Organelles And Microscopes

Question 1

What is the smallest thing that can be seen with a:

Light microscope

Electron microscope

Answer 1

1) mitochondria

2) lipids and other small molecules

Question 2

Formula for magnification

Answer 2

Image/real

Question 3

How many nanometers in a micrometer

Answer 3

1000

Question 4

Light microscope:
Resolution 
Magnification
Ocular lens 
Image produced

Answer 4

200nm

X1500

X10

2D

Question 5

Advantages and disadvantages of light microscope

Answer 5

✅
Portable
Little space
Specimens are easy to prepare
Can see nucleus in cells
❌
Low resolution and magnification as wavelength of light is too long
Cannot see ultrastructure

Question 6

TEM:
Resolution
Magnification 
Image produced
What is it?

Answer 6

0.2nm
X500,000
2D
Beam of electrons is transmitted through s specimen and focused to produce an image

Question 7

Pros and cons of TEM

Answer 7

✅
Used to observe fine detail
High magnification 
❌
Not portable 
2D image 
Expensive equipment

Question 8

SEM:
Resolution
Magnification
Image produced
What is it?

Answer 8

0.2nm
X100,000
3D
A beam of electrons is sent across a surface of specimen and reflected electrons are collected

Question 9

Pros and cons of SEM

Answer 9

✅
3D image
❌
Not portable

Question 10

Name and explain the four types of slide preparation

Answer 10

Dry mount= solid specimen with a cover slip on top
Wet mount= specimens suspended in water or oil cover slip on top
Squash slides= wet mount but using a lens tissue apply pressure to cover slip to squash the specimen
Smear slides= edge of slide is used to smear the specimen then cover slip is added

Question 11

What are the three advantages of staining

Answer 11

• With coloured chemicals that bind to cell organelles and make them visible
• provides a contrast
• allows us to identify different types of cells and organelles

Question 12

Explain the purpose of gram stain technique

Answer 12

Used to see gram positive bacteria with thick peptidoglycan cell walls and gram negative bacteria with thin peptidoglycan cell walls.

Question 13

Describe the process of gram stain technique

Answer 13

The bacteria are taken and crystal violet is added, they are then decolorized using alcohol and counter stained with safranin, the difference in colour allows us to identify which a gram positive and negative bacteria

Question 14

Which bacteria can be killed by penicillin

Answer 14

Gram positive ( it breaks down the cell walls)

Question 15

What is the purpose of acid fast technique

Answer 15

Used to identify mycobacterium (tb) from other bacteria

Question 16

Describe the process of acid fast technique

Answer 16

Carbol fuchsin dye (red) is carried into cells using a lipid solvent, acid/alcohol wash will remove stain from any bacteria but not mycobacterium

Question 17

What is fixing

Answer 17

When chemicals are used to preserve specimens in as near natural state as possible

Question 18

What is sectioning

Answer 18

Specimens are dehydrated and placed in a wax mould to form a hard block- then is thinly sliced with a knife

Question 19

What is staining

Answer 19

When a substance is treated with different coloured chemicals to show the ultra structure

Question 20

What is mounting

Answer 20

The specimens are then secured to a microscope slide with a cover slip

Question 21

Where does most of the reactions take place inside the cell- what separates it

Answer 21

The cytoplasm

Cell surface membrane

Question 22

Describe the structure of the nucleus

Answer 22

Contains genetic information
DNA contained within double membrane called nuclear envelope
Contains pores
Nucleolus- inside nucleus responsible for producing ribosomes

Question 23

What does chromatin do

Answer 23

Creates chromosomes

The chromatic coils and condenses to form the structure

Question 24

What is the job of the nucleolus

What’s it made from

Answer 24

Produces ribosomes

Proteins and RNA

Question 25

Describe the structure of mitochondria

Answer 25

Has double membrane
The inner folding is called cristae
Space inside where DNA is is called matrix

Question 26

Describe vesicles

Answer 26

Membraneous sacs was hat have storage and transport roles in the cell

Question 27

What type of enzymes do lysosomes have

Answer 27

Hydrolytic enzymes

Question 28

Explain microfilaments

Answer 28

Contractile fibres made from the protein actin

Responsible for cell movement and contraction during cytokinesis

Question 29

What is cytokinesis

Answer 29

When cytoplasm of a single cell is divided into two daughter cells

Question 30

What are microtubules

Answer 30

Tubulidentata proteins that polymerise to form tubes that form a scaffold like structure - can also create spindle fibres

Question 31

What are intermediate fibres

Answer 31

Fibres that give mechanicsl strength to cells and help maintain their integrity

Question 32

What is treadmilling

Answer 32

When certain subunits are added at one end and removed at the other

Question 33

Describe the arrangement if cilium

Answer 33

9+2 arrangement

Question 34

What is endosymbiosis

Answer 34

When an organism lives within the cell

Eg mitochondria chloroplast

Acquire double membrane

Question 35

How is dna packaged in a eukaryotes

Answer 35

DNA-wrapped around Histone protein- supercoiled to form chromatin- condenses into chromosome

Question 36

When using a eyepiece graticule: what equals 1EPU

Answer 36

1000 micrometers

Question 37

What happens when using a laser scanning confocal microscope

Answer 37

A high intensity laser is moved across the specimen

This causes fluorescence from the components in the specimen which have been labelled with a dye

Omitted light from the specimen is filtered through a pinhole aperture

Only light from the focused plane is detected

Question 38

Advantages of laser scanning confocal microscopy

Answer 38

No Blur

Very high resolution

Can visualise specific proteins and structures within a cell and watch them move

3D image