Cell Structure Flashcards
Outline a method a student could use to prepare a wet mount using a light microscope
.thin section of tissue
. using a pipette drop water at centre of sample
. add stain to the edge of sample
. place coverslip at 45
degrees
describe how light microscopes work (6 marks)
- clip slide on stage
- use lowest powered objective lens
- use coarse adjustment knob to bring stage up
- look down eyepiece and continue using the coarse adj. knob until its focused
- use fine adjustment knob to focus till you get a clear image
what are the limitations of using a light microscope?
. low resolution: resolution of 200 nm
. low magnification: magnification of x1500
define magnification and resolution
magnification: how much bigger the image is compared to the original
resolution: the ability to see in detail
difference between TEM and SEM
TEM - beam of e- passed through specimen
SEM - e- dont pass through they bounce off
why do samples need to stained for light microscopes?
- higher contrast
- see internal structures more clearly
- organelles bind to stain
state the magnification and resolution of an optical microscope
M: x1500
R: 200 nm
state the magnification and resolution of a TEM
M: x500 000
R: 0.02 nm
state the magnification and resolution of a SEM
M: x100 000
R: 0.2 nm
explain how to measure the diameter of a cell using a light microscope
- use eyepiece graticule
- calibrate using stage micrometer
- measure diameter
- calculate a mean diameter
describe the function of the nucleus
controls cells activities
pores allow substances to enter and exit the nucleus
nuclear envelope - double membrane
nucleolus makes ribosomes
describe the structure and function of the ER
fluid filled space
- RER: covered with ribosomes, for protein synthesis and transport
- SER: lipid synthesis
describe the structure and function of the golgi apparatus
flattened sacs
membrane bound
packages and processes lipids and proteins
makes vesicles,lysosomes and glycoproteins
describe the structure and function of ribosomes
syntheises proteins
on RER
floats freely in cytoplasm
describe the structure of the mitochondrion
double membrane
folded inner membrane forms cristae
fluid matrix
describe the structure of the chloroplast
double membrane
thylakoids
lamellae
stroma
describe the structure and function of lysosomes
single membrane
releases hydrolytic enzymes (lysozymes)
digests phagosome
describe the structure and function of a plant cell wall
made of cellulose
supports plant cells
what are bacterial and fungal cell walls made of
peptidoglycan
chitin
describe the structure and function of centrioles
hollow cylinders
made of microtubules
seperates chromosomes
describe the structure and function of the flagella
hollow helical tube
made of flagellin
9+2 formation
microtubules contract to make it move
describe the structure and function of cilia
hair-like structures found on cell surface membrane of animal cells
9+2 formation of microtubule
contract to make it move
why is the cytoskeleton important
mechanical strength
support
movement of chromosomes
movement of cilia and flagella
how are prokaryotic and eukaryotic cells similar
both have:
cell membrane
cytoplasm
ribosomes
how are prokaryotic and eukaryotic cells different
P:
unicellular
no membrane bound organelles / nucleus
circular DNA
small ribosomes
binary fission
peptidoglycan
E:
multicellular
have membrane bound organelles
linear DNA
larger ribosomes
sexual reproduction
cellulose cell wall
state the unit conversions
m - cm divide by 100
cm - mm divide by 10
mm - um divide by 1000
um - nm divide by 1000
