Lesson 9-14

Roxanne views a slide of dividing cells with a microscope. She observes a cell containing a visible spindle with poles on opposite sides of the cell. The chromosomes are located between the poles, but the chromosomes are clustered into balls, one next to each pole. Roxanne can also see a thin, dashed line halfway between the two clusters of chromosomes. What mitotic stage is Roxanne observing?

Telophase

A group of cells that are dividing uncontrollably, but do NOT possess mutations that promote migration to other tissues form \____.

A benign tumor

During mitosis, DNA is compacted by proteins to form \____.

Condensed chromosomes

In animal cells, the chromosomes line up on a plane located halfway between the two centrosomes during \____.

Metaphase

When is DNA accessible to the enzymes involved in gene expression?

When DNA forms chromatin

Which of these factors is an enzyme that activates cell division by adding a phosphate group to another protein?

Cyclin dependent kinases

During interphase, DNA is organized by proteins to form \____.

Chromatin

Initial packing of DNA forms organized units of DNA wrapped around protein complexes. Each wrapped unit is called a \____.

Nucleosome

During which phase of mitosis does the nuclear envelope begin to break down?

Prophase

The synthesis of DNA occurs during \____.

Interphase

Spindle microtubules bind kinetochores during \____.

Prometaphase

When grown in a culture plate, non-cancerous cells remain in G in response to \____.

Density-dependent inhibition

When a cell fails a check point and correction, the cell usually \____.

Activates apoptosis

Because prokaryotes do not house their DNA inside a nucleus, the divide known as a process known as \____.

Binary fission

Which of the structures below is found in plant cells but NOT in animal cells during mitosis?

Cell plate

Controlled, intentional cell death is known as

Apoptosis

One requirement to move a cell through the G1/S checkpoint is the presence of \____.

Growth factors

In eukaryotic cells, when does cytokinesis usually begin?

Near the end of mitosis

The average cell in the human body spends most of its life in \____.

Interphase

Because cancer cells arise from normal body cells, the majority of treatments for cancer target the cancerous cells by killing cells in mitosis. Therefore, treatment for cancer kills \____.

Any rapidly dividing cells

The majority of cell growth and development occurs during \____.

G1 & G2 phases

What two phases make a complete cell cycle?

Interphase and the M phase

When DNA damage is present, mitotic suppression is induced by \____.

P53, a regulatory protein produced by a tumor-suppressor gene

When looking through a microscope, which structure may be observed in an animal cell during cytokinesis?

Cleavage furrow

Which of the structures below is found in animal cells but NOT plant cells during mitosis?

Centrosomes

Okazaki fragments are \____.

The discontinuous segments of the lagging strand

Complementary base pairing enables \____.

Directed replication of a double helix

Short RNA molecules required to initiate DNA synthesis are produced by the enzyme \____.

Primase

Which enzyme extends the replication forks outward, increasing the size of the replication bubble when DNA synthesis reaches each fork?

Helicase

During semiconservative DNA replication, \___.

Both original strands act as templates (parental strands)

Scientists use polymerase chain reaction to \____.

Produce a large concentration of a short DNA segment

DNA strands are always synthesized \____.

By extending the 3' end, growing from 5' toward 3'

Which pair of nucleotide components is directly bonded by phosphodiester linkages in a DNA polymer?

Deoxyribose and phosphate

A DNA molecule containing sequences from more than one organism is \____.

Recombinant

Chargaff's observation that DNA contained equal amounts of the nitrogenous bases cytosine and guanine and equal amounts of the nitrogenous bases adenine and thymine led Watson and Crick to the conclusion that DNA is composed of two strands, \____.

With bases aligned in complementary pairs across the two strands

The association between two strands stabilizing a DNA double helix depends upon \____.

Hydrogen bonds between purine-pyrimindine base pairs

Rosalind Franklin's work with X-ray diffraction patterns of DNA molecules helped \____.

Watson and Crick develop the DNA double helix model

The enzyme that joins two Okazaki fragments together is \____.

DNA ligase

Agricultural scientists have improved crop production through the use of \___.

Recombinant DNA inserted into plant cloning vectors

In living cells, heritable information is stored in \____.

DNA

The enzyme that reduces excessive twisting of the DNA double helix during DNA replication is \____.

Topoisomerase

Hershey and Chase worked with bacteriophage viruses to determine what hereditary material was passed into bacteria during infection. These researchers demonstrated \____.

that DNA directed synthesis of proteins

During replication, single strand binding proteins bind to single-stranded DNA to \____.

Prevent the parental DNA strands from rejoining

By purifying DNA from S-strain bacteria, Avery, MacLeod, and McCarty \____.

Demonstrated DNA could transform bacteria

Telomeres \____.

Protect linear chromosomes from gene loss

New DNA strands are synthesized by the enzyme \___.

DNA polymerase

The complementary strand of the DNA sequence 5'-CGATTG-3' is \____.

3'-GCTAAG-5'

An identified gene codes for a specific protein. To mass produce this protein, scientists isolate this gene and place it into a \_____.

Cloning vector designed to transform bacteria

Mutations are rare because \_____.

DNA damage and replication errors are easily identified

A DNA double helix containing many replication bubbles simultaneously \____.

Replicates the entire chromosome quickly

In order to synthesize proteins using 20 different amino acids, how many different tRNA molecules must the cell produce?

at least 20 because each amino acid must bond to a different tRNA molecule with a different anticodon.

