week 17 Flashcards
what are atoms
the smallest particles that retain the properties of an element e.g. carbon, oxygen
what are isotopes
atoms which have the same number of protons but different neutron number
what determines chemical bonding
electrons and their distribution
what are the most stable atomic states
ones with paired electrons or filled outer electron shells
how do bonds arise
when atoms share or exchange electrons to fill or empty shells
what is bond capacity also known as
atomic valence
what are hydrogen bonds
interactions between polar molecules
how does fluorescence work when studying cells
light is absorbed by a pigment and excites electrons. energy is released as light as the electrons relax back to ground state.
what is meant by membrane phospholipids being amphipathic
in water, they spontaneously form monolayers and bilayers
describe the permeability of cells
highly permeable for small hydrophobic molecules, limited permeability for water, and very low permeability for ions and large solutes.
what is facilitated diffusion
when the transport molecules create a hydrophilic pore, molecules can diffuse through
what are cation and anion ions
cation= positively charged ions
anions= negatively charged ions
what is the chemical gradient
concentration gradient
what is the electrical gradient
charge gradient
what are stem cells
unspecialised cells which can reproduce indefinitely and differentiate into specialised cell types
define totipotent stem cells
the most unspecialised stem cells capable of differentiating into any cell type within an organism and extra-embryonic tissues e.g. placenta
define pluripotent stem cells
can differentiate into any body cell (all three germ layers) but not extra-embryonic tissues e.g. placenta
define multipotent stem cells
can differentiate into multiple, but limited, body cells
define unipotent stem cells
most specialised stem cells capable of differentiating into only one cell type
how can stem cells be isolated from most tissues
biopsy or bone marrow (for adult tissues and organs), at birth from umbilical cord blood or after pregnancy termination (foetal tissues and organs)
define the difference between autologous and allogenic
autologous- take from an individual and return to the same individual
allogenic- take from an individual and return to a different individual
what is somatic cell nuclear transplantation
technique where the nucleus of a somatic body cell is transferred into an enucleated egg cell (oocyte) to create a genetically identical copy of donor cell
what is a teratoma
an often benign tumour, containing tissues of more than one germ layer arising from totipotent cells
what are the applications of embryonic stem cells
basic research, drug testing, toxicology, drug discovery and therapy (e.g. skin grafts)
