4.1.2 cell division Flashcards
An example of a gamete is a
sperm or egg
How many chromosome pairs are found in the nucleus of a body cell?
23
How many chromosomes are found in an egg or sperm
23
Cells undergo cell division called
mitosis
Mitosis is important for
growth, repair and replace worn out cells
The first step of the cell cycle is
DNA replication - genetic material is doubled
A chromosome looks X shaped because
it has replicated
In mitosis after DNA replication has occurred what happens next?
Replicated chromosomes line up and then separate, the cell then divides into two
What is the end result of mitosis?
two genetically identical daughter cells
What is the meristem?
An area in the plant in which rapid cell division is occurring - usually roots and shoots
What is a stem cell?
A cell that has the capacity to differentiate into ANY cell
Inside the nucleus you will find
Chromosomes made from DNA
In body cells chromosomes are found in
pairs
Cells divide in a series of stages called
the cell cycle
Before the cell divides what does the cell need to do?
increase in size (grow) and increase the number of mitochondria and ribosomes (and replicate its DNA)
The last step of mitosis involves
the cell dividing into two
Uses of stem cells include
treatment of diseases e.g. paralysis
Ethical issues surrounding stem cell use?
destruction of an embryo
There are other sources of stem cells which don’t involve using an embryo, they are?
bone marrow, skin, intestine
A limitation of adult stem cells is
they have a limited differentiation capacity
What is therapeutic cloning?
An embryo is created using the genes of the patients, this way the stem cells from the embryo are not rejected
Reasons to clone plants?
rare species can be cloned to protect from extinction and crops with special features e.g. disease resistance can be cloned.
chromosomes are found where in the cell?
nucleus
