GBIO Ch. 8
About how long does it take for a human to entirely replace the outer layers of the skin?
1 month
Place the following apoptotic events in chronological order, beginning with the first event at the top.
1. A "death receptor" on the cell's membrane is activated. 2. Apoptosis-specific proteins begin to destroy the cell. 3. An immune system engulfs the cell and destroys the remnants.
Place the following steps of DNA replication in the order in which they occur.
1. Helicase separates the two template strands of DNA. 2. Binding of proteins to the two template strands prevents them from rejoining. 3. Primase adds short stretches of RNA to the template DNA strand. 4. DNA polymerase adds DNA nucleotides to create the newly synthesized strand. 5. Enzymes replace the primers, and ligase seal the gaps between existing segments and newly synthesized segments.
If the DNA in one human cell was unpacked and stretched out in a line, the line would be ________________________, and yet when DNA is packaged, it fits into a cell that is less than one-tenth of a millimeter.
2 meters long
Because DNA polymerase can only add nucelotides to the _________ end of a growing strand, DNA replication on the lagging strand produces shorts pieces called
3'; Okazaki fragments
A human skin cell lives on average for about
35 days
Match each organism with the correct number of chromosomes contained in that organism's body cells.
6 chromosomes: mosquito 24 chromosomes: rice 46 chromosomes: human 78 chromosomes: dog 104 chromosomes: carp
What provides energy for the synthesis of nucleotides and the formation of covalent bonds in DNA synthesis?
ATP
Cancer cells do not exhibit ___________________, which means they can divide even when not attached to a solid surface.
Anchorage dependence
Match each description to the correct type of cell death.
Apoptosis: Coordinated series of events, programmed cell death, normal part of development Necrosis: Disorderly, accidental cell death, results from a trauma, such as a cut or bruise.
Select the ways that a person can maintain a healthy lifestyle and reduce their risk of cancer.
Avoid foods rich in animal fats, limit exposure to chemical mutagens, prevent obesity, and exercise regularly.
Why does an RNA primer need to be added to the DNA template for DNA replication?
Because DNA polymerase can only add nucleotides to an existing strand
Why do chemotherapy and radiation therapy cause hair loss, fatigue, and nausea?
Because they target all rapidly dividing cells.
Which of the following illnesses is directly associated with loss of cycle control?
Cancer
Select the true statements that describe cancer cells compared to normal cells.
Cancer cells may have multiple nuclei and cancer cells are less specialized than normal cells.
Select all the events that occur during prophase.
Centrosomes migrate to opposite poles, mitotic spindle begins to form, and chromosomes condense.
What enzyme has proofreading and repair functions during DNA replication?
DNA polymerase
In order for a cell to divide, all of its genetic information has to be duplicated through a process called
DNA replication
Select the functions of apoptosis in animal cells.
Destroying damaged cells, carving out of functional structures like fingers, and weeding out of aging cells.
What statement best describes the overall process of mitosis?
Duplicated chromosomes line up and are pulled to opposite poles of the cell.
While the drug endostatin shrank tumors repeatedly in mice, what was the effect of endostatin in human clinical trials?
Endostatin was ineffective in most human patients.
True or false: in order for an organism to grow to its maximum size, all cells within the organism divide as fast as they can throughout the organism's life span.
False
True or false: During the G1 phase of interphase, the cell replicates the DNA.
False.
The initiation of chromosome condensation and the production of proteins that will coordinate the movements of chromosomes during mitosis occur during what phase of the cell cycle?
G2
Which of the following checkpoints monitors that DNA has been completely replicated and that the spindle-making machinery is in place?
G2
Which of the following occurs after the S phase but precedes mitosis?
G2
Select the phases that occur within the interphase of the cell cycle.
G2, S, G0, and G1
Match each cancer treatment with how it works.
Gene therapy: add functional genes to cells with disabled genes. Drug therapy: target specific molecules in cancer cells. Angiogenesis inhibitors: block the recruitment of blood vessels by a tumor.
What is all the cell's genetic material and consists of one or more chromosomes containing the DNA?
Genome
Select all the body and cellular processes that require cell division to function.
Growth and development, reproduction, and replace dead cells.
Match the parts of the chromosome with their description.
Histone: proteins around which DNA winds Centromere: place where two sister chromatids attach in a replicated chromosome Chromatid: replicated copy of a chromosome Nucleosome: stretch of DNA wrapped around proteins; become tightly arrayed during chromatin condensation
Select all of the following that describe the products of one cell undergoing mitotic cell division.
