Lectures 9 & 10 Flashcards
exocytosis
material is exported out of the cell
endocytosis
material is taken into the cell
endocytic vesicle and types
plasma membrane surrounds material from outside the cell, trapping it in an endocytic vesicle
1. specific using receptors
2. non-specific for water and nutrients
lysosome and types
- membrane-bound vesicles with a low internal pH (4.5-5.0 b/c proton pumps) that contain digestive enzymes
- fuses w/ endocytic vesicle
- Function: to digest material from outside or inside the cell (worn-out organelles that need to be destroyed and recycled)
- primary: not fused yet
- secondary: after fusion, material that is going to be digested meets enzyme that is going to break bacteria down
tuberculosis bacterium
Can prevent fusion of endocytic vesicle and primary lysosome so TB avoids destruction and lives in cell
Extracellular Matrix (ECM) *not organelle
- Network of multiple types of proteins outside of cells
Functions - Structural support outside cells
- Glues cells into higher-order structures, like organs
- Has a role in cell-cell communication (signaling molecules along ECM)
mitochondria (structure, endosymbiotic theory, function)
- Structure: double lipid bilayer membrane
- Outer membrane: covered entire organelle
- Inner membrane: extensively infolded
- Folds are called cristae
- Liquid center called the matrix
- Mitochondria only arise from pre-existing mitochondria (reproduce themselves)
- Endosymbiotic theory: one time mitochondria were free-living prokaryotes and developed an endosymbiotic relationship with current-day eukaryotic cells
- Function: energy metabolism (ATP production)
chloroplasts (structure, function, endosymbiotic theory)
- Structure: double lipid bilayer (DLB) membrane
- Outer and inner LB membranes cover the entire organelle
- Within DLB is an internal membrane into multiple stacks of disks
- Thylakoid: single membrane disk
- Granum: a stack of thylakoids
- Stroma: liquid substance surrounding grana
- Function
- Site of photosynthesis in plant cells
- Light energy converted into usable chemical energy
- Endosymbiotic theory also applies
cytoskeleton *not an organelle
Structure
- Network of multiple types of proteins inside cells
Functions
- Provides structural support within cells (can make cells change shape for when cells need to get into tight spaces)
- Has a role in transport within cells (motor proteins attached to vesicles and CS motor proteins walk vesicles along and take them where they need to go)
- Help mobile cells move
Plasma Membrane (PM)
- Defines the inside and outside of a cell; it’s a barrier
- Are ‘selective barriers’
- Regulates transport into/out of the cells
PM is dynamic (always changing) and cells can adjust the… - chemistry of the pH
- molecules associated with the PM
Why Evert Gorter used red blood cells
- Easy to obtain and count
- Uniform in size across all animals and people
- Was perfect b/c eukaryotes have a nuclear membrane w/ phospholipids which would have messed up the results; mature red blood cells eject all other membranes except for the plasma membrane so it worked perfectly
Fluid mosaic model
plasma membranes are fluid structures
The phospholipid bilayer is like a lake
Molecules are ‘floating’ around in it
How do we know the membranes are fluid structures/evidence?
The membrane proteins of cells were stained with fluorescent dyes (human cell membrane proteins w/ red dye and mouse cell membrane proteins w/ green dye)
The cells were fused together
Conclusion: proteins diffuse around the membrane which means they’re fluid
