bio-181: how eukaryotic cells sort
homologs
Members of a pair of chromosomes
Sister chromatids separate from each other during
anaphase
in the cell cycle, which stage in the non-dividing stage?
g0
a photographic representation of the chromosomes is a type of micrograph called a(n)
karyotype
centrioles
the centrosome in animal cells has a pair that are arrange perpendicular to each other
telophase
the chromosomes have reached their respective poles and decondense
sporophytes
the diploid generation of plants or multicellular protists that have a sporic life cycle; this generation produces haploid spores by the process of meiosis
Replication and compaction of chromosomes into pairs of sister chromatids.
(a) Chromosomal replication produces a pair of sister chromatids. While the chromosomes are elongated, they are replicated during S phase to produce two copies that are connected and lie parallel to each other. This is a pair of sister chromatids. At the start of mitosis, the sister chromatids condense into more compact structures that are easily seen with a light microscope. (b) A schematic drawing of a metaphase chromosome. This structure has two chromatids that lie side-by-side. The two chromatids are held together by cohesin proteins (not shown in this drawing). The kinetochore is a group of proteins that are attached to the centromere and play a role during chromosome sorting.
factors that determine if a cell will divide
-external factors, environmental conditions and signaling molecules -internal factors
events of the cell cycle into chronological order
1. cell grows and commits to divide 2. chromosomes are replicated 3. cell makes proteins for chromosome sorting and cell division 4. cell completes mitosis and cytokinesis
events that occur during prometaphase of mitosis
1. centrosomes move apart and demarcate the two poles 2. the mitotic spindle if fully formed 3. spindle fibers interact with the sister chromatids 4. nuclear envelope completely fragments into small vesicles
in diploid eukaryotic organisms, most cells contain ? sets of chromosomes
2
humans have ... different types of autosomes
22
one set of human chromosomes contain, how many different types of chromosomes?
23
Let's suppose a cell is diploid, with eight chromosomes per set. How many chromatids would be found in the cell after S phase, but prior to cytokinesis?
32
human cells contain a total of how many chromosomes?
46
cell plate
A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.
G0 phase
A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly. postponed making a decision to divide or a cell may become terminally differentiated, which means it will never divide again
autosomes
Any chromosome that is not a sex chromosome there are 22 different ones
metaphase
Chromosomes line up in the middle of the cell
In addition, G1-checkpoint proteins can sense if the ? has incurred damage
DNA
A cell that is an environment that has an abnormally low pH will NOT pass through which checkpoint?
G1
The ? checkpoint monitors if conditions are favorable for cell division
G1
in what stage of the cell cycle do most cells spend the majority of their lives?
G1
The cell cycle is regulated by checkpoints during the _______ phases.
G1, G2, and M
Phases of the cell cycle in order
G1, S, G2, M
A second checkpoint exists in ?
G2
DNA repair enzymes will be highly active during what phase of the cell cycle?
G2
The success of DNA replication is assessed during the ______ phase.
G2
Using your knowledge of cytokinesis, what is the best description for how cytokinesis differs between plants and animals?
In plants two separate daughter cells are formed; in animals two daughter cells are formed but they share a single plasma membrane
Docetaxel is a drug that is used in the treatment of cancer. It interferes with cell division by inhibiting microtubule depolymerization. Specifically, what effect will this have on mitosis?
It will prevent sister chromatids from separating during anaphase.
Why do chromosomes condense during prophase?
So that they will not be damaged when they are moved around the cell.
haploid-dominant species
Species in which the haploid organism is the prevalent organism in the life cycle. Examples include fungi and some protists.