Identical genetic material, 2 daughter cells, and organelles distributed to daughter cells
Select the following that are true about growth factors triggering cell division.
In response to a signal, a cascade of chemical reactions inside the cell initiates cell division. Growth factors bind to receptors on the cell membrane. Epidermal growth factor stimulates skin cells to divide.
Match the following events of the cell cycle with their description.
Interphase: the time between cell divisions in which DNA replication, basic cellular activities, and cell growth take place Mitosis: division of the contents of the nucleus Cytokinesis: division of the cell itself
If the DNA in one human cell is 2 meters long, how does it fit into the nucleus of the cell?
It is efficiently wound around scaffolding proteins
Select all of the following that are true with respect to the G1 checkpoint.
It screens for DNA damage. Through p53, it can promote apoptosis if the DNA damage is too severe. Through p53, it promotes the expression of DNA damage repair enzymes.
Select all of the following that are forms of cancer.
Leukemia, lung cancer, and breast cancer.
The checkpoint that ensures that all chromosomes are aligned and that the spindle fibers are attached correctly is called the
M checkpoint
Select the methods used by physicians to detect cancer and estimate the stage of a patient's cancer.
MRIs, biopsies, ultrasounds, and blood tests
What is the key feature that classifies a disease as cancer?
Malignant cells
What is a specialized type of cell division that produces cells that are genetically different from each other?
Meiosis
A type of cell division that divides a eukaryotic cell's genetic information into two identical daughter nuclei.
Mitosis
What process accounts for the formation of a multicellular adult from a zygote, the repair of tissues, and the replacement of cells lost by every day wear-and-tear?
Mitosis
Because genes encode proteins that control cell division and cell death, ____________, or changes in genes, can lead to cancer.
Mutations
What are true statements 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, and mutations that cause cancer can appear in adults.
Select the true statements about tumor suppressor genes.
Normal copies can promote apoptosis, normal copies can inhibit cell division, and they encode proteins that normally block cancer development
Proto-oncogenes that have been mutated are called ________________, which can lead to cancer.
Oncogenes
Place the phases of mitosis in the order that they occur.
Prophase, prometaphase, metaphase, anaphase, and telophase
Which of the following would you find in chromatin?
Proteins for transcription, DNA, proteins for scaffolding, and proteins for replication
Select the processes that are due to mitotic cell division.
Replacement of lost cells, repair after injury, and growth of a zygote into a multicellular adult
What are some processes involved in asexual reproduction.
Replication of the genetic material and splitting of one cell into two cells.
During the _______ phase of interphase, DNA replication occurs.
S
Select the phases that occur within interphase of the cell cycle.
S, G0, G1, G2
Match the stage of cancer with its description.
Stage I: Cancer has spread to tissue adjacent to the tumor but remains confined to the organ of origin. Stage II: Cancer has spread to nearby tissues beyond the organ of origin but has not yet spread to the lymph nodes. Stage III: Cancer has spread to the lymph nodes and nearby organs but not distant organs. Stage IV: Cancer has spread to distant sites and distant organs.
Select factors that affect the success of cancer treatment.
Stage of cancer, localization of cancer, type of cancer, and introduction of new mutations.
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.
Select all the true statements with respect to benign tumors.
They are usually harmless, they are surrounded by a tough capsule to prevent them from spreading, and they grow slowly.
Select the ways in which cancer cells differ from normal cells.
They divide independently of growth factors, they have uncontrolled cell division, and they have lost contact inhibition.
After DNA replication, what happens to the nucleosomes in chromatin?
They fold and wind into a compact form.
Which of the following is true with respect to proto-oncogenes?
When they are overactive because of mutation, the cell cycle may become accelerated and they encode proteins that stimulate cell division.
In sexual reproduction, the sex cells of two different parents fuse to form
a genetically different offspring.
In prokaryotes, DNA is contained in ______________, and in eukaryotes, DNA is contained in ______________________.
a single chromosome; multiple chromosomes
Select the needs that must be balanced in a eukaryotic cell with a large amount of genetic material.
allowing DNA to be accessible for cell functions and packaging DNA so that it can be divided during cell division
The drug endostatin is a type of cancer-fighting drug called _________________, which specifically attacks endothelial cells of growing ___________________.
an angiogenesis inhibitor; blood vessels
Select the properties that cancer cells lack, enabling the cancer cells to divide uncontrollably and spread to other areas
anchorage dependence and contact inhibition
Cancer cells are able to stimulate the development of new blood vessels, a process called
angiogenesis
During development, the process that "carves" out the fingers from a webbed sheet of tissue is called
apoptosis
Select the types of organisms that can produce new individuals by asexual reproduction.
