryotic gene?

transcription, RNA processing, translation

During the process of translation, __________ matches an mRNA codon with the proper amino acid.

transfer RNA

The translation process requires all of the following: __________.

transfer RNA, ribosomes, AUG codons

Life on Mars is finally discovered and a new organism that has six different nucleotides that encode 30 different amino acids is found on this planet. Which of the following nucleotide combinations would encode the minimum number of amino acids needed in this organism?

two-nucleotide sequence (6^2 combinations)