Chapter 3 Cells The Basis of Life

Environment of the cell

Extracellular environment

*Fluid filled area outside the cell

Intracellular environment

*Fluid filled area inside cell Drawings on p.49 fig. 3-1 a and b

A. Extracellular Environment Area outside the cell. Contains gases, salts,

food particles, and cellular products which are materials synthesized by cell and released by secretion.

*These cellular products are proteins,

hormones and vitamins.Matrix *Solid *Provides structural

support

Intercellular environment

*Compartment of Extracellular environment between adjacent cells

In the extracellular environment, you have extracellular fluid (ECF)

*This is a syrup like mixture of water products and other substances

2 Types of ECF

1. Plasma *Located within vessels *Provides liquid medium for transport of

substances in blood2. Interstitial fluid *Located between cells of body *Provides pathway for substances

going to and from the cells

B. Intracellular Environment

 This is where most internal cell functions occur.

Energy production.

 Energy storage. Synthesis of new

products.

Protoplasm *Substance of a cell.

Composed of water, proteins, carbohydrates, fats, nucleic acids and electrolytes.

*It is alive when all materials carry out activities.

Characteristics of living things.

*Organization, growth, metabolism, reproduction, excitability.

3 Parts of Protoplasm

1.Plasma Membrane (cell membrane)

*Separates inside of cell (intracellular environment) from its outside environment (extracellular environment). Contains intracellular fluid (ICF) which is a mixture of water, proteins and other chemicals.

3 Parts of Protoplasm 2.Cytoplasm

*Thickened gel like material which occupies most of the ICF. This is where the organelles are.

3 Parts of Protoplasm 3. Nucleus

*Regulates activities of cell. Lies within intracellular environment.

Packet questions pp.35-37 1-29

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Cell Structure and Function

Common features of cells are plasma membrane, cytoplasm and nucleus which all work together to provide cellular functions.

Size is small and measured in micrometers which is 1 millionth of a meter. 25,400 micrometers equals 1 inch.

Size varies according to function of cell.

Model of a cell. Drawing p.50 fig.3-3 Also do 2-3 observing a human cell.

Plasma Membrane

*Separates intracellular environment from extracellular environment.

*Regulates movement of materials between these areas.

*Envelopes cell completely.

*Maintains homeostasis because plasma.

*Membrane regulates materials.

A. Structure Lipid bilayer and protein molecules and

a little carbohydrates Is less than one millionth of an inch

thick Selectively permeable: only allows

certain substances to pass through.

Plasma Membrane

Structure Glycoproteins

*Union of proteins and carbohydrates. Receptors for substances that must distinguish between different types of cells like hormones, growth factors and antibodies.

Proteins *Peripheral proteins

attach to outside and inside of cell surface.

*Integral proteins are embedded in the lipid bilayer and extend out. These proteins form channels and give the cell its status of selectively permeable.

 Modifications of Plasma Membrane

1.Microvilli Tiny plasma membrane

extensions Increase surface area More materials cross

over In cells which absorb *cells lining small

intestines*excretory cells in kidneys

 Modifications

2.Cilia Longer Contain protein

microtubules for structure and support

Do not absorb but keep things moving

Cells lining respiratory tract, to keep mucous moving

*ciliary action

 Modifications

3.Flagella 1 and long Contains protein

microtubules Provide propulsion

*sperm cells

http://pictures.ask.com/redir?bpg=http%3a%2f%2fpictures.ask.com%2fpictures%3fq%3dflagella%26o%3d0%26page%3d6&q=flagella&u=http%3a%2f%2fwww.otus.oakland.edu%2fbiology%2flindemann%2findex.htm&s=p&bu=http%3a%2f%2fwww.otus.oakland.edu%2fbiology%2flindemann%2f

 

B. Functions Ways in which materials cross the

plasma membrane

*Based on the energy that is required

1. passive transport

2. active transport

1. Passive Transport Powered by kinetic

energy, force which causes molecules to move about randomly.

