Introduction to Animal Cells

Characteristics of Animal Cells

• They are eukaryotic cells, that means they contain a membrane bound nucleus

• They lack a cell wall that plant cells have• Generally they are larger and more

complex than prokaryotic cells• Contains membrane bound structures

called organelles

Plasma Membrane• Not an organelle• Selectively permeable• Defines boundaries of cell and ensures contents

are retained• Made of proteins and lipids

– Phospholipid bilayer

Nucleus• Considered the “Control Center” of the cell

• Controls cell activity

• Contains nearly all of the cell’s DNA

Nucleolus• Small, dense region within the nucleus• The beginning site of protein assembly

Nuclear Envelope• Double membrane that surrounds nucleus

• Protects and isolates cell DNA

• Selectively permeable

• Contains thousands of nuclear pores that allow material to move into and out of the cell

Centrioles• Located near the nucleus

• Help to organize cell division in animal cells

Ribosomes• Most numerous and smallest organelle

• Composed of RNA and proteins

• Found throughout cytoplasm and attached to Rough Endoplasmic Reticulum

• Site of protein synthesis

• Made of 2 subunits

Endoplasmic Reticulum (ER)

• Site where lipid components of cell membrane and proteins are assembled

• Site of preparation of material to be exported from the cell

• Two types– Rough ER– Smooth ER

Endoplasmic Reticulum cont.

• Rough ER– Has ribosomes

attached to surface– Portion of ER

involved in protein synthesis

• Smooth ER– Lacks ribosomes– Contains enzymes

that are specialized detoxify drugs and synthesize membrane lipids

Golgi Apparatus• Site of protein processing, sorting,

packing, and transport from ER to be secreted from the cell

Mitochondria

• One of the largest organelles

• Breaks down sugar molecules stored in food and converts them to chemical energy for use by the cell (ATP)

• Contain their own DNA, RNA, and ribosomes and are able to reproduce themselves

Mitochondria cont

• The “powerhouse” of the cell

Lysosomes & Peroxisomes• Similar in both structure and function• Lysosomes

– Filled with enzymes to breakdown and digest dead organelles and proteins not being used

• Peroxisomes– Detoxifies hydrogen peroxide and other harmful

compounds– Plays a part in the oxidative breakdown of fatty

acids in animal cells

Vacuoles

• Saclike structure

• Storage area for the cell

• Stores materials like water, salt, proteins and carbohydrates

Cytoskeleton

• Network of protein filaments that help cell maintain its shape

• Involved in movement of cells