archaea, bacteria, some multicellular eukaryotes, and many protists
Usually, warts and moles are ______________ tumors of the skin, meaning they do not invade surrounding tissues or metastasize.
benign
What proteins prevent the two strands of a DNA duplex from rejoining once they are unwound by a helicase?
binding proteins
What proteins prevent the two strands of a DNA duplex from rejoining once they are unwound by helicase?
binding proteins
A drug called endostatin can be effective in treating cancer by stopping the growth of _______________ near tumors.
blood vessels
Select all of the rapidly dividing cells that are affected by chemotherapy and radiation therapy.
bone marrow cells, cancer cells, hair follicles, and cells of the digestive tract
"HeLA" cells are _______________ cells taken from a particular patient that are useful to scientists because they can be maintained in culture indefinitely.
cancer
What describes the time from one cell division to the next?
cell cycle
Not only is cell division a normal part of development, but ___________________ called apoptosis also plays a role in a developing body, as in the loss of a tadpole's tail as a young frog develops.
cell death
Plant cells use a form of _____________________ to limit the spread of a fungal or bacterial infection.
cell death
During cytokinesis in plants, the appearance of the _____________ is the first sign of new cell wall construction.
cell plate
Select all the examples of cells that divide constantly to produce new cells.
cells at the tips of plant roots and bone marrow stem cells
Sister chromatids are attached to one another at the
centromere.
A structure called the _______________ is duplicated during S phase and organizes the proteins that will move chromosomes during mitosis.
centrosome
A structure called the ________________ is duplicated during S phase and organizes the proteins that will move chromosomes during mitosis.
centrosome
Structures that consist of proteins surrounding a pair of centrioles are called ________________, which function to organize the proteins that move chromosomes during mitosis.
centrosomes
Structures that consist of proteins surrounding a pair of centrioles are called ____________________, which function to organize the proteins that move chromosomes during mitosis.
centrosomes
A cell's genetic material is contained in one or more
chromosomes
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 contribute to divide.
chromosomes; telomeres
The major function of nucleosomes is to ______________________ the DNA within the chromosome.
compact
Unlike normal cells, many cancer cells respond to a lack of growth factors by
continuining to divide
The binding of proteins to ______________ can activate transcription factors and stimulate cell cycle progress.
cyclins
Following mitosis, what process splits the organelles, cytoplasm, duplicated nuclei, and macromolecules into two daughter cells?
cytokinesis
A nucleosome is a stretch of DNA wrapped around _______________ proteins
eight histone
The cells of cancerous tumors larger than 1 or 2 mm secrete signals that stimulate _________________ cells in blood vessels to divide, causing angiogenesis.
endothelial
What describes the S phase checkpoint?
ensures that DNA replication occurs properly
How fast can some bacterial cells divide in optimal conditions?
every 20 minutes
Mutations in cancer cells can allow the cells to survive cancer therapy treatments (like chemotherapy) and these "resistant" cells can divide and become more numerous, which is an example of
evolution
In sexual reproduction, the union of sperm and egg occurs in a process called
fertilization
Sperm cells and egg cells are also called
gametes
In order for a cell to divide, by mitosis or meiosis, it needs to first duplicate its entire _______________, which consists of all its genetic material.
genome
Unlike normal cells, many cancer cells can divide even in the absence of
growth factors
What enzyme unwinds DNA to separate the strands for DNA replication?
helicase
Many cancer cells send signals to stimulate angiogenesis, which results in
increased exchange of nutrients and wastes in the area of the tumor.
During a section of the cell cycle collectively called _____________, the cell is not dividing, but protein synthesis, cell growth, DNA replication, and basic cell functions are occuring.
interphase.
A malignant tumor is one that
invades surrounding tissue
Proteins called _______________ are present at the centromeres of chromosomes and become attached to spindle microtubules during prometaphase.
kinetochores
Proteins called ________________ are present at the centromeres of chromosomes and become attached to spindle microtubles during prometaphase.
kinetochores
Proteins called _________________ are present at the centromeres of chromosomes and become attached to spindle microtubules during prometaphase.
kinetochores
On one strand of DNA, called the _______________ strand, the 3' end is exposed, and DNA replication can proceed ____________.
leading; continuously
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 existing segments of DNA are sealed by enzymes called ________________, which form covalent bonds between the two segments.
