7.2 Cell Structure

Cellular Boundaries

All cells are surrounded by a cell membrane. Many cells also have a cell wall. Both cell membranes and cell walls separate cells from the environment and provide support.

Selectively permeable

Allowing some substances, but not others, to pass across them.

Two types of organelles act as power plants of the cells.

Chloroplasts Mitochondria Both types are surrounded by two membranes

How are contractile vacuoles different from other types of vacuoles?

Contractile vacuoles pump excess water out of the cell, while other types of vacuoles hold materials inside of cells

The nucleus contains...and controls...

DNA; the activity of a cell

In which organelle are the lipid components of the cell membrane assembled?

Endoplasmic reticulum

Suppose a cell's Golgi apparatus does not function properly. How might this problem affect other cells?

If the cell manufactures proteins that are normally released to travel to other cells. Those cels would not receive the proteins. The loss of these proteins might cause the "receiver" cells to function poorly.

...chloroplasts, mitochondria are surrounded by a double membrane

Like

What is the role of lysosomes in the cell? Why is this a vital role?

Lysosomes breakdown large molecules and waste without them clutter could accumulate in the cell, which has been linked to serious human diseases

What is the difference between rough ER and smooth ER?

Ribosomes are found on the surface of rough ER. Smooth ER has no ribosomes on its surface.

What are ribosomes? What do they do?

Ribosomes are small particles of RNA and protein found throughout the cytoplasm. They are involved in synthesis of proteins.

What are the two roles of the central vacuole in plant cells?

Storage of materials and support of the cell

Using the cell as a factory analogy, describe the role of the Golgi apparatus in cells.

The Golgi apparatus is like a customization shop in a factory. It puts the finishing touches on proteins before they leave the factory.

In the visual analogy of a cell is a factory, what two functions of the nucleus are represented? How are these functions illustrated?

The nucleus act as the office, or control center, as illustrated by the people at the desk. The nucleus is the source of messages, instructions, and blue prints as illustrated by the two workers helping the chain (of RNA) leave the nucleus.

Describe the relationship between the cytoplasm and the nucleus of a cell

The nucleus of a cell is found in the cytoplasm, but is not part of the cytoplasm. The nucleus and cytoplasm work together to keep a cell alive

What is another possible analogy that could be compared with the structure and function of a cell?

The structure and function of an airport control tower could be compared to the structure and function of a cell

What are vacuoles?

Vacuoles are membrane-enclosed saclike structures that store materials such as water, salts, proteins, and carbohydrates.

What is the function of vesicles in the synthesis of proteins and the release of those proteins outside the cell?

Vesicles transport newly synthesized proteins to the Golgi apparatus. After the Golgi apparatus modifies the proteins, vesicles transport the modified proteins to the cell membrane, where they are released.

Lipid bilayer

What a cell membrane consists of. It is a strong but flexible barrier between the cell and its surroundings. They cell membrane regulates what enters and leaves the cell and also protects and supports the cell. Most biological membranes are selectively permeable, allowing some substances, but not others, to pass across them.

The cytoskeleton

a network of protein filaments; it helps that cell maintain its shape and is involved in movement

Eukaryotic cells contain

a nucleus and many specialized structures

The endoplasmic reticulum (ER):

an internal membrane system where lipid components of the cell membrane are assembled, along with proteins and other materials

Golgi apparatus:

an organelle that appears as a stack of flattened membranes; it modifies, sorts, and packages proteins and other materials form the ER for storage in the cell or release outside the cell

Mitochondria

are found in nearly all eukaryotic cells; they convert the chemical energy stored in food to a usable form

Organelles

are structures that have specialized functions in eukaryotic cells

Chloroplasts

capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis. Cells of plants and some other organisms contain chloroplasts, which contain chlorophyll

Which structures of the cytoskeleton are found in animal cells but not in plant cells?

centrioles

What other structures of the cytoskeleton would show the same pattern of microtubules as a flagellum?

cilia

Both chloroplasts and mitochondria... genetic information in the form of DNA

contain

Cytoplasm

is the portion of a cell outside the nucleus

What does the term organelle mean literally?

little organ

Vacuoles

membrane-enclosed saclike structures that store water, salts, and organic molecules

Nearly all of the ....in your cells were inherited from your mother

mitochondria

Chloroplasts are....found in animal cells

never

Centrioles

organelles made form tubulins; they help organize cell division in animal cells

Besides supporting and protecting a cell, the cell membrane...what enters and leaves the cell.

regulates

Three kinds of organelles work with the nuceus to make and distribute proteins

ribosomes, endoplasmic reticulum (ER), Golgi apparatus

lysosomes

small organelles filled with enzymes that break down large molecules and organelles that are no longer useful

Ribosome

small particles of RNA and protein found throughout the cytoplasm in all cells; they produce proteins by following coded instructions from DNA

Cell walls

support, shape, and protect the cell. Most prokaryotes and many eukaryotes have them. Animals do not have cell walls. Cell walls lie outside the cell membrane. Most cell walls allow materials to pass through them.

Which feature of the nucleus is not clearly shown by the visual analogy?

the chromatin is not shown

Most cell...are porous to water and other materials but strong enough to support and protect cells

walls

Nearly all of the plant tissue called...is make up of cell walls

wood