BIOL FINAL

7. (4) Which of the following genetic changes would convert a proto-oncogene into an oncogene?

1. A mutation within the coding sequence that makes the protein hyperactive. 2. An amplification of the number of copies of the proto-oncogene, causing overproduction of the normal protein. 3. A mutation in the promoter of the proto-oncogene, causing the normal protein to be transcribed and translated at an abnormally high level. ALL 3

How many kinetochores are present in a human cell during mitosis?

92

What is the difference between a malignant and benign tumor?

A malignant tumor invades and colonizes other tissues, while a benign tumor does not.

Which of the following statements is false?

A. Some death-inhibiting members of the Bcl2 family inhibit apoptosis by blocking cytochrome c release from mitochondria.B. Bax and Bak are death-promoting members of the Bcl2 family that induce the release of cytochrome c from mitochondria into the cytosol.C. Some Bcl2 family members promote apoptosis, whereas others inhibit apoptosis. D. The death-promoting members of the Bcl2 family include Bcl2 itself. <<<<<---

Which of the following statements is false?

A. The pairing of homologous chromosomes during prometaphase is called bi-orientation.

For both clinical and cosmetic reasons, plastic surgeons inject substances into connective tissue underlying the skin epidermis. This plumps up areas deficient in soft tissue, and is used to reduce surgical scars or wrinkles, for example. Which normal connective tissue components are good candidates to be injected as fillers in this type of procedure?

A.glycosaminoglycan B. collagen

Which of the following can give rise to cancer-promoting mutations?

A.inhalation of tobacco smoke B.DNA replication errors C.exposure to ionizing radiation D.exposure to excess sunligh

One approach to killing cancer cells is to induce apoptosis. Which of the following are reasonable approaches that researchers can take to induce apoptosis in cancer cells?

A.inhibiting the Bcl2 protein D.activating the Bax protein

Many of the genes mutated in individual tumors are involved with which of the following regulatory pathways?

A.pathways regulating the cell's response to DNA damage or stress C.pathways governing the initiation of cell division

What is the best description of connective tissue?

All of its cells are sparsely distributed in the extracellular matrix.

Cancer is fundamentally which type of disease?

B. a genetic disease

Investigators interested in studying the activation of apoptosis inject cytochrome c into the cytosol of two types of mammalian cells: cells that are normal and cells in which Bak and Bax have been inactivated by mutation. How would these cells be predicted to respond?

Both cell types will undergo apoptosis.

If DNA is damaged or incompletely replicated in S phase, the inhibition of which of these molecules prevents the cell from entering M phase?

Cdc25

Cyclins are needed to activate Cdks, but Cdk activity is not directly correlated with cyclin levels. Why?

Cdks are also regulated by phosphorylation.

Which of the following statements about integrins are true? (select all that are true)

Certain intracellular chemical signals can activate integrins from inside the cell, causing them to reach out and grab hold of extracellular structures. Integrins in fibroblasts can attach indirectly to collagen via fibronectin, an extracellular matrix protein. When an integrin binds to the extracellular matrix, it stretches into an extended, activated state to attach to molecules on the inside of the cell. Integrins undergo extensive conformational changes on binding to molecules on either side of the plasma membrane. ALL

Caspases are proteases that can be activated by binding to cytochrome C. How is binding to cytochrome C regulated?

Cytochrome C only activates caspase when it leaks out of mitochondria

Why does the activation of M-Cdk begin abruptly?

Each M-Cdk complex can activate more M-Cdk.

Most of the diversity in the rates of cell division in the adult body lies in variations in the time that each cell spends in which phase(s)?

G1 phase and G0 phase

Which of the following would block release of cytochrome c from mitochondria? I. the Bcl2 protein II. Survival Factors III. Fas ligand

I and II

Which type of protein in a fibroblast's plasma membrane attaches to the extracellular matrix on the outside of the cell and (through adaptor molecules) to actin inside the cell?

Integrin

What does the phosphorylation of Cdc25 by M-Cdk do?

