Biology chapter 16
M
A cell divides into two daughter cells.
Which of these terms refers to the visual appearance of the full complement of chromosomes in a cell?
Karyotype
Sister chromatids attach to the spindle apparatus if a microtubule makes contact with which of these?
Kinetochore
The bivalents are organized along the metaphase plate, with the sister chromatids randomly aligned in a double row. What phase of cell division is described here?
Metaphase of meiosis I
What animal demonstrates a naturally occurring variation from diploidy?
Male bee
Bivalent formation and crossing over are two key events that typically occur at the beginning of which of these?
Meiosis
The pairs of sister chromatids align themselves in a single row along a plane half-way between the poles during which of the following phases of mitosis?
Metaphase
What does mitotic cell division involve?
Mitosis Cytokinesis
Asexual reproduction and the production and maintenance of multicellularity are two purposes served by:
Mitotic cell division
What cell structure is composed of microtubules and is responsible for organizing and sorting the chromosomes during cell division?
Mitotic spindle
Prophase of mitosis is characterized by which of the following?
Nuclear envelope begins to dissociate Sister chromatids are visible by light microscopy Nucleolus is no longer visible
Identify the phase in which the nuclear envelope completely fragments into small vesicles.
Prometaphase
In mitosis, a pair of sister chromatids is attached to both poles while in meiosis I a pair of sister chromatids is attached to just one pole via kinetochore microtubules. What phase is described here?
Prometaphase
In this phase of meiosis I, the complete breakdown of the nuclear envelope and complete formation of the spindle apparatus occur.
Prometaphase
Identify the phase of the cell cycle in which sister chromatids become microscopically visible, while the nuclear envelope begins to dissociate into small vesicles?
Prophase
The formation of bivalents and subsequent crossing over occur in what phase of meiosis?
Prophase I
Put the events of meiosis I in order, beginning with the earliest event at the top.
Replicated Nuclear bivalent Homologous Chromosomes
Select all of the events that occur during prometaphase of mitosis.
-nuclear envelope completely fragments into small vesicles -the mitotic spindle is fully formed -spindle fibers interact with the sister chromatids -centrosomes move apart and demarcate the two poles
Put the events of the cell cycle into chronological order. Begin at the top with the events of the G1 phase.
1. Cell grows 2. Chromosomes 3. Cell makes 4. Cell completes
Several human disorders are the result of abnormalities in chromosome number. The most common are trisomies of chromosome numbers , , or , or abnormalities in the number of sex chromosomes.
13,21,18
How many chromosomes does a human gamete possess?
23
G1
A cell grows and becomes committed to divide
G2
A cell makes protein for chromosome sorting and cell division.
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 for cell division?
Chromosomes
S
Chromosomes are replicated.
Select all of the following that correctly compare mitosis and meiosis
Crossing over occurs in meiosis but not normally in mitosis. Sister chromatids are separated during both mitosis and meiosis.
What two proteins are responsible for advancing a cell through the phases of the cell cycle?
Cyclin-dependent kinases Adenylate cyclases
Which term describes the removal of a segment from a chromosome?
Deletion
Which of the statements below are true for chromosomes in eukaryotic cells?
Diploid cells have two versions of each chromosome. Diploid cells have a maternal homologue and a paternal homologue.
Which of these terms best describes organisms that have complete sets of chromosomes?
Euploid
Identify the stage, in the cell cycle, which is considered the non-dividing stage.
G0
In a phase of the cell cycle called the phase, the cell has postponed proceeding through G1 and is considered non-dividing.
G0
In a cell's life, cell growth occurs primarily during what phase?
G1
Place the phases of the cell cycle in order. Start at the top with G1.
G1 S G2 M
The levels of which cyclin increase when nutrients and growth factors are in good supply?
G1 cyclin
Meiosis I sorting separates which of these?
Homologous chromosomes
During , the chromosomes have reached their respective poles and decondense.
telophase
Which type of process requires a fertilization event in which two haploid gametes unite to create a diploid cell called a zygote?
Sexual reproduction
What statement about mitosis and meiosis is correct?
Sister chromatids are separated both during mitosis and meiosis.
Select all of the following that correctly compare mitosis and meiosis.
Sister chromatids are separated during both mitosis and meiosis. Crossing over occurs in meiosis but not normally in mitosis.
