Biology Notes Cells Part 2 Pages 81-91

Standard Essential Question: 2.6 ____ Explain the role of cell membranes as a highly selective barrier (passive and active transport) Essential Question: 1. How do materials enter and leave cells?

I. Cell Communication & Cell Membranes Cells must communicate with each other in order to keep an organism in ____________ Homeostasis = regulation of an organism’s ________ environment in order to maintain balance e.g. homeostasis internal pH, body temperature, heart rate, etc.

Cells send messages to other cells about what they _____ and what they need to get rid of in order to keep this homeostasis messages can be sent between cells that are _________ or _________ need chemical electrical

Cell Membrane = the organelle that surrounds cells to provide ________ and protection as well as to regulate what _______ and______ the cell support enters exits a.k.a. – plasma membrane

The cell membrane plays a vital role in cell communication by regulating what messages can ______ and ____ the cell The cell membrane also plays a vital role in homeostasis by regulating what molecules can ______ and ____ the cell e.g. selective permeability = the ability of the cell ___________ to allow some materials to ______ into a cell while keeping others out enter exit enter exit in = H2O, food out = waste, CO2 membrane enter

II. Cell Membrane Structure Protein-lipid bilayer = a strong double layer of _____ containing embedded ________ make up the majority of the cell membrane structure Also called the _____ mosaic model lipids proteins fluid Why would the cell membrane be made out of lipids??? - It needs to be waterproof

The lipids are called ______________ because each one has a __________ molecule attached The lipid heads are not ________ whereas the tails are ________ phospholipids phosphate soluble soluble lipid heads = hydrophilic & polar lipid tails = hydrophobic & non-polar

The embedded ________ carry out most of the functions of the plasma membrane - some proteins serve as _________ and destroy any material that could ______ the cells - cholesterol serves to ____________ the cell membrane other proteins have ______________ attached that serve as a “beacon” for materials needed ______ the cell proteins enzymes harm strengthen carbohydrates inside

DIAGRAM:

III. Cell Membrane Action In order to maintain ____________, the concentration of most substances in and out of the cell must be _________ Concentration = in a ________, the amount of ______ in a given volume of _______ (mass / _______) e.g. What is the concentration of salt if there are 12 grams of salt in 3 liters of water? homeostasis balanced solution solute solvent volume 4g/L

Concentration gradient = the difference in _____________ across a space If the concentration of substances are not ______ in and out of cells, then the cell membrane may take _______ to balance the concentrations there may be exceptions to this rule e.g. concentration equal actions food always in / CO2 always out

A. Diffusion = the net movement of particles from an area of _____ concentration to an area of ____ concentration until dynamic equilibrium is reached Substances are said to be moving ______ their concentration _________ Dynamic equilibrium = when the concentration of particles are ______ both inside and outside of the ____ Diffusion requires no _______ high low down gradients equal cell energy

DIAGRAM:

Diffusion will only occur with small molecules like _____, ____, _____ and ___. Other larger molecules, like ________________, cannot use _________ to enter or exit a cell. CO2 H2O NH3 O2 glucose (C6H12O6) diffusion

B. Osmosis = the diffusion of ______ from an area of _____ concentration to an area of low _____________ through a selectively permeable ___________ requires no _______ because it is _________ occurs in solutions when the solute is too ______ to pass through the membrane so the water will move until the concentrations on either side of the membrane are ______ water high concentration membrane energy diffusion large equal

Why is this picture wrong?

Isotonic solution = a solution in which the concentration of ________ is the same on both sides of the _____ there is no net movement of ______ DIAGRAM: solution cell water

Hypotonic solution = a solution in which the concentration of ________ is lower ________ the cell than ______ the cell water will move ____ the cell and the cell will appear ________ osmotic pressure = pressure created inside the cell when water moves ___ solution outside inside into swollen in

DIAGRAM:

Hypertonic solution = a solution in which the concentration of ________ is higher ________ the cell than ______ the cell water will ______ the cell a and the cell will appear _______ plasmolysis = the drop of ________ pressure inside a cell when water _______ the cell solution outside inside leave wilted osmotic leaves

DIAGRAM:

C. Facilitated Diffusion = movement of materials across a ____ membrane by means of _________ proteins allows ______ molecules like ________ to cross does not require _______ molecules still move ______ their concentration gradient cell transport a.k.a. passive transport larger C6H12O6 energy down

DIAGRAM:

D. Active Transport = the movement of materials across a ____ membrane when it is ________ their concentration gradient requires _______ to move materials from ____ to high concentration DIAGRAM: cell against energy low

E. Endocytosis = a process of taking material ____ the cell by means of _______ the entire cell membrane 1. phagocytosis = a type of endocytosis in which extension of the __________ surrounds a particle and packages it within a food ________ e.g. into moving membrane vacuole How amoebas intake food.

2. pinocytosis = a process by which cells take in _______ from the surrounding environment by forming ________ along the cell ___________ F. Exocytosis = a process by which material is _________ from a cell by ______ with the cell membrane e.g. liquids pockets membrane excreted fusion lysosomes

IV. Everyday Cell Membrane Food Preservation Adding ____ to make food last longer creates a ___________ solution so that water moves out of the _____ prevents food from ________ by killing any ________ Works through _________ salt hypertonic cell spoiling bacteria osmosis

B. Kidneys

The nephron filters the ______ as it moves through the kidneys substances like ___, ____ and waste or excess ____ are removed and sent for _________ e.g. Substances are removed by _________, __________________ and active _________ blood N2 NH3 H2O excretion urine in bladder osmosis facilitated diffusion transport

C. Lungs

The alveoli exchanges _____ for ___ through simple _________ CO2 O2 diffusion