Pearson Biology Ch. 7.2

In many plant cells, there is a single, large central vacuoles filled with liquid. The pressure of the central vacuole in these cells increases their rigidity, making it possible for plants to support heavy structures such as leaves and flowers.

Concept: What is the difference between animal and plant cell vacuoles?

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

Key Question: *What are the functions of chloroplasts and mitochondria?*

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.

Key Question: *What are the functions of vacuoles, lysosomes, and the cytoskeleton?*

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

Key Question: *What is the function of the cell membrane?*

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

Key Question: *What is the role of the cell nucleus?*

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 ER for storage in the cell of release outside the cell.

Key Question: *What organelles help make and transport proteins?*

Threadlike structures made up of a protein called actin that form extensive networks in some cells and produce a tough flexible framework that supports the cell. They also help the cell move.

Concept: What are microfilaments?

Hollow structures comprised of proteins known as tubulins. They play critical roles in maintaining cell shape and cell division, where they form a structure known as the mitotic spindle which helps to separate chromosomes.

Concept: What are microtubules?

The different organelles of the cell can be compared to the specialized machines and assembly lines of the factory. In addition, cells, like factories, follow instructions and produce products.

Analogy: How is a cell comparable to a factory?

Complexes of DNA bound the proteins, normally threadlike and spread around the nucleus in the form of chromatin, carry the cell's genetic info.

Concept: What are chromosomes?

Projections made from microtubules that are arranged in a "9 + 2" pattern that produce controlled movements.

Concept: What are cilia and flagella?

The proteins embedded in the lipid bilayer of most cell membranes that can move around and "float" among the lipids. Because so many different molecules make up the membrane, scientists describe it as a mosaic. These proteins form channels and pumps that move different materials across the cell membrane.

Concept: What is the fluid mosaic model?

The site of the start of the assembly of ribosomes.

Concept: What is the nucleolus?

1) Proteins are assembled on ribosomes. 2)Proteins targeted for export to the cell membrane, or to specialized locations within the cell, complete their assembly on ribosomes bound to the rough ER. 3) Newly assembled proteins are carried from the rough ER to the Golgi apparatus in vesicles. 4)The Golgi apparatus further modifies proteins before sorting and packaging them in membrane-bound vesicles. 5) Vesicles from the Golgi apparatus are shipped to their final destination in, or out of, the cell.

Concept: What is the process of the production of proteins?

The other part of the ER which does not have ribosomes on its surface, instead containing collections of enzymes that perform specialized tasks, including the synthesis of membrane lipids and detoxification of drugs.

Concept: What is the smooth endoplasmic reticulum?

A strong supporting layer around the membrane that animal cells never contain.

Definition: What are *cell walls*?

Organelles formed from tubulins that are located new the nucleus and help organize cell division. They are not found in plant cells.

Definition: What are *centrioles*?

The biological equivalents of solar power plants.

Definition: What are *chloroplasts*?

Small organelles filled with enzymes.

Definition: What are *lysosomes*?

The power plants of the cell.

Definition: What are *mitochondria*?

Small structures in cells that act like specialized organs.

Definition: What are *organelles*?

Small particles of RNA and protein found throughout the cytoplasm in all cells.

Definition: What are *ribosomes*?

Large, saclike, membrane-enclosed structures.

Definition: What are *vacuoles*?

Some substances can pass across them and others cannot.

Definition: What does *selectively permeable (semipermeable)* mean?

An organelle in eukaryotic cells that protein produced in the rough ER move into. It appears as a stack of flattened membranes.

Definition: What is the *Golgi apparatus*?

The portion of the cell outside the nucleus.

Definition: What is the *cytoplasm*?

A network of protein filaments that gives eukaryotic cells their shape and internal organization.

Definition: What is the *cytoskeleton*?

An internal membrane system contained by eukaryotic cells.

Definition: What is the *endoplasmic reticulum (ER)*?

It gives cell membranes a flexible structure that forms a strong barrier between the cell and tis surroundings.

Definition: What is the *lipid bilayer*?