Chapter 12: cell meiosis (test 3) Flashcards
The continuity of life is based on the reproduction of cells, or ___
cell division
In unicellular organisms, division of one cell ___
reproduces the entire organism
Multicellular eukaryotes depend on cell division for
___
___
___
Development from a fertilized cell
Growth
Repair
Cell division is an integral part of the ___, the life of a cell from formation to its own division
cell cycle
Most cell division results in genetically identical ___ cells
daughter
Most cell division results in ___ cells with identical genetic information, DNA
The exception is ___, a special type of division that can produce sperm and egg cells
daughter
meiosis
All the DNA in a cell constitutes the cell’s ___
genome
In prokaryotic cells, a genome can consist of ___ DNA molecule
In eukaryotic cells, a genome consists of a number of ___
a single
DNA molecules
DNA molecules in a cell are packaged into ___
chromosomes
___cells (nonreproductive cells) have two sets of chromosomes
Somatic
___ (reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells
Gametes
Eukaryotic chromosomes ___ of chromatin, a complex of DNA and protein that condenses during cell division
consist
In preparation for cell division, DNA is ___ and the chromosomes ___
replicated
condense
(Distribution of Chromosomes During Eukaryotic Cell Division)
Each duplicated chromosome has two sister ___ (joined copies of the original chromosome)
The ___ is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached
chromatids
centromere
During cell division, the two sister chromatids of each duplicated chromosome ___ and move into two nuclei
Once separate, the chromatids are called ___
separate
chromosomes
Eukaryotic cell division consists of
___, the division of the genetic material in the
nucleus
___, the division of the cytoplasm
Mitosis
Cytokinesis
The cell cycle consists of
___(M) phase (mitosis and cytokinesis)
___ (cell growth and copying of chromosomes in preparation for cell division)
(The majority of the cell cycle is interphase)
Mitotic
Interphase
___ (about 90% of the cell cycle)
G1 phase (“first gap”)
S phase (“synthesis”)
G2 phase (“second gap”)
The cell grows during all three phases, but chromosomes are duplicated only during the
S phase
Interphase
G2 of Interphase
Chromosomes have been ___
Duplicated chromosomes are uncondensed ___
Nucleus and nucleolus are intact
___has been replicated.
duplicated
“chromatin”
Centrosome
Prophase
Chromosomes are ___, consist of 2 sister chromatids
___ forming as centrosomes move apart.
condensed
Early mitotic spindle
Prometaphase
Nuclear envelope ___
During prometaphase, some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes
___ are protein complexes associated with centromeres
broken down
Kinetochores
At metaphase, the chromosomes are all lined up at the ___, a plane midway between the spindle’s two poles
metaphase plate
In ___ the sister chromatids separate and move along the microtubules toward opposite ends of the cell
The microtubules shorten by depolymerizing at their kinetochore ends. Once separated the sister chromatids are chromosomes.
anaphase
In ___, genetically identical daughter nuclei form at opposite ends of the cell
___ begins during anaphase or telophase and the spindle eventually disassembles
telophase
Cytokinesis
The ___ is a structure made of microtubules that controls chromosome movement during mitosis
In animal cells, assembly of spindle microtubules begins in the ___, the microtubule organizing center
An ___ (a radial array of short microtubules) extends from each centrosome
mitotic spindle
centrosome
aster
In animal cells, cytokinesis occurs by a process called ___, forming a cleavage furrow
cleavage
Plant cells contain a cell wall so the mechanism of cytokinesis is different.
In plant cells, cytokinesis occurs by vesicles that move from the Golgi along microtubules to the middle of the cell-forming a ___
cell plate
Prokaryotes reproduce by a type of cell division called ___
In binary fission, the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart
The plasma membrane pinches inward, dividing the cell into two
binary fission (split in 2)
The sequential events of the cell cycle are directed by a distinct ___ control system, which is similar to a clock
The cell cycle control system is regulated by both internal and external controls
The clock has specific ___ where the cell cycle stops until a go-ahead signal is received
cell cycle
checkpoints
___ do not respond normally to the body’s control mechanisms
A normal cell is converted to a cancerous cell by a process called ___
Cancer cells that are not eliminated by the immune system form tumors, masses of abnormal cells.
If abnormal cells remain only at the original site, the lump is called a ___
Cancer cells
transformation
benign tumor
Malignant tumors invade surrounding tissues and can ___, exporting cancer cells to other parts of the body, where they may form additional tumors
To treat metastatic cancers, chemotherapies that target the cell cycle may be used
metastasize
