Cell Membrane

What is the main role of the cell membrane

regulating the passage of molecules into and out of the cell, and separating the cell inside from outside

The cell membrane is a ____

phospholipid bilayer

the bilayer has a ___, and scattered throughout are ___

fluid consistency; proteins

The cell membrane description is called the ___

fluid mosaic model

Label

Phospholipid structure

a polar hydrophilic head and a non-polar hydrophobic tail

glycolipids structure and location

A varying carbohydrate chain attached to a phospholipid on the positive side of the cell membrane.

cholesterol function and found only in what type of cell

Lends stability and prevent drastic decrease in fluidity at low temperatures.
ANIMAL CELL MEMBRANE ONLY

Integral and peripheral proteins differ in ___

attraction to the hydrophobic interior of the bilayer, hence how deep they are embedded in the membrane

integral protein definition

embedded partly of completely in the bilayer

integral proteins that pass completely through the bilayer have ___ and a ___

two hydrophilic ends facing the water; hydrophobic middle region

integral proteins that extend only partly through the membrane have a ___ and a

hydrophobic end suspended in the membrane interior; hydrophilic end facing the water

integral proteins are able to ___ and largely determine ___

move freely in the phospholipid bilayer; a cell membrane specific function

Name five kinds of integral proteins

1. Channel

2. Carrier

3. Cell Recognition

4. Receptor

5. Enzymatic

Peripheral proteins definition

attached to the surface of cell membrane

peripheral proteins are located either …

on the cytoplasmic side (inside) or outer surface side

peripheral proteins are ___

hydrophilic and polar

outer peripheral proteins serve as ___ and inner peripheral proteins serve as ___

links to extracellular matrix; cytoskeleton filaments

Molecules that pass freely through the membrane are ___. Give examples

small noncharged lipid soluble molecules; vitamin A, D, K, carbon dioxide and oxygen gas, water

Macromolecules ___ cross the cell membrane, and are taken in or out by ___. Give examples

cannot; vesicle formation; carbohydrates, proteins, lipids, nucleic acids

More molecules that cannot charge the cell membrane (give examples), and why?

ions and charged molecules; sugars and amino acids; unable to enter the hydrophobic region of the membrane

So sugars and amino acids are assisted by ___

carrier and channel proteins

carrier proteins

combine with an ion or charged molecules before transporting across

channel proteins

form a channel that allows ions or charged molecules to pass through

The cell membrane is ___ charged outside and ___ charged inside.

positively; negatively

Negatives/positive ions move across carrier proteins or through channel proteins from ___

inside/outside the cell to outside/inside the cell

The cell membrane is ___ because ___

selectively permeable; the passage of molecules are restricted

selectively permeable

can discriminate between molecules of the same size

Two basic mechanisms materials cross cell membrane

1. Passive ways

2. Active ways

Passive ways __ require ATP energy

does not

Passive ways depend on ___

differences in concentration inside and outside the cell and the kinetic energy of the molecules

Concentration gradient definition

the difference in concentration inside and outside the cell

The movement of the molecules in passive ways are ___

down the concentration gradient; high to low

Name the passive ways

1. Simple diffusion

2. Facilitated diffusion

3. Osmosis

Simple diffusion definition

movement of molecules down the concentration gradient until equilibrium is reached

diffusion applies to ___

any type of molecules

Chemical and physical properties of the selectively permeable cell membrane ___

only allow just a few types of molecules to enter and exit (molecules that pass freely)

Factors that increase the rate diffusion

1. increase in temperature → more kinetic energy and collisions

2. increase in concentration gradient

Facilitated diffusion definition

diffusion of materials across a cell membrane assisted by a specific proteins

Facilitated diffusion is driven by ___

a concentration gradient, therefore does not require ATP energy

Facilitated diffusion occurs ___

at a faster rate than simple diffusion

Osmosis definition

Passive transport of FREE water molecules across a selectively permeable membrane from high water conc. to low water conc..

