Biology- Chapter 8

A cell's genome is all of its

genetic material.

A cell's ______is defined as all the cell's genetic material (DNA) and consists of one or more chromosomes containing the DNA.

genome

Proteins called ______ are chemical signals that bind to receptors on a cell membrane and trigger cell division.

growth factors

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)

Because genes encode proteins that control cell division and cell death, ______, or changes in genes, can lead to cancer.

mutations

In cancer tumors, drug-resistant cells can survive cancer therapy treatments (like chemotherapy), and these "resistant" cells can divide and become more numerous, which is an example of

natural selection.

Cell death resulting from injury is called ______, whereas programmed cell death that results from a coordinated series of events to dismantle the cell is called ______.

necrosis; apoptosis

A DNA molecule consists of two strands of ______ held together in a ______ structure.

nucleotides; double helix

Proto-oncogenes that have been mutated are called ______, which can lead to cancer.

oncogenes

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.

The major function of nucleosomes is to ______ the DNA within chromatin.

organize

The enzyme called DNA ________ adds new complementary DNA nucleotides to a single-stranded DNA template.

polymerase

Select all of the following that occur during interphase.

protein production DNA replication

Select all of the following that are components of chromatin.

proteins for replication proteins for scaffolding DNA proteins for transcription

Oncogenes are mutated ______ and cause increased levels of or activity of proteins that ______.

proto-oncogenes; stimulate cell division

Select all of the following that are true about apoptosis.

regulated sequence of events programmed cell death normal part of development

Cell division is necessary for an organism to

reproduce

Select all the body and cellular processes that require cell division to function.

reproduction growth and development replacement of dead cells

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

After DNA replication, chromosomes consist of two

sister chromatids.

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

What best describes the major differences between apoptosis and necrosis?

Apoptosis is "programmed" death, whereas necrosis is "accidental" cellular death.

Select the statements that are true with respect to cell cycle control.

When the requirements of a checkpoint are not met, then the cell will not progress to the next stage of the cell cycle. The cell cycle has checkpoints that regulate the transitioning of one phase of the cell cycle into the next.

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

Select the processes involved in asexual reproduction.

splitting of one cell into two cells replication of the genetic material

What type of cells may divide constantly throughout their life?

stem cells

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

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 for successful treatment.

Interphase

the time between cell divisions in which DNA replication, basic cellular activities, and cell growth take place

In DNA replication, continuously 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

What type of genes normally encode proteins that prevent cell division or promote apoptosis?

tumor-suppressor genes

Select all of the following that are true about sexual reproduction.

two parents are required offspring are genetically different from their parents offspring are genetically different from each other

A eukaryotic chromosome consists of

DNA and associated proteins.

What enzyme adds complementary bases to exposed single strands of DNA 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

In order for a cell to divide, all of its genetic information has to be duplicated through a process called

DNA replication.

What statement describes a process that occurs during mitosis?

Duplicated chromosomes line up and are pulled to opposite poles of the cell.

Although they occur rarely, mistakes in DNA replication result in ______, a change in a cell's DNA sequence.

mutation

The term ______refers to any change in a cell's DNA sequence.

mutation

Place the following steps of DNA replication in the order in which they occur, beginning with the first step at the top. Instructions

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 newly synthesized strands. 5.Enzymes replace the primers, and ligase seal the gaps between existing segments and newly synthesized segments.

A cell in early interphase has 10 chromosomes. How many chromatids will the same cell have during prophase?

20

Select all of the following that are true about growth factors triggering cell division.

A growth factor stimulates the production of new skin cells at a wound site. 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.

Select the true statements that describe cancer cells compared to normal cells.

Cancer cells are less specialized than normal cells. Cancer cells may have multiple nuclei.

Stage IV cancer

Cancer has spread to distant sites and distant organs.

Stage III cancer

Cancer has spread to lymph nodes and nearby organs but not distant organs.

Stage II cancer

Cancer has spread to nearby tissues beyond the organ of origin but has not yet spread to the lymph nodes.

Stage I cancer

Cancer has spread to tissue adjacent to the tumor but remains confined to the organ of origin.

Select all the events that occur during prophase.

Centrosomes migrate to opposite poles. Mitotic spindle begins to form. Chromosomes condense.

What occurs during metaphase of mitosis?

Chromosomes align along the equator of the cell.

True or false: The phase of the cell cycle called interphase is a time of inactivity and rest for the cell after mitosis.

False

In the ______ phase of the cell cycle, the cell grows, carries out basic functions, and produces new organelles.

G1

______ is a specialized type of cell division that produces cells that are genetically different from each other.

Meiosis

Select the true statements about tumor suppressor genes.

Normal copies can inhibit cell division. Normal copies can promote apoptosis. They encode proteins that normally block cancer development.

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 of the following that are true about proto-oncogenes.

They encode proteins that stimulate cell division. When they are overactive because of mutation, the cell cycle may become accelerated.

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

Regulated cell death that is a necessary part of development is called

apoptosis

Select all the examples of cells that divide constantly to produce new cells.

bone marrow stem cells cells at the tips of plant roots

In an example of natural selection, ______ cells in cancerous tumors can survive chemotherapy, and these cells go on to divide rapidly in the absence of competition from other cells.

drug-resistant

"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

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

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

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.

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

Following mitosis, what process splits the organelles, cytoplasm, duplicated nuclei, and macromolecules into two daughter cells?

cytokinesis

Unlike normal body cells, what do cancer cells do indefinitely if given enough space and nutrients?

divide

Cytokinesis

division of the cell itself

Mitosis

division of the contents of the nucleus

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

Binary ______is a type of prokaryotic asexual reproduction in which replicated DNA and other cell parts are distributed into two new daughter cells.

fission

In DNA replication, enzymes called ligases

form covalent bonds between segments of DNA.

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

What is the key feature that classifies a disease as cancer?

malignant cells

What process gives rise to gametes in humans?

meiosis

Eukaryotic cell division is more complicated than binary fission because eukaryotes house the DNA in

multiple chromosomes.