5. The Mitotic Cell Cycle Flashcards
State the components that make up a chromosome.
DNA
Histone proteins
Sister chromatids
Centromere
Telomeres
What is the significance of mitosis in respect to growth?
Growth is achieved by an increase in the number of cells in an organism. Mitosis helps to increase cell numbers, thus causing growth.
What is the importance of mitosis in respect to replacing cells?
Cell are constantly dying and need to be replaced by identical cells
What is a stem cell?
a relatively unspecialised cell that retains the ability to divide an unlimited number of times, and which has the potential to become a specialised cell (such as a blood cell or muscle cell)
What is a telomere?
A repetitive sequence of DNA at the end of a chromosome that protect genes from the chromosome shortening that happens at each cell division.
Define mitosis.
The division of a nucleus into two so that the two daughter cells have exactly the same number and type of chromosomes as the parent cell
Name the stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
What happens during the prophase?
- Chromosome condense become visible.
- Centrioles move to opposite poles of cell
- Nucleus disappears
- Phase ends with the breakdown of the nuclear membrane.
Outline the process of metaphase.
- Spindle fibers connect centrioles to chromosomes
- Chromosomes align along equator of cell and attaches to a spindle fiber by its centroomere.
Outline the process of anaphase?
- Centromeres split allowing chromatids to separate
- Chromatids move towards poles pulled by kinesin.
Outline the process of telophase
- Spindle fibers disperse
- Nuclear membranes form around each set of chromatids
- Nuclei form
Define a chromatid.
One of two identical parts of a chromosome, held together by a centromere, formed during interphase by the replication of the DNA strand.
What are the three phases of a cell cycle?
Interphase- G1, G2 and S phase
Mitosis
Cytokinesis
Describe what happens during G1 phase.
During G1, cells make the RNA, enzymes and other proteins needed for growth.
Describe what happens during G2
During G2, the cell continues to grow and the new DNA that was made during the S phase is checked. Any errors are usually repaired.
Define asexual reproduction
The production of new individuals of a species by a single parent organism
What is the main function of telomeres?
To ensure that the ends of the molecule are included in the replication and not left out when DNA is replicated
*to prevent the loss of genes during cell division and to allow continued replication of a cell.
What is potency?
The power of a stem cell to produce different types of cell
Define the word cancers
A group of diseases that result from a breakdown in the usual control mechanisms that regulate cell division; certain cells divide uncontrollably and form tumors, from which cells may break away and form secondary tumors in other areas of the body (metastasis)
What is a mutation?
A random change in the base sequence of DNA or in the structure of chromosomes
What is a carcinogen?
A substance or environmental factor that can cause cancer
Difference between malignant and benign tumors
Benign are tumors that do not spread from their site of origin and are not cancerous.
Malignant tumors spread though the body, invading and destroying other tissues.
What are totipotent cells
Stem cells that can produce any type of cell
What are histones and what do they do?
Organize and condense the DNA tightly so it fits in the nucleus.
Why are stem cells important?
-required to replace old cells
-produce new specialized cells when necessary
Totipotent cells
These stem cells can divide and produce any type of body cell.
Pluripotent stem cell
These stem cells are found in embryos and can become almost any type of cell.
Can be used to regrow damaged cells in humans
Multipoint stem cells
Adult stem cells that are mature and can divide to form a limited number of different cell types
Describe the role of spindle fibers during mitosis
Attaches to the centromeres
Arranges the chromosomes on the equator
Pulls chromosomes apart to the poles
Describe the role of microtubules in mitosis
-form spindle fibers
-move chromosomes to the equator
- attached to centromere
