Cell division Flashcards
Chromosomes definition
In normal body cells they are found in pairs
They carry a large number of genes
Made up o DNA
Found in the nucleus in animal and plant cells
Cell cycle
They form two daughter cells
Mitosis is important for the growth and repair of cells for example the replacment of skin cells
Stage 1:
Cell grows bigger
DNA replicates (chromosomes are duplicated)
Increase the number of sub-cellular structures, such as ribsomes and mitochondria.
Stage 2 (mitosis)
A complete set of chromosomes is pulled to each end of the cell
The nucleus divides to form two nuclei
Stage 3:
Cytoplasm and cell membrane divide to form two identical daughter cells
Stem cell definition
They are an undifferentiated cell that can develop into one or more types of specialised cells
There are two types of stem cells in mammals:
Adult stem cells
Embryonic stem cell
They can be cloned to produce large numbers of identical cells
Adult stem cells, where are they found, what can they differentiate into advantages and disadvantages
Specific parts of the body in adults and children example- bone marrow
Differentiate into form of certain types of cells
bone marrow can only turn into blood cells
Advantages:
fewer ethnic issues-adults can consent to have their stem cells removed and used
Treating diseases such as leukaemia
safe to use as treatment
Disadvantages:
Requires a donor- long wait to find someone suitable
Can only differentiateinto certain type of specilised cells so can be used to treat fewer diseases
Embryonic stem cells where are they found, what can they differentiate into advantages and disadvantages
Early human embroys (often taken from spare embryos from fertility clinics)
Can differentiate into any cell in the body for example a nerve cell
Advantages:
Can treat a wide range of diseases
May be possible to grow whole replacment organs
Usually no donor is needed
Disadvantages:
Ethnic issues as the embryo is destroyedand each Embryo is potential human life
Risk of transferring viral infections
Newer treatmentso relatively under easearched-not yet clear if they can cure as many diseases as they thought
Plant meristem where are they found, what can they differentiate into advantages and disadvantages
In the roots and shoots of plants
Can differentiate into all cell types- they can be used to create clones of whole plants
Advantages:
Rare speacies of plat can be cloned to prevent extinction
Plants with desirable traits, such as disease resistance, can be cloned to produce large numbers of identical plants
Fast and low-cost production of large number of plants
Disadvantages:
Cloned plants are genetically identical, so a whole crop is at risk of being destroyed by a single disease of a generic defect
Therapeutic cloning
Cells from a paicient’s body are used to create cloned early embryo of themselves
Stem cells from this embryo can be used for medical treatments and growing new organs
These stem cells have the same genes as the patient, so are less likely to be rejected when transplanted
