2.3 Cell Division Flashcards
An important activity of all kinds of cells
Cell division
The division of cells in animals body
Allows animals ( and us) to grow
Replaced old cells that die
Mitosis
Produce two diploid (2n) somatic cells that are genetically identical to each other and the original parent cell
Mitosis
Before a dividing cell enters mitosis, it undergoes a period of growth called interphase. About 90 percent of a cell’s time in the normal cellcycle may be spent in interphase.
This is the non-mitotic stage.
Interphase
The period prior to the synthesis ofDNA. In this phase, the cell increases in mass in preparation for cell division.
The first gap phase
G1 phase
The period during whichDNA is synthesized.
S phase
The period after DNA synthesis has occurred but prior to the start of prophase
G2 phase
During this period structural changes of chromosomes are visible.
M phase
M phase may be subdivided into four stages,
Prophase, Metaphase, Anaphase and Telophase
This stage is characterized by the appearance of coiled, contracted threads – the chromosomes. The chromosomes are longitudinally double, each half is a chromatid. The chromatin condenses into discrete chromosomes.
Prophase
the spindlereaches maturity and the chromosomes align at the metaphase plate
Metaphase
the paired chromosomes (sister chromatids) separate and begin moving to opposite ends (poles) of the cell.
Anaphase
is accomplished by the formation of a cell plate, as the chromosomes separate during anaphase, the cytoplasm divides and the cytoplasmic contents are distributed.
Cytokinesis
In sexually reproducing organisms, the special kind of cell division whereby the chromosomes number of the cells is reduced to half its usual number.
Meiosis
This process, in which homologous chromosomes trade parts is called
Crossing over
It helped along by a protein structure called the
Synaptonemal complex
occur when there is a defect in a chromosome, or in the arrangement of the genetic material on the chromosome.
Chromosomal abnormalities
can be in the form of additional material which may be attached to a chromosome, or where part or a whole chromosome is missing, or even in defective formation of a chromosome.
Abnormalities
There are two main types of chromosomal abnormality which can occur during meiosis and fertilization:
numerical aberrations
structural aberrations
These are usually caused by a failure of chromosome division, which results in cells with an extra chromosome or a deficiency in chromosomes.
Numerical aberration
These occur due to loss or genetic material or a rearrangement in the location of the genetic material
Structural Aberrations
What are the structural Aberrations?
- Deletion
- Duplication
- Translocation
- Inversions
- Rings
- Isochromosome
is a type of eukaryotic cell that lacks a cell wall and has a true, membrane-bound nucleus along with other cellular organelles.
Animal cell
contains the specific instructions that make each type of living creature unique
DNA
are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA)
Chromosomes
This is the basic physical and functional unit of heredity. Genes
are made up of DNA.
Genes
This is one of a pair of genes that appear at a particular location
on a particular chromosome and control the same characteristic, such as blood type or color blindness.
Alleles
The organism’s complete set of DNA, that contains all of the
information needed to build and maintain that organism.
Genome