G1 phase
The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.
cleavage furrow
The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate. constricts like a drawstring to separate the cells
alternation of generations
The phenomenon that occurs in plants and some protists in which the life cycle alternates between multicellular diploid organisms, called sporophytes, and multicellular haploid organisms, called gametophytes.
cell division
The reproduction of cells, highly regulated process that distributes and monitors the integrity of the genetic material
meosis II
The second division of a two-saged process of cell division in sexually reproducong organisms that result in the cell with half the number of chromosome sets as the original cell.
g2 phase
The second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.
prometaphase
The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.
s phase
The synthesis of DNA, the genetic material
Female sex chromosomes
XX
Male sex chromosomes
XY
zygote
a diploid cell formed by the fission of two haploid gametes
metaphase plate
a plane halfway between the poles of the spindle apparatus on which the sister chromatids align during the metaphase stage of mitosis
A type of organism that exhibits alternation of generations is
a plant
asexual reproduction
a process in which genetically identical offspring are produced from a single parent
sexual reproduction
a process in which two haploid genetics unite to form diploid cell called a zygote
cell cycle
a series of events that results in cell division
which of the following statements about eukaryotic chromosomes sets is true?
a set is composed of several different types of chromosomes
mitotic spindle
a structure made of microtubules that controls chromosome movement during mitosis
pole
after the chromosomes separate from each other during mitosis, each centrosome defines a ? of the spindle apparatus, one within each of the future daughter cells
after metaphase, the next step in the sorting process of mitosis is known as
anaphase
cyclins and cyclin-dependent kinases
are responsible for advancing a cell through the phases of the cell cycle
Chromosomes that are not sex chromosomes are called
autosomes
g1 phase is a period of a cell's life when it is metabolically active and during which the cell may also?
become committed to divide
the ? ? is a series of highly regulated events that leads to cell division
cell cycle
the sequence of growth, replication, and division that produces new cells is called
cell cycle
which of the following refers to a highly regulated process that ensures cell division occurs?
cell cycle
the kinetochore is a group of proteins that attach to the ? during mitosis
centromere
The point in the cell cycle at which conditions are assessed before continuing is called a ____________ .
checkpoint
the proteins that control the various specific stages in the cell cycle are called which of the following
checkpoint proteins
during interphase of the cell cycle, the cell grows and copies which of the following in preparation of cell division?
chromosomes
in eukaryotic cells, what is separated and sorted during mitosis?
chromosomes
Which of the following events do NOT occur in prophase of mitosis?
chromosomes are replicated
prophase
chromsomes have already replicated to produce 12 chromatids, joined as 6 pairs of sister chromatids that have condensed into highly compacted structures readily visable by light microscopy
anaphase
connection between the pairs of sister chromatids are broken
haploid
contain one set of chromosomes
Cyclins are named because their levels ____________ during gap, S and M phases.
cycle
After a cell enters S phase, the G1 ____________ will be degraded.
cyclin
The activity of a ____________ depends on interaction with a cyclin
cyclin-dependent kinase
A protein that drives a cell through the cell cycle is a ________. It is directly controlled by a ________.
cyclin-dependent kinase, cyclin
if DNA damage is detected, the checkpoint proteins prevent the formation of active ? , thereby stopping the advancement of the cell cycle.
cyclin/cdk complexes
identify the phase in which the two nuclei are segregated into separate daughter cells by the division of cytoplasm
cytokinesis
mitosis if followed by ?
cytokinesis
the checkpoint proteins prevent the division of a cell that has DNA ? or abnormalities in the chromosomes ?
damage & number
sex chromosomes
determine the sex of an individual
interphase
dividing cells, the g1 nd g2. cell grows and copies its chromosomes in preparation for cell division
In the G1 phase, what cues help a cell accumulate changes that might cause it to progress through the rest of the cell cycle?
environmental and signaling
by studying the karyotypes of many species, scientists have discovered that ? chromosomes occur in sets. Each set is composed of ? different types of chromosomes
eukaryotic and several
cell growth typically occurs during which phase?
g1
cell ? usually occurs during the g1 phase
growth
identify the chromosomes that consist of two slightly different copies of the same chromosomes
homologous chromosomes
bivalent
homologous pairs of sister chormatids associated with each other, lying side by side
if an organism is diploid, the two membranes of a pair of chromosomes are called
homologues
gametophytes
in plants and many multicellular protists, the haploid stage that produces gametes by mitosis
Each cell has two sets because?
individual's inherit one set from father and one set from mother
in actively didving cells, the g1, s, and g2 phases are known as which of the following?
