Eukaryotic Cell Structures

Question 1

Two types of cell

Answer 1

Prokaryotic
Eukaryotic

Question 2

What is the cytoplasm made of?

Answer 2

Cytosol (water, salts and organic molecules)

Question 3

Function of membranes

Answer 3

Selectively permeable and controls the movement of substances into and out of cells and organelles

Question 4

Nucleus

Answer 4

• contains DNA
• usually the nucleus is the biggest single organelle in the cell
• nuclear envelope with nuclear pores allows substances to move into and out of the nucleus
• DNA is too large to leave the nucleus

Question 5

DNA

Answer 5

• directs the synthesis of all proteins needed by the cell
• controls metabolic activities of the cell
• associates with proteins called histones to form chromatin
• chromatin coils and condenses to form chromosomes

Question 6

Nucleolus

Answer 6

• area within the nucleus
• responsible for producing ribosomes
• made of proteins and RNA

Question 7

Mitochondria

Answer 7

• site of cellular respiration
• number of mitochondria reflects the amount of energy it uses
• double membrane
• inner membrane is highly folded to form cristae
• contains small amount of DNA, mitochondrial DNA (can produce their own enzymes)

Question 8

What is the fluid inside mitochondria called?

Answer 8

Matrix

Question 9

Vesicles

Answer 9

• membranous sacs that have storage and transport roles
• single membrane with fluid inside
• used to transport materials inside the cell

Question 10

Lysosomes

Answer 10

• specialised form of vesicles containing hydrolytic enzymes
• break down waste material in cells, eg old organelles
• responsible for breaking down pathogens ingested by phagocytic cells
• play an important role in programmed cell death or apoptosis

Question 11

What are hydrolytic enzymes?

Answer 11

Enzymes that break down materials

Question 12

Apoptosis

Answer 12

Form of programmed cell death

Question 13

Cytoskeleton

Answer 13

• present throughout cytoplasm of all eukaryotic cells
• network of fibres needed for the shape and stability of a cell
• organelles are held in place by the cytoskeleton
• controls cells movement

Question 14

3 components of the cytoskeleton

Answer 14

• microfilaments
• microtubules
• intermediate fibres

Question 15

Microfilaments

Answer 15

• contractile fibres formed form actin protein
• responsible for cell movement and cell contraction during cytokinesis

Question 16

Microtubules

Answer 16

• globular tubulin proteins polymerise to form tubes
• determines the shape of a cell
• act as tracks of movement for organelles around the cell

Question 17

What are spindle fibres composed of?

Answer 17

Microtubules

Question 18

Intermediate fibres

Answer 18

• give mechanical strength to cells
• help maintain cell integrity

Question 19

Centrioles

Answer 19

• component of the cytoskeleton
• present in most eukaryotic cells
• composed of microtubules
• two centrioles together form the centrosome

Question 20

Centrosome

Answer 20

Involved in the assembly and organisation of spindle fibres during cell division

Question 21

Which eukaryotic cells do not contain centrioles?

Answer 21

Flowering plants and most fungi

Question 22

What do centrioles do in organisms with flagella and cilia?

Answer 22

Play a role in the positioning of these structures

Question 23

What are flagella and cilia?

Answer 23

Extensions that protrude from some cell types

Question 24

Difference between flagella and cilia

Answer 24

Flagella are longer than cilia, but cilia are usually present in larger numbers

Question 25

Flagella

Answer 25

• whip like tails
• enable cell motility
• sometimes used as a sensory organelle detecting changes in the cell’s environment

Question 26

Cilia

Answer 26

• mobile or stationary
• stationary cilia are important in sense organs
• mobile cilia beat in a rhythmic manner, creating a current and cause objects near the cell move

Question 27

Structure of cilia

Answer 27

• contains 2 central microtubules surrounded by 9 pairs of microtubules
• this is the 9+2 arrangement
• pairs of parallel microtubules slide over each other, causing the cilia to move in a beating motion

Question 28

What is the endoplasmic reticulum?

Answer 28

Network of membranes enclosing flattened sacs called cisternae

Question 29

2 types of Endoplasmic Reticulum

Answer 29

Smooth endoplasmic reticulum
Rough endoplasmic reticulum

Question 30

Smooth endoplasmic reticulum

Answer 30

Responsible for lipid and carbohydrate synthesis and storage

Question 31

Rough endoplasmic reticulum

Answer 31

Ribosomes bound to the surface and is responsible for the synthesis and transport of proteins

Question 32

Ribosomes

Answer 32

• can be free floating in the cytoplasm or attached to the ER
• not membrane bound
• made of RNA molecules made in the nucleolus of the cell
• site of protein synthesis
• mitochondria and chloroplasts also contain ribosomes

Question 33

Golgi apparatus

Answer 33

• compact structure made of cisternae
• does not contain ribosomes
• modifies proteins and packages them into vesicles

Question 34

Protein production

Answer 34

1) ribosomes synthesise proteins which bind to the ER
2) pass into cisternae of ER and are packaged into transport vesicles
3) vesicles containing the synthesised proteins move towards the Golgi apparatus via the cytoskeleton
4) vesicles fuse with the cis face of the Golgi apparatus and proteins enter
5) proteins are modified and leave the Golgi apparatus in vesicles from the trans face
6) secretory vesicles carry proteins that will be released from the cell towards the cell membrane and contents are released by exocytosis