Chapter 8 Connect Questions
Normal cells only divide about 50 times because the ______ gradually become shorter, but cancer cells have an enzyme that extends the ______ and allows cancer cells to continue to divide.
Chromosomes; telomeres
What describes chromosomes at the end fo the S phase of interphase?
Consist of two chromatids
Suppose a centromere does not split during anaphase. Describe the chromosomes in the daughter cells.
If a centromere failed to split during anaphase, one daughter cell would be missing one chromosome, and the other daughter cell would receive a replicated version of one chromosome.
Proteins called _____ are chemical signals that bind to receptors on a cell membrane and trigger cell division.
Growth factors
Telomeres are located at the ends of chromosomes and consist of ______.
Hundreds of repeated nucleotides.
In a DNA molecule, _____ bonds form between nitrogenous bases, such that A (adenine) pairs with its complement _____, and G (guanine) pairs with its complement _____.
Hydrogen; T (thymine); C (cytosine)
In asexual reproduction, the offspring are genetically _____ to each other.
Identical.
The cell cycle has internal _____ that do not let the cell proceed to the next stage of the cell cycle until the previous stage is complete.
Checkpoints
The goal of ______ is to stop cell division in cancer cells anywhere in the body, whereas the goal of ______ is to kill cancer cells in limited areas.
Chemotherapy; radiation therapy
A replicated chromosome consists of two attached copies called sister _____.
Chromatids
Eukaryotic chromosomes consist of _____, which is composed of uncondensed DNA and associated proteins.
Chromatin
A single molecule of DNA and its associated proteins is called a(n) _____.
Chromosome.
A cell's genetic material is contained in one or more _____.
Chromosomes
What occurs during metaphase of mitosis?
Chromosomes align along the equator of the cell.
Name all of the events that occur during prophase.
Chromosomes condense, mitotic spindle begins to form, centrosomes migrate to opposite poles
A tumor suppressor gene called ______ encodes a protein that acts at checkpoints to control the cell cycle.
p53
Name the three cellular processes that require cell division to function.
1) Reproduction 2) Growth and development 3) Replacement of dead cells
Proteins encoded by proto-oncogenes normally act to _____.
Stimulate cell division
Proteins encoded by proto-oncogenes normally act to ______.
Stimulate cell division
Normal human cells have a "cellular clock" that limits the number of divisions to about 50, whereas cancer cells have lost this and become "immortal" because their _____ stay long.
Telomeres
In the eukaryotic cell cycle, the time of cell growth between successive cell divisions is called _____.
Telophase
The spread of cancer can be described in stages I, II, III, and IV, but in general, the lower the stage, _____.
The better the prospect fr successful treatment.
Describe what will happen to a cell if interphase happens but mitosis does not.
The cell will grow larger and produce more organelles in G1, copy its DNA in S phase, and prepare for division in G2, but it will fail to divide its replicated DNA. A cell with too much DNA would not be normal and would probably undergo apoptosis.
What are the events of binary fission?
The cell's DNA replicates, and the two chromosomes attach to the cell membrane. The cell grows between the two attachment points, pulling the two chromosomes apart. The cell wall and cell membrane then pinch inward, dividing the cell into two identical daughter cells.
What describes cytokinesis?
The cytoplasm and two nuclei are distributed into daughter cells
What steps must occur before DNA polymerase can synthesize new DNA?
The double-stranded DNA is unwound, and RNA primer is added.
What are the steps of DNA replication?
The helicase enzyme unwinds and separates a double-stranded DNA molecule; binding proteins keep the strands separate. The primase enzyme forms a short stretch of complementary RNA on each DNA template. Starting at the end of RNA primer, DNA polymerase adds DNA nucleotides that are complementary to the template strand, proofreading and correcting errors as it goes. Another enzyme removes the RNA primers and DNA polymerase fills in the gaps left by the primers. The ligase enzyme seals the resulting nicks in the newly synthesized DNA.
What events happen in a cell undergoing apoptosis?
A cell undergoing apoptosis first receives a signal at a membrane protein called a death receptor. The signal triggers the release of enzymes that destroy the cell from within. Eventually, immune system cells engulf the dying cell, degrading or recycling its components.
