Cell membrane and transport

Homeostasis of a cell is maintained by

the plasma membrane (cell membrane), controls what goes in and out

The cell membrane acts as

a barrier between the cell and the outside environment

The cell membrane controls the

movement of material in and out of the cell

Describe the Bilayer of phospholipid are arranged

lipid tails are between phosphate heads creating a barrier

Transport proteins

aid in moving larger molecules in and out of the cell examples: ions, sugar , water

Cholesterol

add strength to the cell membrane, lipid molecules located in the bilayer that makes cell membranes more rigid

Selectively permeable

the property of the cell membrane that allows it to regulate what goes in and what goes out of the cell, usually based on size and charge of the substance

Diffusion (no energy required)

when substances move from an area of higher concentration to an area of lower concentration

Facilitated diffusion (no energy required)

when larger substances are moved across the cell membrane from high to low concentrations with the help of carrier proteins (glucose sugars)

Osmosis (no energy required)

movement of water molecules through a selectively-permeable membrane from an area of greater water concentration to an area of lower water concentration

Active transport (energy required)

movement of solid or liquid particles into and out of the cell with an input of energy; moving particles from low to high concentration across a cell membrane (going against the concentration gradient), uses the help of a transport protein such as a protein pump.

The surface to volume ratio of a cell limits

• As cells increase in size, the surface area to volume ratios decrease, making cells less efficient in obtaining nutrients or remove wastes.

• Small cells have a very large surface area to volume ratio

• Cells divide to stay small and efficient

Hypertonic solution

a solution with more solutes than inside the cell, causing water to leave the cell

Hypotonic solution

a solution with fewer solutes than inside the cell, causing water to enter the cell

Isotonic solution

concentration of solutes is equal inside and outside cell; water moves in and out at Equilibrium

Equilibrium

A state of balance, molecules still move around but no net flow

Endocytosis (active transport)

process where a cell takes in material by engulfing it with the membrane

Pinocytosis (active transport)

type of endocytosis where the cell takes in liquid

Phagocytosis

type of endocytosis where the cell takes in large particles or cells

(active transport)

when solids are moved into a cell creating a vacuole, cell eating (food/large particles)

Exocytosis (active transport)

the bulk removal of waste from a cell. removing large particles, large proteins, cell products, hormones, starch from the cell

the plasma membrane diagram

peripheral proteins

membrane proteins that are only inserted into one side of the lipid bilayer , its funtion is chemical signaling adhesion

hydrophobic tails

component of a phospholipid molecule that is non-polar

plasma membrane

cell structure that regulates the movement of materials into and out of the cell

phospholipid bilayer

a two-layer structure of molecules that makes up the cell membrane

integral proteins

membrane proteins that extend through the lipid bilayer. transport mechanism

phospholipid fatty acid tail

hydrophilic head and a hydrophobic tail, the tail is hydrophobically composed of a fatty acid chain

membrane protein functions

transporters, anchors, receptors, enzymes

transporters

channels, carriers/pumps

receptors

e.g. hormones: helps with cell signaling/communication

The cell membrane is

very flexible

Cholesterol stabilizes the membrane by

preventing the fatty acid tails from sticking together, otherwise the membrane is too liquid

Cholesterol is located

wedged between fatty acid tails

carbohydrate chain function

communicate with other cells; cell to cell communication via signaling -identification tags (cell recognition tags that identifies cells to the body's immune system)

fluid

the phospholipid bilayer is the fluid portion of the membrane

3 types of passive transport

simple diffusion, facilitated diffusion, osmosis

diffusion

the net transport of molecules from a region of higher concentration to a region of lower concentration, no energy needed, the movement of a substance down it's gradient.

examples of simple diffusion

-diffusion of co2 and o2 into and out of lung alveoli

-diffusion of co2 and 02 into and out of eye cornea cells.

