2.1.1- Cell Structure + Microscopy

Question 1

what are the 3 main microscopes used in biology?

Answer 1

• light microscope
• transmission electron microscope
• scanning electron microscope

Question 2

what is a light microscope?

Answer 2

a microscope that uses light to produce an image.

Question 3

what is a transmission electron microscope?

Answer 3

a microscope where a beam of electrons are transmitted through a specimen, producing a 2D image of the surface of the specimen.

Question 4

what is a scanning electron microscope?

Answer 4

a microscope where a beam of electrons are sent across the surface of a specimen, producing a 3D image.

Question 5

what is a laser scanning confocal microscope?

Answer 5

when a stained (with fluorescent dye) specimen is hit with a laser that filters through, producing an image.

Question 6

compare the light microscope + T + S electron microscope?

Answer 6

• wavelength= L= 400nm, E=0.4nm
• resolution= L= 200nm, T=0.2nm, S= 3-10nm
• magnifaction= L=1500x T= 500,000x, S=100,000x
• image= L=natural colour, E=black+white (enhanced)
• specimen= L=living/non-living, E=non,living, stain/vacuum kill it
• easy? L= yes easy E=no, difficult due to preparation

Question 7

what staining is used for light microscopes?

Answer 7

coloured chemicals/fluorescent dyes

Question 8

what staining is used for electron microscope?

Answer 8

salts of heavy metal ions/particles

Question 9

why is staining used? 2 reasons?

Answer 9

• enhance visualisation

- to differentiate structures + living/dead cells

Question 10

what is magnification?

Answer 10

the number of times larger an image is compared to the object itself.

Question 11

what is resolution?

Answer 11

the ability to distinguish between objects very close together.

Question 12

what is the equation of magnification?

Answer 12

image size / actual size

Question 13

what is a eukaryotic cell?

Answer 13

a cell that contains a membrane and a membrane-bound nucleus.

Question 14

what is a cytoskeleton?

Answer 14

a network of protein fibres in cell cytoplasm

Question 15

what is the function of the cytoskeleton?

Answer 15

• to give structure + shape
• to move organelles around inside
• to enable movement

Question 16

what is the function and key notes on the NUCLEUS?

Answer 16

function= controls activities of cell, stores + protects DNA
notes= double membrane/nuclear envelope, with pores

Question 17

what is the function and key notes of the NUCLEOLUS?

Answer 17

function= site of ribosome assembly

key notes= composed of RNA + protein, is the inner region of the nucleus

Question 18

what is the function and key notes of the SMOOTH ENDOPLASMIC RETICULUM?

Answer 18

function= lipid + carbohydrate synthesis/storage

key notes= made up of a network of membranes that are bare

Question 19

what is the function and key notes of the ROUGH ENDOPLASMIC RETICULUM?

Answer 19

function= synthesis/transport of proteins between organelles

key notes= a membrane network, studded with ribosomes

Question 20

what is the function and key notes of the GOLGI APPARATUS?

Answer 20

function= involved in sorting, storing, modification + export of secretory products
key notes= assembly of vesicles, folded membranes near cell membranes

Question 21

what is the function and key notes of the RIBOSOMES?

Answer 21

function= makes proteins for amino acids

key notes= no membrane, made of RNA/protein, found on RER or free

Question 22

what is the function and key notes of the MITOCHONDRION?

Answer 22

function= aerobic respiration

key notes= double membrane, inner membrane, folded into internal cristae

Question 23

what is the function and key notes of the LYSOSOMES/VESICLES?

Answer 23

function= break down waste material

key notes= membrane sacs filled with hydrolytic enzymes, important role in immune system+cell death

Question 24

what is the function and key notes of the CHLOROPLASTS?

Answer 24

function= photosynthesis

key notes= found in green part of plant, double membrane, internal stacks of membranous discs.

Question 25

what is the function and key notes of the CELL MEMBRANE+WALL

Answer 25

``` function of CW= provides strength/protection against mechanical stress function of CM= keep toxic substances out, only allow specific molecules in, protect/organise cell ```

Question 26

what is the function and key notes of the CENTRIOLE?

Answer 26

function= involved in cell division + positioning of structures key notes= hollow cylinders containing ring of microtubules

Question 27

what is the function and key notes of the FLAGELLA?

Answer 27

function= moves cells | key notes= hairlike cylinders, on surface of cells

Question 28

what is the function and key notes of the CILIA?

Answer 28

function= moves liquids across surface | key notes= hairlike cylinders, cells contain a large number

Question 29

what is the function and key notes of the PLANT VACUOLE?

Answer 29

function= store water/solutes, supports plants | key notes= large sac, bound in single membrane, cell can become turgid

Question 30

what is protein secretion?

Answer 30

the method used by organisms to actively move protein molecules manufactured within a cell to the space outside of the cell.

Question 31

what is an example of protein secretion?

Answer 31

cell in pancreas making insulin

Question 32

what is the first step of secretion?

Answer 32

1- NUCLEUS - mRNA copy of instructions for protein hormone is made - mRNA leaves through the nuclear pore

Question 33

what is the second step of secretion?

Answer 33

2- RER/RIBOSOME - mRNA attaches to ribosome, reads instructions to assemble - protein molecules 'pinched off' in vesicle towards gologi

Question 34

what is the third step in secretion?

Answer 34

3-GOLGI - vesicle fuses to golgi, where protein is processed/packaged for release - packaged protein in vesicle transported to cell membrane

Question 35

what is the fourth step in secretion?

Answer 35

4-CELL SURFACE MEMBRANE | -vesicle fuses, opens to release protein outside of cell

Question 36

what are the 3 similarities between eukaryotic cells + prokaryotic cells?

Answer 36

- both contain ribosomes - have a cell wall (plant) - living cells

Question 37

what are the 3 differences between eukaryotic cells + prokaryotic cells?

Answer 37

E=nucleus, P=no true nucleus, DNA carried in single chromosome E=membrane bound, P=no membrane size, E is larger than P

Question 38

what are two examples of staining?

Answer 38

- acid-fast technique | - gram stain technique.

Question 39

what are the steps involved with the gram stain technique?

Answer 39

- apply crystal violet - apply iodine to fix dye - gram positive bacteria= blue/purple - gram negative bacteria= don't take up violet, so safrarin must be added.