Cell specialisation Flashcards
What is fertilisation?
Fertilisation is a multi-step process in which a sperm and egg cell fuse to form a single cell called a zygote.
In what does fertilisation occur?
Fertilisation cours in sexually reproducing organisms that produce haploid gametes (e.g. in plants and animals).
What happens when the zygote is divided by mitosis?
The zygote is divided by mitosis to form an embryo composed of genetically identical cells.
What are the cells in the zygote and embryo?
The cells in the zygote and embryo are unspecialised stem cells.
What happens to the zygote and embryo (unspecialised stem cells) as the cells of the embryo continues to divide?
As the cells of the embryo continue to divide, they begin to specialise in structure and function.
What does cell specialisation allow cells to do?
Cell specialisation allows cells to perform a function with increased efficiency.
What is differentiation?
Differentiation is the development of specialised structures and functions in cells.
When does differentiation occur?
Differentiation occurs when different cell types express different genes.
What is gene expression?
Gene expression is the process by which the information encoded in a gene is turned into a function.
How does the position of a cell within the embryo determine how it differentiates?
The position of a cell in an embryo impacts how it differentiates by exposing the cell to specific signalling molecules and physical cues from neighbouring cells.
What do the positional cues (of a cell in an embryo) create?
They create gradients of molecules called morphogens which establishes a spatial pattern in the embryo. Cells interpret these gradients and other environmental signals to “decide” which genes to express, leading to specialized cell types.
Explain the morphogen gradient?
Cells near the source of a morphogen (a signaling molecule that diffuses from one location) receive higher concentrations than those farther away. The concentration of a morphogen at a cell’s position signals which genes to turn on or off, guiding the cell toward a particular fate.
What is retinoid acid and what important roles does it have?
Retinoid acid is a morphogen that plays important roles in cell growth, differentiation and organ development.
What does retinoid acid do?
It diffuses throughout the embryo switching genes on and off and imparting different cell fates depending on its concentration.
What is a stem cell?
A stem cell is a cell that can be divided by mitosis an unlimited number of times.
What is a stem cell niche?
A stem cell niche is a specific location where stem cells remain in the human body.
Explain how bone marrow is a stem cell niche.
-Bone marrow provides a niche for stem cells which are used to replace red blood cells, white blood cells and platelets
-This is important for continual production of these cells which are required indefinitely
Explain how a hair follicle is a stem cell.
-This niche is located at the root of the hair where the hair is anchored into the skin
-Stem cells here promote continual hair growth
What are the requirements of the environment of a stem cell niche?
The environment provided by the niche must have
-The ability to maintain an inactive state of the stem cells
-The ability to stimulate stem cell proliferation and differentiation
What is potency?
The ability of stem cells to differentiate into more specialised cell types is known as potency.
What is totipotency?
Totipotent stem cells are stem cells that can differentiate into any cell type found in an embryo, as well as extra-embryonic cells (the cells that make up the placenta).
What are pluripotent cells?
Pluripotent stem cells are embryonic stem cells that can differentiate into any cell type found in an embryo but are not able to differentiate into extra-embryonic cells (the cells that make up the placenta)
what are multipoint cells?
Multipotent stem cells are adult stem cells that can differentiate into closely related cell types.
What are unipotent cells?
Unipotent stem cells are adult cells that can only differentiate into their own lineage.
In what do eukaryotic cells become specialised for specific functions (division of labour)?
In complex multicellular organisms.
How does specialisation enable the cells in these tissues to function more perfectly?
They develop specific adaptations for their role. The development of these distinct specialised cells occurs by differentiation
How is the structure of a cell adapted?
the structure of a cell is adapted to help it carry out its function (this is why specialised eukaryotic cells can look extremely different from each other)
What do structural adaptations include?
Structural adaptations include:
The shape of the cell
The organelles the cell contains (or doesn’t contain)
For example: Cells that make large amounts of proteins will be adapted for this function by containing many ribosomes (the organelle responsible for protein production)
What do cells that have differentiated come in?
They come in different shapes and sizes.
Give examples of the cells that have differentiated that come in
