cell division Flashcards
where are chromosomes contained
in the nucleus of the cell
what are the different forms of genes called
alleles
how are the chromosomes normally found in body cells
in body cells the chromosomes are normally found in pairs
why do body cells divide by mitosis
body cells divide by mitosis to produce additional cells during growth or to produce replacement cells
what happens when a body cell divides by mitosis
- copies of the genetic material are made.
- the cell then divides once to form two genetically identical body cells.
what do cells in reproductive organs divide to form
gametes
how does a cell divide to form gametes
a cell divides to form gametes by meiosis
what happens when a cell divides to form gametes
- copies of the genetic information are made.
- the cell then divides twice to form four gametes, each with a single set of chromosomes.
what happens to the gametes at fertilisation and then to the cell as the organism develops
the gametes join to form a single body cell with new pairs of chromosomes.
this cell repeatedly divides by mitosis to form many cells.
as an organism develops, these cells differentiate to form different kinds of cells.
what is the difference in how cells differentiate in plants and animals
most types of animal cell differentiate at an early stage whereas many plant cells retain the ability to differentiate throughout life
what is cell division restricted to in mature animals
in mature animals, cell division is mainly restricted to repair and replacement
what type of cells can be made to differentiate into many types of human cell e.g. nerve cell
cells from human embryo and adult bone marrow, called stem cells
what happens in therapeutic cloning
an embryo is produced with the same genes as the patient. stem cells from the embryo will not be rejected by the patient’s body so they may be used for medical treatment.
what could treatments with stem cells be used to help
conditions such as paralysis
what are some of the social and ethical issues concerning the use of stem cells from embryos in medical research and treatments
- People argue that it violates human rights to use embryos who ‘can’t decide’ to be used, that new life begins at the point of conception, so an embryo has rights. And who should decide when a human life ends?
- “We should not mess with human life.”
- Some argue that stem cell research in the far future can lead to knowledge on how to clone humans. It is hard to say whether this is true, but we have seen devastating consequences of other research-programs, even with good intentions, such as nuclear research.
- A life is a life and that should never be compromised. A fertilized egg should be valued as a human life even if it is in its very first weeks. Destroying human life in the hopes of saving human life is not ethical.”
