Cells and microscopy

Question 1

How does an optical microscope work?

Answer 1

direct light through specimen

light focused through objective lens

image viewed through eyepiece lens

Question 2

What is calibration?

Answer 2

uses a stage micrometre (a second scale in micrometres on the slide)

Question 3

How does cell fractionation work?

Answer 3

Cells broken open in homogeniser, tissue suspended in buffer solution and kept cold

filtered using a gauze - removes large tissue

centrifuge- pow speed , large organelles form pellet

supernatant spun again, smaller organelles form pellet

Question 4

What is magnification?

Answer 4

how many times the bigger the image is

Question 5

What is resolution?

Answer 5

the ability to see 2 structures very close together as separate structures

Question 6

what are the advantages of optical microscopes

Answer 6

live specimens can be used

cheap

Question 7

what are the disadvantages of optical microscopes?

Answer 7

lower resolving power

Question 8

what are the advantages of electron transmission microscopes?

Answer 8

high resolving power

can see viruses, ribosomes, cell surface membranes

magnification up to x1,000,000

Question 9

What are the disadvantages of electron transmission microscopes?

Answer 9

live specimens cannot be used

artefacts can occur

Question 10

what are the advantages of an electron scanning microscope?

Answer 10

3D

High resolving power

Question 11

what are the disadvantages of electron scanning microscope

Answer 11

no live specimens

artefacts can occur

Question 12

How big are bacterial cells?

Answer 12

0.1- 10 micrometres

Question 13

what are bacterial cell walls made from?

Answer 13

meurin

Question 14

What do some bacterial cells secrete?

Answer 14

a capsule of mucilaginous slime

Question 15

Give five comparisons of prokaryotic feels and eukaryotic cells

Answer 15

Prokaryotic- no true nucleus, eurkarytoic - nucleus with nuclear envelope

prokaryotic- no membrane bound organelles

prokaryotic- ribosomes are smaller - 70s, 80s in eukaryotic cells

Prokaryotic cell wall made is murein , in eukaryotes, cellulose

prokaryotic cell have plasmid DNA, DNA is linear in eukaryotes

Question 16

What is the structure of the cell surface membrane?

Answer 16

Phospholipid bilayer

carrier proteins embedded in membrane

glycoproteins attaches to protein

Question 17

what is the function of a cell surface membrane?

Answer 17

keeps unwanted substances out

allows transport of nutrients into cell and waste products out

Question 18

What is the structure of the nucleus?

Answer 18

nuclear envelope with nuclear pores

nucleoplasm

contains DNA

Question 19

What is the function of the nucleus ?

Answer 19

Nucleolus makes tRNA

Nucleus contains DNA

Question 20

What is the structure of the mitochondrion ?

Answer 20

double membrane

inner layer forms cristae

mitochondrial matrix

has own dna and ribosomes

Question 21

what is the function of the mitochondrion?

Answer 21

produces ATP during aerobic respiration

Question 22

What is the structure of a lysosome ?

Answer 22

contains digestive enzymes (hydrolytic) which fuse with cell membrane to release

Question 23

what is the function of the lysosome?

Answer 23

phagocytosis

recycling

Question 24

what is the structure of a ribosome?

Answer 24

does not have a membrane

rRNA and protein

large unit - binding sites for tRNA

small unit- binding sites for mMRA

Question 25

what is the role of a ribosome ?

Answer 25

site of translation protein synthesis

Question 26

what is the structure of the rough endoplasmic reticulum?

Answer 26

fluid filled cisternae covered with ribosomes vesicles can pop off

Question 27

what is the function of the RER?

Answer 27

proteins folded into secondary and tertiary structures

Question 28

what is the structure of the SER?

Answer 28

a series of tubes (cisternae )

Question 29

what is the role of the SER?

Answer 29

synthesises lipids

Question 30

what is the structure of the golgi apparatus?

Answer 30

stack of flattened sacs plasma membrane vesicles pinches off cisternae

Question 31

what is the function of the golgi?

Answer 31

packages and processes molecules for use in other parts of the cell or to export out the cell

Question 32

What is the structure of the cell wall?

Answer 32

cellulose in plants chitin in fungi meurin in bacteria permeable cellulose microfibrils embedded with pectin

Question 33

what is the function of the cell wall?

Answer 33

provides cell with strength resists beinf expanded

Question 34

What is the structure of the vacuole?

Answer 34

tonoplast, thin membrane cell sap

Question 35

what is the function of the vacuole?

Answer 35

structural support storage, waste , protection

Question 36

what is the structure of chloroplasts

Answer 36

inner and outer membrane with empty space between thylakoids , grana and stroma(dense fluid inside) thylakoids contain chlorophyll

Question 37

What is the function of chloroplasts?

Answer 37

site of photosynthesis

Question 38

what is the structure of centrioles?

Answer 38

two rings of microtubules positioned at right angles to each other

Question 39

what is the functions of centrioles ?

Answer 39

produce spindle fibres

Question 40

What is the cytoplasm?

Answer 40

70% water metabolic reactions

Question 41

what is a phospholipid ?

Answer 41

a lipid molecule with glycerol, two fatty acid chains and a phosphate group

Question 42

PROKARYOTIC What organelles are in a prokaryotic cell?

Answer 42

cell wall- muerin cell surface membrane circular DNA food reserve granule ribosomes plasmids slimy capsule cytoplasm flagellum

Question 43

How much smaller are viruses than bacteria?

Answer 43

50x smaller viruses are acellular replicate inside a living cell

Question 44

VIRUS What is the viral structure?

Answer 44

Capsid made of capsomeres genetic material