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How to convert from centimetre to millimetre?
x10
How to convert from millimetre to micrometre?
x1000
How to convert from micrometre to nanometre?
x1000
Magnifying power of light microscope
x1500
Resolving power of light microscope
200nm
Magnifying power of electron microscope
x500 000
Resolving power of electron microscope
0.5nm
Why can’t ribosomes be seen using a light microscope?
light wavelengths are too big to interfere with ribosomes which are too small
What is magnification?
how many times bigger the image is when compared to the object
What is resolution?
the minimum distance apart that two objects can be, in order for them to appear as separate items
What is the formula for magnification?
image size / actual size
What needs to be the same when calculating magnification?
units of measurement
What does TEM stand for?
transmission electron microscope
What does SEM stand for?
scanning electron microscope
Do electron microscopes show colour?
No
What can TEM see?
things beyond the surface of the cell
What can SEM see?
the sample’s surface and composition
Specimens in electron microscopes must be…?
dead/in a vacuum
Differences between TEM and SEM?
TEM specimen must be thin, TEM cannot view 3D images
Main difference between prokaryotes and eukaryotes?
prokaryotes don’t have a nucleus
What are the 4 things that make up the nucleus?
nucleolus, chromatin, nuclear pore, nuclear envelope
The nuclear envelope is a ________ membrane?
double
What is chromatin?
DNA when it is not dividing
What are chromosomes?
DNA when it divides
What does the nucleolus produce?
ribosomes and RNA
What are ribosomes made of?
ribosomal RNA and protein
How big are ribosomes?
25nm in diameter
Where are 80S ribosomes found?
cytoplasm and attached to RER
Where are 70S ribosomes found?
cytoplasm and mitochondria, also found in prokaryotes
What is endoplasmic reticulum made of?
cisternae
What is dotted along the surface of RER?
ribosomes
RER is the location of…?
extracellular protein synthesis
RER membrane can be pinched off to form…?
a vesicle
Where is RER found in the cell?
next to he nucleus, sometimes joined to nuclear envelope
What is the function of the SER?
to manufacture lipids and steroids such as certain hormones
What is the structure of SER?
same as RER but without the ribosomes
What occurs in the mitochondria?
aerobic respiration which produces ATP
What is the fluid that fills mitochondria?
matrix
What is the inner membrane of mitochondria folded into?
cristae
What do cristae provide?
large surface area
How big are mitochondria?
1000nm
Can mitochondria be seen using a light microscope?
Yes
What type of cells are centrioles found in?
animal cells
Where are pairs of centrioles found?
near the nucleus, at right angles to each other
How many microtubules make up a centriole?
9
What are centrioles used for?
cell division
What does a microtubule spindle do?
attach to the chromosomes and pull them apart
What do lysosomes do?
breakdown unwanted structures
How many enzymes do lysosomes contain?
60+
What examples of enzymes are found in lysosomes?
proteases, lipases, nucleases
How do vesicles release their contents?
exocytosis
What does Golgi do?
modifies proteins
What is the cytoskeleton made from?
microtubules and protein microfilaments
What does the cytoskeleton do?
gives cells structure, moves and holds organelles
How many layers does the cell wall have?
2
What does the middle lamella contain in a cell wall?
pectin
What is the 2nd layer of the cell wall?
cellulose microfibrils
What does plasmodesmata do (gaps in cells)?
links together plant cells
How many membranes does a chloroplast have?
2
What is chlorophyll?
the green pigment required for photosynthesis
What is the inner membrane of chloroplasts folded into?
thylakoids
What do thylakoids stack up to form?
a granum
What are granum linked by?
lamella
What is the liquid in the chloroplast?
stroma
What kind of vacuole do plant cells have?
large permanent vacuole
What is the vacuole filled with?
cell sap which is dissolved substances in water
What is the tonoplast?
the membrane that surrounds the vacuole
What do tonoplasts control?
what enters and leaves the vacuole
What potential do tonoplasts control?
osmotic potential
What are viruses made of?
protein coat (capsid), genetic material, and sometimes an envelope
What kind of cells do viruses reproduce in?
living cells
How do most viruses get into animal cells?
endocytosis at the cell membrane
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