Ch. 2 Flashcards
Molecules in Water(3)
- Hydrophilic
- Hydrophobic
- Amphipathic
Hydrophilic
Water loving molecules that are easily coated and transported in water because they dissolve
Hydrophobic
Water hating molecules do NOT dissolve in water and are NOT easily transported.
They separate from water
Hydrophilic types
Polar molecules
Hydrophobic types
Non polar molecules
Lipids
Proteins
Amino acids
Amphipathic
Consists of 2 regions: one polar and one non-polar
Phospholipid bilayer
Layered form of amphipathic molecule
Cell membrane
Is a phospholipid bilayer containing many different molecular components, including proteins and cholesterol, some with carbohydrate groups attached
Plasma membrane
Cell structure that defines the internal and external environments of the cell
Proteins of Plasma Membrane (2)
- Integral
2. Peripheral
Integral Protein
Span the length of the membrane
Peripheral Protein
Proteins found only on the inside or outside of the cell
List the Types of Membrane Proteins (6)
Ion channel Receptor Linker Transporter Enzyme Cell identity marker
Ion Channel (integral)
Allows specific ions to pass through the plasma membrane
- the conformation of the channel has an opening that allows passage into the cell
Receptors (integral)
Involved in cellular communication and control
- cell regulation and signaling
- bind specific molecules called ligand which causes a change in conformation that results in an internal response in the cell
Transporter (lntegral)
Transports matter across the membrane
- molecules bind to the protein and modify its conformation which allows the substance to enter the cell
Enzyme (integral and peripheral)
Catalyzes a chemical reaction inside or outside the cell depending on which side the binding site is facing
Linker (integral and peripheral)
Anchors filaments inside and outside the plasma membrane, providing structural stability and shape for the cell
Cell Identity Marker (integral)
A glycoproteins
Used in cell identification and communication
Type of Cell Junctions
Anchoring
Tight junction
Gap junction
What are membrane junctions?
Specialized connections between adjacent cells
Involved specific proteins
3 Main Types of Membrane Junctions
Desmosome
Tight junction
Gap junction
Desmosome
Fibrous proteins that are synthesized by each cell extended out to the adjacent cell and LINK together
The cell membrane DO NOT TOUCH, allowing ECF to flow between connected cells
Holds cells in position
Where are Desmosome found?
Located primarily in the epithelium cells and occasionally in muscle cells
Tight junctions
Membrane proteins in both cells link tightly together
Prevent the movement of ECF BETWEEN THE CELLS
Gap junctions
Ion Channels extend from each cell and link together across the extracellular space
Membranes of the cells DO NOT TOUCH, only the ion channels
Ions can flow from one cell to another
A form of electrical communication between cells
Where are gap junctions found?
Located in muscle and nervous tissues
Allows for coordination of cells of the heart muscle
Membrane Transport
The movement of substances across a membrane
Diffusion
The movement of a substance across a membrane down its concentration gradient
Diffusion ceases when equilibrium is reached across the membrane
Types of Diffusion
Simple diffusion
Facilitated diffusion
Carrier mediated
Simple diffusion
The substance can pass through the membrane without the help of a membrane protein
Occurs primarily with non polar molecules
Examples of Simple Diffusion
Water
Gasses
Solids
Lipid soluble vitamins
Facilitated Diffusion
Requires transport membrane proteins or ion channel for the movement of polar substances across the membrane
Examples of facilitated diffusion
Occurs with Ions and polar molecules such as glucose, amino acids, and proteins
Channel mediated diffusion
An ion channel allows the substance to cross the membrane
Controls the diffusion of extracellular sodium into the cells and intercellular potassium out of cells
Types of Ion Channels
Passive/leakage
Gated
Passive/ leakage channel
Channel protein that is always open
Gated channel
The confirmation of the channel protein has a “gate” that can change its shape and open or close the channel
Carrier mediated channel
A transport protein in the membrane binds the substance being transported
Results in a change in transport protein conformation and move substances into or out of the cell
Example of carrier mediated diffusion
Glucose
