Chapter 19- Patters of Chromosome Inheritance
G2 Checkpoint is ___________. It proceeds if ____________. It stops if ___________.
Mitosis checkpoint, DNA is properly replicated, DNA is damaged and unrepaired
Which of the following phrases best describes the events that occur during anaphase?
The spindle fibers shorten and the sister chromatids begin to separate and move to opposite ends of the cell.
The purpose of the spindle fibers is to
aid in sorting and aligning the chromosomes for their movement to opposite ends of the cell.
Separation of ________ occurs in anaphase II of meiosis.
sister chromatids
What cells in the body are most likely to have originated through the process of meiosis?
sperm and egg cells
Sister chromatids can best be described as
the two genetically identical chromatids that result from the replication of the chromosome.
There are _______ important checkpoints throughout the cell cycle.
three
What is the overall purpose of meiosis?
to produce four genetically different haploid cells.
The overall purpose of mitosis is to produce
two daughter cells that are genetically identical to one another.
A tetrad is made up of
two homologous chromosomes, each consisting of two chromatids
Cytokinesis
-Part if the cell division phase of the cell cycle -Division of the cytoplasm -Two daughter cells are produced
Mitosos
-Part of the cell division phase of the cell cycle -A type of nuclear division -A duplication division -Chromosomes are distributed to two daughter nuclei
Consider a cell that has three pairs of chromosomes. What fraction of the gametes produced from this cell will contain only maternal chromosomes?
1/8
Consider a cell that has four pairs of chromosomes. What is the number of possible chromosome orientations in that cell?
16
G1 Checkpoint is ___________. It proceeds if ____________. It stops if ___________.
Cell cycle checkpoint, the cell is committed to dividing, DNA is damaged and unrepairable.
Which of the following events does not occur during prophase?
Chromosomes replicate themselves.
Which of the following events occur during prophase of mitosis?
DNA condenses to form chromosomes, Nuclear membrane breaks down, Nucleolus breaks down, Mitotic spindle begins to form
Centromeres divide during metaphase.
False. Centromeres divide during anaphase.
Cytokinesis in plant cells occurs by means of a cleavage furrow.
False. Cytokinesis in animal cells occurs by means of a cleavage furrow. In plant cells, cytokinesis occurs when a cell plate forms between the two cells.
DNA replication occurs in mitosis.
False. DNA replication occurs during the S phase, before mitosis begins.
Interphase, which is one part of the cell cycle, is subdivided into four other phases.
False. Interphase is subdivided into three distinct phases: G1, S, and G2. (Mitosis consists of four phases: prophase, metaphase, anaphase, and telophase.)
Replication of chromosomes occurs between meiosis I and meiosis II.
False. The replication of chromosomes occurs before meiosis begins during the S phase of the cell cycle.
The cell cycle is regulated by checkpoints during the _______ phases.
G1, G2, and M
What is the order of the phases of the cell cycle?
G1, S, G2, M
The success of DNA replication is assessed during the ______ phase.
G2
Match each checkpoint to its description.
G2/M: A cell that has successfully completed all three stages of interphase is allowed to pass this checkpoint. G1/S: This critical checkpoint is influenced by external signals and growth factors. Spindle checkpoint: At this checkpoint, it is verified that all chromosomes have attached in preparation for anaphase.
During which portion of interphase are centrioles replicated?
Gap 1 phase, or G1
Select all of the following ways in which meiosis II is different than meiosis I.
Interkinesis doesn't involve the replication of chromosomes, whereas interphase does, Crossing-over doesn't occur in prophase II, whereas it does in prophase I, Cells in meiosis II are haploid and cells in meiosis I are diploid, Sister chromatids separate in anaphase II, whereas homologous chromosomes separate in anaphase I
The stages of Meioses
Prophase I: Chromosomes have duplicated, Homologous chromosomes pair during synapsis, Crossing-over occurs Metaphase I: Homologous chromosomes align independently at the equator Anaphase I: Homologous chromosomes separate and move towards the poles Telophase I: Daughter cells have one chromosome from each homologous pair Interkinesis: Chromosomes still consist of two chromatids; duplication does not occur. Prophase II: Cells have one chromosome from each homologous pair Metaphase II: Two kinetochores of each centromere bind to spindle fiber of opposite poles Anaphase II: Sister chromatids separate and become daughter chromosomes Telophase II: Reformation of four nuclei, Cytokinesis occurs between the four cells
What is the correct order of the phases of mitosis?
Prophase, Metaphase, Anaphase, Telophase
what occurs during and immediately following mitosis (Mitosis II)
Prophase: Condensed chromosomes form, Nucleus disappears, Spindle fibers begin to form, Chromosomes duplicate Metaphase: Chromosomes align at the equator, Spindle fibers attach to chromatids Anaphase: Sister chromatids split, Daughter chromosomes are fully formed Telophase: Nucleus reappears, Daughter cells form Cytokinesis: Cleavage furrow forms, Cells physically split into two distinct cells
Match each subphase of interphase to its description.
S Phase: DNA replicates G1 Phase: All of the organelles and cytoplasmic components replicate. G2 Phase: The enzymes required for cell division are produced.
M Checkpoint is ___________. It proceeds if ____________. It stops if ___________.
Spindle assembly checkpoint, Every duplicated chromosome is ready for sister chromatids to separate, Chromosomes are not properly aligned
Which of the following statements about microtubules during anaphase is true?
Those attached to chromosomes shorten, while those that are unattached elongate.
Crossing-over occurs during prophase I of meiosis.
True
In animal cells, cell division is accomplished by the formation of a cleavage furrow.
True
The actual structure that homologues bind to is called the spindle axis.
True
The region of the cell where chromosome pairs line up is referred to as the plate or metaphase plate.
True
A cell encounters several checkpoints during the cell cycle to ensure the cycle is occurring accurately.
True.
After cytokinesis, the cell enters the G1 phase.
True.
Crossing-over allows the reassortment of linked genes.
True.
Mitosis and cytoplasmic division result in the formation of two genetically identical cells.
True.
Preparation for cell division occurs in the G2 phase.
True.
Relatively speaking, eukaryotic cells spend more time in interphase and a short period of time actually undergoing cell division.
True.
Interphase is a process that a cell goes through in order to prepare for _______ _______.
cell division
Place the following events in order as they occur during cell division through mitosis.
chromatin replicates and condenses into chromosomes, spindle fibers attach to sister chromatids and align them at the center of the cell, spindle fibers begin to shorten and drag the sister chromatids to opposite ends of the cell, the nucleus re-forms around the chromosomes, the plasma membrane pinches apart into two distinct cells
A eukaryotic cell that receives a "go-ahead" signal at the G1 checkpoint of the cell cycle will
complete the cycle and divide.
The division of the cytoplasm is called
cytokinesis
At the end of meiosis II, there are
four haploid cells, with each chromosome consisting of a single chromatid
The mitotic spindle fibers attach to chromosomes via special structures termed
kinetochores.
Random orientation of homologous chromosomes occurs in ________ of meiosis.
metaphase I
A crossover in meiosis is an exchange of genetic material between
nonsister chromatids of homologous chromosomes
The spindle apparatus is fully formed by the end of
prometaphase II
The exchange of genetic material between nonsister chromatids is called crossing-over and occurs during which phase of meiosis?
prophase I.
