Unit 4: Cell Differentiation, Cell Membrane Structure and Cell Transport Flashcards
Genome
all the genetic life info of an organism.
*Organism in the same species share most of genome.
All cells within an organism share the same genome
House keeping Genes
Genes that code for proteins that are associated with basic cellular functions, such as cell regulation, DNA replication, and metabolism
Differentiation
different cell types express different genes
Gene Expression
The process by which the information encoded in a gene is turned into a function
*Signaling chemicals called morphogens impact gene expression
Benefits of Specialization
1) They can focus on fewer tasks
2) They can have a specialized structures and metabolism
3) They can evolve faster in that particular task
Stem Cell
A cell that can become anything
Process of embryo formation
Fertilization, zygote, embryo, fetus
2 hypothesis for how cells formed clusters (multicellularity)
1) A group of independent cells come together
2) When a unicellular organism divides, the daughter cells fail to separate, resulting in an aggregate of identical cells
Benefits**
- provides a survival benefit (strength in #s)
- minimizes predation
Properties of stem cells
1) Divide indefinitely to create more stem cells
2) Differentiate to become a specialized cell type
*stem cell niche = where adult stem cells live
Totipotent
“entirely potential”
Can become any body cell. Ex. Zygotes
Pluripotent
“many problems”
Can become any body cell (but not placenta)
Ex. inner cell mass of a blastocyst
Multipotent
“multiple potentials”
Has partially differentiated, but can still become multiple, related cell types
Ex. Adult stem cells, hematopoietic stem cells
Induced Pluripotent Stem Cells (iPSC)
Adult cells that can reprogrammed to form pluripotent stem cells
–> can differentiate into all of the cells of the adult body
Cell Membrane
Lipid Bilayer
- peripheral protein
- integral protein
- Glyco protein
- cholesterol
Phosphate Head
Polar (hydrophilic)
Fatty Acid Tail
Non-polar (hydrophobic)
Selectively Permeable Membrane
Allows what goes in and out
Semi-Permeable
Small, neutral or negatively charged, non-polar except for water can enter
Passive Transport
No ATP needed - moves from high to low concentration along the concentration gradient
Active Transport
Requires energy (ATP) because materials are moving against the concentration gradient
**is performed by specific carrier proteins on the membrane
Diffusion
-Dissolves substances
- Describes the movement from along a concentration gradient
Facilitated Diffusion
When a substance is aided across a membrane by ionophores (lipid-soluble molecules)
*high to low
- things are passed through a protein channel
Osmosis
Net movement of water molecules across a partially permeable membrane from higher to lower concentration
*water will always move towards regions of more negative water potential ( equals a higher concentration of solute molecules)
Hypotonic Solution
Water enters the cell causing it to swell, there is a low amount of solute outside of the cell
TURGID.
What is it called when a cell explodes
Cytolysis
Hypertonic Solution
The membrane shrinks away from the cell wall, the vacuole collapses and the cell becomes FLACCID.
-There is a high amount of solute outside of the cell
- This state is called plasmolysis and is irreversible!
Isotonic Solution
There is the same amount of solute outside the cell as inside the cell
Sodium-Potassium Pumps
Exchange of sodium ions for potassium ions across the membrane
Protein Pumps
use energy from ATP to move hydrogen ions from inside the cell to outside
- creates a large difference in the proton concentration
What are different types of proteins?
Junctions : serve to connect and join two cells together
E
Transport : responsible for facilitated diffusion and active transport
Recognition : may function as a marker for cell identification
Anchorage : attachment points for cytoskeleton and extracellular matrix
T
Freeze Fracture Electron Microscope
Rapidly freezing cells then fracturing them to reveal the internal structure of the membrane. This has revealed a mosaic pattern of integral proteins within the lipid bilayer
Fluorescence Recovery After photobleaching (FRAP)
- Proves that proteins drift through the membrane
- proteins were labeling with fluorescent marker tabs
Unsaturated Fats
- liquids at room temperature, the double bonds prevent them from packing tightly together
Saturated Fats
- solid a room temperature (butter, animal fats)
- lack the double bonds allowing them to pack tightly together
