Biology 7.2

Lipid bilayer

Gives cell membranes a flexible structure that forms a strong barrier between the cell and it's surroundings.

Cytoskeleton

Gives cells their shape and internal organization by these networks of protein filaments

Microtubules

Hollow structures made up of proteins known as tubulins that play critical roles in maintaining shape.

Golgi apparatus

In eukaryotic cells, proteins produced in the rough ER move next into an organelle which appears as as stack of flattened membranes.

Centrioles

Located near the nucleus and help organize cell division. Not found in plant cells.

Vacuoles

Many cells contain large, saclike, membrane-enclosed structures.

What organelles help make and transport proteins?

Proteins are assembled on ribosomes. Proteins made on the rough ER include those that will be released, or secreted, from the cell as well as many membrane proteins and proteins destined for lysosomes and other specialized locations within the cell. The Golgi apparatus modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell.

Lysosomes

Small organelles filled with enzymes.

Ribosomes

Small particles of RNA and protein found throughout the cytoplasm in all cells. Produce proteins by following coded instructions that come from DNA.

Selectively permeable

Some substances can pass across them and others cannot.

What is the function of the cell membrane?

The cell membrane regulates what enters and leaves the cell and also protects and supports the cell.

What is the role of the cell nucleus?

The nucleus contains nearly all the cell'a DNA and, with it, the coded instructions for making proteins and other important molecules.

Cytoplasm

The portion of the cell outside the nucleus.

Mitochondria

The power plants of the cell.

Microfilamemts

Threadlike structures made up of a protein called actin.

Organelles

"Little organs"

Cell wall

A strong supporting layer around the membrane.

Porous

Allowing materials to pass through.

Chloroplasts

Biological equivalents of solar power plants.

What are the functions of chloroplasts and mitochondria?

Chloroplasts capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis. Mitochondria converts the chemical energy stored in food into compounds that are more convenient for the cell to use.

Endoplasmic reticulum

Eukaryotic cells contain an internal membrane-system known also as ER.

What are the functions of vacuoles, lysosomes, and the cytoskeleton?

Vacuoles store materials like water, salts, proteins, and carbohydrates. Lysosomes break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell they are also involved in breaking down organelles that have outlived their usefulness. The cytoskeleton helps the cell maintain its shape and is also involved in movement.