BIO CH 8

Cell division in eukaryotes is more complex than in prokaryotes. Select all of the reasons for this.

-DNA in eukaryotes is wound tightly around proteins that condense into chromosomes

eukaryotes contain more --DNA than prokaryotes

Interphase of a eukaryotic cell contains ______.

three phases (G1, S, and G2)

is the mechanism of cell division that occurs in a eukaryotic organism's nonreproductive cells.

mitosis

Select the correct sequence of the phases of the cell cycle.

G1, S, G2, M, C

Which of the following is the correct order of the phases of mitosis?

Prophase, Metaphase, Anaphase, Telophase

A cell division process called blank divides the DNA in sexually reproductive germ line cells and results in the production of gametes.

meiosis

Select all the true statements about chromosomes.

-Chromosomes were first observed by Walther Flemming in 1879.

-The cells that chromosomes were first observed in were salamander larval cells.

-Mitosis is based on the Greek word "mitos", meaning thread.

Eukaryotes have ______ compared to that in prokaryotes because eukaryotes have more DNA than prokaryotes and eukaryotic DNA is wound tightly around proteins.

more complex cell division

G1

S

G2

1 main growth phase of interphase, and often the longest phase of a cell's life span

main growth phase of interphase, and often the longest phase of a cell's life span

2 matches

Choice, phase of interphase in which DNA replicates

phase of interphase in which DNA replicates

3 phase of interphase in which organelles replicate, chromosome condensation begins, and synthesis of microtubules takes place

phase of interphase in which organelles replicate, chromosome condensation begins, and synthesis of microtubules takes place

1. G1 2. S 3. G2 4. M 5. C

prophase, metaphase, anaphase, telophase

______ have between 10 and 50 chromosomes in their body cells.

most eukaryotes

Salamander cells, a primitive microscope, and a German scientist named Walther Flemming are all associated with the discovery of cellular structures called ______.

chromosomes

Pairs of chromosomes in somatic cells that carry information about the same traits are called ______.

homologous chromosomes

Interphase of a eukaryotic cell contains ______.

three phases (G1, S, and G2)

Cell that have two of each type of chromosome, one inherited from the mother and the other inherited from the father, are specifically referred to as blank cells

diploid

Most species of eukaryotes contain about ______ chromosomes in their body cells.

10-50

When a eukaryotic cell undergoes DNA replication the two identical copies of the DNA are referred to as ______.

sister chromatids

Eukaryotic chromosomes exist in cells as pairs called ______ chromosomes.

homologous

Differentiating between sister chromatids and homologous pairs is made easiest by remembering that sister chromatids are attached to one another by a ______.

centromere

How many of each type of chromosome does a diploid cell have?

two

In a human, diploid cell, the total number of chromosomes before DNA replication is ______, while the total number of chromatids in a cell after replication, but before mitosis is ______.

46,92

______ chromosomes are a pair of the same chromosome, one inherited from the mother and one inherited from the father, while ______ chromatids are the two replicated copies of a single chromosome held together with a centromere.

Homologous; sister

When a chromosome is replicated, two identical copies called ______ are produced and remain attached at the centromere.

sister chromatids

The knoblike, linkage region of a chromosome is called the blank which is the site where sister chromatids remain joined after chromosome replication.

centromere

Scientists arrange homologous pairs of chromosomes into a karyotype in order to compare ______ of chromosomes.

shape

size

location of centromeres

Trisomy is a condition in which an individual has ______.

extra chromosome

Chromatin is composed of ______.

DNA and protein

A replicated chromosome consists of two identical blank chromatids joined at the centromere.

sister

A blank is a display of condensed chromosomes.

karyotype

Having three of a particular chromosome is a condition called ______.

trismony

Histones are proteins that play a role in the ______.

coiling of DNA in chromatin

Chromosomes are composed of

chromatin

A complex within chromatin consisting of DNA wrapped around eight histone proteins is called a ______.

nucleosome

The period between cell divisions when DNA replicates and begins to condense is called

interphase

The positively charged proteins that DNA wraps around are called ______.

histones

During interphase the DNA is replicated and then begins the process of ______ where it winds up tightly.

condensation

Chromatin is composed of

DNA and protein

prophase

metaphase

anaphase

telophase

1 chromosomes condense; nuclear envelope breaks down

chromosomes condense; nuclear envelope breaks down

2 chromosomes line up along the central plane of the cell

chromosomes line up along the central plane of the cell

3 centromeres divide; chromatids move to the poles

centromeres divide; chromatids move to the poles

4 chromosomes uncoil; new nuclear envelopes form

chromosomes uncoil; new nuclear envelopes form

Select all of the characteristics of prophase.

network of spindle fibers begins to form between centrosomes

nuclear envelope dismantled

condensed chromosomes first become visible

Select all of the characteristics of interphase.

chromosomes begin to wind up tightly

chromosomes replicate

the long period between cell divisions

sets the stage for cell division

Spindle fibers are made of ______ and extend between poles of the cell and also attach to the ______ of each chromatid.

microtubules; kinetochore

Chromosomes undergo replication and begin to condense during a phase of the cell cycle called ______.

interphase

During which phase of mitosis does a new nuclear membrane form?

telophase

During blank of mitosis the condense chromosomes first become visible, the nuclear envelope breaks down, and the spindle apparatus begins assembly.

prophase

Select all of the characteristics of anaphase.

microtubules drag daughter chromosomes toward opposite poles

sister chromatids separate

Beginning in prophase, spindle fibers form, and some will attach to ______ on opposite sides of the centromeres.

kinetochores

During blank the final stage of mitosis, two new nuclear envelopes form around each of the separated sets chromosomes.

telophase

Cytokinesis, the division of the cytoplasm during cell division, occurs directly after ______.

telophase

Select all of the characteristics of metaphase.

