Microscopes And Cells

Question 1

What must a specimen be to be observed under a light microscope?

Answer 1

Thin and stained

Question 2

Name and explain the 4 types of mounts

Answer 2

Dry mount: specimen is placed on a slide and covered with a cover slip

Wet mount: specimen is placed on a slide and suspended in a liquid. Then cover slip is added on top at an angle to prevent bubbles

Squash: wet mount is prepared then a lense tissue is used to press down on the cover slip to create a thin layer of specimen

Smear slide: the edge of cover slip is used to smear the specimen over the slide to create a lon layer

Question 3

What is sectioning, and why must it happen?

Answer 3

When specimens are thinly sliced to allow light to pass through

Question 4

Define magnification

Answer 4

How many times larger the image of specimen is compared to the actual size of the specimen

Question 5

Define resolution

Answer 5

The ability to clearly distinguish between 2 organelles

Question 6

Name some properties of electron microscopes

Answer 6

Shorter wavelength
Higher resolution
Vacuum

Question 7

What is the magnification equation?

Answer 7

Magnification = size of image ÷ actual size of specimen

Question 8

Outline how a transmission electron microscope works

Answer 8

An electron beam is transmitted through the specimen with a resolving power of 0.5nm and magnification of ×500,000 and produces a 2d image of specimen

Question 9

Outline how a scanning electron microscope works

Answer 9

Electron beam is sent across the surface of the specimen and is bounced off with a resolving lower of between 3 and 10nm and a magnification of × 100,000 produces a 3d image of specimen

Question 10

What are the 4 preparation methods?

Answer 10

Fixing: using chemicals and freezing

Dehydration: passing specimen through an alcohol bath

Staining: using heavy metals

Sectioning: set in resin to allow the cutting of thin slices

Question 11

What are artefacts?

Answer 11

Visible structures created by the processing of a specimen and is not part of their biological make up

Question 12

What is lazer scanning confocal microscopy?

Answer 12

A single spot of focused lazer light is moved across the specimen causing fluorescent dye to light up, creating a 3d image

Question 13

What are the uses of lazer scanning microscopy?

Answer 13

Development of drugs and non invasive treatment

Question 14

What is the role of the nuclear envelope?

Answer 14

It’s job is to allow mRNA out of the nucleolus through the nuclear pore. It has 2 membranes

Question 15

What is cristae?

Answer 15

The folded inner membrane of mitochondria

Question 16

What are vesicles?

Answer 16

Membrane bound sacs that transport molecules around the cell

Question 17

What are lysosomes?

Answer 17

Specialised cells that break down cellular waste

Question 18

What is the cytoskeleton?

Answer 18

Network of fibres that provide stability in the cella and help vesicles move around

Question 19

What are microfilaments?

Answer 19

Contractile fibres formed from actin involved in cell movement

Question 20

What are microtubules?

Answer 20

Spindle fibres used to pull chromosomes to poles in cell division

Question 21

What is the role of the intermediate fibres?

Answer 21

Help maintain cell integrity

Question 22

What organelles are involved in protein synthesis?

Answer 22

Endoplasmic reticulum, ribosomes, golgi apperatus

Question 23

What is the role of the smooth endoplasmic reticulum?

Answer 23

Lipid storage and production

Question 24

What is the role of the golgi apperatus?

Answer 24

Stacks of single membranes that modify proteins for specific functions

Question 25

Outline protein production

Answer 25

Amino acids chain is synthesised on the ribosomes bound to the RER where they are also packaged into vesicles. They then move to the golgi apperatus to be modified and move using the cytoskeleton to the cell surface membrane where they bind and leave via exocytosis

Question 26

What are the features of the cellulose cell wall?

Answer 26

Permeable and strong

Question 27

What is plasmolosist?

Answer 27

Where water is lost from the cell and so pulls away from the membrane and is unstable

Question 28

What are thylakoids?

Answer 28

Flattened sacs which pile up called grana in chloroplasts and have a large SA:V

Question 29

What are prokaryotic cells?

Answer 29

Cells that have no nucleus or any membrane bound organelles