interphase
in actively dividing cells, the G1, S, and G2 phases are collectively known as which of the new following
interphase
cytokinesis
is the division of the cytoplasm to produce two distinct daughter cells
mitosis is usually followed by cytokinesis, which is
is the division of the cytoplasm to produce two distinct daughter cells
to be active, ? controlling the cell cycle must bind to a ?
kinases and cyclin
The mitotic spindle fibers attach to chromosomes via special structures termed
kinetochores
Microtubules
long, cylinderical protein fibers that are a components of the cytoskeleton
A third checkpoint, called the ? checkpoint, senses the integrity of the spindle apparatus, which is involved in chromosome sorting and described later in this chapter.
metaphase
the ? checkpoint is the 3rd checkpoint in the cell cycle
metaphase
The alignment of bivalents occurs during
metaphase 1
karyotype
micrograph that reveals the number, size, and form of chromosomes found within an actively dividing cell
scientists use ? to understand the chromosomal composition of cells and the behavior of chromosomes during cell division
microscope
during the M phase the sister chromatids can be seen with the aid of light
microscopy
during the eukaryotic cell cycle, the first portion of M phase is
mitosis
during what part of the M phase are chromatids separated and sorted so that each daughter cell eventually receives the same complement of chromosomes ?
mitosis
m phase
mitosis and cytokinesis
multicellularity relies on the repeated processes of ? and ?
mitosis and cytokinesis
Just before mitosis, a ____________ cyclin interacts with an appropriate cdk to start M phase.
mitotic
A eukaryotic cell that receives a "go-ahead" signal at the G1 checkpoint of the cell cycle will
move into the S phase and continue the cell cycle.
genetics use what letter to represent the set of chromosomes?
n
mitosis serves to divide ? cell nucleus into ? nuclei. this allows each daughter cell to receive the same complement of duplicated chromosomes
one and two
sister chromatids become attached to spindle fibers during
prometaphase
meosis with crossover
prometaphase metaphase anaphase telophase
In meiosis I, crossing over occurs during
prophase
which phase marks the beginning of mitosis
prophase
list the phases of mitosis in the correct order, earliest on top
prophase prometaphase metaphase anaphase telophase
In addition, the G2 checkpoint monitors the levels of ? that are needed to advance through M phase
proteins
cyclins and cyclin-dependent kinases are ? that are responsible for advancing a cell through the phases of the cell cycle
proteins
centrosomes
referred to as microtubule organizing centers
This checkpoint also checks for DNA damage and ensures that all of the DNA has been ?
replicated
In eukaryotes, DNA replication produces sister chromatids. This event occurs during
s phase
chromosome replication occurs in the ? phase of the Eukaryotic cell cycle
s phase
At these checkpoints, a variety of proteins, referred to as checkpoint proteins, act as ? to determine if a cell is in the proper condition to divide.
sensors
meiosis 1
separates homologous chromosomes from each other
life cycle
sequence of events that produces another generation of organisms
in humans, the X and Y chromosomes are called the ? chromosomes
sex
homology
similarity resulting from common ancestry
dipolid-dominant species
species in which the diploid organisms is the prevalent organism in the life cycle. animals for example
during ? the chromosomes have reached their respective poles and decondense
telophase
cytogenetics
the field of genetics that involves the microscopic examination of chromosomes
meiosis
the process by which haploid cells are produced from a cell that was originally diploid
synapsis
the process of forming a bivalent
gametes
the sperm and egg cells
what statement is true of eukaryotic chromosomes
they occur in pairs in diploid cells
Which of the following statements about microtubules during anaphase is TRUE?
those attached to chromosomes shorten, while those that are unattached elongate
checkpoints
three critical regulatory points that occur in the cell cycle of eukaryotic cells
kinetochore
tje centromete serves as an attachment site for a group of proteins, a structure necessary for sorting each chromosome
in sexual reproduction in eukaryotes, each parent contributes one set of chromosomes to the offspring
true
a cell that is diploid has
two sets of chromosomes and pairs of homologous chromosomes
centromere
two sister chromatids are tightly associated at a region
diploid
when the cells of an organism carry two sets of chromosomes
mitotic cell division
which a cell divides to produce two new cells that are genetically identical to the original cell