chapter 2 section 4 looking inside cells. introduction organelles tiny structures that carry out...

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