Chapter 4- Cells

Organisms are composed of one to many microscopic cells

Unicellular

Multicellular

Multicellular organisms are composed of one or more types of tissues

Different types of tissues are grouped to form organs

The Two Major Types of Cells

The Three Domains of Life

Domain Bacteria Domain Archaea

•Prokaryotic cells

-Prokaryotic cells

-Eukaryotic cells

1. Bacteria

2. Archaea

3. Eukarya

Domain Eukarya includes all of the eukaryotic organisms.

Domain Eukarya

Protists (multiple kingdoms) Kingdom Plantae

Kingdom Fungi Kingdom Animalia

•Eukaryotic cells

Diagram of a plant cell

All eukaryotic cells and prokaryotic cells have at least three components in common:

-an outer cell membrane or plasma membrane

-cytoplasm

-ribosomes

The plasma membrane

Prokaryotic flagella

Nucleoid region (DNA)

Ribosomes Plasma membrane

Cell wall

Capsule

Pili

The plasma membrane is composed of phospholipids, proteins, and

other materials.

Domain Eukarya includes several different kingdoms

The cytoplasm consists of the entire region of the cell between the nucleus and plasma membrane

Ribosomes, are composed of protein and RNA.

Cell Membrane Structure and Function

The membranes of cells are composed of:

•The lipids belong to a special category called phospholipids

The cell membrane is described as selectively permeable because it allows free passage of some materials and not

others.

Hydrophilic head

Hydrophobic tail

Outside cell

Cytoplasm (inside cell)

(a) Phospholipid bilayer of membrane

Hydrophilic region of protein

Phospholipid bilayer

Hydrophobic region of protein

(b) Fluid mosaic model of membrane

The cytosol is the cellular fluid.

-Other molecules do not pass through the cell membrane easily without specific membrane transport proteins or

energy input.

Ex:

-Very small, uncharged molecules can easily pass through the cell membrane

Ex:

-lipids

-proteins

Selective membrane permeability is the basis for osmosis.

Osmosis and Water Balance in Cells

Osmosis is the diffusion of water across the cell

membrane in response to differences in concentrations of

solutes (dissolved substances) such as sugars or ions.

Diffusion

Water, like many substances, will move from where it is

more concentrated to where it is less concentrated.

If the concentration of solutes inside and outside the cell is the same, then the cell is

osmotically balanced.

If the solute concentration is lower outside a cell than inside,

Osmosis and Water Balance in Cells

Prokaryotes, protists, fungi, and plants have cell walls that limit

the increase of cell volume through the uptake of water.

If the concentration of solutes outside the cells is higher than inside, water leaves the cell and the cytoplasm shrinks.

Diffusion is the tendency for molecules of any substance

to spread out into the available space.

isotonic

hypotonic

hypertonic

The nucleus is the major site of genetic information (DNA) storage in eukaryotic cells.

The nuclear envelope

Nuclei also contain nucleoli (nucleolus, sing.),

Ribosomes Chromatin Nuclear envelope

Nucleolus Pore

Eukaryotic nuclear DNA is combined with proteins to

form chromosomes.

•Many of the membranous organelles in the cell belong to the endomembrane system

The endoplasmic reticulum (ER)

Nuclear envelope

Ribosomes

Rough ER Smooth ER

Rough ER

•The “roughness” of the rough ER is due to ribosomes that

stud the outside of the ER membrane

Ribosomes

Small globular structures composed of protein and RNA

that generate proteins from amino acids.

Transport vesicle buds off

Ribosome Secretory protein inside transport vesicle

Protein

Rough ER

Polypeptide

1 2

3

4

After the rough ER synthesizes a molecule it packages

the molecule into transport vesicles

• Eukaryotic cells

Smooth ER

lacks the surface ribosomes of rough ER Nuclear envelope

Ribosomes

Rough ER Smooth ER

The Golgi apparatus

Works in partnership with ER

The Golgi apparatus of a cell consists of 1 or more Golgi bodies.

The cytoskeleton consists of three major types of long, thin, protein fibers:

Flagella and Cilia

Eukaryotic flagella typically contain a pair of single microtubules, surrounded by a

cylinder of nine paired microtubules (9 + 2 arrangement).

Mitochondria

Peroxisomes

-surrounded by single membrane

Each mitochondrion is enclosed by an envelope

composed of an outer membrane and a highly folded

inner membrane.

Study outline for Chapter 4-Cells

Define unicellular. Give an example.

Define multicellular. Give an example.

Name the two major types of cells.

Define prokaryotic. Give an example.

Define eukaryotic. Give an example.

Name the three domains of life.

Prokaryotic organisms are included in Domain ___________ and Domain _____________.

Name three characteristics of prokaryotic cells.

Which kingdoms are included in Domain Eukarya?

Name two characteristics of eukaryotic cells.

Name three components that eukaryotic and prokaryotic cells have in common.

Define plasma membrane.

Define cytoplasm.

Define cytosol.

Define ribosome.

Study outline for Chapter 4-Cells

Cell membranes are made up of ________ and ___________.

Define phospholipids.

Define hydrophilic.

Define hydrophobic.

Label the figure below using the following terms:

-outside the cell

-inside the cell

-hydrophilic head

-hydrophobic tail

-phospholipid bilayer

Define selectively permeable.

Which types of molecules pass easily through the cell membrane?

Which types of molecules do not pass easily through the cell membrane?

•Define osmosis.

•Define diffusion.

•Define isotonic.

•Define hypotonic.

•Define hypertonic.

•Define turgid.

•Define plasmolysis.

•Label the figures below using the following terms:

•-isotonic

•-hypertonic

•-hypotonic

•Which figure is turgid?

•Which figure shows the process of plasmolysis?

water water water water

Study outline for Chapter 4-Cells

What is the function of the following eukaryotic cellular structures?

-nucleus

-nuclear envelope

-chromosomes

-rough endoplasmic reticulum

-smooth endoplasmic reticulum

-Golgi apparatus

-mitochondria

-peroxisome

Which of the organelles above belong to the endomembrane system?

Name the three major types of protein fibers of the cytoskeleton.

What is the difference between flagella and cilia? Give an organismal example for each.

What is the “9x2” arrangement in eukaryotic flagella?