Most insertions and deletions are frameshift mutations. However, an insertion mutation that adds three nucleotides to the sequence of a gene is not considered a frameshift mutation because this insertion \_____.

does not alter the grouping of codons following the mutation

The process of converting a nucleotide sequence to an amino acid sequence is \____.

Translation

Initiation of protein synthesis requires \____.

an AUG in the mRNA

Knock-out mutations may be caused by \_____.

Either point mutations or frameshift mutations

Expression of a gene is regulated by \____.

transcription factors binding to the promoter

The three-dimensional structure of a tRNA molecule supports its ability to \____.

Recognize and bind to a mRNA codon during translation

DNA and RNA polymers differ in that RNA polymers tend to be \___.

Shorter and single-stranded

One difference between prokaryotic and eukaryotic transcription is that \____.

Prokaryotic transcription occurs in the cytoplasm

The enzyme that unwinds DNA during transcription is \____.

RNA polymerase

The codon AUG is unique because it codes for the amino acid methionine and \____.

Initiates protein synthesis

In a person diagnosed with sickle cell anemia, the hemoglobin gene contains a single nucleotide mutation resulting in a change in one amino acid. The hemoglobin still carries oxygen through the bloodstream, although less efficiently. This mutation is an example of a \____.

Missense mutation

The mechanism of translation that converts the information in a sequence of nucleotides into a sequence of amino acids \____.

is consistent among living organisms

How many nucleotides code for an amino acid?

3

The 3' end of eukaryotic mRNA is modified with nucleotides thought to assist in nuclear exit and stability of the mRNA. The structure of this 3' tail is best described as:

A long, repetitive series of adenine nucleotides.

Reactions that remove introns from mRNA are catalyzed by \____.

Spliceosomes

DNA functions to \____ information, whereas RNA \____ information.

Store; transfers

A single base is mismatched during transcription and becomes a permanent change in the DNA sequence. This nucleotide change is called \____.

A point mutation

During transcription, \_____.

both DNA strands contain genes, but each gene only uses one strand as its template

Elongation of a protein continues until \____.

Release factors bind to the active site of the ribosome

A mature strand of mRNA is composed of \____.

Exons

Experimental evidence indicates that the rRNA in the active site of ribosome \____.

Catalyzes the formation of a peptide bond between amino acids of the growing polypeptide

The insertion or deletion of a single nucleotide into the coding sequence of a gene causes a \____.

Frameshift mutation

One major difference between DNA and RNA structure is that in RNA adenine binds with \____.

Uracil

The process of forming mRNA from a DNA template is \____.

Transcription

In order to synthesize proteins using 20 different amino acids, how many different tRNA molecules must the cell produce?

at least 20 because each amino acid must bond to a different tRNA molecule with a different anticodon.

Most insertions and deletions are frameshift mutations. However, an insertion mutation that adds three nucleotides to the sequence of a gene is not considered a frameshift mutation because this insertion \_____.

does not alter the grouping of codons following the mutation

The process of converting a nucleotide sequence to an amino acid sequence is \____.

Translation

Initiation of protein synthesis requires \____.

an AUG in the mRNA

Knock-out mutations may be caused by \_____.

Either point mutations or frameshift mutations

Expression of a gene is regulated by \____.

transcription factors binding to the promoter

The three-dimensional structure of a tRNA molecule supports its ability to \____.

Recognize and bind to a mRNA codon during translation

DNA and RNA polymers differ in that RNA polymers tend to be \___.

Shorter and single-stranded

One difference between prokaryotic and eukaryotic transcription is that \____.

Prokaryotic transcription occurs in the cytoplasm

The enzyme that unwinds DNA during transcription is \____.

RNA polymerase

The codon AUG is unique because it codes for the amino acid methionine and \____.

Initiates protein synthesis

In a person diagnosed with sickle cell anemia, the hemoglobin gene contains a single nucleotide mutation resulting in a change in one amino acid. The hemoglobin still carries oxygen through the bloodstream, although less efficiently. This mutation is an example of a \____.

Missense mutation

The mechanism of translation that converts the information in a sequence of nucleotides into a sequence of amino acids \____.

is consistent among living organisms

How many nucleotides code for an amino acid?

3

The 3' end of eukaryotic mRNA is modified with nucleotides thought to assist in nuclear exit and stability of the mRNA. The structure of this 3' tail is best described as:

A long, repetitive series of adenine nucleotides.

Reactions that remove introns from mRNA are catalyzed by \____.

Spliceosomes

DNA functions to \____ information, whereas RNA \____ information.

Store; transfers

A single base is mismatched during transcription and becomes a permanent change in the DNA sequence. This nucleotide change is called \____.

A point mutation

During transcription, \_____.

both DNA strands contain genes, but each gene only uses one strand as its template

Elongation of a protein continues until \____.

Release factors bind to the active site of the ribosome

A mature strand of mRNA is composed of \____.

Exons

Experimental evidence indicates that the rRNA in the active site of ribosome \____.

Catalyzes the formation of a peptide bond between amino acids of the growing polypeptide

The insertion or deletion of a single nucleotide into the coding sequence of a gene causes a \____.

Frameshift mutation

One major difference between DNA and RNA structure is that in RNA adenine binds with \____.

Uracil

The process of forming mRNA from a DNA template is \____.

Transcription