ligases
When the cell is not dividing, nucleosomes are _________________ so that the DNA is accessible for cell activities.
loosely packed
Once mitosis has begun, the checkpoint that allows a cell to progress into anaphase is called the
metaphase checkpoint
A malignant tumor is likely to _____________, meaning break away and spread to distant locations.
metastasize
The mitotic spindle is composed of protein fibers called _____________ that coordinate the movements of ____________________ during mitosis.
microtubules; chromosomes
What part of the cell cycle occurs immediately after the G2 phase?
mitosis
What term refers to any change in a cell's DNA sequence?
mutation
Units of chromatin called __________ consist of a stretch of DNA wrapped around eight histones.
nucleosomes
A DNA molecule consists of two strands of __________ held together in a _________ structure.
nucleotides; double helix
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 newly synthesized and the other strand is from the parent molecule.
DNA replication takes place simultaneously at hundreds of places along the DNA molecule called
origins of replication
If the paternal copy of a proto-oncogene is mutated in an individual, the abnormal protein encoded by the oncogene _______________ the product of the maternal copy of the proto-oncogene, and cancer can develop.
overrides
In ____________________ cells, the mitotic proteins are organized not at centrosomes but rather at many locations throughout the cell.
plant
Due to the action of motor proteins, overlapping spindle fibers slide past one another during anaphase and push the ____________________ of the dividing cell apart.
poles
Due to the action of motor proteins, overlapping spindle fibers slide past one another during anaphase and push the ________________________ of the dividing cell apart.
poles
The enzyme called DNA _______________ adds new complementary DNA nucleotides to a single-stranded DNA template.
polymerase
Because apoptosis is an intentional act on the part of the cell, it is sometimes referred to as "______________ cell death"
programmed
Select the traditional cancer treatments.
radiation therapy, chemotherapy, and surgical tumor removal
Binary fission in prokaryotes begins with
replication of the single chromosome
Binary fission in prokaryotes begins with the
replication of the single chromosome
Cell division is necessary for an organism to
reproduce
Select all of the following that increase the risk of cancer.
sexually transmitted viruses, smoking, and UV radiation
The mitotic __________ consists of fibers that will grow outward toward the chromosomes during mitosis.
spindle
During anaphase, the shortening of ________________ attached to kinetochores pulls attached chromatids to opposite poles of the cell.
spindle microtubules
The enzyme that maintains the telomere ends of chromosomes is called
telomerase
The caps at the end of chromosomes that get smaller and smaller after each cell division, except in cancer cells, are called
telomeres
The caps at the ends of chromosomes that get smaller and smaller after each cell division, except in cancer cells, are called
telomeres
What explains why the chance of inheriting harmful BRCA1 mutations is much higher in Ashkenazi Jews?
the founder effect
BRCA1 and p53 are both examples of _____________ suppressor genes, which normally act to prevent cell division.
tumor
What are all the types of genes in which genetic mutations can cause cancer to develop?
tumor suppressor genes and oncogenes
Many cancer cells do NOT
undergo apoptosis
The growth rate of malignant tumors
varies in cancer patients
Unlike in mice, the drug endostatin ______________ in most human patients.
was ineffective
A type of asexual reproduction seen in bacteria that replicates DNA and distributes other cell parts into two new daughter cells.
Fission
Cells in the G1 phase in interphase can enter a functioning but nondividing phase of the cell cycle called
G0
Most cells of the human body at any given time are in the _____________ phase of the cell cycle.
G0
In the ____________ phase of the cell cycle, the cell grows, carries out basic functions, and produces new organelles.
G1
The initiation of a chromosome condensation and the production of proteins that will coordinate the movements of chromosomes during mitosis occur during what phase of the cell cycle?
G2
True or false: One difference between animal and plant cytokinesis is that animal cells produce a cleavage furrow in order to divide, whereas plant cells produce new cell wall along a cell plate to complete division.
True
True or false: in general, cancer cells are less specialized than normal cells.
True
True or false: most plant cells lack centrosomes and centrioles that organize mitotic patterns.
True
What can lead to the formation of a tumor?
Uncontrolled cell division and lack of programmed cell death
Select all the reasons that cells need to control their rate of division.
Uncontrolled cell division can lead to abnormal growth, too little cell growth will not allow injuries to be repaired, cells that make up different types of tissues require different rates of division for proper function.
Structures that consist of proteins surrounding a pair of centrioles are called ________________________, which function to organize the proteins that move chromosomes during mitosis.
centrosomes
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
A replicated chromosome consists of two attached copies called sister
chromatids
