1.6 vocabulary Flashcards
- what is mitosis
- the four stages of mitosis
- the functions of mitosis
The process of nuclear division, where duplicated DNA molecules are arranged into separate nuclei
To create two daughter cells with genetically identical nuclei as the parent cell
Mitosis starts with interphase then is divided into four stages: prophase, metaphase, anaphase, telophase (PMAT)
Functions of Mitosis (TOAD)
Tissue repair/ replacement
Damaged or aged cells replaced with identical healthy ones
Organismal growth
Multicellular organisms derive new cells via mitosis
Asexual reproduction
Vegetative propagation in plants occurs via mitotic division
Development (of embryos)
Zygotes undergo mitosis and differentiate to become embryos
- what is interphase
- interphase in eukaryotic cell
- the process of interphase
The stage in the development of a cell between two successive divisions
- DNA is found as long thin strands called chromatin
- DNA is contained within a clearly defined nucleus
- Centrosomes and other organelles have been duplicated (# of organelles increase)
- The cell is enlarged in preparation for division (a lot of protein synthesis and metabolism is occurring)
- Cells performing their differentiated function
- The longest part of the cell cycle
- DNA replication occurs
Key processes: (DOCTOR)
- DNA replication (DNA is copied during the S phase of interphase)
- Organelle Duplication (Organelles must be duplicated for twin daughter cells )
- Cell Growth (Cytoplasmic volume must increase prior to division)
- Transcription/ translation (Key proteins and enzymes must be synthesized )
- Obtain nutrients (Vital cellular materials must be present before division)
- Respiration (cellular) (ATP production is needed to drive the division process)
G1 phase
First intermediate gap stage in which the cell grows and prepares for DNA replication
S phase
Synthesis stage in which DNA is replicated
G2 phase
Second intermediate gap stage in which the cell finishes growing and prepares for cell division
Prophase
DNA supercoils and chromosomes condense (becoming visible under microscope)
Chromosomes are comprised of genetically identical sister chromatids (joined at a centromere)
Paired centrosomes move to the opposite poles of the cell and form microtubule spindle fibres
The nuclear membrane breaks down and the nucleus dissolves
Metaphase
Microtubule spindle fibers from both centrosomes connect to the centromere of each chromosome
Microtubule depolymerization causes spindle fibers to shorten in length and contract
This causes chromosomes to align along the center of the cell (equatorial plane or metaphase plate)
Anaphase
Continued contraction of the spindle fibers causes genetically identical sister chromatids to separate
Once the chromatids separate, they are each considered an individual chromosome in their own right
The genetically identical chromosomes move to the opposite poles of the cell
Telophase
Once the two chromosome sets arrive at the poles, spindle fibers dissolve
Chromosomes decondense (no longer visible under a light microscope)
Nuclear membranes reform around each chromosome set
Cytokinesis occurs concurrently, splitting the cell into two
Cytokinesis
Cytokinesis is the process of cytoplasmic division, whereby the cell splits into two identical daughter cells
Cytokinesis occurs concurrently with the final stage of mitosis (telophase) and is different in plant and animal cells
Cytokinesis in animal cells
After anaphase, microtubule filaments form a concentric ring around the center of the cell
The microfilaments constrict to form a cleavage furrow, which deepens from the periphery towards the center
When the furrow meets in the center, the cell becomes completely pinched off and two cells are formed
Because this separation occurs from the outside and moves towards the center, it is described as centripetal
Cytokinesis in plant cells
After anaphase, carbohydrate-rich vesicles form in a row at the center of the cell (equatorial plane)
The vesicles fuse together and an early cell plate begins to form within the middle of the cell
The cell plate extends outwards and fuses with the cell wall, dividing the cell into two distinct daughter cells
Because this separation originates in the center and moves laterally, it is described as centrifugal
Chromatin
DNA is usually loosely packed within the nucleus as unraveled chromatin
In this unraveled form, the DNA is accessible to transcriptional machinery and so genetic information can be translated
DNA is organized as chromatin in all non-dividing cells and throughout the process of interphase
Chromosome
DNA is temporarily packaged into a tightly wound and condensed chromosome prior to division (via supercoiling)
In this condensed form, the DNA is able to be easily segregated however is inaccessible to transcriptional machinery
DNA is organized as chromosomes during the process of mitosis (condense in prophase, decondensed in telophase)
Centromere
Links a pair of sister chromatids together during cell division. This constricted region of the chromosome connects the sister chromatids, creating a short arm and a long arm on the chromatids