Identify the phase of mitosis where each group of chromosomes reaches a pole of the cell and decondenses.
Telophase
What happens to chromosomes when a cell is about to divide?
The chromosomes become compacted.
Why is aneuploidy usually harmful to eukaryotic species?
The over- or under-expression of some genes may interfere with the proper functioning of cells.
Which of these are characteristics of meiosis II? Choose all that apply.
The sorting event is similar to that of mitosis The resulting daughter cells are haploid Sister chromatids are separated
What statement is true of eukaryotic chromosomes?
They occur in pairs in diploid cells.
Which of the following statements describe meiosis I in humans? Choose all that apply.
Two haploid cells are produced. Genetic diversity is generated. Chromosome pairs are separated.
In humans, what chromosomes determine the sex of the individual?
X and Y chromosomes
In humans, females have a sex chromosome composition of
XX
The main reason for mitosis in animals is to create
a diploid multicellular organism.
After metaphase, the next step in the sorting process of mitosis is known as
anaphase
During ______ of mitosis, the kinetochore microtubules shorten, pulling the chromosomes toward the pole to which they are attached.
anaphase
A phenomenon called refers to an alteration in the number of particular chromosomes so that the total number of chromosomes is not an exact multiple of a set.
aneuploidy
Mitotic cell division is important for reproduction and for the production and maintenance of multicellularity.
asexual
The G1 phase is a period in a cell's life when it is metabolically active and during which the cell may also
become committed to divide.
Synapsis is the process of forming a(n)
bivalent
The sequence of growth, replication, and division that produces new cells is called
cell cycle
Cell cycle progression is tightly regulated to ensure that the nuclear genome is intact and the conditions are appropriate for ______.
cell division
Mitotic cell division in humans is:
cell division that results in two diploid daughter cells
Because of the location of the _______, each chromosome has a short arm and a long arm.
centromere
Each chromosome has a short arm and a long arm because the is not exactly in the center of a chromosome.
centromere
In a replicated chromosome, the two sister chromatids are bound closely at a region known as the .
centromere
Name the region where the two sister chromatids are tightly associated.
centromere
What does a karyotype reveal about chromosomes found in actively dividing cells?
centromere position number size
Put the events of the plant life cycle in order. Begin at the top with the step involving the production of haploid spores.
certain cells in repeated gametophyte certain cells within two gametes repeated sporophyte
During the cell cycle, a variety of proteins act as sensors to determine if a cell is in the proper condition to divide. These proteins are collectively called proteins.
checkpoint
To assess if a cell is in an appropriate condition to divide, the cell employs sensors called ______ proteins.
checkpoint
What proteins delay the division of a cell that has DNA damage or abnormalities in the chromosome number?
checkpoint proteins
The three critical regulatory points found in the cell cycle of eukaryotic cells are called
checkpoints
At anaphase of mitosis, sister separate from one another and begin to move toward the poles of the cell.
chromatids
The letter n is used in genetics to refer to a set of .
chromosomes
The mitotic spindle is responsible for organizing and sorting the during cell division.
chromosomes
Homology pertains to similarity due to
common ancestry.
The suffixes -ploid and -ploidy refer to a set of chromosomes.
complete
In a particular species, the composition of chromosomes remains relatively
constant
Which two key events occur at the beginning of meiosis but not mitosis?
crossing over bivalent
In multicellular eukaryotic organisms, the production of new cells follows a highly regulated sequence of growth, DNA replication, and division. This sequence is referred to as the cell , which consists of the G1, S, G2, and M phases.
cycle
As the cell progresses through mitosis, mitotic ______ is degraded.
cyclin
To be activated, the kinases controlling the cell cycle must bind to a ______.
cyclin
In order to be active, cdks must bind to proteins called
cyclins
The field of genetics that involves the microscopic examination of chromosomes is called .
cytogenetics
The phases of the cell cycle are G1, S, G2, and M phase. Mitosis and occur during the M phase.
cytokinesis
The process of mitotic cell division encompasses mitosis, where the nucleus divides into two nuclei, and , where the mother cell divides into two daughter cells.
cytokinesis
The checkpoint proteins prevent the division of a cell that has DNA or abnormalities in the chromosome .
damage, number
Mitotic cyclin is ______ as the cell progresses through mitosis.
