Eukaryotic Cells and Organelles

Question 1

Organisms can be made up of two different cells, what are these?

Answer 1

Organisms can be prokaryotes or eukaryotes. Prokaryotic organisms are prokaryotic cells and eukaryotic organisms are made up of eukaryotic cells.

Question 2

Prokaryotic and eukaryotic cells both contain what?

Answer 2

Both types of cells contain organelles - each one has a specific function

Question 3

Eukaryotic cells are what type of cell?

Answer 3

Animal and plant cells

Question 4

Plant cells have all the same organelles as animal cells, but with what extra?

Answer 4

1. A cellulose cell wall with plasmodesmata
2. A vacuole
3. Chloroplasts

Question 5

Are algal and fungal cells like plant cells?

Answer 5

Algal cells are like plant cells - they have all the same organelles.
Fungal cells are a lot like plant cells, but with two differences:
1. their cell walls are made of chitin
2. they don’t have chloroplasts

Question 6

Describe the structure of the cell-surface (plasma) membrane

Answer 6

The membrane found on the surface of animal cells and just inside the cell wall of other cells. It’s made mainly of lipids and proteins

Question 7

What is the function of the cell-surface (plasma) membrane?

Answer 7

It 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 8

Describe the structure of the nucleus

Answer 8

A large organelle surrounded by a nuclear envelope (double membrane), which contains many pores. The nucleus contains chromosomes (which are made from protein bound linear DNA) and one or more structure(s) called a nucleolus

Question 9

What is the function of the nucleus?

Answer 9

The nucleus controls the cell’s activities (by controlling the transcription of DNA). DNA contains instructions to make proteins. The pores allow substances to move in-between the nucleus and the cytoplasm. The nucleolus makes ribosomes

Question 10

Describe the structure of the mitochondrion

Answer 10

They’re usually oval-shaped. They have a double membrane - the inner one is folded to form structures called cristae. Inside is the matrix, which contains enzymes involved in respiration

Question 11

What is the function of the mitochondrion?

Answer 11

It is 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 12

Describe the structure of the chloroplasts

Answer 12

A small, flattened structure found in plant and algal cells. It’s 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 13

What is the function of the chloroplasts?

Answer 13

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

Question 14

Describe the structure of the Golgi apparatus

Answer 14

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

Question 15

What is the function of the Golgi apparatus?

Answer 15

Processes lipids and proteins. Combines lipids with proteins. Packages lipids and proteins for exocytosis

Question 16

Describe the structure of the Golgi vesicle

Answer 16

A small fluid-filled sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus

Question 17

What is the function of the Golgi vesicle?

Answer 17

It stores lipids and proteins made by the Golgi apparatus and transports them out of the cell (via the cell-surface membrane)

Question 18

Describe the structure of a lysosome?

Answer 18

A round organelle surrounded by a membrane, with no clear internal structure. It’s a type of Golgi vesicle

Question 19

What is the function of a lysosome?

Answer 19

It contains digestive enzymes called lysozyme. 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 the cell

Question 20

Describe the structure of a ribosome

Answer 20

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

Question 21

What is the function of a ribosome?

Answer 21

It is the site where proteins are made

Question 22

Describe the structure of the rough endoplasmic reticulum (RER)

Answer 22

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

Question 23

What is the function of the rough endoplasmic reticulum?

Answer 23

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

Question 24

Describe the structure of the smooth endoplasmic reticulum (SER)

Answer 24

A system of membranes enclosing a fluid filled space

Question 25

What is the function of the smooth endoplasmic reticulum?

Answer 25

It synthesises and processes lipids

Question 26

Describe the structure of the cell wall

Answer 26

A ridged structure that surrounds cells in plant, algae and fungi. In plants and algae it’s made mainly of the carbohydrate cellulose. In fungi, it’s made of chitin

Question 27

What is the function of the cell wall?

Answer 27

It supports the cells and prevents them from changing shape

Question 28

Describe the structure of the cell vacuole

Answer 28

A membrane-bound organelle found in the cytoplasm of plant cells. It contains cell sap - a weak solution of sugar and salts. The surrounding membrane is called the tonoplast

Question 29

What is the function of the cell vacuole?

Answer 29

It helps to maintain pressure inside the cell and keeps the cell rigid. This stops plants wilting. It is also involved in the isolation of unwanted chemicals inside the cell

Question 30

Epithelial cells in the small intestine are specialised to absorb food efficiently, why?

Answer 30

The walls of the small intestine have lots of finger-like projections called villi. These increase surface area for absorption. The epithelial cells on the surface of the villi have folds in their cell-surface membranes, called microvilli. Microvilli increase surface area even more. They also have lots of mitochondria - to provide energy for transport of digested food molecules into the cell

Question 31

What are specialised cells organised into?

Answer 31

In multicellular eukaryotic organisms, specialised cells are grouped together to form tissues. A tissue is a group of cells working together to preform a particular function. Different tissues work together to form organs. Different organs make up an organ system