It activates Cdc25, which in turn activates more M-Cdk.

What must happen for a Cdk to be active?

It must bind to its cyclin partner.

It is often useful for scientists to study a population of cells that are all at the same stage of the cell cycle. For example, the discovery of cyclins and Cdks was enabled by studying frog eggs that divided synchronously after fertilization; extracts from the embryos were thus representative of the cell-cycle stage at which the extract was made. Researchers have devised means to synchronize asynchronous populations of cultured cells. For example, serum starvation deprives cells of mitogens and blocks cells in the G0/G1 phase of the cell cycle. Another method involves gently shaking culture flasks and harvesting the cells that release from the substratum. In what stage of the cell cycle are these cells most likely to be?

M phase

Soon after nerve growth factor (NGF) was discovered, investigators injected newborn mice with antibodies that inactivated it. Compared to control mice, those that received the antibody showed massive amounts of nerve cell death. After a week of daily antibody injections, up to 99% of the neurons in certain parts of the nervous system of these mice were gone. What do these results suggest?

NGF is a survival factor for developing neurons.

In a highly secret, terrorist research laboratory the scientists are trying to develop a strain of large, dog-sized rats to be let loose in the United States. The plan is that these rats will destroy our food supply. Which of the following strategies would be the Best choice to produce larger rats?

Overproduce mitogens

In the extracellular matrix of animal tissues, which of the following molecules allows the matrix to resist compression?

Proteoglycans

Which cancer-causing gene can be activated by a single mutation in only one copy?

Proto-oncogene

The signal to commence DNA replication comes from which of the following?

S-Cdk

What happens during G1 in the cell cycle of a proliferating cell?

The cell makes more proteins, lipids, organelles, etc. and grows in size

Which of the following structural changes is not typically seen in a cell that is undergoing apoptosis?

The cell swells.

The cell-cycle control system initiates chromosome segregation only after which of the following has occurred?

The duplicated chromosomes are correctly aligned on the mitotic spindle.

What is a major problem with using foreign cells grown in culture for transplantation in humans?

The host immune system would destroy such cells.

Which feature of glycosaminoglycans (GAGs) allows the extracellular matrix in cartilage to resist compression?

The negative charges on GAGs attract sodium ions, which draw water into the extracellular matrix to form a water-filled gel.

Which statement is true about stem cells?

They can divide for the lifetime of the organism.

Which is true of cadherin proteins?

They link epithelial cells together by binding to similar cadherins in adjacent epithelial cells.

Which of the following statements describes how growth factors stimulate animal cell enlargement?

They stimulate intracellular protein synthesis.

Which class of cancer-critical gene must be inactivated to promote the development of cancer?

Tumor suppressor gene

Colon cancer can occur when cells in the crypt become mutated and do not migrate properly out of the crypt. Which of the following drugs could potentially block the development of colon cancer?

a drug that leads to degradation of β-catenin

A certain mutation in the receptor for epidermal growth factor (EGF) causes the mutated receptor protein to send a positive signal along associated intracellular signaling pathway even when EGF is not bound to it. This leads to abnormal cell proliferation in the absence of growth factor. On the basis of this information, how would you class the normal form of the gene for the EGF receptor?

a proto-oncogene

The gene that encodes p53 is

a tumor suppressor

Viral genomes

a. can be made of DNA. b. can be made of RNA. c. can be either double-stranded or single-stranded. d. All of these answers are true. <<<-

What is metastasis?

ability of cancer cells to travel from the site of an initial tumor, through the blood or lymph to another location, and form a secondary tumor

What is the contractile ring made of?

actin and myosin

Which type of epithelial cell junction plays a major role in an epithelial sheet's ability to develop tension and change its shape?

adherens junction

A normal cell is converted into a cancer cell by

an accumulation of mutations affecting several different genes.

