cells and control Flashcards
why do organisms have to continuously repair old cells
growth, development or repair injuries
what are scientific names of the 5 stages in the cell cycle ( P, M, A, T, C)
prophase = growth of subcellular structures and duplication of chromosomes
metaphase = chromosomes line in the centre of the cell
anaphase = fibres pull them to either side of the cell
telophase = a nucleus is formed around each new set of chromosomes
cytokinesis = cell membrane and cytoplasm split into 2 daughter cells
how many chromosomes do humans have
23 pairs of 46 individual chromosomes (half from each parent)
how is a sperm cell specialised to its job
half the genetic material to combine with an egg, flagellum(tail) to help it swim, streamlined for quick moving and lots of mitochondria for energy
what is a specialised cell
a cell with a specific function in the body, which has adaptations to help them fulfil their job
what is differentiation
the process where cells become specialised
what are stem cells
basic cells, which divide by mitosis and can differentiate into specialised cells
what is a zygote
the single cell created when a sperm and egg combine, which splits and becomes a human
what is an embryo
the small group of cells created when a zygote splits
what are embryonic stem cells
the cells in an embryo, which can differentiate into any type of cell
how many embryonic stem cells do adult humans have
none
what are adult stem cells
found in bone marrow, they can divide by mitosis but can only differentiate into different types of blood cells
why do we have adult stem cells
they can replace damaged cells to keep us alive even though they cant form new tissues like embryonic stem cells do
where are plant stem cells found
in the roots or shoots as they are continually growing
what is a difference between plant and animal stem cells
plant stem cells persist for their entire lives, but the ones in animals disappear when fully developed
what do we call plant tissues that are continually growing and contain stem cells
meristems
why do we use stem cells in medicine
replace faulty cells with healthy ones to repair damages
what are the 4 steps of a stem cell transplant
- take embryonic stem cells from early embryos
- grow them in a lab
- stimulate them to differentiate into the type of specialised cell we want
- give them to the patient
what are the 2 negatives to stem cell transplants
- it requires embryonic stem cells which has a very limited supply and some ethical issues
- rejection, as the patient and stem cell have different genomes the body may reject them, however this can be reduced with medication
what is an alternative to stem cell transplants and a negative of it
use adult stem cells from the patient as it wont reject, however it can only be used to treat blood cell conditions
what are two risks of using any type of stem cell in medicine
- virus transmission from the taken stem cells
- tumor development as stem cells divide so quickly, they may get out of control and develop into cancer
