Stem Cells and cancer
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What Is a somatic cell?
any cell in the human body that is not involved in reproduction
how many chromosomes do somatic cells have?
46
are somatic cells diploid or haploid
diploid
what does diploid mean
A cell containing two complete sets of chromosomes, one from each parent
what is a germline cell
the cells involved in reproduction
what are the male and female gametes
male - sperm female - ova
are gametes haploid or diploid
haploid
how does one diploid germline cell become four haploid gametes
• diploid germline cells divide by mitosis to produce two identical diploid germline cells • these then undergo meiosis to produce four haploid gametes
how many chromosomes does a haploid gamete contain
23
what happens during the two divisions of meiosis
first division - separation of homologous chromosomes second division - separation of the chromatids
what is fertilisation?
the process by which the male and female gametes fuse to form a zygote
explain some of the differences between mitosis and meiosis
• mitosis produces genetically identical daughter cells whereas meiosis produces genetically varied daughter cells • daughter cells are diploid following mitosis whereas the daughter cells are haploid following meiosis • 2 daughter cells are produced in mitosis whereas 4 daughter cells are produced in meiosis
what is cellular differentiation?
When a cell expresses specific genes to produce proteins characteristic of a certain type of cell. it is the process by which an unspecialised cell becomes altered to perform a specialised function
what are stem cells
unspecialised cells which can either replicate themselves or differentiate into a range of different cell types
what are the two types of stem cell
embryonic stem cells and tissue stem cells
which of the stem cell types are pluripotent
embryonic stem cells
what does pluripotent mean
all of the genes in an embryonic stem cell can be expressed, giving rise to any type of cell
are tissue stem cells multipotent or pluripotent
multipotent
what does multipotent mean
the cell can differentiate into any of the types of cell of the same tissue type
where are blood stem cells found in adults
bone marrow
examples of cell types which a blood stem cell can differentiate into
• red blood cell • platelet • phagocyte/lymphocyte ( white blood cells)
how are stem cells used for research?
they are used as model cells to study how diseases develop for drug testing
what three ways are stem cells used therapeutically
• corneal repair • skin grafting for burns • bone marrow transplantation
what are the ethical issues surrounding stem cells
• the extraction of human embryonic stem cells for research purposes results in the destruction of human embryos • at what stage in development should an embryo be regarded as a person?