chapter 5 Flashcards
Channel Protiens
Allows a particular molecules or ion to cross the plasma membrane freely. act like tunnels for small molecules (ex: aquaporins for water)
What are the main functions of the plasma membrane?
Structure and protection of the cell, selective permeability, communication with the environment
The plasma membrane regulates the movement of substances in and out of the cell, maintaining homeostasis.
What are the different structural components of membranes?
- Phospholipids
- Proteins
- Carbohydrates
- Cholesterol
These components contribute to the fluidity and functionality of the membrane.
What is the fluid-mosaic model?
A model describing the structure of cell membranes as a mosaic of various proteins embedded in or attached to a fluid lipid bilayer
This model emphasizes the dynamic nature of the membrane.
What diverse roles do proteins play in membranes?
- Transport
- Enzymatic activity
- Signal transduction
- Cell recognition
- Intercellular joining
- Attachment to the cytoskeleton and extracellular matrix
Membrane proteins facilitate various functions critical for cellular processes.
Why does the plasma membrane exhibit selective permeability?
It allows certain molecules to pass while blocking others based on size, charge, and solubility
This property is essential for maintaining the cell’s internal environment.
What is the difference between diffusion and osmosis?
Diffusion is the movement of solute particles from high to low concentration, while osmosis is the movement of water across a semipermeable membrane
Both processes are passive transport mechanisms.
What role do proteins play in the movement of molecules across a membrane?
Proteins act as channels or carriers to facilitate the transport of specific molecules
These proteins can be integral or peripheral and are crucial for both passive and active transport.
What are the effects of hypotonic, isotonic, and hypertonic solutions on animal cells?
- Hypotonic: Swell and may burst
- Isotonic: No net movement, stable size
- Hypertonic: Shrink and may crenate
The osmotic balance is crucial for cell survival.
What are the effects of hypotonic, isotonic, and hypertonic solutions on plant cells?
- Hypotonic: Turgid (ideal state)
- Isotonic: Flaccid
- Hypertonic: Plasmolyzed
Plant cells rely on turgor pressure for structural integrity.
How does active transport move substances across a membrane?
It requires energy, usually in the form of ATP, to move substances against their concentration gradient
This process is vital for maintaining cellular concentrations of ions and nutrients.
What is the difference in energy requirements between passive and active transport?
Passive transport does not require energy, while active transport does require energy
This distinction is fundamental to understanding cellular transport mechanisms.
What is the contrast between bulk transport of large and small substances into a cell?
- Bulk transport (vesicular transport) is used for large substances (e.g., endocytosis, exocytosis)
- Small substances typically use protein channels or carriers
Bulk transport involves vesicles and membrane folding, while small molecules pass through protein structures.
What role does the extracellular matrix play in an animal cell?
It provides structural support, segregates tissues, and regulates intercellular communication
The extracellular matrix is crucial for tissue organization and cellular signaling.
What are the differences in structure and function of adhesion, tight, and gap junctions in animals?
- Adhesion junctions: Anchor cells together
- Tight junctions: Prevent leakage of materials between cells
- Gap junctions: Allow communication between adjacent cells
These junctions are essential for maintaining tissue integrity and communication.
What is the role of plasmodesmata in plants?
They are channels that connect plant cells, allowing for the transport of materials and communication between cells
Plasmodesmata are vital for maintaining the symplastic pathway in plants.
Carrier Protein
Selectively interacts with a specific molecule or ion so that it can cross the plasma membrane.
change shape to move substances (ex: glucose transporters)
Cell recognition protein
Labels a cell as belonging to a specific organism and/ or tissue. help immune system distinguish self vs. non-self
Receptor protein
Is shaped in such a way a way that a specific molecule can bind it. signals like hormones
Enzymatic Proteins
Catalyzes a specific reaction.
Junction proteins
hold cells together (ex: tight junctions in skin)
Diffusion
Toward lower concentration by using the concentration gradient; lipid soluble molecules, gases
Facilitated transport
Toward lower concentration by using channels or carrier and concentration gradient; some sugars and amino acids
Active transport
Toward higher concentration by using carrier plus energy; sugars, amino acids, ions
