Unit 1 Flashcards
A stem cell is an unspecialised cell that can:
make copies of itself and differentiate (make copies of itself)
Differentiation occurs when
when unspecialised cells become specialised
A differentiated cell only
Has a few genes switched on
the 2 types of stem cells are
embryonic and adult (tissue)
embryonic stem cells are
derived from an embryo
embryonic stem cells have the ability to
differentiate into all cell types
Where are adult stem cells found?
in small numbers in the tissue and organs of adults and children, including the brain, bone marrow, skeletal muscle and skin
adults stem cells give rise to
a more limited range of cell types.
the theraputic uses of stem cells incude:
bone marrow transplants
skin graphs for burns
stem cell graphs for cornea repair
stem cell research gives us information including:
the study of diseases
drug testing
how the processes of growth, differentiation and gene regulation work
which type of stem cells has ethical issues surrounding it
embryonic stem cells
somatic cells are
the differentiated cells that form the different types of body tissue
type of somatic cells are:
epithelial cells (cover the body surface and line body cavities) connectives tissue ( includes blood, bone and cartilage cells) muscle cells (form muscle tissue) nerve cells (form nerve tissue)
during growth and repair, somatic cells
always divide by mitosis to maintain diploid chromosome number
germline cells include
the gametes and the cells that produce gametes (gamete mother cells)
germline cells can divide by mitosis to
produce more germline cells
germline cells can also divide by meiosis to
produce haploid gametes
if a genetic mutation occurs in a germline cells, it
will be passed on to the offspring during sexual reproduction
genetic mutations that occur in somatic cells will
not be passed to the offspring, as these cells are not involved in sexual reproduction
Cancer cells continue to
reproduce to produce a mass of abnormal cells called a tumor
cancer cells do not
respond to regulatory signals that would instruct them to stop dividing
DNA consists of
units called nucleotides
Nucleotides are made up of
phosphate
base
deoxyribose sugar
there are four different types of
nucleotides, depending on the base
certain bases are complementary to
each other, this is called the base pairing rule
a pairs with
t
g pairs with
c
bases in adjacent strands are
held together by hydrogen bonds
DNA is held together by a strong chemical bond between
the phosphate of one nucleotide and the carbon 3 of the sugar on another nucleotide
the double helix is described as
having two anti-parallel chains of nucleotides because one side goes 5’ to 3’ and the opposite side goes 3’ to 5’
the base sequence of a DNA determines
the genotype
DNA is arranged in
tightly coiled nucleotides
the DNA is packed with
proteins
DNA replication occurs in
the nucleus and involves DNA unwinding
once the DNA has unwound it
unzips to expose its bases
the DNA bases are now
used as a template for a new DNA strand to be made
once the nucleotides are exposed, free floating
nucleotides in the nucleus join on to their complementary bases
once the nucleotides are lined back up, they
join to their partner by hydrogen bonds
the DNA strand forms a
sugar phosphate backbone
the DNA strand then
Winds back up to form 2 identical double helix’s
each double helix contains
one original strand and one “new” strand