Cytoplasmic Organelles

What are ribosomes made of?

RNA and protein

Where can ribosomes be found?

Floating freely or attached to rough ER

What is the function of ribosomes?

Protein synthesis

What is the endoplasmic reticulum?

A membranous system of tubules extending throughout the cytoplasm

What are the two types of endoplasmic reticulum?

Rough and smooth ER

What makes the rough ER different from the smooth ER?

Rough ER has ribosomes attached to it

What is the major function of rough ER according to Table 4.1?

Protein synthesis

Rough ER is also involved in:

Storage and transport of proteins

Which organelle is primarily associated with protein synthesis because it has ribosomes?

Rough ER

Which type of ER is involved in steroid and lipid synthesis?

Smooth ER

Smooth ER is involved in:

Steroid and lipid synthesis, lipid metabolism, and drug detoxification

What does the Golgi apparatus look like structurally?

A stack of flattened sacs with bulbous ends and small associated vesicles

Where is the Golgi apparatus generally located?

Close to the nucleus

What is an important function of the Golgi apparatus?

Packaging proteins and other substances

The Golgi apparatus packages substances for:

Export from the cell or incorporation into the plasma membrane

The Golgi apparatus is also involved in packaging:

Lysosomal enzymes

What are lysosomes?

Membranous sacs containing digestive enzymes

What types of enzymes are found in lysosomes?

Acid hydrolases

What do lysosomes digest?

Worn-out cell organelles and foreign substances

Why are lysosomes sometimes called “suicide sacs”?

If they rupture, their enzymes can cause cell destruction

What are peroxisomes?

Small lysosome-like membranous sacs

What type of enzymes do peroxisomes contain?

Oxidase enzymes

What is the major function of peroxisomes?

Detoxification

Peroxisomes help detoxify:

Alcohol, free radicals, and other harmful chemicals

Peroxisomes are particularly abundant in which cells?

Liver and kidney cells

What type of membrane surrounds mitochondria?

A double membrane

What are the folds of the inner mitochondrial membrane called?

Cristae

What is the function of the mitochondrial inner membrane folds?

They provide an area associated with energy-producing reactions

What do mitochondria produce?

Cellular energy in the form of ATP

Mitochondria are often referred to as the:

Powerhouse of the cell

How are centrioles arranged?

In pairs at right angles to each other

Where are centrioles located?

Close to the nucleus

What are centrioles composed of?

Nine triplets of microtubules

What is one role of centrioles during cell division?

They determine the formation of the mitotic spindle

Centrioles also form the bases of:

Cilia and flagella

When centrioles form the bases of cilia and flagella, they are called:

Basal bodies

What is the cytoskeleton?

An internal scaffolding that provides cellular support

They cytoskeleton also functions in:

Intracellular transport

What are the three types of cytoskeletal elements?

Microfilaments, intermediate filaments, and microtubules

Microfilaments are formed largely from which protein?

Actin

Microfilaments are especially important in:

Cell mobility

Microfilaments are particularly important in:

Muscle cells

What is a major characteristic of intermediate filaments?

They are stable and composed of various proteins

What is an important function of intermediate functions?

Resisting mechanical forces acting on cells

Microtubules form the internal structure of the:

Centrioles

Microtubules help determine:

Cell shape

Which cytoskeletal element is associated with the internal structure of centrioles?

Microtubules

Which organelle is the actual site of protein synthesis?

Ribosome

Which organelle packages proteins for export from the cell?

Golgi apparatus

Which organelle contains acid hydrolases?

Lysosome

Which organelle contains oxidase enzymes?

Peroxisome

Which organelle has cristae?

Mitochondrion

Which organelle is associated with drug detoxification?

Smooth ER

Which structure is composed of nine triplets of microtubules?

Centriole

Which cytoskeletal element is formed largely from actin?

Microfilaments

Which cytoskeletal element helps cells resist mechanical forces?

Intermediate filaments

Which cytoskeletal element helps determine cell shape?

Microtubules