Topic 2 - Cells and Control Flashcards
Where is DNA found
In nuclei as chromosomes - coiled up.
Cell Cycle
Interphase - majority of time
Mitosis - where the cell divides
Asexual reproduction
Using mitosis to reproduce
eg. Strawberry plants produce runners
Interphase
DNA spread out in long strings, Then it is Duplicated and forms X-Shaped chromosomes - each arm is the copy of the other. Extra sub cellular structures : mitochondria and ribosomes.
Order of the cell cycle
I PMAT C
Prophase
Chromosomes condense - shorter and fatter. Nucleus membrane breaks down releasing chromosomes to the cytoplasm. Centrioles form and move to poles.
Metaphase
Centrioles produce spindle fibres and attach to centromere. Chromosomes line up at the equator.
Anaphase
Spindle fibres condense pulling chromatids from certromeres to opposite poles of the cell.
Telophase
Nuclear membranes form around each set, the nuclei of the 2 daughter cells
Cytokinesis
The cytoplasm and cell membrane separate
Mitosis produces
2 identical diploid cells
Calculate number of cells
2^n
n= divisions
What growth involves
Cell division, differentiation, elongation (plants)
Cell differentiation
Cell becomes specialised (stem cells)
Cell Division
Mitosis
Cell Elongation
Plant cell expands.
Growth in animals
Growth when young until full growth. Cell division is for repair. Cell differentiation is mostly lost.
Growth in plants
Height is due to cell elongation. Cell division takes place in roots and shoots (meristem). Plants continue to grow.
Cancer
Rate of cell division is controlled by genes. A mutation alters these genes resulting in uncontrolled cell division resulting in the formation of tumours (mass of abnormal cells). The tumour invades and destroys surrounding tissue this is called cancer.
Percentile charts
Asses a child’s growth. Can identify obesity, malnutrition or dwarfism. Uses Length, Mass and Head circumference. They are plotted. If a child is an outlier to the correlation eg. 0.4th and 99.6 percentile doctors will investigate
Embryonic stem cells
Can differentiate into any cell
Where are stem cells found
Bone marrow
Adult stem cells
Used for repair as it has only a limited selection
Meristems
Found roots and shoots, produce a unspecialised cells that are able to divide (mitosis) and form any cell type (eg. Xylem and phloem). Live as long as plant does.