Mitotic Cycle Flashcards
Prophase
Super coiling of DNA
Nuclear membrane breaks down
Spindle develops and centrosome move to the poles
Metaphase
Chromosomes line up along the equator
Microtubules attach to centromere
Anaphase
Chromosomes pulled apart due to microtubules shortening
Telophase
Chromosomes reach the poles and the nuclei reforms
Cytokinesis
When the cytoplasm and cell splits
Centromere
Middle bit of chromosomes
Centrosome
Makes microtubules
Centrioles
Two in centrosome, no function
Phases of the cell cycle?
2
Mitosis- cell division, no growth
Interphase- normal cell activity
What happens in interphase?
G1- cell undergoes majority of growth
S- each chromosome relocates (synthesis) to produce sister chromatids
G2- cell continues to grow and dna is checked for errors
Structure of chromosome
Telomeres
Genes- each chromosome has several thousand
Centromere- holds the chromatids together, there are no genes here and it can be at any place in the chromosome
Chromatids- two identical chromatids make one chromosome, each contain one dna molecule
Mitosis definition
A type of cell devision which results in two genetically identical daughter cells.
When do cells duplicate their genetic material?
Before they divide so that each daughter cell receives an exact copy of DNA
Mitosis-growth
The daughter cells formed have the same number of chromosomes as the parent cells and are genetically identical, allows multicellular organisms to result from a unicellular zygote.
Mitosis- replacement of cells
Mitosis followed be cell devision. Cells are constantly dying and being replaced by identical cells ie skin which retain function
Mitosis- asexual reproduction
The offspring are genetically identical to their parent. The production of new individuals of a species by a single parent.
Mitosis- immune response
The cloning of B and T lymphocytes during the immune response is dependent on mitosis
Telomeres- lots of info
They are at the end of genes. The copying enzyme cannot run to the end of the DNA, it stops a little short. By adding some more bases, without any useful information, to the end of the dna ensures that the copying enzymes copy’s all meaningful DNA. No vital info is lost when the DNA is replicated. Extra bases are added at each cell cycle by the enzyme telomerase to ensure it doesn’t run out.
Telomeres- main function
To prevent the loss of genes during cell devision and to allow continual replication of a cell
Cancer before it gets big
The result of uncontrolled mitosis, is caused by a change in the gene that controls cell devision. Most mutated genes die or are destroyed. An oncogene does not and reproduces by mitosis to form a tumour.
What is the name of a mutated gene that causes cancer?
Oncogene
Cancer after it’s a tumour
The tumour gets bigger and is supplied with blood and lymph vessels. The tumour cells spread in the blood and lymph to other parts of the body. Tumour cells invade other tissues.
What is metastasis?
When secondary cancers form throughout the body
What is the extent or the power of a stem cell to produce different cell types called?
Potency
Totipotent
Stem cells which can produce any type of cell ie the zygote
Pluripotent
Embryonic stem cells which lead to the development of the embryo
Multipotent
Can only produce a few types of cells ie the bone marrow can only produce blood cells
Stem cells
A cell that can decide an unlimited number of times, the new cell can remain a stem cell or develop into a specialised cell. As cells become more specialised they loose their ability to devide till they can’t. A small population of stem cells remain which can produce new cells.
Chromatin
DNA+ proteins (histones) Histones are basic so interact with DNA Packed very closely Makes up chromosomes In subunits known as nucleosomes