The conc. of water is determined by …

the conc. of solutes

Solute definition

a substance dissolved in a solvent

Solvent defintion

a fluid that dissolve the solute

Tonicity defintion

The solute strength / conc. in the solution (OUTSIDE)

Isotonic solution definition

Solute conc. in the solution is the same as inside (the cell)

hypotonic solution definition

Solute concentration in the solution is less than inside (the cell)

hypertonic solution

Solute concentration is greater than inside (the cell)

Water movement of typical ANIMAL cell in an ISOTONIC solution

No net movement of water

Overall effect of typical ANIMAL cell in an ISOTONIC solution

No change

Overall effect of typical ANIMAL cell in an HYPERTONIC solution, and the PROCESS is called …

Cell loses water, shrinks, shrivels, and dies; CRENATION

The animal cell after being placed inside a HYPERTONIC solution is call a …

crenated cell

Overall effect of typical ANIMAL cell in an HYPERTONIC solution, and the PROCESS is called …

Cell gains water, swells and bursts due to water pressure; LYSIS

The animal cell after being placed inside a HYPOTONIC solution is call a …

lysed cell

Water movement of typical PLANT cell in an ISOTONIC solution

no net movement of water

Overall effect of typical PLANT cell in an ISOTONIC solution

no change

Overall effect of typical PLANT cell in an HYPERTONIC solution, and the process is called

cell loses H2O, same size, but vacuole, cytoplasm, and cell membrane shrink; PLASMOLYSIS

A plant cell after being in a HYPERTONIC solution are called …

plasmolysed cell

A plant with plasmolysed cell is

wilted

Overall effect of typical PLANT cell in an HYPOTONIC solution

cell gains H2O → swell but does not burst because of strong cell wall (turgor pressure)

A plant cell after being in a HYPOTONIC solution is called …

a turgid cell

A plant with plasmolysed cell is

healthy and upright

Active ways of transport …

requires ATP energy

3 examples of active ways of transport

1. Active transport

2. Endocytosis

3. Exocytosis

Active transport definition

the transfer of a substance into or out of the cell from a region of lower concentration to a region of higher concentration by a process that requires protein and ATP energy.

Each molecule type is transported by ….

a specific carrier protein

ATP can become … when …, and …

adenosine diphosphate (ADP); the last phosphate is split of; releases free-energy

Cells involved primarily in active transport have …

a large number of mitochondria near the membrane for active transport

Active transport three major functions

1. Possible to uptake fuel and essential nutrients from the environment, even when concentration is low

2. Allows various substances (secretory products, waste material, and sodium ions) to be removed from the cell or organelle, even when concentration outside is greater.

3. Enables cell to maintain constant optimal internal concentrations of inorganic electrolytes

An example of active transport

Absorption of sugar in the intestine

Endocytosis definition

process in which a vesicle is formed at the cell membrane to bring a macromolecule into the cell

Vesicle is called a …

intracellular vesicle

The vesicle fuse with … to …, and …

lysosomes; break down molecules; incorporated into cytoplasm for use.

Endocytosis includes

1. Phagocytosis

2. Pinocytosis

Phagocytosis definition

Large sized material, such as food particle or another cell, is taken into the cell via vesicle formation.

Pinocytosis

Liquid of small molecules that are in solution are taken into the cell via vesicle formation.

Exocytosis definition

Process in which a secretory vesicle fuses with the inner cell membrane, and vesicle contents are released to the outside of the cell.

Exocytosis is required for …

secretion

Surface area is … ,and significance

the outer surface of a cell; site of exchange between cell and its environment

Volume is …, and determines …

the amount of materials inside a cell; the amount of nutrients needed and waste secreted

Volume and surface increase …, and volume … surface area

unproportionally; increases at a faster rate than

Cells cannot grow … because …

too large; not enough SA to supply cell w/ nutrients and secrete waste.

So they cells want a … SA:V ratio

high

the significance of the SA:V ratio

determines the rate of molecules are exchanged across the membrane.

A high/low SA:V ratio means the metabolism is …

high/low

A high/low SA:V ratio means the rate of exchange of materials and energy in and out of the cell is …

high/low