Control of Gene Expression - Mutations and Stem Cells Flashcards
what is a mutation?
any change to 1 or more nucleotide bases or any rearrangement of bases in DNA
what are the types of gene mutation?
substitution
deletion
addition
duplication
inversion
translocation
what is a substitution mutation?
when a nucleotide is replaced by another of a different base
what are the effects of substitution mutation?
stop codon formed - polypeptide production stopped early
codon for different amino acid formed - slightly different structure
formation of different codon but same amino acid - no effect
what is deletion mutation?
when a nucleotide is removed from the sequence
what are the effects of deletion mutations?
causes a frame shift to the left
most triplets different so polypeptide very different
what is addition mutation?
when a nucleotide is inserted into the sequence
what are the effects of addition mutation?
frame shift to the right
not as big an effect if 3 are inserted
what is duplication mutation?
one or more nucleotides repeated
what are the effects of duplication mutation?
causes frame shift to the right
what is inversion of bases mutations?
a group of nucleotides becomes seperated from the sequence and rejoins in the same position but inverse order
what are the effects of inversion of bases mutations?
only affects one amino acid if 3 are reversed
what is translocation mutation?
a group of nucleotides becomes seperated from the sequence and becomes inserted into the DNA of another chromosome
what is the effect of translocation mutations?
significant affect on gene expression leading to abnormal phenotype, including development of some cancer
what are the causes of mutations?
during DNA mutations
can be increased by mutagenic agents
what is a mutagenic agent?
something that increases the risk of mutations
what are two mutagenic agent?
high energy ionising radiation
chemicals such as NO2
what are the advantages of mutations?
produces genetic diversity necessary for natural selection
what are the disadvantages of mutations?
can produce an organism less well suited to an environment
if occurs in body cells, leads to disruption of normal cellular activities such as cell division which then leads to cancer
how do differentiated cells all differ from each other?
they all produce different proteins
what are the different ways that stem cells go through mitosis?
- one daughter cell differentiates, one stays as a stem cell
- both daughter cells stay as stem cells
- both daughter cells differentiate
what are the types of stem cell?
embryonic
adult
umbilical cord
placental
totipotent
induced pluripotent
where are embryonic stem cells found?
blastocyst stage in embryos
what are embryonic stem cells used for?
grow cultures of stem cells
what types of cell can embryonic stem cells differentiate into?
most types of cell
where are adult stem cells found?
tissues around the body, mainly ones that need to regenerate more often
what types of cell can adult stem cells differentiate into?
only into specific cells
eg blood stem cells can only differentiate into specialized blood cells
what are the properties of umbilical cord stem cells?
similar to adult stem cells
what are the properties of placental stem cells?
similar to adult
where are totipotent stem cells found?
early embryos - zygotes
what types of cell can totipotent stem cells differentiate into?
any cell type, including pluripotent stem cells
what are induced pluripotent stem cells?
genetically reprogrammed body cells
what are the properties of induced pluripotent stem cells?
behaves like embryonic stem cells
what is potency?
measure of how many types of specialized cell a stem cell can make
what is a totipotent cell?
a cell that can differentiate into any type of cell
what is a pluripotent cell?
a stem cell that can differentiate into almost any type of specialized cell
which stem cells are pluripotent?
induced pluripotent
embryonic
what is a multipotent cell?
a stem cell that can make multiple types of specialized cell
which stem cells are multipotent?
placental stem cells
umbilical cord blood stem cells
adult stem cells
how can stem cells be obtained?
from spare embryos created during IVF
theraputic cloning
from bone marrow
from umbilical cord blood
how are stem cells obtained from spare embryos in IVF?
at 8 cell stage, cell removed for genetic diagnosis
cell cultured to produce stem clels
what is the process of theraputic cloning?
nucleus of ovum removed, replaced with nucleus from patient
cell given small electric shock to start it dividing
once blastocyst stage reached, stem cells removed and should be genetically identical to patient
what are some uses of stem cells?
help with diseases caused by faulty cells (parkinsons, diabetes)
can also potentially grow organs identical to patient for transplant