How are chromosomes and chromatin related?
A chromosome is composed of chromatin.
Which population evolves more quickly: cancer cells treated with standard therapy, or cancer cells treated with adaptive therapy? Why?
A population of cancer cells treated with standard therapy evolves more quickly than a pop. of cancer cells treated with adaptive therapy. Recall that evolution is the change in allele frequencies in a population over time. Standard therapy very effectively kills susceptible cancel cells; as these susceptible cells die, the cancel cell alleles that confer susceptibility to drug treatments are quickly eliminated form the population. In contrast, adaptive therapy does not kill all susceptible cells, so the allele frequencies in the pop. are relatively stable.
In prokaryotes, DNA is contained in _____, and in eukaryotes, DNA is contained in _____.
A single chromosome; multiple chromosomes
What is the role of the enzyme DNA polymerase in DNA replication?
Add complementary DA nucleotides.
What is the role of mitotic cell division in the human life cycle?
Allows for tissue repair/replacement and for an organism's development from a fertilized egg (zygote) to an adult.
Describe two functions of apoptosis.
Apoptosis carves out excess cells to form a body structure, and it eliminates damaged or aging cells.
What best describes the major differences between apoptosis and necrosis?
Apoptosis is "programmed" death, whereas necrosis is "accidental" cellular death.
Regulated cell death that is a necessary part of development is called ______.
Apoptosis.
What type of reproduction results in the production of genetically identical offspring?
Asexual
Binary fission is a type of _____ seen in prokaryotes, such as archaea and bacteria.
Asexual reproduction
What is the difference between a benign and a malignant tumor?
Benign tumors are surrounded by a capsule; they do not spread to other areas of the body or invade nearby tissues. A malignant tumor invades nearby tissues and may matastasize, spreading to other areas of the body.
Due to its proofreading accuracy, DNA polymerase incorporates an incorrect nucleotide only about one in a _____ nucleotides.
Billion
In order for cancer to form, usually ______ of a tumor suppressor gene must be mutated.
Both copies
"HeLa" cells are _____ cells taken from a particular patient that are useful to scientists because they can be maintained in culture indefinitely.
Cancer
"HeLa' cells are _____ cells taken from a particular patient that are useful to scientists because they can be maintained in culture indefinitely.
Cancer
A class of diseases characterized by malignant cells is called _____.
Cancer
Genetic mutations can cause changes in proteins that control the cell cycle and lead to a disease characterized by uncontrolled cell growth called ______.
Cancer
What type of cells lack specialized features, are differently-shaped, often have multiple nuclei, and divide eternally?
Cancer cells
Name a true statement about cancer cells
Cancer cells can divide even in the presence of "stop"" signals
The _____ describes the series of events that occur in a eukaryotic cell from cell division, including division of the genetic material and the cytoplasm, through the interval of cell activity before the next cell division.
Cell cycle
What happens at cell cycle checkpoints?
Cell cycle checkpoints ensure that key steps in interphase and mitosis have been successfully completed before the next step begins. If a cell does not successfully pass a checkpoint, the cell cycle may stop, or the cell may enter apoptosis and die.
Cancer cells, unlike normal cells, do not undergo _____, even when they are damaged.
Cell death
Why are both cell division and apoptosis necessary for the growth and development of an organism?
Cell division produces the new cells that make up an organism. Apoptosis (programmed cell death) carves out structures such as fingers and toes; it also protects an organism by eliminating damaged cells that might otherwise become cancerous.
Name some examples of cells that divide constantly to produce new cells.
Cells at the tip of plant roots and bone marrow stem cells
The two sister chromatids of a replicated chromosome attach at a point called the _____.
Centromere
What is the relationship between genetic mutations and cancer?
DNA encodes each of the many proteins that regulate the cell cycle and apoptosis. These genes include proto-oncogenes and tumor supressor genes. Mutations in these genes can cause the signaling proteins to be abnormal, cause malfunctions in the cell's response to the signaling proteins, or cause apoptosis to fail. Any of these changes can result in cells that divide uncontrollably.
