2.1.2 Cell Structure - (Organelles)

Question 1

What is the structure of plasma membrane?

Answer 1

> It is the membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells.
Its mainly made of lipids

Question 2

Function of a cell surface membrane

Answer 2

> It regulates the movement of substances in and out of the cell
It has receptor molecules which allow it to respond to chemicals such as hormones

Question 3

What is the structure of cell wall?

Answer 3

A rigid structure that surrounds plant cells, mainly made of carbohydrate cellulose

Question 4

What is the function of a cell wall?

Answer 4

> Provide strength and support
Maintain cell shape
Are permeable so allow solutions to pass through

Question 5

What is the structure of nucleus?

Answer 5

A large organelle surrounded by a nuclear envelope with nuclear pores and contains a nucleolus and chromatin (which is made from DNA and proteins)

Question 6

Role of a Nucleus

Answer 6

> The nucleus control the cell activity (by controlling the transcription of DNA.
DNA contains instructions to make proteins
The pores allow substances (e.g. RNA) to move between the nucleus and the cytoplasm
The nucleolus makes ribosomes

Question 7

What is the structure of a Lysosome?

Answer 7

> These are formed from the Golgi apparatus

> Its a round organelle surrounded by a membrane, with no clear internal structure

Question 8

Role of a Lysosome?

Answer 8

Contains digestive enzymes, which are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down work out components of the cell

Question 9

What is the structure of a Ribosome?

Answer 9

> A very small organelle that either floats free in the cytoplasm or is attached to the RER
Its made up of proteins and RNA in the nucleolus
Its not surrounded by a membrane

Question 10

Role of a Ribosome?

Answer 10

The site where proteins are made

Question 11

What is the structure of a RER?

Answer 11

> A system of membranes enclosing a fluid - filled space.
The surface is covered in ribosomes
They have large surface are for protein synthesis

Question 12

Role of RER

Answer 12

Folds and processes proteins that have been made at the ribosomes

Question 13

What is the structure of a SER?

Answer 13

A system of membranes enclosing a fluid - filled space. No ribosomes

Question 14

Role of SER

Answer 14

Its got enzymes which that catalyse reactions involved with lipid metabolism, such as Synthesising and processing lipids

Question 15

What is the structure of a Vesicle?

Answer 15

> Its a small, fluid-filled sac in the cytoplasm surrounded by a membrane
Some are formed by the Golgi apparatus or the endoplasmic reticulum, while others are formed at the cell surface

Question 16

Role of a Vesicle

Answer 16

> Transports substances in and out of the cell (via the plasma membrane) and between organelles where fusion occurs

Question 17

What is the structure of a Golgi Apparatus?

Answer 17

An organelle that contains membrane bound, flattened sacs with vesicles on the outside

Question 18

Role of the Golgi apparatus

Answer 18

> Processes and packages new lipids and proteins

> Makes lysosomes

Question 19

What is the structure of mitochondria

Answer 19

> An 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.
They are self-replicating, so more can be made if the cell’s energy needs increase
The outer membrane controls the flow of materials in and out of the mitochondria

Question 20

Role of mitochondria

Answer 20

> The site of aerobic respiration, where ATP is produced.

> Mitochondria are found in large number in cells that are very active and require a lot of energy

Question 21

What are cristae?

Answer 21

extensions of the inner membrane which increases the surface area for the attachment of enzymes

Question 22

What is the matrix?

Answer 22

the matrix is found inside the mitochondria and contains, lipids, trace DNA along with enzymes for respiration

Question 23

What is the structure of Chloroplast

Answer 23

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 grant. Grant are linked together by lamellae - thin, flat pieces of thylakoid membrane.

Question 24

Role of Chloroplasts

Answer 24

Place of photosynthesis - some parts happen in the grand (stacked up membranes), and other parts happen in the storm (a thick fluid found in the chloroplasts)

Question 25

What is the structure of Centriole

Answer 25

> Small, hollow cylinders made from microtubules. They are found in all animal cells but only some plant cells
Microtubules are made of Tubulin protein subunits

Question 26

Role of Centriole

Answer 26

They are involved in the separation of chromosomes during cell division

Question 27

What is the structure of Cilia

Answer 27

They are 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 a single pair of microtubules in the middle.

Question 28

Role of Cilia

Answer 28

The microtubules in the cillia allow the cilia to move and this movement is used by the cell to move substances along the cell surface

Question 29

What is the structure of a Flagellum?

Answer 29

> They are like cillia but longer.
They stick out from the cell surface and are surrounded by the plasma membrane
They have 9 microtubules in a ring and two in the centre

Question 30

Role of flagellum

Answer 30

the microtubules contract to make the flagellum move and the flagella are used as outbouard motors to propel cells forward (e.g. when a sperm cell swims)