Chapter 12: The Cell Cycle Flashcards
Cell division
The reproduction of cells
Genome
The genetic maturely of an organism or virus; the complete complement of an organism’s or virus’s genes along with its non coding nucleic acid sequences
Chromosomes
A cellular structure consisting of one DNA molecule and associated protein molecules. A duplicated chromosome structure has two DNA molecules
Chromatin
The complex of DNA and proteins that makes up eukaryotic chromosomes when the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope
Somatic cell
Any cell in a multicellular organism except a sperm or egg or their precursors
Contains 46 chromosomes in humans
Gamete
A haploid reproductive cell, such as an egg or sperm, that is formed by meiosis or is the descendant of cells formed by meiosis. Gametes unite during sexual reproduction to produce a diploid zygote
Sister chromatids
Two copies of a duplicated chromosome attached to each other by proteins at the centromere, and sometimes along the arms. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II.
Centromere
In a duplicated chromosome, the region on each sister chromatid where it is most closely attached to its sister chromatid by proteins that bind to the centromere cells DNA. Other proteins condense the chromatin in that region so it appears as a narrow waist on the duplicated chromosome.
An unduplicated chromosome has 1 centromere
Mitosis
A process of nuclear division in eukaryotic cells conventionally divided into five stages. Mitosis conserves chromosome number by allocating replicated chromosomes equally to each of the daughter nuclei.
Prophase, Prometaphase, metaphase, anaphase, and telophase
Duplication of chromosomes
IN an undivided cel, chromosomes are in long thin chromatin fibers
Once duplicated, the chromosome consists of two sister chromatids.
Molecular and mechanical processes separate the sister chromatids into two chromosomes and distribute them to two daughter cells.
Cell Cycle
An ordered sequence of events in the life of a cell, from its origin in the division of a parent cell until its own division into two. The eukaryotic cell cycle is composed of interphase and M phase
Mitotic or M phase
The phase of the cell cycle that include mitosis and cytokinesis
Interphase
The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase often accounts for about 90% of the cell cycle
Stages of Interphase
G1 phase - the first growth phase of the cycle. Consists of the portion of interphase before DNA synthesis begins
S phase - the synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated
G2 phase - the second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs
Prophase
The first stage of mitosis, in which the chromatin condenses into discrete chromosomes visible with a light microscope, the mitotic spindle begins to form, and the nucleolus disappears but the nucleus remains intact
Prometaphase
The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes
Metaphase
the third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate
Anaphase
The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell
Telophase
The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun
Cytokinesis
The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or Meiosis II.
Cleavage
The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane
Cleavage furrow
The first sign of cleavage in an animal cell; a shallow groove around the cell in the cell surface near the old metaphase plate.
Plants cells have cell plate instead
Mitotic Spindle
An assemblage of microtubules and associated proteins that are involved in the movement of chromosomes during mitosis
Centrosome
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. Each centrosome has two centromeres during interphase
Kinetochore
A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle
Metaphase plate
An imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromere of all the duplicated chromosomes are located
Cell Cycle Control System
A cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinated key events in the cell cycle
Checkpoint
A control point in the cell cycle where stop and go-ahead signals can regulate the cycle
Cyclin
A cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle
Cyclin Dependent Kinase
A protein kinase that is only active when attached to a particular cyclin
M phase Promoting Factor
M Phase promoting factor or maturing; a protein complex required for a cell or progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase
G0 Phase
A non dividing state occupied by cells that have left the cell cycle, sometimes reversible
Growth Factor
A local regulator that acts on nearby cells to stimulate cell division. It is a protein released by certain cells
G1 Checkpoint
Before the S phase
Checks for nutrients, growth factors, and DNA damages
G2 Checkpoint
Before mitosis
Checks for cell size and DNA replication
M Checkpoint
Occurs at the end of a metaphase
Checks for chromosome spindle attachment
