b2 Flashcards
What is the basic structure of all cell membranes?
A phospholipid bilayer with hydrophilic heads facing outwards and hydrophobic tails facing inwards, along with embedded or associated proteins.
What factors influence membrane permeability?
- Size and charge of particles
- Lipid solubility
- Presence of transport proteins
- Concentration gradients
- Temperature
Define diffusion.
The passive movement of particles from an area of higher concentration to an area of lower concentration, resulting in uniform distribution until equilibrium is reached.
How do particles diffuse across the phospholipid bilayer?
- Simple diffusion
- Facilitated diffusion
- Osmosis
What is an integral protein?
A type of protein permanently embedded within the phospholipid bilayer, functioning as channels, pumps, receptors, or enzymes.
What is a peripheral protein?
A type of protein loosely attached to the surface of the cell membrane, involved in cellular signaling and other regulatory functions.
Define osmosis.
The movement of water molecules from an area of high concentration to an area of low concentration through a selectively permeable membrane.
What is an aquaporin?
An integral membrane protein that functions as a water channel, facilitating rapid water transport across the membrane.
Describe how an aquaporin works.
- Water enters from the high-concentration side
- Moves single-file through a narrow channel
- Exits on the low-concentration side
- Channel has a positive charge to repel ions
Define facilitated diffusion.
The passive movement of particles across a cell membrane with the assistance of transport proteins.
What is a channel protein?
A type of transport protein that forms a pore in the cell membrane, allowing specific particles to pass through by facilitated diffusion.
Define active transport.
The movement of particles from an area of lower concentration to an area of higher concentration against the concentration gradient, using energy.
Describe how a pump protein works.
- Binds to a specific particle on one side
- Uses ATP to change shape
- Releases the particle on the other side
Describe what is meant by a selectively permeable membrane.
A membrane that allows certain particles to pass while restricting others, crucial for maintaining cellular homeostasis.
What is a glycoprotein?
A type of protein that has one or more carbohydrate molecules attached, playing roles in function, stability, and cell-cell recognition.
What is a glycolipid?
A type of lipid molecule with a carbohydrate attached, involved in cell-cell recognition, signaling, and maintaining membrane structure.
What are functions of glycoproteins?
- Cell-cell recognition
- Cell signaling
- Immune response
- Protein stability and folding
- Cell adhesion
- Hormone activity
- Enzyme activity
What are functions of glycolipids?
- Cell-cell recognition
- Cell signaling
- Cell adhesion
- Membrane structure
- Immune response
- Tumor cell markers
- Neural development
Describe the fluid mosaic model of a cell membrane.
A dynamic, fluid structure composed of a phospholipid bilayer with embedded proteins, allowing free movement of phospholipids.
How does using saturated vs unsaturated fatty acids in a phospholipid affect membrane fluidity?
- Saturated fatty acids: less fluid, pack tightly
- Unsaturated fatty acids: more fluid, do not pack tightly
What is the function of the outer membrane of the mitochondrion?
Regulates the movement of materials in and out of the mitochondrion.
What happens in the intermembrane space of the mitochondrion?
Contains enzymes involved in various mitochondrial processes.
What happens in the inner membrane of the mitochondrion?
Site of the electron transport chain and ATP synthesis, folded into cristae.
What occurs in the stroma of the chloroplast?
Site of the Calvin cycle, containing enzymes and pigments necessary for photosynthesis.