The surface of the villi in the small intestine is covered by a single layer of epithelial cells called enterocytes. Enterocytes absorb nutrients from the intestinal lumen as they move up the side of the villus. The enterocytes are shed from the end of the villus through apoptosis after 3 to 4 days. Consequently, new cells must be continuously supplied from the crypt and move up the villus. When a stem cell in the crypt divides, what are its immediate daughter cells?

another stem cell and a transit amplifying cell

You are a virologist interested in studying the evolution of viral genomes. You are studying two newly isolated viral strains and have sequenced their genomes. You find that the genome of strain 1 contains 25% A, 55% G, 20% C, and 10% T. You report that you have isolated a virus with a single-stranded DNA genome. Based on what evidence can you make this conclusion?

because double-stranded genomes have equal amounts of A and T

The goal of gene-therapy techniques is to provide cells with functional copies of mutated genes. One technique involves introducing functional genes on an "artificial chromosome." Somatic cells in which the artificial chromosome has been inserted have 47 chromosomes instead of the normal 46 (i.e., for human cells). To be effective, the artificial chromosome must be passed to daughter cells during mitosis, which requires that the artificial chromosome contain sequences on which kinetochores can assemble. With this in mind, what should designers of artificial chromosomes include to ensure proper kinetochore assembly on the artificial chromosome?

centromere

Which of the following occurs during metaphase?

chromosomes being aligned under tension at the spindle equator

In animal connective tissues, tensile strength is chiefly provided by

collagen fibrils and fibers

Fibroblasts are the major cellular component in which tissues?

connective

With age comes an increase in facial wrinkles and a decrease in the thickness of lips. Therefore aged seekers of beauty can counteract those characteristics by increasing tissue volume around the eyes in order to smooth wrinkles or in the lips to make them fuller. Which of the following would be most effective to inject for these beauty-enhancing procedures?

d. proteoglycans

Which of the following properties would you expect a cancerous cell to have?

decreased adhesion to neighboring cells

Which of the following animal cell types, under appropriate conditions, can be kept proliferating indefinitely in culture and yet retain unrestricted developmental potential?

embryonic stem cells

The inactivation of M-Cdk leads to which of the following?

exit from mitosis

What attaches epithelial cells to the basal lamina?

hemidesmosomes

Which of the following can increase the likelihood that a person will get cancer? (choose all the correct answers)

infection by certain viruses, such as human papilloma virus living in, and adopting the lifestyles of certain countries errors in DNA replication, which occur in all individuals over their lifetime being obese smoking tobacco ALL

Some cancer cells are missing a key protein needed to repair double-strand DNA breaks. They survive by relying on alternative DNA repair mechanisms. To treat these cancers, researchers have developed drugs that do which of the following?

inhibit alternative DNA repair mechanisms

At desmosomes, cadherin molecules are connected to

intermediate filaments.

Treatment with methotrexate blocks the folate pathway and causes defects during embryogenesis in vertebrates. In humans, a lack of folate during pregnancy can lead to development of neural tube defects. In zebrafish development, methotrexate blocks embryo development at the stage of early somite formation. Which of the following events would also be blocked by methotrexate treatment of zebrafish embryos if development stops early in the stage of somite formation?

internalization of yolk into the developing gut cavityeye development

The entire period between one M phase and the subsequent M phase is called what?

interphase

Which of these human cells undergoes the most rapid turnover?

intestinal epithelial cells

A basal lamina

is a thin layer of extracellular matrix underlying an epithelium.

Microtubules capture chromosomes by binding specifically to which of the following?

kinetochores on the sister chromatids

Microtubules capture chromosomes by binding to

kinetochores on the sister chromatids.

What is the mitotic spindle made of?

microtubules

When a cell is acutely injured, it usually dies by which process?

necrosis

Which of the following determines the direction that cellulose microfibrils are laid down in the extracellular space of a plant cell?

orientation of microtubules on the cytoplasmic side of the plasma membrane

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundance between and among the osteocytes. The collagen and calcium salts are:

part of the extracellular matrix.

