Edexcel A-Level Biology I Unit 7 Modern
Genetics I Primrose Kitten 2024 Exam
Completely Solved 100% Pass
TOTIPOTENT STEM CELL - Answer>>These can divide and
produce any type of body cell e.g. zygote. Totipotent cells only
occur for a limited time in early mammalian embryos.
PLURIPOTENT STEM CELL - Answer>>These are found in the
embryos and can differentiate into almost any type of cell.
Examples of pluripotent stem cells include embryonic and foetal
stem cells. Pluripotent stem cells can divide in unlimited numbers
and can be used to treat human disorders such as Parkinson's
disease; macular degeneration; type 1 diabetes; skin grafts for
burns and wounds.
MULTIPOTENT STEM CELL - Answer>>These are found in
mature mammals and can differentiate into a limited number of
specialised cells of a particular type e.g. stem cells in the bone
marrow can produce any type of blood cell. Examples of
multipotent cells are adult stem cells and umbilical cord blood
stem cells.
UNIPOTENT STEM CELL - Answer>>These are found in
mature mammals but they can only differentiate into a single type
of cell. They are derived from multipotent stem cells and are
made in adult tissue e.g. cardiomyocytes.
INDUCED PLURIPOTENT STEM CELL - Answer>>A type of
pluripotent stem cell that is produced from unipotent stem cells,
which can be almost any adult body cell. The unipotent cells are
genetically altered in the laboratory using protein transcription
factors, to acquire the characteristics of embryonic stem cells. IPS
, cells are capable of self renewal and could potential replace
embryonic stem cells in medical research and treatment.
BLASTOCYST - Answer>>Formed during early embryo
development from a cluster of berry like cells called a morula. A
blastocyst consists of an inner cell mass [which later forms the
embryo], an outer layer of cells called the trophoblast [which later
forms the basis of the placenta] and a fluid filled cavity called the
blastocoel.
SOMATIC CELL - Answer>>Any cell in the body that are not
gametes. Mutations in somatic cells can affect the individual but
they are not passed onto the offspring.
TRANSCRIPTION FACTOR - Answer>>A specific molecule
e.g. oestrogen, which can move from the cytoplasm into the
nucleus. Each transcription factor has a site which binds to a
specific base sequence on DNA to trigger transcription of that
base sequence.
EPIGENETICS - Answer>>A relatively new scientific field which
involves heritable changes in gene expression without changes in
the base sequence of DNA. Epigenetics provides explanations as
to how environmental influences such as stress, diet, toxins can
alter the genetic inheritance of an organism's offspring.
EPIGENOME - Answer>>The chemical tags which form a
second layer around DNA and histones. The epigenome
determines the shape of the DNA-histone complex. The
epigenome keeps genes which are inactive in a tightly packed
arrangement so that the nucleotide sequence cannot be read.
[epigenetic silencing]. The epigenome unwraps active genes so
that the DNA is exposed and can be easily transcribed.
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