degraded
When a segment of chromosomal material is deficient in a significant amount of genetic material, a chromosomal mutation called a(n) occurs.
deletion
The possible effects of these two chromosomal mutations depends on their size and whether they include genes vital to the organisms' development.
deletion duplication
There are four main types of changes in chromosome structure. The possible effects of two of them ( and ) depend on their size and whether they include genes vital to the organisms' development.
deletion, duplication
List the types of chromosomal mutations.
deletion, duplication, inversion, translocation
Chromosomal mutations are categorized as , , , and translocations.
deletions, duplications, inversions
If a microtubule does not collide with a kinetochore, the microtubule will ______ and retract to the centrosome.
depolymerize
When a cell prepares to divide, the chromosomes become more tightly compacted. This process decreases the apparent length of the chromosomes and increases their .
diameter
When the cells of an organism carry two sets of chromosomes, that organism is said to be .
diploid
Because most species of animals are diploid and their haploid gametes are considered to be a specialized type of cell, animals are viewed as - species.
diploid dominant
In ______ cells, eukaryotic chromosomes occur in ______.
diploid; homologous pairs
The reproduction of cells is also known as cell
division
Chromosome structure can change in different ways. In a(n) , a chromosome segment is repeated two or more times in a row.
duplication
If a portion of a chromosome occurs two or more times in a row it is termed what?
duplication
Which chromosomal mutations change the total amount of genetic material in a single chromosome?
duplications deletions
The study of chromosomal variation is important because these variations in chromosome structure and number can have major effects on the characteristics of an organism. Also, these changes have been an important force in the of new species.
evolution
True or false: Chromosome composition within a given species is variable.
false
During the fungal life cycle, meiosis of the zygote produces ______ spores.
four haploid
A human contains only 23 chromosomes.
gamete
A zygote is created when two haploid cells, called , fuse.
gametes
The haploid multicellular organism produced during the plant life cycle is known as a(n)
gametophyte
Cell usually occurs during the G1 phase.
growth
The metaphase plate is a plane located
halfway between the poles
An example of naturally occurring variations from diploidy in animals is the male bee. The drone contains a single set of chromosomes and is therefore
haploid
Cells, such as gametes, that contain one set of chromosomes are called ______ cells.
haploid
The main reason for meiosis in animals is to produce
haploid sperm or egg cells
If an organism is diploid, the two members of a pair of chromosomes are called
homologous
In a diploid organism, a pair of chromosomes consists of two
homologs.
G1, S, and G2 phases are collectively known as in actively dividing cells.
interphase
In actively dividing cells, the G1, S, and G2 phases are collectively known as which of the following?
interphase
While preparing to divide, the cell grows and copies its chromosomes during:
interphase
A change in the direction of the genetic material along a single chromosome describes a(n)
inversion
If a segment of a chromosome is reversed end to end, a chromosomal mutation called a(n) occurs.
inversion
A photographic representation of the chromosomes is a type of micrograph called a(n) .
karyotype
In prometaphase, there is a key difference between mitosis and meiosis I. In mitosis, a pair of sister chromatids is attached to both poles. In meiosis I a pair of sister chromatids is attached to just one pole via microtubules.
kinetochore
Sister chromatids become attached to the spindle apparatus if a microtubule makes contact with a protein complex called the
kinetochore
The sequence of events that produces another generation of organisms is known as a(n) cycle.
life
The three most commonly used features used by cytogeneticists to classify and identify chromosomes are
location of the centromere size banding patterns revealed when chromosomes are stained
Polyploidy is generally a lethal condition in
mammals
Certain diploid cells in the testes or ovaries undergo to produce haploid sperm or eggs, respectively.
meiosis
During the life cycle of a diploid animal, what process produces haploid gametes?
meiosis
Homologous chromosomes are separated from each other during
meiosis I only
What are the two main types of cell division used by eukaryotic cells?
meiosis mitosis
During the chromosomes are aligned midway between the spindle poles.
metaphase
The plate is a plane halfway between the poles along which chromosomes align during mitosis.
metaphase
In animals, a diploid zygote undergoes repeated cell divisions of a process called to produce a diploid multicellular organism.
mitosis
What sorting process divides one cell nucleus into two nuclei?
