Cell Structure

Question 1

What is an organelle?

Answer 1

A tiny cellular structure that performs specific functions within a cell.

Question 2

What is a plasma membrane?

Answer 2

The membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells. Its made of lipids and protein.

Question 3

What is the function of a plasma membrane?

Answer 3

Regulates the movement of substances into and out of the cell. It also has receptor molecules on it which allow it to respond to chemicals like hormones.

Question 4

What is a cell wall and its function?

Answer 4

A rigid structure that surrounds plant cells. Its made mainly of the carbohydrate cellulose. Supports plant cells.

Question 5

What is a nucleus?

Answer 5

A large organelle surrounded by a nuclear envelope (double membrane), which contains many pores. The nucleus contains chromatin (which is made from DNA and proteins) and a structure called the nucleolus.

Question 6

What is the function of a nucleus?

Answer 6

The nucleus controls the cell’s activities by controlling the transcription of DNA. The pores allow substances to move between the nucleus and the cytoplasm. The nucleolus makes ribosomes.

Question 7

What is a lysosome and its function?

Answer 7

A round organelle surrounded by a membrane, with no clear internal structure. Contains digestive enzymes. These are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down worn out components of cells.

Question 8

What is a ribosome and its function?

Answer 8

A very small organelle that either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum. It’s made up of proteins and RNA. It’s not surrounded by a membrane. Ribosomes are the site where proteins are made.

Question 9

What is a rough endoplasmic reticulum?

Answer 9

A system of membranes enclosing a fluid-filled space. The surface is covered with ribosomes.

Question 10

What is the function of a rough endoplasmic reticulum?

Answer 10

It folds and processes proteins that have been made at the ribosomes.

Question 11

What is a smooth endoplasmic reticulum and its function?

Answer 11

Similar to a rough endoplasmic reticulum, but with no ribosomes. Synthesises and processes lipids.

Question 12

What is a vesicle?

Answer 12

A small fluid-filled sac in the cytoplasm, surrounded by a membrane.

Question 13

What is the function of a vesicle?

Answer 13

It transports substances in and out of the cell (via the plasma membrane) and between organelles.

Question 14

What is a Golgi apparatus?

Answer 14

A group of fluid-filled, mebrane-bound, flattened sacs. Vesicles are often seen at the edges of the sacs.

Question 15

What is the function of a Golgi apparatus?

Answer 15

It processes and packages new lipids and proteins. It also makes lysosomes.

Question 16

What is a mitochondrion?

Answer 16

Usually oval-shaped organelle with a double membrane - the inner one is folded to form structures called cristae. Inside is the matrix, which contains enzymes involved in respiration.

Question 17

What is the function of a mitochondrion?

Answer 17

The site of aerobic respiration, where ATP is produced. They’re found in large numbers in cells that are very active and require a lot of energy.

Question 18

What is a chloroplast?

Answer 18

A small, flattened structure found in plant cells. Its surrounded by a double membrane, and also has membranes inside called thylakoid membranes.
These membranes are stacked up in some parts of the chloroplast to form grana. Grana are linked together by lamellae - thin, flat pieces of thylakoid membrane.

Question 19

What is the function of a chloroplast?

Answer 19

The site where photosynthesis takes place. Some parts of photosynthesis happen in the grana, and other parts happen in the stroma (a thick fluid in chloroplasts).

Question 20

What is a centriole?

Answer 20

Small, hollow cylinders made of microtubules (tiny protein cylinders). Found in animal cells, but only some plant cells.

Question 21

What is the function of a centriole?

Answer 21

Involved with the separation of chromosomes during cell division.

Question 22

What is cilia?

Answer 22

Small, hair-like structures found on the surface membrane of some animal cells. In cross-section, they have an outer membrane and a ring of nine pairs of protein microtubules inside, with two microtubules in the middle.

Question 23

What is the function of cilia?

Answer 23

The microtubules allow the cilia to move. This movement is used by the cell to move substances along the cell surface.

Question 24

What is flagella?

Answer 24

Flagella on eukaryotic cells are like cilia but longer. They stick out from the cell surface and are surrounded by the plasma membrane.

Question 25

What is the function of flagella?

Answer 25

The microtubules contract to make the flagellum move. Flagella are used like outboard motors to propel cells forward (e.g. when a sperm cell swims).