Cell division Flashcards
What is a gamete?
it is a sex cell
eg sperm, ova, pollen
What is a haploid?
It is a cell or nucleus that has half the usual number of chromosomes.
What is a diploid?
It is a cell or nucleus which has pairs of chromosomes
What is mitosis?
Where cells replicate and make 2 identical copies of themselves
What are the steps in mitosis?
1 nucleus disappears and chromosomes make copies of themselves
- Copied chromosomes line up along the cells midpoint
- Original chromosomes are pulled to one side of the cell and the copies to the other
- The cell divides down the midpoint
- A new nucleus is formed in each of the new cells.
What are daughter cells?
The new cells produced by mitosis
What is a cell cycle?
The steps in which the DNA material doubles and the cell divides into 2 identical cells.
What needs to happen to a cell before mitosis can take place?
- The sub cellular structures need to grow and increase so that there are enough for each daughter cell.
- The DNA needs to double
What is a stem cell?
An undifferentiated cell which can develop into a specialist cell
What does differentiate in cells mean?
to specialise in a particular function
eg heart muscle cell, hair cell, skin cell
What are the two types of stem cells?
Embryonic and adult
What is an embryonic stem cell?
Only found in the zygote and embryo stages of reproduction, it is an unspecialised cell which can develop into one of many specialised ones.
What is an adult stem cell?
They can make a few different cells eg different blood cells but not a full range of cells.
Eg those in the bone marrow which make blood cells.
some animals such as crab can regenerate limbs if they loose them
What is a meristem of a plant?
where cell division happens in a plant, usually in the tips of roots or shoots
What is a hormone?
is a chemical which tells a cell to do a job or change in some way
What is a clone
an organism which has the same DNA as it’s parent.
What is genetic variation?
the inherited differences in organisms
eg height, eye colour, number of petals
What is environmental variation?
differences in the organism which have developed because of environment.
eg different size due to having different nutrients
Give arguments for agreeing with stem cell research
1 . can improve the lives of people with diseases such as diabetes by replacing cells that don’t work properly.
- can replace defective organs
- could allow paralysed people to walk by replacing damaged nerve cells
Give arguments against stem cell research
- some religions believe that the embryo is a life with human rights
- some people think that it is the first step in experimenting on people
- There could be an issue with viral infections being passed on
Where do the embryos in stem cell research come from
excess embryos used for IVF fertility treatment are frozen and may not be needed in the future.
