Cell Structure and Function

Human Epidermis – Animal cells

Staphylococcus epidermis

Cardiac (heart) Muscle

Stems

Leaves

Amoeba proteus

Root tip

What are some similarities and differences that you observed by looking at a variety of cells?

Explain: Cells

The Cell Theory

All living things are composed of cells.

Cells are the basic units of structure and function in living things.

New cells are produced from existing cells.

Types of Cells

Two kinds of cells depending on whether they have a nucleus

Prokaryote

Eukaryote

Genetic material

Prokaryotes

Usually small and simple

Genetic material (DNA) is not contained in a nucleus

The ONLY prokaryotes in the world are BACTERIA.

Prokaryotic Cells

Eukaryotes

Usually larger and more complex than prokaryotes.

May be unicellular like an amoeba or multicellular like a plant

Contain dozens of specialized structures called organelles.

Includes protists, fungi, plants and animals.

Eukaryotic cell structure

Two major parts: Nucleus

Cytoplasm-portion of the cell outside the nucleus

Eukaryotic cells

Nucleus-The control center

Function:

Contains almost all of the cell’s DNA for coding proteins and other molecules.

DNA is found on chromosomes which contain genetic information.

Nucleus-The control center

Structure: Surrounded by a double

membrane called a nuclear envelope. It is dotted with many pores (holes) to allow materials (RNA, proteins, etc) in and out of the nucleus.

Small internal region called a nucleolus where ribosomes are made.

Ribosomes

Function: Site of protein

assembly.

Structure: Small pieces of RNA

and protein found throughout the cell.

Endoplasmic Reticulum

Function: Site where lipid parts of

cell membrane are made, along with proteins and other materials to export from the cell.

Structure: Rough ER- has

ribosomes on surface to assemble proteins

Smooth ER-NO ribosomes on surface

Golgi Apparatus

Function: Modify, sort, and

package proteins and other materials from the ER for storage in the cell or release from the cell. It puts the finishing touches on proteins.

Structure: Stack of closely

packed membranes

You have 3 minutes to compare your notes with a neighbor. Be sure to ask questions and fill in any blanks you may have in your notes at this time.

Lysosomes-The Clean Up Crew

Function: Breakdown of lipids,

carbohydrates and proteins into small molecules to be used by the rest of the cell

Breakdown used up organelles

Get rid of all “stuff” in the cell

Structure: Small, filled with

enzymes

Vacuoles - Storage

Function: Stores water, salts,

proteins and carbohydrates

Structure: Sac-like Plant cells have one

large central vacuole Animal cells have

many small vacuoles

Mitochondria - Energy

Function: Convert chemical

energy in food into materials easier for the cell to use.

Structure: Enclosed by two

membranes with the inner membrane folded up.

Contains it’s own DNA (unlike other organelles) that is identical to your mother’s!

Chloroplasts – Energy in Plants

Function: Captures energy from the

sun (solar energy) and changes it into food (chemical energy) for plants (photosynthesis)

Structure: Surrounded by two

membranes Contains own genetic

information like mitochondria

Contains green pigment called chlorophyll

Not found in animal cells!

With your neighbor, list similarities and differences between mitochondria and chloroplasts. Be prepared to share with the class.

Cytoskeleton- structure and support

Function: Helps maintain cell

shape Helps with

movement of the cell (i.e. flagella and cilia)

Structure: Two types:

microfilaments and microtubules

Cell Membrane

Function: Regulates what enters

and leaves the cell Provides protection

and support Structure:

Double membrane called a lipid bilayer

Flexible structure that forms a strong barrier between the cell and its surroundings

Cell Wall

Function: Provides support and

protection for the cell

Structure: Lies outside the cell

membrane Found in plants,

algae, fungi and many bacteria

NOT FOUND IN ANIMAL CELLS!

Individually, write down 3 differences between plant and animal cells.