-chromosomes align on a plane in center of cell

-microtubules are attached to each side of the centromeres

How does cytokinesis occur in an animal cell?

A cleavage furrow forms around the cell's circumference and pinches inward

In plant cell cytokinesis, ______ are deposited by vesicles to form a cell plate that grows outward and eventually divides the two daughter cells.

membrane components

Cytokinesis is best described as ______.

division of the cytoplasm

during blank of mitosis the spindle fibers are attached to the kinetochores and the chromosomes line up along the center of the cell.

metaphase

Select the true statements about the life of a cell.

Most human cells die on schedule after 50 divisions.

Cells can replace damaged parts, but usually do not live forever.

Some cells undergo programmed cell death.

As demonstrated by cell cultures, humans cells tend to divide about ______ times and then die.

50

In animal cell cytokinesis, a belt of actin filaments called the ______ begins contracting at the cell exterior and progressively pinches the cytoplasm inward.

cleavage furrow

Select all of the reasons for checkpoints in the cell cycle.

-feedback signals from the cell about its size can trigger subsequent phases of the cell cycle.

-feedback signals from the cell about the condition of its chromosomes can trigger subsequent phases of the cell cycle

-feedback signals from the cell can delay the next phase until the current phase is completed

Select all of the characteristics of telophase.

-nuclear envelope forms around chromosomes

-mitotic spindle disassembles

-nucleolus reappears

During cytokinesis in plant cells, membrane components assemble in the cell interior to form an expanding partition called a ______.

cell plate

Select all of the principal checkpoints that control the cell cycle in eukaryotes.

G2 checkpoint

M checkpoint

G1 checkpoint

The cell cycle has key _____ where feedback signals from the cell about its size and the condition of its chromosomes can either trigger or delay subsequent phases.

checkpoints

cell blank is assessed at the G1 checkpoint.

growth

Select all of the characteristics of the G2 checkpoint.

triggers the start of M phase

DNA replication is assessed

The three principal checkpoints that control the cell cycle are

G1, G2, and M.

The checkpoint of the cell cycle that triggers the exit from mitosis and cytokinesis, and the beginning of the G1 phase, is the ______ checkpoint.

M

Cell division is initiated by small proteins called

growth factors

Select all of the characteristics of the G1 checkpoint.

cell growth is assessed

located just before entry into S phase

Platelet-derived growth factor was one of the first growth factors isolated and was found in _______.

blood serum

DNA blank is assessed at the g2 checkpoint

replication

Put in sequence the events in the correct order after a growth factor binds to its receptor.

1. receptor is activated

2. receptor reacts by triggering a series of events within the cell

3. the dna is replicated

4. cell division occurs

Select all of the characteristics of the M checkpoint.

triggers the beginning of G1

triggers the exit from mitosis and cytokinesis

occurs at metaphase

mitosis is assessed

How do growth factors in the cell cycle work?

They bind to the plasma membrane and trigger intracellular signaling systems.

If cells are deprived of appropriate growth factors, their growth and division is arrested and they remain in the _____ phase.

G0

Platelet-derive growth factor (PDGF) is responsible for ______.

stimulating cell division

The term ______ limit has been ascribed to the number of doublings that occur in a cell population.

Hayflick

Select all of the characteristics of growth factors.

-some growth factors affect a broad range of cell types

-cellular sensitivity of a particular growth factor depends upon which target cells bears its unique receptor

-each growth factor is recognized by a specific cell surface receptor

Telomeric regions are repeated sequences of TTAGGG found at the end of

chromosomes.

Identify the nongrowing state of the cell cycle that is distinct from the interphase stages G1, S, and G2.

G0

Shortening of telomeres in body cells results in ______.

cell death after approximately 50 doublings

The enzyme responsible for maintaining the constant length of chromosomes in sperm and eggs is ______.

telomerase

the blank region of the chromosome contains the machinery used in DNA replication and is slowly worn down every time the cell replicates.

telomere

Sperm and egg can continuously divide because the enzyme telomerase ______.

allows them to maintain the length of their chromosomes

Metastases can be described as ______.

tumors formed at distant sites from the original cancer

genes known as blank encode proteins that stimulate cell division

proto-oncogenes

The two general classes of growth factor genes involved in cancer are

proto-oncogenes and tumor suppressor genes.

When proto-oncogenes are mutated, they become

cancer-causing genes called oncogenes.

Select all of the characteristics of proto-oncogenes.

proto-oncogenes can mutate into oncogenes, which are cancer causing

proto-oncogenes code for proteins that stimulate cell division

New cancer tumors that have formed at sites away from the original cancer are referred to as ______.

metastases

Proteins encoded by ______ normally act to stop cell division.

tumor-suppressor genes

Select all of the characteristics of a proto-oncogene.

mutated proto-oncogenes become cancer causing genes

encode proteins that stimulate cell division

Select the two general classes of growth factor genes involved in cancer.

proto-oncogenes

tumor suppressor genes

Cell division is normally turned off in healthy cells by proteins encoded by blank blank genes

tumor suppressor

Mutated proto-oncogenes become cancer-causing genes called

oncogenes

What type of genes encode proteins that promote cell division and can mutate into oncogenes?

proto-oncogenes

Mutations in tumor- blank genes can result in uncontrolled cell divisions leading to tumors.

: suppressor or suppressing

Select all of the characteristics of tumor-suppressor genes.

mutations to these genes allow the cell containing the mutated gene to divide uncontrolled

act as brakes on cell division

In animal cell cytokinesis, a belt of actin filaments called the ______ begins contracting at the cell exterior and progressively pinches the cytoplasm inward.