mitosis
The two sorting processes eukaryotic cells may follow to produce new daughter cells that receive the correct number and types of chromosomes are and .
mitosis meiosis
During the process of cell division, a cell divides to produce two new cells that are genetically identical to the original cell.
mitotic
Animals are viewed as diploid-dominant species because:
most species are diploid and their haploid gametes are considered to be a specialized type of cell
A heritable change in chromosome structure that may or may not be beneficial to the organism is best described as
mutation
A heritable change in genetic material is termed:
mutation
Chromosomal can create heritable changes in chromosome structure.
mutations
Deletions and duplications are chromosomal that are changes in the total genetic material in a single chromosome.
mutations
Abnormalities in the number of the sex chromosomes or trisomies 21, 18, 13 are most likely due to
nondisjunction
The progression through the cell cycle is highly regulated to ensure that the ______ is intact and the conditions are appropriate for a cell to divide.
nuclear genome
What chromosomal variations have major effects on the characteristics of an organism?
number structure
The G1 cyclin is made in response to sufficient and growth factors.
nutrients
Mitosis is the cell division process that divides
one cell nucleus into two nuclei.
The letter ______ is used to refer to the short arm of a chromosome.
p
Human abnormalities in chromosome number are influenced by the age of the
parents
Which of these terms describes an organism with three or more sets of chromosomes?
polyploid
Unlike animals, plants often possess more than two sets of chromosomes. Plants thus exhibit
polyploidy
A life cycle is best described as the process that
produces another generation of organisms.
In I of meiosis, the replicated chromosomes condense, the homologous chromosomes form bivalents, and crossing over occurs.
prophase
Which phase marks the beginning of mitosis?
prophase
Correctly order the phases of meiosis I, beginning with the earliest phase at the top.
prophase promataphase metaphase anaphase telophase
Mitosis occurs as a continuum of phases that proceed in the following order: , prometaphase, metaphase, , and lastly .
prophase, anaphase, and telophase
During metaphase I of meiosis, the bivalents are organized along the metaphase plate. In particular, the sister chromatids are
randomly aligned in a double row.
Cell division refers to the of cells.
reproduction
The G1 checkpoint is also called the point.
restriction
Fertilized human eggs that have abnormalities in chromosome number
result in embryos that are usually spontaneously aborted.
Checkpoint proteins act as ______ to determine if a cell is in the proper condition to divide.
sensors
Choose the most common human disorders that are the result of abnormalities in chromosome number.
sex chromosome abnormalities trisomy 21 trisomy 13 trisomy 18
The process in which two haploid gametes unite to form a diploid zygote is called
sexual reproduction
Chromosomes that have replicated consist of two copies that are still joined to each other. The two copies are referred to as a pair of
sister chromatids
In an organism, each set of chromosomes is composed of several different types of chromosomes. The chromosomes are numbered according to
size
Several different types of chromosomes make up each set in eukaryotes. What describes how chromosomes are numbered?
size
Chromosomes are distinguished based on three major features: , location of the , and banding patterns.
size centromere
The largest chromosomes have the numbers based on the size ordering system.
smallest
Put the events that occur during the fungal life cycle in the correct order. Begin at the top with the production of reproductive cells.
some cells haploid meiosis repeated
In prometaphase I of meiosis, the nuclear envelope is completely broken down into vesicles, and the apparatus is entirely formed.
spindle
The process of forming a bivalent is termed pairing, or
synapsis
A(n) ______ organism has four sets of chromosomes.
tetraploid
Chromosomes are numbered according to size. What chromosomes are numbered with the smallest numbers, such as 1, 2, and 3?
the largest chromosomes
A(n) ______ occurs when a segment of one chromosome is joined to another chromosome.
translocation
Consider one segment of a chromosome that becomes attached to a different chromosome. This change in chromosome structure is a type of chromosomal mutation known as a(n)
translocation
An organism that has three sets of chromosomes is called a(n)
triploid
In organisms that are normally diploid, an individual that is 2n + 1 is said to have
trisomy
Mitotic cell division is a process by which a cell divides to produce ______ new daughter cells that are genetically ______ the original cell.
two ; identical to
A diploid organism contains
two sets of chromosomes
Cyclins were given this name since their level ______ throughout the cell cycle.
varies
When two haploid gametes unite, they create a diploid cell called a
zygote
