Cell Ultrastructure

Question 1

What is the maximum magnification of a light microscope?

Answer 1

Up to 1500x in total

Question 2

What limits the resolution of a light microscope?

Answer 2

The wavelength of visible light

Question 3

Name two advantages of light microscopes

Answer 3

• Relatively cheap

- Wide range of alive specimens can be observed

Question 4

Name the two ways of preparing a specimen for viewing under a light microscope?

Answer 4

• Staining

- Sectioning

Question 5

Give 2 disadvantage of using a light microscope?

Answer 5

• Relatively low resolution doesn’t give detailed information
• Non-coloured specimens must be stained for specific organelles/molecules

Question 6

Give 2 advantages of using an Electron microscope

Answer 6

• Produces detailed images of the structures INSIDE cells

- SEM produces detailed 3D images showing contour of cells

Question 7

Give 2 disadvantages of using an Electron microscope

Answer 7

• Extremely expensive

- Samples must be dead and in a vacuum

Question 8

State the magnification formula

Answer 8

Magnification = image size / object size

Question 9

Give the definition of Magnification?

Answer 9

Number of times larger an image appears compared to the real size of the object

Question 10

Give the definition of Resolution?

Answer 10

The ability to distinguish between two adjacent but separate points

Question 11

Describe the structure of the nucleus (3)

Answer 11

• Surrounded by nuclear envelope
• Contain chromatin
• Nucleolus at the centre

Question 12

What is the function of the Nucleus (3)

Answer 12

• Houses all of cells genetic material
• Chromatin consists of DNA and proteins
• Has instructions for making proteins

Question 13

What is the Nucleolus?

Answer 13

Dense spherical structure inside the nucleus

Question 14

What is the function of the nucleolus?

Answer 14

• Makes RNA and ribosomes

- These pass into cytoplasm and are the site of protein assembly

Question 15

What is the structure of the nuclear envelope

Answer 15

• Surrounds nucleus
• It is 2 membranes with fluid between them
• Nuclear pores go through the envelope

Question 16

What is the function of the Nuclear envelope?

Answer 16

The pores in the envelope allow passage of relatively large molecules

Question 17

Describe the structure of the Rough Endoplasmic reticulum

Answer 17

• Flattened membrane sacs called cisternae
• Continuous with outer nuclear membrane
• Studded with ribosomes

Question 18

Describe the function of the Rough Endoplasmic Reticulum

Answer 18

• Transports proteins made on attached ribosomes
• Some of these proteins are secreted from the cell
• Some are placed on the cell surface membrane

Question 19

Describe the structure of the Smooth Endoplasmic reticulum?

Answer 19

• Flattened membrane sacs called Cisternae
• Continuous with outer nuclear membrane
• NO RIBOSOMES LIKE RER

Question 20

What is the function of the Smooth Endoplasmic Reticulum?

Answer 20

Involved in essential lipid production

Question 21

Describe the structure of the Golgi apparatus

Answer 21

A stack of membrane bound flattened sacs

Question 22

What is the function of the Golgi apparatus?

Answer 22

• Receives proteins from the SER and modifies them
• Packages modified proteins into vesicles for transportation
• Some are then secreted from surface of the cell

Question 23

Describe the structure of a Ribosome

Answer 23

• No outer membrane
• Tiny organelles
• Each consists of 2 sub units

Question 24

Where in the cell are ribosomes found?

Answer 24

Some in the Cytoplasm, some bound to the RER

Question 25

What is the function of Ribosomes?

Answer 25

- Site of protein synthesis in the cell | - Act as an assembly line where mRNA is used to assemble proteins from Amino Acids

Question 26

Describe the structure of Mitochondria

Answer 26

- Spherical/sausage shaped - Double membrane - Membrane separated by a fluid filled space - Highly folded inner membrane forms Cristae - Central part called matrix

Question 27

What is the function of Mitochondria

Answer 27

- Site of ATP production | - Powerhouse of the cell

Question 28

Describe the structure of Lysosomes

Answer 28

- Spherical sacs | - Surrounded by single membrane

Question 29

What is the function of Lysosomes?

Answer 29

- Contain powerful digestive enzymes | - Enzymes break down materials

Question 30

Where are Chloroplasts found?

Answer 30

Plants and some protoctists

Question 31

Describe the structure of Chloroplasts

Answer 31

- Double membrane - Separated by a fluid filled space - Continuous inner membrane with network of flattened membrane sacs called Thylakoids

Question 32

Describe the structure of the Cell Surface Membrane

Answer 32

Continous outer membrane and cell receptors present on surface

Question 33

What is the function of the cell surface membrane?

Answer 33

- Selectively permeable - Controls exchange between cell and environment - Receptors on cell surface allow for Endocytosis and Exocytosis

Question 34

Describe the Structure of Centrioles

Answer 34

- Two bundles of Microtubules | - Small tubes of Tubulin protein fibres

Question 35

Where are Centrioles found?

Answer 35

In a pair next to nucleus of animal cells

Question 36

What is the function of Centrioles?

Answer 36

- Take part in cell division | - Form spindle fibres, moving chromosomes in cell division

Question 37

Describe the structure of Flagella

Answer 37

- Extension sticking out from the cell - Cylinder contains nine microtubules arranged in a circle - Long - Usually present in 1 or 2

Question 38

What is the function of Flagella

Answer 38

- Acts as a ‘Tail” | - Enables movement

Question 39

Describe the structure of Cilia

Answer 39

- Hair-like extensions - Stick out from the cell surface - Cylinder contains nine microtubules arranged in a circle - Short - Usually present in large numbers

Question 40

What is the function of Cilia?

Answer 40

- ‘Hairs’ | - Allow for movement of substances

Question 41

What is a Cytoskeleton?

Answer 41

A network of fibres made from proteins

Question 42

What are the two components of the Cytoskeleton?

Answer 42

Actin filaments and microtubules

Question 43

What do the Actin filaments in the Cytoskeleton cause?

Answer 43

They move against each other causing the movement seen in WBC’s. They also move some organelles around within the cell

Question 44

What are Microtubules made from?

Answer 44

Tubulin

Question 45

What are Microtubules in the Cytoskeleton used to do?

Answer 45

To move microorganisms through a liquid, or waft a liquid past a cell

Question 46

What is the role of the Cytoskeleton?

Answer 46

- Provide mechanical strength for the cell - Aids transport within cell - Enables cell movement

Question 47

In what two ways does the Cytoskeleton aid transport within the cell?

Answer 47

- Movement of chromosomes during cell division | - Movement of vesicles from the ER to Golgi

Question 48

What type of Ribosomes are present in Eukaryotes?

Answer 48

80s ribosomes

Question 49

What type of Ribosomes are present in Prokaryotes?

Answer 49

70s Ribosomes

Question 50

What are Prokaryote cell walls made out of?

Answer 50

Peptidoglycan

Question 51

What are Eukaryote cell walls made out of?

Answer 51

Plants - Cellulose | Fungal - Chitin

Question 52

How is DNA stored in Eukaryotes compared to in Prokaryotes?

Answer 52

In Eukaryotes = Stored as Chromosomes within nucleus | In Prokaryotes = DNA is free in Cytoplasm in a single loop and some other little loops called plasmids

Question 53

Where does ATP production take place in Prokaryotes compared to Eukaryotes?

Answer 53

In Prokaryotes = In the cell surface membrane | In Eukaryotes = In the Mitochondrial Cristae

Question 54

What type of respiration happens in Prokaryotic vs Eukaryotic cells?

Answer 54

In Eukaryotes = Strictly aerobic only | In Prokaryotes = Sometimes capable of anaerobic respiration