Lesson 9 (Mitosis and Cancer)

The first step of bacterial replication is _____. a. separation of daughter cells b. pinching of the plasma membrane c. DNA replication d. attachment of the DNA to the plasma membrane

c. DNA replication -->The DNA must be copied in order to proceed.

Bacteria divide by: a. meiosis b. mitosis c. binary fission d. sexual reproduction

c. binary fission -->Binary fission is the method used by bacteria to divide.

An individual with a malignant tumor is said to have _____.

cancer

_____ is the spread of cancer cells from their site of origin to other sites in the body.

Metastasis

Which are risk factors that suggest someone who has not been tested for a BRCA mutation should get tested? (select all that apply) a. Has three or more family members with breast cancer on the same side of the family b. Has a single individual in the family who has had two or more breast cancers. c. Has had a previously identified BRCA1 or BRCA2 mutation in the family d. Are of South American descent

a. Has three or more family members with breast cancer on the same side of the family b. Has a single individual in the family who has had two or more breast cancers. c. Has had a previously identified BRCA1 or BRCA2 mutation in the family -->It is the families of Ashkenazi Jewish descent THAT ALSO have a personal or family history of breast, ovarian or pancreatic cancer that are at higher risk.

Which of the following best describes the relationship between a chromosome and sister chromatids? a. Joined identical copies of a duplicated chromosome are called sister chromatids. b. Two different chromosomes combine to make a pair of sister chromatids. c. Two sister chromatids will duplicate and separate into four identical chromosomes. d. A sister chromatid contains half of the original chromosome's genetic material.

a. Joined identical copies of a duplicated chromosome are called sister chromatids. -->When an individual chromosome is duplicated, two identical copies are made. Those identical copies are called sister chromatids. Sister chromatids are held together at a centromere, and each contains the same genetic information as the original chromosome.

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other? a. The sequence in one chromatid is complementary to the sequence in the other. b. The sequences are identical. c. The sequences are similar, but not identical. d. The sequences are unrelated.

b. The sequences are identical. -->Except for the occurrence of rare mutations, this is always the case. Both sister chromatids come from replication of a single DNA molecule, which is present in the one chromatid before replication.

You are asked to culture an unidentified sample of animal tissue. You notice that the cells seem to fail to exhibit density-dependent inhibition. The source of this tissue sample is most likely a. liver from a cow b. a cancerous tumor c. skin from a human d. sperm-producing tissue of the testis

b. a cancerous tumor

As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of a. anchorage independence b. density-dependent inhibition c. density-independent inhibition d. growth factor inhibition

b. density-dependent inhibition

A woman who is negative for a BRCA gene test (meaning she does not have this mutation): select all that apply a. has an 80-90% chance of developing breast cancer by age 70 b. has a less than 10% chance of developing breast cancer by age 70 c. will not get cancer since she does not have one of the BRCA mutations d. we cannot calculate a risk, but we know its a possibility

b. has a less than 10% chance of developing breast cancer by age 70 -->Just because a woman doesn't have BRCA mutation doesn't mean she doesn't not have other risk factors (environment, other mutations in difference cancer causing genes etc.).

A ______ is an abnormally growing mass of cells that is actively spreading through the body.

malignant tumor

Population studies suggest the overall risk for someone with a BRCA mutation for developing breast cancer by age 70 is _______. a. about 85% b. over 95% c. about 10% d. about 35%

a. about 85% -->There are other factors to consider that increase or decrease this risk for each individual, but this is the number that emerges from population studies.

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called a. cytokinesis b. telophase c. mitosis d. binary fissioin

a. cytokinesis

Which of the following statements correctly describes the timing of DNA synthesis? a. DNA is synthesized only during mitosis. b. DNA is synthesized continuously throughout the cell cycle. c. DNA is synthesized in G2 of interphase immediately preceding mitosis. d. DNA is synthesized in the S phase of interphase.

d. DNA is synthesized in the S phase of interphase. -->Single chromosomes enter the synthesis, or S phase, of interphase. At the end of this phase, after DNA replication, the chromosomes are double, each consisting of two sister chromatids.

What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells? a. the amount of DNA present b. whether the DNA is housed in a nucleus or not c. whether the DNA is linear or circular d. all of the above are differences between prokaryotic and eukaryotic DNA

d. all of the above are differences between prokaryotic and eukaryotic DNA

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis? a. anaphase b. telophase c. interphase d. metaphase e. prophase

b. telophase -->Telophase is the final phase of mitosis, when the chromosomes have arrived at the poles and the nuclear envelopes of the two new cells form.

A _______ is a lump of abnormal cells, although growing out of control, remains at its original site.

benign tumor

Asexual reproduction requires ________ individual(s), whereas sexual reproduction requires _______ individual(s). a. 2 ; 2 b. 1 ; 1 c. 1 ; 2 d. 2 ; 1

c. 1 ; 2

Imagine that a human skin cell went through mitosis but did not undergo cytokinesis. How many chromosomes would be in the cell? a. 46 b. 23 c. 92 d. 69

c. 92 -->When the cell prepared to divide, the chromosomes were replicated, and the chromosome number went from 46 to 92. Because these were not separated into daughter cells during cytokinesis, the cell still has 92 chromosomes.

