2.1 Cell structure

Question 1

What is a light microscope?

Answer 1

A microscope that uses visible light to magnify and observe small objects or organisms that are living.

Question 2

What are the advantages of light microscopes?

Answer 2

You can view specimens in colour.
You can view specimens in real time.

Question 3

What are the disadvantages of light microscopes?

Answer 3

It has a low magnification (*1500)
It has a low resolution (200mm)
It is difficult to see organelles of the cell.

Question 4

How do you calculate magnification?

Answer 4

Magnification = image size / Actual size

Question 5

What can you see with a light microscope?

Answer 5

Even at maximum magnification, it is only possible to observe the larger features of the cells such as the nucleus or chromosomes during mitosis.

Question 6

What are the two different types of electron microscopes?

Answer 6

Transmission electron microscope
Scanning electron microscope

Question 7

How does a transmission electron microscope work?

Answer 7

It uses electrons to produce 2D image of the inside of a cell. they have a maximum magnification of *200,000

Question 8

How does a scanning electron microscope work?

Answer 8

It uses a beam of electrons to produce 3D images of the outside surface of cells. they have a maximum magnification of *200,000

Question 9

What are the advantages of electron microscopes?

Answer 9

Higher resolution and magnification capabilities

Question 10

What are the disadvantages of electron microscopes?

Answer 10

You can only view dead specimens
Specimens can be viewed only in black and white
Expensive and need training to use them.

Question 11

What is a laser scanning microscope?

Answer 11

it uses lasers to produce images at different depths within the cell.

Question 12

What are the advantages of laser scanning microscopes?

Answer 12

You can view living cells in colour,
You can observe cells in real time,
Sections can be made through the cell either vertically or horizontally.

Question 13

What are the disadvantages of laser scanning microscopes?

Answer 13

Magnification and resolution are low compared to electron microscopes,
require training to use them,
Expensive

Question 14

What is magnification?

Answer 14

The number of times greater the image is then the specimen.

Question 15

What is resolution?

Answer 15

The ability to distinguish between two points on an image. the higher the resolution, the sharper the image.

Question 16

What are the different types of microscopes?

Answer 16

Light microscopes,
Transmission electron microscope,
Scanning electron microscope,
Laser scanning microscope

Question 17

How do you prepare a microscope slide?

Answer 17

Take a thin slice of your specimen and place it onto a clean microscope slide, add a drop of water or stain onto the specimen, take a clean cover slip and lower onto the specimen, taking care to avoid air bubbles.

Question 18

Why are stains used?

Answer 18

To highlight particular organelle, e.g. red blood cells and white blood cells.
To distinguish different tissue types, e.g. smooth muscle tissue.

Question 19

How do you use an eyepiece graticule?

Answer 19

Line up the eyepiece graticule and the stage micrometer, using the *4 objective lens. Once lined up you can use it to measure objects on the microscope stage.

Question 20

What is the function of the nucleus?

Answer 20

The nucleus is the control centre of the cell, responsible for storing and protecting the cell’s DNA, and regulating gene expression and cell activities.

Question 21

What is the function of the nucleolus?

Answer 21

Ribosome production

Question 22

What is the function of the nuclear envelope?

Answer 22

Separates the nucleus from the cytoplasm and regulate the passage of molecules in and out of the nucleus

Question 23

What is the function of mitochondria?

Answer 23

Energy production and site of respiration.

Question 24

What is the function of the Golgi body?

Answer 24

Protein modification and packaging.

Question 25

What is the function of the rough endoplasmic reticulum?

Answer 25

Contains ribosomes, transport proteins

Question 26

What is the function of the smooth endoplasmic reticulum?

Answer 26

Lipid synthesis and detoxification

Question 27

What is the function of the chloroplasts?

Answer 27

The function of the chloroplasts is to carry out photosynthesis, converting sunlight into chemical energy in the form of glucose.

Question 28

What organelles do eukaryotic cells have?

Answer 28

They are animal, plant and fungi cells. They contain a nucleus, nuclear envelope and nucleolus, cytoplasm, cytoskeleton, plasma membrane, mitochondria, Golgi apparatus, RER, SER< small vesicles and ribosomes.

Question 29

What is the function of the ribosomes?

Answer 29

Protein synthesis

Question 30

What is the function of centrioles?

Answer 30

Cell division - chromosomes attach to spindle and pull them apart. they are involved in formation of cilia and undulipodia and absent in higher plants.

Question 31

What is the function of the cytoskeleton?

Answer 31

Structural support and cell movement

Question 32

What is the function of the cellulose cell wall?

Answer 32

It provides the cell walls of plants with support and strength, maintains the cells shape, contributes to strength and support of the whole plant, are permeable and allow solutions to pas through

Question 33

How are proteins made?

Answer 33

they are produced by the nucleus and ribosomes by the processes of transcription and translation.

Question 34

How are proteins produced?

Answer 34

Each gene in the nucleus codes for a particular protein. When the cell wants to make a protein, a messenger RNA (mRNA) copy is made of the gene. The mRNA moves out of the nucleus and travels to ribosomes on the rough ER. Ribosomes translate the mRNA and produce the protein. The protein travels through the rough ER and is packaged into vesicles to travel to the Golgi body.

Question 35

What organelles do prokaryotic cells have?

Answer 35

Like eukaryotic cells they have a plasma membrane, cytoplasm, ribosomes for assembling amino acids into proteins, DNA and RNA. They also differ as they are much smaller, have less well-developed cytoskeleton with no centrioles, they don’t have a nucleus, the organelles aren’t membrane-bound and their cell wall is made of peptidoglycan.