Celll structure

Light Microscopes

• Poor resolution due to long wavelength of light

• Can use living samples - cam have colour image

Transmission electron microscopes

• Much higher magnification and resolution - short wavelength

• Electrons pass through specimen - 2d image internal structure

• Cannot use living samples electrons are absorbed in air- must be in vaccum

• Black and white - so stained

Scanning electron microscope

• High magnification and resolution - short wavelength

• Electrons are bouncing off specimen - 3D image surface

• Cannot use living samples electrons are absorbed in air- must be in vaccum

• Black and white - so stained

Laser Scanning confocal Microscope

• High resolution and 3D imaging

• Laser light used to create imade

What is resolution?

• The minimum distance between two objects where you can still view them as different

What is magnification?

This is how many times larger the image is compared to the actual object

Dry mount

This is when a thin slice or a whole specimen is viewed - only coverslip

Wet mount

• Water is added to specimen before placing a coverslip and a needle is used to remove air bubbles

Squash Slide

• Wet mounts in which you push down coverslip to smear specimen in a thin layer so light can pass through

Smear Slide

• Place a drop of sample and use edge of another slide to smear across specimen

Magnification

Size of image/ Size of real object

cm → mm x 10

mm → um x 1000

What is differntial stianing?

• Using many chemical stains to stain different parts of cells different colour - to be able to be differntiated

• Crystilne violet and Mehtlyne blue are positively charged so attracted to and stain negatively charged materials

Nucleus

Nucleus

Centrioles

• Form spindle fibres

• Connect chromosomes in meiosis and mitosis

Ctytoskeleton

• Network of fibres proving mechanical strength - shape, stability

• Organelles are bound to it

RER

• Contain folded cisternae

• Proteins are processed and synthesised and transported in vesicles to golgi body in cell

SER

• Contain folded cisternae

• Lipids and carbohydrates are synthesised and stored

Golgi apparatius

• Contain folded cisternae

• Adds carbohydrates to proteins to form glycoproteins

• Modifies and stores lipids

• Finished products transported in vesicles put of cell

Lysozymes

• Hydrolyse pahgocytic cells

• Release enzymes out cell exocytosis

Ribosomes

• Site of protein synthesis

• 80s ribosomes larger - found in eukaryotic cells

• 70s smaller found in prokaryotic cells

Chlroplasts

• Site of photosynhteiss

• Double membrane with thylakoid folds - stack up into granum

• Fluid with enzymes for - photosynhteiss

Protein synthesis

• Polypeptide chains are synthesised on ribosomes

• These chains move to cisternae on RER and are modified and package into vesicless → golgi

• Golgi apparatus modified further and packaged in vesicles released out of cell surface membrane - exocytosis

Prokaryotic vs Eukaryotic cells

• No membrane bound organellles vs membrane bound organelles

• 70s vs 80s ribosomes

• No nucleus (circular DNA) vs Nucleus

• Cell walls made of peptidoglycan vs cellulose/chitin

• Can contain plasmids/ flagella/ capsule