What enzyme adds complementary bases to exposed single strands of DNA during DNA replication?
DNA polymerase
What enzyme has proofreading and repair functions during DNA replication?
DNA polymerase
Why does an RNA primer need to be added to the DNA template for DNA replication?
DNA polymerase can only add nucleotides to an existing strand.
The process of reading a DNA strand and making a complementary DNA copy of that strand is called _____.
DNA replication
Unlike normal body cells, what do cancer cells do indefinitely if given enough space and nutrients?
Divide
What statement describes a process that occurs during mitosis?
Duplicated chromosomes line up and are puled to opposite poles of the cell.
What happens during interphase?
During interphase, the cell grows and produces proteins needed to carry out its functions. In addition, DNA replicates as the cell prepares to divide.
Why do enzymes work at multiple origins of replication?
Each cell contains an enormous amount of DNA. Having multiple origins of replication greatly reduces the amount of time required for DNA replication.
A nucleosome is a stretch of DNA wrapped around _____ proteins.
Eight histone
True or false: During the G1 phase of interphase, the cell replicates the DNA.
False
True or false: The phase of the cell cycle called interphase is a time of inactivity and rest for the cell after mitosis.
False
Binary _____ is a type of prokaryotic asexual reproduction in which replicated DNA and other cell parts are distributed into two new daughter cells.
Fission or binary fission
In DNA replication, enzymes called ligases _____.
Form covalent bonds between segments of DNA.
In the _____ G1 phase of the cell cycle, the cell grows, carries out basic functions, and produces new organelles.
G1
The checkpoint that regulates the cell cycle by screening for DNA damage prior to the start of DNA replication during the S phase is called the _____ checkpoint.
G1
In sexual reproduction, meiosis results in the production of genetically unique sperm cells and egg cells, which are also called _____.
Gametes
Sperm cells and egg cells are also called _____.
Gametes
Cancer is caused by _____ that cause cells to divide uncontrollably.
Genetic mutations.
In order for a eukaryotic or prokaryotic cell to divide, it needs to first duplicate its entire _____, which consists of all of its genetic material.
Genome.
What are the three main events of the cell cycle?
Interphase, mitosis, and cytokinesis
Why does DNA replicate?
It replicates before a cell divides so that each daughter cell receives a complete set of genetic info.
In DNA replication, gaps between newly synthesized segments of DNA and existing segments of DNA are sealed by enzymes called _____, which form covalent bonds between the two segments.
Ligases
In DNA replication, gaps between newly synthesized segments of DNA and exiting segments of DNA and existing segments of DNA are sealed by enzymes called ______, which form covalent bonds between the two segments.
Ligases
What is the key feature that classifies a disease as cancer?
Malignant cells
What process gives rise to gametes in humans?
Meiosis
_____ is a specialized type of cell division that produces cells that are genetically different from each other.
Meiosis
What is the role of meiosis in the human life cycle?
Meiosis creates genetically variable nuclei that each contain half the genetic material of the rest of the body's cells.
Name the processes that occur during anaphase.
Microtubules move the poles of the cell farther apart, centromeres split, and sister chromatids are pulled toward opposite poles.
Distinguish between mitosis and cytokinesis.
Mitosis is the division of duplicated chromosomes into a new daughter nuclei. Cytokinesis is the division of cytoplasm and organelles into two new daughter cells.
Eukaryotic cell division is more complicated than binary fission because eukaryotes house the DNA in _____.
Multiple chromosomes
Although they occur rarely, mistakes in DNA replication result in _____, a changed in cell's DNA sequence.
Mutation
The term _____ refers to any change in a cell's DNA sequence.
Mutation
How does a person acquire the mutations associated with cancer?
Mutations can be inherited form the parents or they may be caused by exposure to mutagens such as UV radiation or tobacco. Some sexually transmitted viruses also cause cancer.
Give some true statements about cancer development.
Mutations that cause cancer can appear in adults The mutations that cause cancer can be inherited Mutations that cause cancer can arise in the gametes and not be present in the parents
Name some truths about cancer development.
Mutations that cause cancer can arise in the gametes and not be present in the parents The mutations that cause cancer can be inherited Mutations that cause cancer can appear in adults.