Which statement about Deb Lindner (the woman from the Amy Harmon NY TIMES article) is TRUE? a. Deb is opposed to breast removal and reconstructive surgery, she prefers mammograms and MRIs until she is in her 40's. b. her mother died from ovarian cancer d. Deb's sister is also a BRCA carrier (has the mutation) and has already had her breasts and ovaries removed

c. Deb will have her breasts removed first, her ovaries will be later -->Removing her breasts will leave little chance of developing breast cancer (the doctors cannot remove every cell, so there is still a SLIM chance.) She is still at high risk for ovarian cancer. Many women choose to have children (ovaries produce eggs) and then have their ovaries removed.

Which statement regarding the cell cycle control system is false? a. The cell cycle control system receives messages from outside the cell that influence cell division. b. The cell cycle control system includes three key checkpoints to complete a cell cycle. c. The cell cycle control system operates independently of the growth factors. d. The cell cycle control system triggers and controls major events in the cell cycle.

c. The cell cycle control system operates independently of the growth factors.

Asexual and sexual reproduction differ in that sexual reproduction _____. a. is the only way multicellular organisms can reproduce b. is the only way single-celled organisms can reproduce c. can produce great variation among the offspring d. will produce offspring identical to the parents

c. can produce great variation among the offspring -->As long as there is some genetic variation in the parents, different offspring will inherit unique combinations of genes from each parent, creating variation among offspring.

At the end of the mitotic (M) phase, the cytoplasm divides in a process called a. meiosis b. replication c. cytokinesis d. condensation e. telophase

c. cytokinesis -->Cytokinesis is the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis.

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis? a. anaphase b. interphase c. prophase d. telophase e. metaphase

c. prophase -->Prophase is the first phase of mitosis, when the centrosomes begin moving toward opposite poles and the nuclear envelope breaks up.

The most common type of cancer is a ______; this type always originates in tissues that line organs.

carcinoma

This video highlights the duplication and distribution of a single chromosome. Human cells have 46 chromosomes in their nuclei. When considering all 46 chromosomes, how many sister chromatids are there total in a human cell immediately after a. 2 b. 23 c. 46 d. 92

d. 92 -->Immediately after interphase, each of the 46 chromosomes would be copied into 2 sister chromatids held together at a centromere. Therefore, there would be 46 pairs for a total of 92 sister chromatids. The sister chromatid pairs would then separate during mitosis and become chromosomes again. Two newly forming daughter cells would each receive one copy of every chromosome. Each daughter cell would contain 46 chromosomes total, same as the original cell.

Which statement regarding cell division is false? a. Cell division is the basis of both sexual and asexual reproduction. b. Cell division can reproduce an entire organism. c. Cell division is necessary for development to occur. d. Cell division is common in eukaryotes but rare in prokaryotes.

d. Cell division is common in eukaryotes but rare in prokaryotes.

Immune system cells enter a resting phase after undergoing mitosis. When activated—for example, by an infection—they can reenter the sequence of events in the cell cycle that leads to cell division. What would be the correct cell cycle sequence of events for these reactivated cells? a. S, G1, G2, M b. G1, G2, S, M c. G1, M, G2, S, G1 d. G1, S, G2, M

d. G1, S, G2, M -->After reactivation, these cells move into G1. Here they grow in preparation for DNA replication (S phase). Once complete, the cells move into G2 and make the final preparations for mitosis.

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis? a. metaphase b. telophase c. prophase d. anaphase e. interphase

d. anaphase -->Sister chromatids separate and start their migration toward opposite poles during anaphase.

A benign tumor and a malignant tumor differ in that _____. a. a benign tumor only forms from solid tissues such as skin or muscle and a malignant tumor only forms from blood and lymphatic tissue b. cells of a benign tumor spread by metastasis and cells of a malignant tumor spread by expansion of the tumor mass c. benign tumors are harmless and malignant tumors are lethal d. cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues

d. cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues

During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles? a. telophase b. prophase c. anaphase d. metaphase

d. metaphase

In the telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in _____. a. interphase b. anaphase c. metaphase d. prophase

d. prophase -->During prophase we observe the formation of the spindle, the condensation of chromatin, and the disappearance of the nucleolus, which are the opposite events to those occurring during telophase.

What must happen before a cell can begin mitosis? a. A mitotic spindle must form. b. The nucleus must divide in two. c. The nuclear envelope must break up. d. The sister chromatids must be separated. e. The chromosomes must be duplicated.

e. The chromosomes must be duplicated. -->Before mitosis can begin, the chromosomes, or genetic material, must be copied, which occurs during interphase.

The chromosomes line up in the center of the cell during which phase of mitosis? a. telophase b. prophase c. anaphase d. interphase e. metaphase

e. metaphase -->Metaphase occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell.