plasma membrane & organelles Flashcards
what must a cell do?
Manufacture cellular materials
Obtain raw materials
Remove waste
Generate the required energy
Control all of the above
what is a plasma membrane?
the boundary of the cell that separates it from the environment because there are specific conditions inside the cell compared to outside and it acts like a semi-permeable barrier
what are cells bound by?
plasma membrane
what are some characteristics of plasma membrane?
- a semi-permeable barrier
- allows passage of oxygen, nutrients,
waste - controls movement of substances in
and out of the cell
this interaction with the environment
limits the maximum size of a cell (they are 3d structures) - a small cell has a greater surface to
volume ratio than a larger cell
what is a phospholipid bilayer?
double layer of phospholipids with various embedded or attached proteins
what are the critical parts of the phospholipid bilayer?
- hydrophilic head (likes water)
- hydrophobic tails (doesn’t like water)
- heads are faced outwards and the tails face towards each other
what is a phospholipid bilayer?
two layers of phospholipids that can bead proteins which will give us different functions
what is separated by the phospholipid bilayer?
the inside and outside of the cell
what are some things that control how fluid the plasma membrane is?
Saturation:
- Saturated – packed tightly together, less fluidity
- Unsaturated – tails prevent tight packing, more fluidity
Temperature:
- High temps more fluidity
- Low temps less fluidity
Cholesterol:
- Stabilises membrane fluidity
what does saturated mean in terms of the plasma membrane?
- packed tightly together so it’s a viscous fluid
- less fluidity
what does unsaturated mean in terms of the plasma membrane?
- tails prevent tightly packing
- more fluidity
what stabilizes the fluidity of the membrane?
cholesterol
what do proteins do?
- Proteins determine the function of the membrane
what are specific to a cell type and each cell can have multiple different types and functions?
proteins
what is involved in signal transduction?
membrane protein
what is signal transduction?
- relay messages from the body (or environment) into the cell
- turning one signal into another type
- for example tell it to grow, divide, move, make something, die, etc.
what is involved in cell recognition?
membrane protein
what is cell recognition?
- often involves glycoproteins (proteins with added sugars)
- protein has a receptor for the detected sugar because it knows and recognizes what the cell is might be to send it info or to attack it
what is intercellular joining?
- proteins link to each other
-some proteins form long-lasting connections between cells
what is involved in intercellular joining?
membrane protein
what is Linking Cytoskeleton & Extracellular Matrix?
- cells have a structure inside called the cytoskeleton and inside the cell is an extracellular matrix (things cells produce that inside the cell)
- useful to not have it move around can link it to the extracellular matrix through the membrane protein
- allows a cell to physically connect with protein
structures outside the cell (the extracellular matrix) - holds cells in place
what is involved in the Linking Cytoskeleton & Extracellular Matrix?
membrane protein
what is involved in Membrane Transport?
Membrane Proteins
what is Membrane Transport?
- allows small amounts of molecules to move across the membrane
- allows us to move from one side to the other
- Can be passive (no energy) or active (needs energy)
How do substances move across membranes?
- Depends on what the molecules are
- How big the substances are
- How much is moving at once
- Bulk transport- large substances/large volumes
- For small molecules in small volumes membrane transport
how many different types of passive membrane transport?
- normal diffusion
- facilitated diffusion
what are the characteristics and mechanisms of passive diffusion?
- No energy needed (passive)
- Molecules move down a concentration gradient
- move down from where there are lots of them to an area where there are very few
how many different types of active membrane transport?
- Active transport
- Co-transport (indirect active transport)
what are the characteristics and mechanisms of transport?
- Energy needed (active)
- Molecules move against a concentration gradient
- moving from where there is few of them to where there is lots
what is diffusion?
- Membranes are permeable to lipid-soluble (hydrophobic) molecules such as steroid hormones and gasses
- They move down their concentration gradient and thus do not require energy (passive transport)
- In contrast, the membrane restricts
movement of water-soluble and charged molecules such as glucose, ions, and water
what is facilitated diffusion?
- Movement of hydrophilic molecules requires membrane proteins called channels and carriers
- Aid the movement of specific substances down their concentration gradient.
- No energy is required but some channels open or close in response to signals
- Carriers undergo a shape change to help guide the molecules
what are called channels and carriers?
The movement of hydrophilic molecules requires membrane proteins called channels and carriers
what are aquaporins?
The movement of water across a cell membrane requires channels called aquaporins
what is osmoregulating?
Cells osmoregulate to prevent swelling or shrinking under varying conditions
what happens when the cell gets bigger and bigger?
lose the ability to get things efficiently across the plasma membrane
what is embedded in facilitated diffusion (passive transport)?
membrane proteins
how do you use passive transport for osmosis?
- Movement of water across a cell membrane requires channels called aquaporins.
- A process called osmosis
- Movement from a high water (low solute) concentration to a low water (high solute) concentration.
- Cells osmoregulate to prevent swelling or shrinking under varying conditions
how do you use facilitated diffusion (passive transport) for osmosis?
- Movement of water across a cell membrane requires channels called aquaporins.
- A process called osmosis
- Movement from a high water (low solute) concentration to a low water (high solute) concentration.
- Cells osmoregulate to prevent swelling or shrinking under varying conditions
what is active transport? (requires energy)
- Requires transport proteins, which are carriers that use energy (ATP)
- Move specific substances against their concentration gradient.
- Active transport allows a cell to have an internal concentration of a substance that is different from its surroundings
- May for example be higher inside the cell than outside the cell
- An example of this is the sodium-potassium pump
what is co-transport? (requires energy)
- indirect active transport
- one substance pumped across the membrane
- and its concentration gradient used to power the movement of a second substance against its concentration gradient
what does the proton pump do?
- pushes out protons
- takes the proton from outside the cell using energy forces it outside the cell where there is high concentration
- pushing it outside means there is high concentration outside the cell and low concentration inside
How do different parts of the cell do different things?
Different processes - different
conditions - separate compartments
what are the different functions of organelles?
- Provide special conditions for specific processes
- Keep incompatible processes apart
- Allow specific substances to be concentrated
- Form concentration gradients
- Package substances for transport or export.
What’s bound by membranes?
organelles
what are all cellular membranes composed of?
phospholipid bilayer
-nucleus has 2
- photosynthesis has 3 (inner, outer, and thylakoid)
what are some organelles that have its own special conditions?
- endoplasmic reticulum
- lysosomes
- mitochondria (two membranes)
- nucleus (the nuclear envelope- two membranes)
what are some structures both plant and animal cell have in common?
- endoplasmic reticulum (ER)
- nucleus
- golgi apparatus
- mitochondrion
what are some organelles specific to plants and animals?
plants: chloroplast, central vacuole
animals: lysosome