Requires no energy from the cell.

3 types

i. Diffusion

ii. Osmosis iii. Filtration

I.Diffusion *Kinetic energy only*Molecules move from a

region of higher concentration to a region of lower concentration.

*Movement continues until equilibrium is reached

*Diffusion moves with a concentration gradient

*A diffusion in concentration from one region to another

EX. Spray a freshener in air.

EX. In body, movement of oxygen molecules from air sacs in lungs to blood vessels that surround air sacs.

Diffusion Diffusion through

plasma membrane.

*lipid-soluble solutes diffuse right in.

*lipid-insoluble solutes like glucose use

facilitated diffusion with the integral protein to

get in

Passive Transport

 

II. Osmosis The movement of water

molecules across a selectively permeable membrane from a region of higher water molecule concentration to a region of lower water molecule concentration (lower water molecule concentration means higher solute concentration).

Just like diffusion, osmosis moves with a concentration gradient until equilibrium is reached.

Osmosis Osmotic pressure is the

force exerted by the water molecule. It depends on magnitude of concentration gradient.

In cells, osmosis is important to cell survival. The water molecules move quickly through channels formed by the integral proteins.

 

3 examples of osmosis with respect to the solution.

1. Isotonic

2. Hypertonic

3. Hypotonic

ISOTONIC Put a red blood cell (RBC) into a solution

which contains equal amounts of solute. The water will flow from inside cell to outside cell at equal rate and visa versa. This happens because concentration is equal on both sides. The state of equilibrium of extracellular fluid is ISOTONIC to intracellular fluid. (iso means equal).

HYPERTONIC Put a RBC into a solution

that contains a greater concentration of solutes. This means that there is less water in the solution then in the RBC, so water will tend to flow out of the cell. This causes the cell to shrink. This is known as crenation. The extracellular fluid is HYPERTONIC to the intracellular fluid.

(hyper means above normal).

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

HYPOTONIC Put a RBC into a solution

that contains a lesser concentration of solutes. This means that there is more water in the solution then in the RBC, so water will tend to move into the cell. This causes the cell to swell. This is known as hypertrophy. The Extracellular fluid is HYPOTONIC to the intracellular fluid. (hypo means below normal)

http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

 III. Filtration Movement of molecules across a

selectively permeable membrane from a region of high pressure to a region of low pressure.

Occurs in kidneys when waste product urea is forced by pressure of blood to cross membrane.

2. Active Transport Needs energy from cell

(ATP)Recall ATP ADP +

PO4-2 + E

Active Transport*Requires use of energy

(ATP)*Transport of substancesagainst a concentration gradient across aselectively permeableMembrane.*Requires carrier proteins for

assistance.*Needed to maintain levels

of ions inside cell in spite of concentration gradient.

*Also used for amino acids to be carried into cell where their numbers are larger.

*CYTOSIS is the transport of large volume of materials and large particles across the membrane.

There are 2 types: endocytosis and exocytosis.

1. Endocytosis *Import material into the

cell A. Phagocytosis (fig. 3-

10) *Portion of membrane

forms pseudopod, engulfs substance. Substance is digested by enzymes from lysosome.

*Notable in WBC.

B. Pinocytosis “cell drinking”

*Bulk movement of fluid into cell.

*Only slight folding of plasma.

*Cells lining blood vessels and kidneys.

Endocytosis

2. Exocytosis Export material out of

cell. Releases either waste

products or molecules manufactured in cytoplasm.

The membranes of the organelles fuse with plasma membrane and release materials into extra cellular environment.

A. Excretion *Removal of waste

materials B. Secretion *Releasing

molecules produced by organelles into Extracellular environment. i.e. Digestive enzymes, mucous, hormones, antibodies.

Exocytosis

Packets pp. 39-43

Quiz on pp.48-59 and all notes from ch. 3

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