CELLS 1 (fractionation, microscopes & viruses)

Question 1

what is the resolution of an optical microscope (light)?

Answer 1

200nm

Question 2

what is the resolution of a SEM microscope?

Answer 2

20nm

Question 3

what is the resolution of a TEM microscope?

Answer 3

0.1nm

Question 4

which type of microscope forms coloured images?

Answer 4

Light only. NOT ANY ELECTRON

Question 5

which microscope type produces 3D images?

Answer 5

SEM

Question 6

what is the difference in electron beam firing in the two types of electron microscope?

Answer 6

SEM: electron beam fired and bounce off of sample, then focus on a fluorescent screen

TEM: electron beams fired through sample

Question 7

Which microscope has biggest resolution and magnification?

Answer 7

transmission electron microscope

Question 8

equation for magnification

Answer 8

mag = image/actual
I
A M

Question 9

what’s some drawbacks of an electron microscope?

Answer 9

B+W image only, expensive, need training to use, samples in vacuum ( electrons absorbed by air)

Question 10

why is electron microscope sample in a vacuum?

Answer 10

Electrons are absorbed by the air, so the beam wouldn’t reach the specimen.

Question 11

what is the relationship between wavelength and resolution?

Answer 11

inversely proportional.
increase wavelength = down res.

Question 12

why is the resolution higher in a TEM microscope than light microscope?

Answer 12

light has a longer wavelength than electrons.

Question 13

how to convert between micrometers (μm) and nanometres (nm)

Answer 13

μm -> nm
= x1000

Question 14

mm -> μm conversion

Answer 14

x1000

Question 15

define resolution

Answer 15

the ability to distinguish between 2 points on an image

Question 16

what is the order of units. biggest to smallest?

Answer 16

cm -> mm -> μm -> nm

Question 17

define magnification

Answer 17

how much bigger a sample appears to be under a microscope than it is irl.

Question 18

positives of a light microscope over electron.

Answer 18

portable, cheap, easy to use, live samples, colour image

Question 19

define cell fractionation

Answer 19

separating cell organelles out by breaking them up to produce a pure sample of one organelle

Question 20

order of density of organelles

Answer 20

nucleus, chloroplast, mitochondria, lysosomes, rough er, plasma membrane, smooth er, ribosomes

Question 21

which organelle is separated last into the pellet in cell fractionation?

Answer 21

ribosomes

Question 22

which organelle is separated first into the pellet in cell fractionation?

Answer 22

nucleus

Question 23

what are organelles separated by in cell fractionation?

Answer 23

order of density. biggest to smallest.

Question 24

what is meant by homogenisation in cell fractionation?

Answer 24

when the cells are broken open in a blender or homogeniser

Question 25

what are samples spun in during cell fractionation?

Answer 25

centrifuge

Question 26

what is the liquid that rises in cell fractionation called?

Answer 26

The supernatant, re-spunfaster each time until only pellet remains.

Question 27

why do you put the tissues into ice cold mixture in in cell fractionation?

Answer 27

To reduce enzyme activity to prevent digestion of organelles

Question 28

why do you put the tissues into isotonic mixture in cell fractionation?

Answer 28

it has the same water potential as the tissue to prevent osmotic damage eg shrinking due to pressure changes

Question 29

why do you put the tissues into buffer solution in cell fractionation?

Answer 29

so the pH is constant to avoid protein denaturation

Question 30

what is the role of cell fractionation

Answer 30

to study a particular organelles function and structure

Question 31

what type of cell is a virus?

Answer 31

its acellular because it does not have a cellular structure

Question 32

what's a virus made of?

Answer 32

nucleic acids surrounded by capsid proteins

Question 33

what's a viruses capsid?

Answer 33

The protein coat around the nucleic acid virus core

Question 34

how do viruses replicate?

Answer 34

- attachment proteins to bind to complementary receptor proteins on a host cell surface - inject dna to host cells - host cell replicates

Question 35

what's the role of attachment proteins on a virus?

Answer 35

- to bind to host cells in order to replicate.

Question 36

what enzyme do viruses use to insert its RNA into host cells dna

Answer 36

reverse transcriptase enzymes