Cells

Question 1

what is magnification ?

Answer 1

the number of times larger the image is compared to the object

Question 2

what is resolution ?

Answer 2

the closest two points can be and still be distinguished as separate, giving the clarity of the image

Question 3

magnification =

Answer 3

image size/object size

Question 4

how many nano / micro meters in a mm ?

Answer 4

nano - 1x10’6

micro - 1x10’3

Question 5

Describe the light microscope

Answer 5

• uses light
• max resolution is .2 micrometers
• max magnification is x1500
• consists of 2 glass lenses (eyepiece and objective)

Question 6

where is the image created from the microscope?

Answer 6

retina

Question 7

what limits the magnification of the light microscope?

Answer 7

wavelength of light

Question 8

Describe the laser scanning confocal microscope

Answer 8

• use laser beams to scan fluorescent dyed specimen
• laser causes dye to give off light, which is focused through a pinhole onto a detector (hooked to a comp), generating an image

Question 9

why is a laser scanning confocal microscope better than a light microscope?

Answer 9

pinhole means any out-of-focus light is blocked, producing a clearer image
also can look at objects at different depths

Question 10

what are prokaryotic cells ?

Answer 10

small simple cells that belong to single - celled organisms

Question 11

what are eukaryotic cells ?

Answer 11

complex cells that belong to mulit - cellular organisms

Question 12

function of sap vacuole ?

Answer 12

storage space for salts / sugars / proteins and waste

Question 13

function of middle lamella ?

Answer 13

cements 2 adjoing cells together at cell wall

Question 14

function of plasmodesma ?

Answer 14

channel through cell wall that allows molecules and substances through

Question 15

function of mitochondrion ?

Answer 15

site of aerobic respiration, where ATP is produced

Question 16

function of ribosome ?

Answer 16

site of protein production

Question 17

function of rough endoplasmic recticulum ?

Answer 17

folds and processes proteins

Question 18

function of smooth endoplasmic recticulum ?

Answer 18

synthesises and processes lipids

Question 19

function of golgi body ?

Answer 19

processes and packages new lipids / proteins

makes lysosomes

Question 20

function of lysosome ?

Answer 20

contains digestive enzymes to digest invading cells or break down worn out components

Question 21

function of centriole ?

Answer 21

involved with chromosome separation during cell division

Question 22

function of spindle ?

Answer 22

forms protein structure that divides the genetic material in a cell

Question 23

function of nuclear membrane ?
(a.k.a. nuclear envelope)

Answer 23

membrane around nucleus that keeps nucleoplasm contained

Question 24

function of nuclear pore ?

Answer 24

allows transport of molecules across nuclear membrane

Question 25

function of microvillus ?

Answer 25

increases surface area for absorption and secretion functions

Question 26

function of cilium ?

Answer 26

moves substances along the cell surface

Question 27

function of nucleolus ?

Answer 27

makes ribosomes

Question 28

function of vesicle ?

Answer 28

transports substances in and out of cell and between organelles

Question 29

describe the process of (out-of-cell) protein production

Answer 29

- ribosomes make proteins - proteins folded / processed in rough ER - transported to golgi body in vesicles - further processing in golgi body - vesicles transport proteins to surface - proteins excreted

Question 30

whats the difference with in-cell protein production ?

Answer 30

proteins made at free ribosomes

Question 31

what is the cytoskeleton ?

Answer 31

network of protein threads in the cytoplasm, arranged as micro filaments (solid strands) and micro tubules (cylinders)

Question 32

functions of the cytoskeleton :

Answer 32

- supports organelles - strengthens and holds cell's shape - responsible for movement of materials - can cause cell to move, e.g. cilia and flagella

Question 33

differences of prokaryotes (P) and eukaryotes (E) | 7 differences

Answer 33

- E have larger cells - E DNA is linear / P DNA is circular - E have a nucleus - P have polysaccharide cell walls / E have cellulose or chitin - P have less organelles and no membrane-bound organelles - E have larger ribosomes - P have flagella made of protein flagellin in helix / E made of microtubule proteins arranged in 9+2

Question 34

what differences are there between and electron microscope and a light microscope?

Answer 34

electron microscope uses electrons to form an image | they have higher resolution (so have higher magnification)

Question 35

Describe Transmission Electron Microscopes

Answer 35

Uses electromagnets to focus a beam of electrons through the specimen. Denser parts absorb more electrons, making them darker. Good because provide high resolution but only used on thin specimens.

Question 36

Describe Scanning Electron Microscopes

Answer 36

Scans a beam of electrons across a specimen, knocking off electrons which are gathered in a cathode ray tube to form an image. Can be 3D but lower res than TEMs

Question 37

what is the res of all 3 microscopes ?

Answer 37

LM : 0.2 micro m TEM : 2x10'-4 micro m SEM : 2x10'-3 micro m

Question 38

what is the magnification of all 3 microscopes ?

Answer 38

LM : x 1500 TEM : > x 1,000,000 SEM : < x 500,00

Question 39

7 stages of preparing a section :

Answer 39

fixation - dehydration - clearing - embedding - sectioning - staining - mounting

Question 40

Describe the fixation stage

Answer 40

specimen soaked in a fixative (chemical) which preserves and stops the material from changing

Question 41

Describe the dehydration stage

Answer 41

remove water with dehydrating agent (ethanol)

Question 42

Describe the clearing stage

Answer 42

drive out the alcohol by putting into a clearing agent

Question 43

Describe the embedding stage

Answer 43

heat wax, put in specimen and leave to cool | this will support it and allow you to carve off a section

Question 44

Describe the sectioning stage

Answer 44

cut off a section of the specimen, which will be measured in micro meters

Question 45

Describe the staining stage

Answer 45

use appropriate staining chemical (dye for LM / melted lead for EM) which will attach to organelle's chemical (e.g. if looking at cell wall, attaches to cellulose)

Question 46

Describe the mounting stage

Answer 46

put on slide, put on appropriate liquid, put on cover slip

Question 47

describe structure of mitochondrion

Answer 47

- 2 membranes - inner membrane is folded to form cristae (crista) - inside is matrix (has enzymes for respiration)

Question 48

describe structure of chloroplast

Answer 48

- contains granum / stroma / lamella - photosynthesis occurs in stroma / grana - 2 membranes + thylakoid membrane inside

Question 49

what is centriole made up from ?

Answer 49

micro tubules

Question 50

describe structure of cilia

Answer 50

ring of 9 pairs of protein micro tubules, with 2 in the middle (known as 9 + 2 formation)

Question 51

describe strucutre of flagellum

Answer 51

9 + 2 formation

Question 52

what does Golgi body make ?

Answer 52

lysosomes