Flashcards in B2- Cell Division And Differentiation Deck (17)
What is a chromosome?
A long thin thread of DNA
How many chromosome do humans have?
23 pairs (46 in total)
What is a gene? What does it do?
A section of DNA In a chromosome
- it controls characteristics
What are the 4 Base pairs?
What are gametes?
sex cells and only contain 23 chromosomes, e.g sperm and egg cells which combine together and share their chromosomes
Name and describe stage 1 of cell division
Interphase, this is the longest part
-sub cellular structures increase
- cell replicates it DNA to form 2 copies of each chromosome
- grows bigger + increase in mass
Name and describe stage 2 of cell division
- in this process one set of chromosomes is pulled to each end of the cell and the nucleus divides
Describe stage 3 of cell division
Cytoplasm and the cell membrane divide to form 2 identical daughter cells
Where are stem cells found in an animal?(2)
-early human embryos
-adult bone marrow
Name 2 ways in which stem cells can be used to fix problems in the human body
-be transferred to replace faulty cells i sick people
- injected into spine of paralysed people to make more nerve cells
- make insulin producing cells for people with diabetes
Name 2 reasons why someone will be against the use of stem cells
- by using embryos you are ending a potential life (or from a religious point of view killing actual life)
- you could potentially clone people if you splint the embryo in 2
What do scientist say in argument to the issues raised by the use of stem cells? (Apart from the fact that they can help people)
- more embryos die than live so it just better that they are used
- to prevent cloning some some scientist have began taking stem cells from a much earlier stage, blastocyst, which doesn't allow cloning
Whats so special about stem cells?
They are undifferentiated so can develop into any specialist cell
When cells transform into specialist cells that perform a particular job and have particular sub cellular structures structures for this
How is differentiation different in plant cells?
Once cells specialise (differentiate)they can re-differentiate into other specialised cells. So if you took a rose's leave and plant it in the right conditions you would grow a rose plant
Where are stem cells found in a plant?