2.1.1 Cell Structure Eukarotes

Question 1

What is the Plasma membrane ?

Answer 1

The membrane found surrounding all animal, plant and prokaryotic cells, a lipid and protein bilayer

Question 2

Function of the plasma membrane?

Answer 2

It regulates the movement of substances into and out of the cell
Has receptor molecules on it which allow it to respond to chemicals such as homones

Question 3

What is the cell wall and what is it made of?

Answer 3

A rigid structure that surrounds cell
Plant cell - cellulose
Fungal cell - chitin
Prokaryotes - Murein

Question 4

What is the function of the cell wall?

Answer 4

To support the cell

Question 5

What is the Nucleus

Answer 5

A large organelle surrounded by the nuclear envelope (double membrane) containing pores. The Nucleus also contains chromatin (made of DNA and proteins ) and also the nucleolus

Question 6

What is the function of the nucleus?

Answer 6

It controls the cells activities by controlling the transcription of DNA and RNA which contains instructions to make proteins.

Question 7

What is the function of Nuclear Pores?

Answer 7

The pores allow substances such as RNA to move between the nucleus and the ribosomes

Question 8

What is a lysosome?

Answer 8

A round organelle surrounded by a membrane with no clear internal structure but containing hydrolytic digestive enzymes

Question 9

Function of a lysosome?

Answer 9

Contains digestive enzymes which are kept separate from the cytoplasm by the surrounding membrane. Used to digest invading cells / old components of cell

Question 10

What is the ribosome?

Answer 10

A very small organelle (22nm or 18nm) which either floats free in cytoplasm or is attached to the RER. Made up of proteins and RNA but not surrounded by a membrane.

Question 11

Function of the ribosome?

Answer 11

The site where proteins are made

Question 12

What is the Rough Endoplasmic Reticulum?

Answer 12

A system of membrane tat enclose a fluid filled space and the surface is covered with ribosomes.

Question 13

What is the function of the RER?

Answer 13

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

Question 14

What is the Smooth Endoplasmic reticulum

Answer 14

A system of membranes enclosing a fluid filled space

Question 15

Function of the smooth endoplasmic reticulum

Answer 15

Synthesises and processes lipids

Question 16

What is a vesicle?

Answer 16

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

Question 17

What is the function of the vesicle?

Answer 17

Transports substances in and out of cell via the plasma membrane and between organelles (transport vesicle) . Some are made at Golgi apparatus or the endoplasmic reticulum

Question 18

What is the Golgi apparatus?

Answer 18

A group of fluid filled, membrane bound, flattened sacs and vesicles are often seen at the edge

Question 19

Function of the Golgi apparatus?

Answer 19

Processes and packages proteins eg: adding carbohydrates to make them glycoproteins
and makes lysosomes,

Question 20

What is the mitochondrion?

Answer 20

An oval shaped organelle which is double membranes and the inner one is folded to form structures called cristae. Inside there is a matrix which contains enzymes involved in respiration

Question 21

Function of the mitochondrion?

Answer 21

The site of aerobic respiration and where ATP is produced

Question 22

What is a chloroplast?

Answer 22

A small flattened structure found only in plant cells and is surrounded by. double membrane and also has membranes inside called thylakoid membranes. The thylakoid membranes are stacked in some parts to form grana which are linked together by lamellae which are thin flat pieces of thylakoid membrane. It also contains a thick fluid within itself called stroma.

Question 23

What is the function of the chloroplast

Answer 23

The site where photosynthesis takes place. Some parts of photosynthesis happen in the grand and some in the stroma

Question 24

What is a centriole?

Answer 24

A small hollow cylinder made of microtubules (tiny protein cylinders) and is found in animal cells and some plant cells

Question 25

Function of the centriole?

Answer 25

It is involved in the separation of chromosomes during cell divisions

Question 26

What is cilia?

Answer 26

Small hair like structure found on the surface membrane of some animal cells. Made up of 9+2 structure of microtubules

Question 27

Function of Cilia?

Answer 27

The microtubules allow the cilia to move and the movement is used to move substances along the cell surface

Question 28

What is the flagellum?

Answer 28

On eukaryotes, they are like cilia but longer, surrounded by the plasma membrane. Also have 9+2 structure

Question 29

Function of the flagellum

Answer 29

The microtubules contract to make the flagellum move as the flagellum is used to propel cells forward

Question 30

What is the plasmodesmata

Answer 30

Channels within the cell wall and membrane of a plant cell

Question 31

Function of the plasmodesmata?

Answer 31

Channels for exchanging substances with adjacent cells

Question 32

What are the four main functions of the cytoskeleton

Answer 32

• support the cells organelles
• strengthen the cell and maintain its shape
  -movement of materials within the cell
  -movement of the entire cell

Question 33

Actin filaments

Answer 33

8nm in diameter, and connect to the cell surface membrane proteins which allows them to control the movement of the cell surface membrane and therefore changing the shape of the entire cell.
Actin filaments also found in the contractile ring during cell division

Question 34

Intermediate filaments

Answer 34

10nm in diameter
Responsible for mechanical stability and provide scaffolding to the cells organelle within the cell

Question 35

Microtubules

Answer 35

25nm in diameter
Responsible for moving organelles around the cell, they are very dynamic and are always being broken and rebuilt
Seen in cilia and flagella in a 9+2 structure