chapter 2 - cell structure

Question 1

ultrastructure

Answer 1

the detail revealed by the electron microscope

Question 2

organelles

Answer 2

the structures found inside the cell

Question 3

staining

Answer 3

coloured chemicals that bind to molecules in a specimen

Question 4

uses of stains

Answer 4

• makes cells visible; so they can be seen
• increases contrast; different components of a cell take up different amounts of the stain
• detail inside the cell can be seen ie organelles

Question 5

examples of stains

Answer 5

iodine solution - stains starch
blue methylene blue - stains living cells blue
acetic orcein - stains nuclei and chromosomes red

Question 6

differential staining

Answer 6

using more than one stain to provide contrast ie between different organelles/organisms

Question 7

magnification

Answer 7

the number of times larger an image is compared with the actual size of the object

Question 8

resolution

Answer 8

the ability to distinguish between two separate points that are very close together - gives clarity

Question 9

magnification equation

Answer 9

magnification = image size / actual size

Question 10

function of cromatin in nucleus

Answer 10

contains DNA that codes for proteins; during cell division chromatin condenses into chromosomes

Question 11

function of nuclear envelope in nucleus

Answer 11

double membrane that encloses DNA and keeps it separate from reactions in the cytoplasm

Question 12

function of nuclear pores in nucleus

Answer 12

allows entry of molecules for DNA replication and exit of RNA for protein synthesis

Question 13

function of nucleolus in nucleus

Answer 13

manufactures ribosomes

Question 14

function of cisternae in endoplasmic reticulum

Answer 14

allow transport within cell

Question 15

function of rough ER

Answer 15

synthesise and transport proteins

Question 16

function of smooth ER

Answer 16

synthesise and transport lipids and steroids

Question 17

function of ribosomes

Answer 17

carry out protein synthesis

Question 18

function of cisternae in golgi apparatus

Answer 18

modifies proteins and packages them into vesicles or lysomes

Question 19

function of secretory vesicles in golgi apparatus

Answer 19

fuse with cell surface membrane to release hormones or enzymes from the cell

Question 20

function of vesicles in lysomes

Answer 20

isolate potentially harmful enzymes from the cell

Question 21

wavelength of a beam of electrons

Answer 21

0.004nm

Question 22

how does a scanning electron microscope (SEM) work?

Answer 22

electrons knocked off the specimen are detected

Question 23

what are SEMs useful to study?

Answer 23

surfaces of objects

Question 24

what type of image do SEMs produce?

Answer 24

3D images

Question 25

what is the maximum magnification of SEM?

Answer 25

x200,000

Question 26

what is the resolution of SEM?

Answer 26

2nm

Question 27

how do transmission electron micrsope (TEM) work?

Answer 27

electrons that pass through the specimen are detected

Question 28

what type of image do TEM produce?

Answer 28

2D images

Question 29

what are TEMs useful to study?

Answer 29

the inside of objects

Question 30

what is the maximum magnification of TEM?

Answer 30

x2,000,000

Question 31

what is the resolution of TEM?

Answer 31

0.2nm

Question 32

function of double membrane in mitochondria

Answer 32

isolates products from aerobic respiration

Question 33

function of cristae in mitochondria

Answer 33

increases surface area for enzymes to be attatched

Question 34

function of matrix in mitochondria

Answer 34

contains ribosomes for protein synthesis

Question 35

function of circular DNA in mitochondria

Answer 35

codes for proteins

Question 36

function of enzymes in mitochondria

Answer 36

for aerobic respiration

Question 37

function of double membrane in chloroplasts

Answer 37

isolate photosynthesis reactions

Question 38

function of thylakoids in chloroplasts

Answer 38

increases surface area for chlorophyll molecules to be attatched

Question 39

function of stroma in chloroplasts

Answer 39

contains enzymes for photosynthetic reactions

Question 40

function of starch grains in chloroplasts

Answer 40

carbohydrate store

Question 41

function of small ribosomes in chloroplasts

Answer 41

protein synthesis

Question 42

function of DNA in chloroplasts

Answer 42

codes for proteins

Question 43

function of lipid droplets

Answer 43

for membranes

Question 44

function of centrioles

Answer 44

form spindle fibres during nuclear division to control the separation of chromatids and chromosomes

Question 45

structure of cytoskeleton

Answer 45

- microtubules (fine hollow tubes) - microfilaments (small solid protein strands) - intermediate filaments (more stable protein strands)

Question 46

function of cytoskeleton

Answer 46

- support cell organelle position - enable movement of organelles ie vesicles and proteins - strengthen cell and maintain shape

Question 47

structure of cilia and flagella

Answer 47

composed of 2 central microtubules surrounded by 9 pairs

Question 48

structure of vacuole

Answer 48

cell sap is contained within the tonoplast (vacuolar membrane)

Question 49

function of vacuole

Answer 49

maintains turgor for support and provides storage ie for dissolved sugars and enzymes

Question 50

function of cellulose in cell wall

Answer 50

provides support and protection and allows cell to become turgid. prevents osmotic bursting of the cell

Question 51

function of plasmodesmata in cell wall

Answer 51

links neighbouring cells

Question 52

function of middle lamella in cell wall

Answer 52

cements neighouring cells together

Question 53

division of labour in protein synthesis

Answer 53

1 - nucleolus manufactures ribosomes 2 - nuclear pores allow molecules to move in and out of the nucleus 3 - ribosomes can be found on the rough endoplasmic reticulum and carry out protein synthesis 4 - ER transports proteins to the Golgi apparatus 5 - Golgi apparatus modifies and packages proteins into vesicles 6 - vesicles bind to the cell surface membrane and proteins are expelled

Question 54

structures always found in prokaryotic cells

Answer 54

- circular DNA - cell surface membrane - cytoplasm - ribosomes - cell wall - cytoskeleton

Question 55

structures sometimes found in prokaryotic cells

Answer 55

- pili - plasmids - slime capsule - mesosome - infolding of plasma membrane - flagellum

Question 56

function of pili

Answer 56

for attatchment to other cells or surfaces; involved in "sexual" reproduction

Question 57

plasmids

Answer 57

small circles of DNA; can confer antibiotic resistance

Question 58

function of mesosome

Answer 58

associated with DNA during cell division helps with formation of new cell walls aerobic respiration occurs here

Question 59

function of infolding of plasma membrane

Answer 59

may form photosynthetic membrane or carry out nitrogen fixation

Question 60

function of flagellum

Answer 60

for locomotion (movement)