Mutations that prevent Bcl2 family proteins Bax and Bak from interacting with the outer mitochondrial membrane would have which effect?

preventing the release of cytochrome c and inhibiting apoptosis

In the intestine, what do Wnt proteins promote?

proliferation of the stem cells and precursor cells at the base of each intestinal crypt

The mitotic spindle begins to assemble in which phase of the cell cycle?

prophase

The extracellular matrix in mammalian tissues is derived from

proteins secreted from cells.

What do cells do during G1 phase?

repair DNA damage destroy cyclins

Survival factors are important for tissues because

they increase the expression of apoptosis inhibitors so the cells won't die.

Which epithelial cell junctions serve to seal neighboring cells together so that water-soluble molecules cannot easily leak between them?

tight junctions

Cadherin is a(n)

transmembrane cell adhesion protein

The anaphase-promoting complex (APC) triggers the onset of anaphase by

triggering the destruction of the cohesin proteins holding the sister chromatids together.

The anaphase-promoting complex (APC) triggers the onset of anaphase by doing which of the following?

triggering the destruction of the cohesins that hold the sister chromatids together

The apoptosis promoter Bax normally found in human cells could be considered which of the following?

tumor suppressor

Some types of cancer run in families: individuals in such predisposed families are prone to develop these cancers early in adult life. Mutations in which type of cancer-critical gene would most likely be responsible for "hereditary" cancers that are not immediately present in the phenotype of offspring but develop as age increases?

tumor suppressor genes

The protein p53 is an important tumor suppressor that arrests the cell cycle if DNA is damaged. P53 functions by

turning on the transcription of a protein that binds to and inhibits Cdks/cyclin complexes.

Viruses reproduce inside a host cell because

viruses use host-cell ribosomes to produce viral coat proteins.

Why can you be infected with SARS-CoV-2 yet have no symptoms and infect other people?

· Following the eclipse period, virus has been made and can be 'shed' (released - through a cough, for example), this can occur before enough cells have been damaged to display symptoms.

Summarize how viruses take advantage of receptor-mediated endocytosis, and the endocytic pathway to replicate. (you can use bullet points - that's probably easiest)

· Virus binds a specific receptor on the outside of the cell · Receptor-mediated endocytosis brings the virus into the cell in an endosome · Endosomes fuse with lysosomes, the decreasing pH in the two vesicles helps uncoat the viral genetic material · Viral genetic material is released into the cell so it can 'pirate' the cellular machinery, replicate it's genetic material and made viral proteins.

The simplest method for identifying proteins that bind tightly to one another is co-immunoprecipitation. What protein was discovered to co-immunoprecipitate with Adenomatous Polyposis Coli (APC) protein?

β-catenin

What gives the plant cell wall its tensile strength?

cellulose

Which of the following statements about tumor suppressor genes are true?

1. Gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a proto-oncogene. 3. Inactivation of tumor suppressor genes leads to enhanced cell survival and proliferation. 4. Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene. ALL 3

Investigators wish to study the possible causes of a form of cervical cancer that is on the rise in the tropical Pacific Ocean. To determine whether environmental risk factors play a role, the researchers collect statistics from different populations on each of three islands. The indigenous populations include individuals who were born and raised on the island and the immigrant populations include individuals who moved there from elsewhere. What can be concluded about this form of cervical cancer based on the data collected?

1. The incidence of this cancer is strongly influenced by something in the environment.

Human papilloma virus (HPV) is the most common sexually transmitted infection, with 45% of 20-24 yr old women infected. Infection of the genitalia and cervix with HPV increases the risk of cervical cancer 10-fold. Two proteins encoded by HPV DNA bind to p53 and Rb. Which of the following do you think would Best describe the function of those two HPV proteins?

1. oncogenes

During vertebrate development, a sheet of epithelial tissue invaginates to form the neural tube, a structure that eventually forms the spinal cord and brain. Mutations that interfere with the function of which proteins would be most likely to disrupt the epithelial sheet movement that drives this developmental process?

cadherins