CHAPTER 2 SECT ION 4
LOOKING INSIDE CELLS
INTRODUCTION
• Organelles• Tiny structures that carry out specific
functions within the cell
• Compare to organs in your body…
CELL WALL
• Rigid layer of nonliving material that surrounds the cells of PLANTS• Function: helps to protect and support the cell• Made of cellulose• Animal cells DO NOT have cell walls
CELL MEMBRANE
• In cells with cell walls, the cell membrane is located just inside the cell wall• In other cells, the cell membrane forms an
outside boundary • Function: controls what substances come into
and out of a cell
PARTS OF THE NUCLEUS
• Nucleus• Acts as the “brain” of the cell• The cell’s control center, directs cell’s activities
• Nuclear envelope• Nucleus is surrounded by this membrane• Materials pass in and out of the nucleus through pores in this
structure• Chromatin• Contains instructions that direct the functions of a cell• Thin strands, contain genetic material
• Nucleolus• Where ribosomes are made
THE NUCLEUS
ORGANELLES IN THE CYTOPLASM
• Cytoplasm• The region between the cell membrane and
the nucleus• Clear, thick, gel-like fluid
• Many organelles are found in the cytoplasm
MITOCHONDRIA
• Convert energy in food molecules to energy the cell can use to carry out its functions• “powerhouse”
ENDOPLASMIC RETICULUM
• Passageways carry proteins and other materials from one part of the cell to another• Mail truck
RIBOSOMES
• Function as factories to produce proteins• Sometimes attached to the endoplasmic
reticulum or float in cytoplasm
GOLGI BODIES
• Receive proteins and other newly formed materials from the endoplasmic reticulum, package them, and distribute them to other parts of the cell• Mail room
CHLOROPLASTS
• Capture energy from sunlight and use it to produce food for the cell• Only in plant cells
VACUOLES
• Storage area of cells (food and other materials)• Plants cells have ONE large vacuole• Animal cells have many small vacuoles, or none
at all
LYSOSOMES
• Small, round structures containing chemicals that break down certain materials in the cell• “garbage truck”
SPECIALIZED CELLS
• In many-celled organisms, the cell are often quite DIFFERENT from each other• Cells are specialized to perform specific
functions• Cells ---- Tissues ---- Organs ---- Organ Systems
