B2.3 Cell Specialisation Flashcards
Define Zygote
An unspecialized cell produced from fertilization.
Define differentiation
Process during development where newly formed cells become more specialized and distinct from one another.
Impact of chemical gradients on gene expressions within early-stage embryo
Morphogens, signaling molecules distributed unevenly across embryo, creating gradient. Cells in different positions within this gradient will receive varying concentrations of these signals.
This differential exposure influences gene expression patterns, leading to the specialization of cells.
Two properties of stem cells
Can divide endlessly (to make more stem cells)
Can differentiate into multiple types of cells.
Define Stem cell niche
Locations that have stem cells and provide and environment that allows stem cells to regenerate and/or differentiate.
E.g. Bone marrow, liver, skin, muscle.
Changes in environment may determine whether stem cell differentiates.
Stem cell niche recreated in labs to grow stem cells.
Differences between totipotent, pluripotent and multipotent stem cells.
Totipotent: can become any cell type. (E.g. Zygote)
Pluripotent: can develop into many but not all cell types (E.g. Embryonic stem cells)
Multipotent: can develop into a few different cell types. (Umbilical cord stem cell)
Evidence that cells that have different functions have different sizes and shapes.
Sperm: long and narrow
Egg: big and rounded
Red blood cells: 8 micrometer wide with an indented middle
White blood cells: grow from 10-30 micrometers when activated
Motor neurons: large cell body and long axon
Activities occurring in the volume and at the surface of the cell
Volume: metabolic reactions
SA: where things enter/exit cell
Calculate the SA:V ratio of a cube
surface area/volume
Benefits of using cubes to model the SA and V of a cell
Simple
Mathematically easy to calculate
Drawbacks of using cubes to model the SA and V of a cell
Too simple
Doesn’t account for internal structures
Two examples of cells that are specialized for exchange of materials and have adaptations to increase the SA:V ratio.
Red blood cells:
- Small size
- Flat/concave shape
- Oxygen moves in and out more quickly.
Proximal convoluted tubule cells:
- Reabsorbing things in kidney
- Microvilli and infoldings increase SA (better absorption and more room for membrane proteins)
Define Alveolar epithelium
A thin layer of tissue lining the alveoli: air sacs om the lungs.
Crucial for gas exchange, acting as barrier between air and bloodstream.
Composed of Type I and II pneumocytes
Structure and function of type I pneumocytes
Structure: thin, few mitochondria, high SA:V ratio
Function: diffusion of gasses
Structure and function of type II pneumocytes
Structure: cube shaped, lots of organelles, low SA:V ratio
Function: production of surfactant
Surfactant: keeps alveoli from collapsing in on each other + provides moisture for more efficient diffusion
