BIO101-Chapter8

Select all the true statements about chromosomes.

-The cells that chromosomes were first observed in were salamander larval cells. -Mitosis is based on the Greek word "mitos", meaning thread. -Chromosomes were first observed by Walther Flemming in 1879.

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

-eukaryotes contain more DNA than prokaryotes -DNA in eukaryotes is wound tightly around proteins that condense into chromosomes

Select all of the characteristics of tumor-suppressor genes.

-mutations to these genes allow the -cell to divide uncontrolled act as brakes on cell division

Select all of the characteristics of telophase.

-nuclear envelope reforms -nucleolus reappears -mitotic spindle disassembles

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

Put the levels of chromatin coiling into increasing order of compaction, beginning with the simplest, least compact organization of chromatin at the top.

1. DNA double helix coiled around histone 2. nucleosome complex 3. solenoid 4. looped domains connected to scaffold protein 5. rosettes of radial loops around scaffold of protein 6. compacted chromosome

Match the order (first to third) of events that take place in a prokaryotic cell cycle.

1. DNA replication 2. DNA partitioning 3. cell fission

humans have _______pairs of chromosomes

23

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

Most carcinogens are potent mutagens, chemicals that damage ______.

DNA

Chromatin is composed of ______.

DNA and protein

Match each phase of the eukaryotic cell cycle with its correct description.

G1-main growth phase of interphase, and often the longest phase of a cell's life span S-phase of interphase in which DNA replicates G2-phase of interphase in which organelles replicate, chromosome condensation begins, and synthesis of microtubules takes place M-microtubules bind to replicated chromosomes and pull them apart C-cytoplasm divides, creating two daughter cells.

Prophase, metaphase, anaphase and telophase occur in what phase of the eukaryotic cell cycle?

M

Trisomy is a condition in which an individual has _____

an extra chromosome (3)

Nucleosomes are formed ______.

by the DNA duplex wrapped around eight histone proteins

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

cell plate

A human chromosome that is not condensed, when laid out would be about 5 ______ long.

centimeters

In addition to chromosomes, what other cell structure replicates during interphase in animal cells?

centrioles

After a chromosome replicates, sister chromatids are joined by a linkage site called a ______.

centromere

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

centromere

anaphase

centromeres divide; chromatids move to the poles

Chromosomes are composed of ___________, which is a complex of DNA and protein

chromatin

Beginning in prophase, spindle fibers form and attach to to opposite sides of a replicated ______.

chromosome

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

chromosomes

What process is completed during interphase?

chromosomes are replicated

Prophase

chromosomes condense; nuclear envelope breaks down (network of spindle fibers begins to form between centrosomes)

metaphase

chromosomes line up on the central plane of the cell (microtubules are attached to each side of the centromeres)

telophase

chromosomes uncoil; new nuclear envelopes form

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

Histones are proteins that play a role in the _________

coiling of DNA in chromatin

The division of the cytoplasm in a cell after mitosis is called _________________

cytokinesis

The new daughter cells produced at the end of telophase of mitosis are ______.

diploid

What term refers to having two of each type of chromosome in the nucleus of a cell?

diploid

Prokaryotes divide by a process called binary__________

fission

Negatively charged DNA in chromatin is able to tightly coil into a chromosome by first wrapping around positively charged ______ proteins, eight of which then form a complex called a ______ every 200 nucleotides, and these complexes are further coiled into solenoids, loops, and rosettes of radial loops.

histone; nucleosome

The positively charged proteins that DNA wraps around are called _____

histones

Eukaryotic chromosomes exist in cells as pairs called ______ chromosomes.

homologous

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

homologous chromosomes

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

homologous chromosomes

______ 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

Centrioles, if present, replicate during ______.

interphase

Scientists examine chromosomes by size, shape, and centromere location and create an arrangement of the chromosomes called a ______.

karyotype

Select the three types of human cancers that are responsible for the greatest number of deaths in the United States.

lung breast colorectal

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

meiosis

In sexually reproducing organisms, the type of eukaryotic cell division that results in the production of gametes from germ cells is called ______.

meiosis

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

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

microtubules; centromere

A typical human chromosome contained about 140 ______ nucleotides in its DNA.

million

The mechanism of eukaryotic cell division that occurs in an organism's somatic cells is called ______.

mitosis

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

mitosis

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

mitosis

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

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

most eukaryotes

Cancer results from damage to DNA, which is called _____________

mutation

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

nucleosome

Cell division through binary fission is carried out by ______.

prokaryotes

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

proto-oncogenes

A replicated chromosome consists of two identical_______________chromatids joined at the centromere.

sister

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

telophase

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

telophase

Interphase of a eukaryotic cell contains ______.

three phases (G1, S and G2

p53 is a ______ that inspects DNA; 50% of all cancers have a disabled p53 gene.

tumor suppressor gene

Proteins encoded by ______ normally act to stop cell division.

tumor-suppressor genes

Metastases can be described as ______.

tumors formed at distant sites from the original cancer

Mitosis produces ______ daughter cells, each of which is ______ with regard to chromosome number.

two; diploid

Select all of the agents that can cause mutations that lead to cancer.

viruses ultraviolet radiation chemicals