3.2.3 Transport Across Cells Flashcards
Do plants have cell membrains
Yes
Do bacteria have cell membrains
Yes
Name four substances needed for a cell and what there function is
Water - metabolic reactions
Amino acids - protein synthesis
Glucose - respiration
O2 - aerobic respiration
Lipids - cholesterol
Why does soup dissolve the membranes easily
Dissolves the nuclear membrane and plama membrane , as it is made up of pipes and fats
What are the two main components of a cell membrane
Phospholipids and proteins
What sort of partials do phospholipids allow to pass between themselves
Small
No charge
Lipid soluable
What is the role of cholesterol
To reduce the fluidity of the cell membrane
Can be effected by heat
What is a tonoplast
The membrane that surrounds the vacuole
What are the 6 main functions of the cell membrane
- Defines the boundary of the cell
- Controls which substances pass through
- Provides a receptor site for hormones
- Plays a role in cell recognition (immune system)
- Allows it to change shape
- Helps cells to stick together
What are the three main functions of the internal membrane
- Compartmentalisation (isolating organelles )
- A site of biological reactions
- Controls which substances go in and out of
What is another name for the cell membrane
Plasma membrane
Which part of the phospholipid bi layer is
Hydrophobic
And
Hydrophilic
Fatty acids are - hydrophobic
Phosphate group is hydrophilic
What are the three functions of phospholipids
- Allow lipid soluble substances to pass through
- Prevent water soluable substances to go through
- Make the membrane flexible and self sealing
There are two types of proteins embedded on a cell membrane what are those two protein types and give a small description
Intrinsic - they pass through the phospholipid bilayer either fully or partially
Extrinsic - only sit / lay on the phospholipid bilayer
What are the function of extrinsic proteins ?
Act as a receptors for molecules ( mostly hormones)
Provide a mechanical support adhesion
What is the function of intrinsic proteins
Protein channels- allows water soluble molecules to pass through
Carrier/ channel proteins that aid in transport
What type of molecules use intrinsic proteins
Water
Na+
Cl-
Cholesterol is a _______ and is found in the phospholipid bilayer . They add ______ to the membrane . Cholesterol are very _______ and therefore play an important role in _______. ______
Lipid
Strength
Hydrophobic
Limiting movement
What are three functions of cholesterol
- Reduce lateral movement of the membrane
- Make the membrane less fluid at higher temperatures
- Prevents leakage of water and ions
What is the function of glycolipids
Recognition site
Helps maintain membrane stabablilty
Helps cells attach to each other
What is the function of glycoproteins
Recognition site
Helps attach to cells to form tissue
Used in cell recognition
What does the model name fluid mosaic mean
Fluid - because the individual phospholipids can move laterally and change places with each other
Mosaic - when seen under above looks line a mosaic of phospholipids
Name some organelles that have an internal membrane
Mitochondria , chloroplast , vacuole , nucleus
What are the five ways that’s substances can move across a membrane and say if there passive or active
Passive - does not require atp
Simple diffusion
Facilitated
Osmosis
Active - require atp
Active transport
Co-transport
What is the definition of diffusion
The movement of particles from a region of high concentration to a region of low concentration
What are the six factors that effect diffusion
Temperature - more kenetic energy
Concentration gradient - increases rate of diffusion
Stirring - increases kenetic energy
Surface area - more chance of molecules moving through
Diffusion distance
Size of molecule - smaller molecules diffuse more quickly
Why can O2 and CO2 pass through cell membrane
As they are lipid soluable
What is the definition of osmosis
Osmosis is the passage of water molecules from a solution of high water potential to a lower water potential through a selective permeably membrane
What are the similarities and differences of osmosis and diffusion
Sim
Go through selective permeable membrane
Passive no energy
Differences
High to low water potential
Only involves water
What does hypertonic mean in osmosis
Lots of solute , therefore low water potential
What does hypotonic mean in osmosis
Little solute therefore high water potential
What does isotonic
At an equalibriam
Is something has a high water potential it’s water molecules are
Free
What does free water molecules mean
The amount of non bound water molecules that have the potential to move across a semi permeable membrane .
Pure water has a Kpa of
-0
What is a protoplast
Refers to the entire cell , excluding the cell wall , is not in a animal cell as it does not have a cell wall
In animal cell
Water potential out side: hypotonic
Net movement of water is ?
State of cell
Net move : into the cell
State of cell: burst
In animal cell
Water potential out side: isotonic
Net movement of water is ?
State of cell
Net move: none / equilibrium
State of cell : normal
In animal cell
Water potential out side: hypertonic
Net movement of water is ?
State of cell
Net move : out of cell
State of cell : shrunk / shrivelled
In plant cell/ bacteria
Water potential out side: hypotonic
Net movement of water is ?
State of cell
Protoplast
Net movement: into the cell (turgid )
State of cell: turgid
Protoplast : touching cell wall
In plant cell/ bacteria
Water potential out side: isotonic
Net movement of water is ?
State of cell
Protoplast
Net movement : equilibrium
State of cell : flaccid
Protoplast : barely touching the cell wall
In plant cell/ bacteria
Water potential out side: hypertonic
Net movement of water is ?
State of cell
Protoplast
Net move : out of cell
State : plasmolysed
Protoplast not touching cell wall vacoul shrunk
What does incipient plasmolysis mean
Around 50% of the plan cells are plasmolyed
Describe the net movement of water in
Flaccid
Turgid
Plasmollyed
Plant cells
Flaccid - no net movement
Turgid - water is moving into cell
Plasmolyed - water is moving out of cell
Describe a channel protein
They transport SMALL polar and charged molecules
They are gated so that can be shut off
Describe a carrier protein
Allows larger polar molecules such as sugars and amino acids to pass through
Has a specific binding site and changes shape when it binds
What type of diffusion is channel and carrier proteins
And do they require atp ?
Facilitated
No they do not require atp
Describe a protein pump
They are specific pumps that work against the concentration gradient and require atp
Draw out co-transport
Check with internet
