B2.3 Cell Specialisation Flashcards
what are the properties of stem cells
- divides indefinitely to create more
- no limit to times it can divide
- differentiates to become a specialised cell
differentiation
development of specialised structures and functions in cells
what are stem cells
undifferentiated cell in embryo or adults that can undergo unlimited division and can give rise to one of many different cell types
when does differentiation occur
when different cell types express different genes
gene expression
information encoded in a gene is turned into a function
protein translation - sequence of a dna is transcribed to form RNA
Some of the tissues which retain stem cells within a niche
bone marrow
hair follicles
bone marrow niche
- niche for stem cells which are used to replace rbc, abc and platelets
- important for continual production of cells - required indefinitely
hair follicle niche
- located at the root of the hair where the hair is anchored into the skin
- Stem cells here promote continual hair growth
what should the environment provided by the niche cells have
- The ability to maintain an inactive state of the stem cells
- The ability to stimulate stem cell proliferation and differentiation
where have stem cell niches been found
brain, bone marrow, skeletal muscle, skin, teeth, heart, intestines, liver, etc.
what are stem cell niches
locations within the tissues where stem cells reside and recieve physical and chemical signals
potency
The ability of stem cells to differentiate into more specialised cell types
Totipotency
entirely potential
capable of giving rise to any cell type in an organism, including making more totipotent stem cells and making the cells that become the placenta
example of totipotent cell
zygote - can become any body cell
Pluripotency
many potentials
able to develop into many different types of cells or tissues in the body, except for becoming placental cells or totipotent
example of Pluripotency
inner cell mass of a embryo
can become anything except placenta
Multipotency
multiple potentials
can create, maintain and repair the cells of one particular organ tissue
partially differentiated but can still become multiple cell types
example of Multipotency
adult stem cells
bone marrow stem cells differentiate into different blood cells
Unipotency
unipotent stem cells are adult cells that can only differentiate into their own lineage
Most cells in animal bodies are unipotent
example of Unipotency
heart muscle cells (cardiomyocytes) can generate new cardiomyocytes through the cell cycle to build and replace heart muscle.
fertilisation
multstep process in which a sperm and egg fuse to form zygote
sexual reproduction
zygote - embryo
zygote divides through mitosis to form an embryo which are genetically identical cells
nucleus of zygote
is diploid
2 sets of chromosomes
morphogens
A morphogen is defined as signaling molecules
act over long distances to induce responses in cells based on the concentration of morphogen that the cells interact with.
cell specialisation
allows cells to perform a function with increase efficiency
embryonic stem cells
undifferentiated cell in early stage embryo, capable of continual cell division and of developing into all the cell types of an adult organisation
specific of adaptation of stem cells
cells can develop into specific shapes and sizes
cells can create protiens needed to carry out specific metabolic reactions
Red blood cells
are small to allow movement through narrow capillaries
human sperm cell size and structure
long and narrow cells with a strong flagellum for movement
human sperm benefits
adapted to reduce resistance as the cell moves towards the egg
human egg cell size and structure
large and spherical - largest of any human cell
human egg cell function
stores all of the nutrients and materials needed for initial development of embryo
neurone cell size
large cell body with long narrow axon that can extend for a meter or more
neurone cell function
rapid transmission and information along the distance
striated muscle fibre cell size and structure
long, narrow, cylindrical shaped cells
striated muscle fibre cell function
generates force and contracts in order to cause movement
surface area to volume ratio
As cells increase in size their surface area to volume ratio (SA:V) decreases as there is less surface area in relation to the volume of the organism
