B3 Cell Division Flashcards
What does the nucleus contain?
It contains chromosomes.
What do chromosomes carry?
A large number of genes.
Are chromosomes found singularly or in pairs?
In pairs.
What are chromosomes made out of?
They are made of DNA molecules.
What is the cell cycle?
When the body cells divide to form two identical daughter cells.
Where can mitosis be found?
In asexual reproduction.
What is stage 1 of the cell cycle?
•cell grows bigger
•DNA replicates (chromosomes are duplicated)
•increase in number of sub-cellular structures, such as ribosomes and mitochondria
What is stage 2 of the cell cycle?
Mitosis
•a complete set of chromosomes is pulled to each end of the cell
•the nucleus divides to form two nuclei
What is stage 3 of the cell cycle?
•cytoplasm and cell membrane divide to form two identical daughter cells
What is a stem cell?
A cell that is undifferentiated that can develop into one or more types of specialised cell.
What are the two types of stem cells found in mammals?
Adult step cells and embryonic stem cells.
What does it mean when step cells are ‘cloned’?
They produce a large number of identical cells.
Where are adult stem cells found?
Specific parts of the body, for example, bone marrow.
What can adult stem cells differentiate into?
Only certain types of cell, for example, stem cells from bone marrow can only differentiate into types of blood cells.
What are the advantage of adult stem cells?
•fewer ethical issues (adults can consent to have their stem cells removed and used
•an established technique for treating diseases such as leukaemia
•relatively safe to use as a treatment and donors recover quickly
What can embryonic cells differentiate into?
Any type of specialised cell.
What are the advantages of embryonic cells?
•can treat a wide range of diseases as can form any specialised cell
•may be possible to grow whole replacement organs
•usually no donor needed as they are obtained from spare embryos from fertility clinics
Where are plant meristem found?
In the roots and shoots of plants.
What can plant meristem differentiate into?
Can differentiate into all cell types, can create clones of whole plants
What are the advantages of plant meristem?
•rare species of plants 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 numbers of plants
What are the disadvantages of adult stem cells?
•requires a donor, potentially meaning a long wait time to find someone suitable
•can only differentiate into certain types of specialised cells, so can be used to treat fewer diseases
What are the disadvantages of embryonic stem cells?
•ethical issues as the embryo is destroyed and each embryo is a potential human life
•risk of transferring viral infections to the patient
•newer treatment so relatively under researched- not yet clear if they can cure as many diseases as thought
What are the disadvantages of plant meristem?
•cloned plants are genetically identical, so a whole crop is at risk of being destroyed by a single disease or genetic defect
What is therapeutic cloning?
Cells from a patient’s body are used to create a cloned early embryo of themselves.
Benefits of therapeutic cloning?
Stem cells from this embryo can be used for medical treatments and growing new organs.
Benefits when transferring to a patient using therapeutic cloning?
These stem cells have the same genes as the patient, so are less likely to be rejected when transplanted.
