Cells and microscopy Flashcards
How does an optical microscope work?
direct light through specimen
light focused through objective lens
image viewed through eyepiece lens
What is calibration?
uses a stage micrometre (a second scale in micrometres on the slide)
How does cell fractionation work?
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
What is magnification?
how many times the bigger the image is
What is resolution?
the ability to see 2 structures very close together as separate structures
what are the advantages of optical microscopes
live specimens can be used
cheap
what are the disadvantages of optical microscopes?
lower resolving power
what are the advantages of electron transmission microscopes?
high resolving power
can see viruses, ribosomes, cell surface membranes
magnification up to x1,000,000
What are the disadvantages of electron transmission microscopes?
live specimens cannot be used
artefacts can occur
what are the advantages of an electron scanning microscope?
3D
High resolving power
what are the disadvantages of electron scanning microscope
no live specimens
artefacts can occur
How big are bacterial cells?
0.1- 10 micrometres
what are bacterial cell walls made from?
meurin
What do some bacterial cells secrete?
a capsule of mucilaginous slime
Give five comparisons of prokaryotic feels and eukaryotic cells
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
What is the structure of the cell surface membrane?
Phospholipid bilayer
carrier proteins embedded in membrane
glycoproteins attaches to protein
what is the function of a cell surface membrane?
keeps unwanted substances out
allows transport of nutrients into cell and waste products out
What is the structure of the nucleus?
nuclear envelope with nuclear pores
nucleoplasm
contains DNA
What is the function of the nucleus ?
Nucleolus makes tRNA
Nucleus contains DNA
What is the structure of the mitochondrion ?
double membrane
inner layer forms cristae
mitochondrial matrix
has own dna and ribosomes
what is the function of the mitochondrion?
produces ATP during aerobic respiration
What is the structure of a lysosome ?
contains digestive enzymes (hydrolytic) which fuse with cell membrane to release
what is the function of the lysosome?
phagocytosis
recycling
what is the structure of a ribosome?
does not have a membrane
rRNA and protein
large unit - binding sites for tRNA
small unit- binding sites for mMRA
what is the role of a ribosome ?
site of translation
protein synthesis
what is the structure of the rough endoplasmic reticulum?
fluid filled cisternae
covered with ribosomes
vesicles can pop off
what is the function of the RER?
proteins folded into secondary and tertiary structures
what is the structure of the SER?
a series of tubes (cisternae )
what is the role of the SER?
synthesises lipids
what is the structure of the golgi apparatus?
stack of flattened sacs
plasma membrane
vesicles pinches off
cisternae
what is the function of the golgi?
packages and processes molecules for use in other parts of the cell or to export out the cell
What is the structure of the cell wall?
cellulose in plants
chitin in fungi
meurin in bacteria
permeable
cellulose microfibrils
embedded with pectin
what is the function of the cell wall?
provides cell with strength
resists beinf expanded
What is the structure of the vacuole?
tonoplast, thin membrane
cell sap
what is the function of the vacuole?
structural support
storage, waste , protection
what is the structure of chloroplasts
inner and outer membrane with empty space between
thylakoids , grana and stroma(dense fluid inside)
thylakoids contain chlorophyll
What is the function of chloroplasts?
site of photosynthesis
what is the structure of centrioles?
two rings of microtubules
positioned at right angles to each other
what is the functions of centrioles ?
produce spindle fibres
What is the cytoplasm?
70% water
metabolic reactions
what is a phospholipid ?
a lipid molecule with glycerol, two fatty acid chains and a phosphate group
PROKARYOTIC
What organelles are in a prokaryotic cell?
cell wall- muerin
cell surface membrane
circular DNA
food reserve granule
ribosomes
plasmids
slimy capsule
cytoplasm
flagellum
How much smaller are viruses than bacteria?
50x smaller
viruses are acellular
replicate inside a living cell
VIRUS
What is the viral structure?
Capsid made of capsomeres
genetic material
