Cell Division (1.2) Flashcards
What does the nucleus of a cell contain?
chromosomes made of DNA molecules
i.e. genetic material
What does each chromosome carry?
a large number of genes
In body cells, chromosomes are normally found in…
pairs
23 pairs in human body cells
What is the cell cycle?
Cells divide in a series of stages
What happens during the cell cycle to the genetic material and cells?
the genetic material is doubled and then divided into two identical cells.
Before a cell can divide (undergo mitosis), what needs to happen?
it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria.
The DNA replicates to form two copies of each chromosome.
What happens during mitosis?
one set of chromosomes is pulled to each end of the cell and the nucleus divides
What happens during the last stage of the cell cycle?
the cytoplasm and cell membranes divide to form two identical (daughter) cells
Put these in order from smallest to largest: nucleus, DNA, gene, chromosome
gene, DNA, chromosome, nucleus
What is cell division by mitosis important for?
the growth and development of multicellular organisms.
What is a stem cell?
undifferentiated cells that can produce specialised cells and more stem cells
What is the function of human embryonic stem cells?
Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells
What is the function of adult bone marrow cells?
Stem cells from adult bone marrow can form many types of cells including blood cells
What is the function of stem cells from meristem tissue in plants?
Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant
There are more, but you only need to recall two of them?
Which conditions may treatment with stem cells may be able to help with?
diabetes and paralysis
What occurs during therapeutic cloning? How is this useful?
an embryo is produced with the same genes as the patient.
stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment.
What are two problems with the use of stem cells?
- there are potential risks such as transfer of viral infection
- some people have ethical or religious objections
3 points
What are the uses of stem cells from meristem in plants?
- they can be used to produce clones of plants quickly and economically
- Rare species can be cloned to protect from extinction.
- Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.
How can bone marrow cells help to treat medical conditions?
can differentiate into many types of cell
so will cure diseases where new cells are needed
Why might the levels of bacteria level out in a nutrient broth solution?
shortage of nutrients
so cells die (death rate = rate of cell division)