Name some truths about tumor suppressor genes
Normal copies can promote apoptosis, they encode proteins that normally block cancer development, normal copies can inhibit cell division
A DNA molecule consists of two strands of _____ held together in a _____ structure.
Nucleotides; double helix
What type of cancer-causing genes act too accelerate the cell cycle and are formed from mutated proto-oncogenes?
Oncogenes
Name the two kinds of genes in which genetic mutations can cause cancer to develop.
Oncogenes and tumor suppressor genes
Proto-oncogenes that have been mutated are called ______, which can lead to cancer.
Oncogenes.
In many types of cancer, mutations have converted proto-oncogenes to _____ or have inactivated other genes called _____ _____ genes.
Oncogenes; tumor; suppressor
DNA replication is called semiconservative because _____.
One strand of a new DNA double helix is composed of RNA nucleotides and the other strand is composed of DNA nucleotides.
The major function of nucleosomes is to _____ the DNA within chromatin.
Organize
How do cancer cells differ from normal cells?
Overall, cancer cells are different from normal cells in that they have lost control of the cell cycle. The division of cancer cells is therefore unregulated, effectively making those cells affected, immortal.
In DNA replication, a(n) _____, which is made of RNA, needs to be added to the DNA template in order for DNA polymerase to add new DNA nucleotides.
Primer
Because apoptosis is an intentional act on the part of the cell, it is sometimes referred to as "_____ cell death."
Programmed
Describe apoptosis
Programmed cell death, coordinated series of events
Which cell types divide by binary fission?
Prokaryotic cells (bacteria and archaea)
The p53 protein acts at the G1 checkpoint to _____.
Promote DNA repair.
The chromosomes condense and become visible under a light microscope and the nucleolus disappears in what phase of mitosis?
Prophase
What two major processes occur during interphase?
Protein production and DNA replication
Name all of the components of chromatin.
Proteins for transcription, for scaffolding, for replication, and DNA
Name some facts about the proto-oncogenes.
Proto-oncogenes encode proteins that normally block cancer development. When they are overactive because of mutation, the cell cycle may become accelerated.
Name the 3 traditional cancer treatments.
Radiation therapy, surgical tumor removal, and chemotherapy
What processes are involved in asexual reproduction?
Replication of the genetic material, and splitting of one cell into two cells
Cell division is necessary for an organism to _____.
Reproduce
What cell cycle stage follows G1 but preceds G2?
S
Because one of the two strands of a replicated DNA molecule is newly synthesized and the other is the original template, DNA replication is said to be a _____ process.
Semiconservative
The production of offspring with a genetic makeup derived from two parents is called ______.
Sexual reproduction
After DNA replication, chromosomes consist of two _____.
Sister chromatids
What type of cells may divide throughout their life?
Stem cells
What is the role of fertilization in the human life cycle?
The nuclei may be packaged int gametes; the male gamete fertilizes the female gamete during sexual reproduction, forming a zygote with a full set of genetic material.
Which of the following best describes the overall process of mitosis?
The type of cell division that separates chromosomes and produces two daughter cells with identical nuclei.
Name some truths about telomeres in normal cells.
They are so short after 50 cell divisions that the cell stops dividing, repeats of a specific DNA sequence, and gradually get shorter with each round of cell division
Name some facts that are true with respect to the G1 checkpoint.
Through p53, it promotes the expression of DNA damage repair enzymes, and it can promote apoptosis if the DNA damage is too severe. Additionally, it screens for DNA damage.
In DNA replication, continuous synthesis occurs on the leading strand _____.
Toward the origin of replication
True or false: In general, cancer cells are less specialized than normal cells.
True
BRCA1 and p53 are both examples of ______ suppressor genes, which normally act to prevent cell division.
Tumor
What type of genes normally encode proteins that prevent cell division or promote apoptosis?
Tumor-suppressor genes
Cancer cells are characterized by _____.
Uncontrolled cell divison
Give some truths about proto-oncogenes.
When they are overactive because of mutation, the cell cycle may become accelerated. They encode proteins that stimulate cell division.