facilitated diffusion

transport proteins in the cell membrane allow larger molecules or charged particles to pass. H->L

facilitated diffusion is different than simple diffusion because

-molecules move through a channel protein in the membrane

-used for small charged molecules (ion) or larger molecules (glucose)

some molecules can't diffuse through the phospholipids and require

special protein channel to move through

channels (usually) or carrier proteins "help"

molecules across the membrane

osmosis

the movement of water by diffusion across a selectively permeable membrane to equalize solute concentrations

osmosis moves from

high to low concentration

Water is an excellent

solvent

solute

Particles dissolved in a liquid (solvent)

osmosis moves from an area of high concentration of water to an area of low concentration of water

this means that water moves from an area of low concentration of solutes to an area of high concentration of solutes.

osmosis depends on

the amount of solutes in solutions in relation to each other

hypotonic

a solution that has lower solute solute concentration and higher water concentration: water moves INTO the cell

isotonic

when two solutions have the same solute concentration, no net water movement

hypertonic

solution with higher solute concentration and a lower water concentration: water moves OUT of the cell

concentration gradient

variation between solute quantities of two different solutions

impermeable

a membrane that does not allow any substances to pass through

permeable

a membrane that allows substances to pass through by diffusion and osmosis

simple diffusion is when

small or uncharged particles cross the membrane through bilayer H to L

active transport requires

carrier proteins and ATP

2 types of active transport

protein pumps and bulk transport

bulk transport

endocytosis and exocytosis. larger molecules (proteins, starch) are transported in bulk by vesicles

protein pumps

transport small molecules and ions against their concentration gradients using ATP, from l to h against the gradient

endocytosis

vesicles move substances in. process by a cell which takes in large materials by infolding the cell membrane.

exocytosis

vesicles move substances out. is the process y a cell releasing large materials from inside the cell to outside the cell.

carrier proteins or pumps

found in the membrane move solutes from low to high concentration (with an input of energy) against it's gradient

sodium potassium pump

sodium na is transported out of the cell against its concentration gradient. potassium k is transported into the cell against it's concentration gradient

bulk transport vesicles

require energy input. bulk movement of large or charged particles into or out of cell requires a vesicle for transport.

vesicle

small membrane sacs that specialize in the transportation of particles

sodium-potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

protein channels

proteins in the membrane whose role it is to pass molecules that cannot go through the membrane

functions of cell membrane

-to maintain homeostasis of a cell

-acts as a barrier between cell and external environment

-controls the movement of materials in and out of the cell

-allowing for communication between cells

-involved in recognition of cells to help with metabolic functions

active vs passive transport

passive: does not require energy, small molecules, oxygen, carbon dioxide, H to L, down gradient, requires

active: requires energy (atp), requires carrier proteins, against the gradient, L to H,

both: maintain homeostasis, method of cell transport, sugar, large charge particles

prefix that means outside

exo

prefix that means inside

endo

word that means "cell"

cyto

tonic means

water

Glycolipid

carbohydrate group is attach to the phospholipid, helps in cell recognition.

Glycoprotein

carbohydrate groups attached to proteins. cell markers and other function

phophosplipid head

phosphate head, composed of phosphate groups, charged or polar and hydrophillic

dynamic equilibrium

Result of diffusion where there is the continuous movement of particles but no overall change in concentration

Is the environment of this cell hypotonic , hypertonic, isotonic

Hypotonic and results in plants cells being turgid, more water and less solutes compared to the inside of the cells

Is the environment of this cell hypotonic , hypertonic, isotonic

isotonic, water is entering and leaving in the same rate. equal water inside and outside of the cell .

Is the environment of this cell hypotonic , hypertonic, isotonic

hypertonic environment, less water and more solutes compare to the inside of the cell

What organelle helps fresh water organism such as the paramecium to maintain water balance.

contractile vacuole

Identify the type of transport shown in the image

exocytosis

Identify the type of transport, the blue represents water

osmosis

Identify the type of cell transport

facilitated diffusion

Why is the cell membrane fluid

the tails of phospholipids can be bent, which makes them unsaturated, bent tails take up more space and are less dense and less rigid, which is ideal for colder conditions, they have a lower packing density that makes them more fluid, proteins interrupt packing and decrease the packing density in the phospholipids

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

What conditions is a plant cell turgid?

in an hypotonic environment (more water)

Turgor pressure in plant cells is

-A way to help the cell maintain its structure by pushing outward on the cell wall

-The force of water against the inside of the cell wall

-Necessary to keep plants from wilting

-A result of the walled cell being in a hypotonic environment