THE CELLStructures and

Functions

The Cell

• Outside of cells is extracellular fluid.

• Inside the cell is an aqueous solution called cytosol in which many organelles are suspended.

• The cell membrane separates the cytosol from the extracellular fluid.

Cell Membrane

• Controls what enters and exits the cell• Gives the cell shape and support• Composed of a bilayer (double layer) of

lipid (fat) molecules. These molecules are called phospholipids.

• Proteins and carbohydrates are embedded in the phospholipid bilayer.

• Found in both plant and animal cells.

Cell Membrane• Each phospholipid consists of a head that

is hydrophilic and two tails that are hydrophobic.

• Hydrophilic = water loving• Hydrophobic = water fearing

Cell Wall

•Gives the cell structure and shape.

•Lining surrounding the cell membrane.

•Found only in plant cells.

Cytoplasm

• Jelly-like substance located between the nucleus and cell membrane.

• Nutrients are absorbed, transported, and processed.

• All organelles are suspended by this fluid called cytoplasm.

Nucleus

• The control centre of the cell; directs all of the cell’s activities

• The nucleus is separated from the cytoplasm by the nuclear envelope. The envelope is filled with nucleic acids, such as DNA and RNA.

• Found in both plant and animal cells.

Ribosomes

• Produce proteins• Can be free-floating or attached to

membranes.• Found in both plant and animal cells.

Endoplasmic Reticulum (ER)

• Membranous tubes and canals that connect with the nuclear envelope.

• There are two types of ER:

– Rough ER: containing attached ribosomes and thus manufacture proteins.

– Smooth ER: manufacture fat molecules

• The products of the ER pinch off as vesicles and travel to the golgi apparatus.

• Found in both plant and animal cells.

Golgi Apparatus

• Membranous tubes that are stacked.• Chemically change the protein and fat

produced in the ER and are packaged into vesicles.

• These vesicles then travel through the cytoplasm and release the contents in the extracellular fluid to be used by cells.

• Found in both plant and animal cells.

Lysosomes

• Some vesicles produced by the golgi apparatus are lysosomes.

• Contain proteins and can digest particles as well as potentially dangerous microorganisms (bacteria or viruses) that could harm the cell.

• Called “suicide sacs” because they can decompose an entire cell if it is old or damaged.

• Found only in animal cells.

Mitochondria

• The powerhouse of the cell.• Carries out cellular respiration.• Cells which require large amounts of

energy, such as muscle cells, will contain large numbers of mitochondria.

• Found in both plant and animal cells.

Vacuoles

• Membrane-bound sacs filled with a watery solution containing sugars, minerals, and proteins.

• The water creates a pressure which helps keep the cell membrane pressed firmly against the cell.

• Plant cells have large vacuoles which results in the firm texture of vegetables such as celery.

• Found in both plant and animal cells.

Chloroplasts

• Carry out photosynthesis.• Contains the green pigment chlorophyll

which helps begin the process of photosynthesis and gives plants their green colour.

• Found only in plant cells

and algae.

Cell Structure vs. City StructureCell Structure City Structure Function

Nucleus King’s Castle Control for all activities

DNA King/Queen Controlling body

Ribosomes Merchants Production of products

ER Secret Passages Transport of important materials

Golgi Apparatus Sewage system Packaging and Secretion

Lysosomes Guards Fights off intruders

Cytoplasm Infrastructure & logistics Movement

Mitochondria Power Supply Provides energy for all activities

Cell membrane City wall Protection, limits

Vacoules Rooms Storage for materials