M2 C2 - Basic Components of Living Systems

Parts of a microscope

• Light source (bulb/mirror)

• Stage

• Specimin

• Objective

• Fine focus

• Coarse focus

• Turret

• Eyepiece lens

Light microscope

• cheap, portable, simple prep, can see color

• Low magnification (x2000), low resolution

Transition electron microscope (TEM)

• High magnification (x500,000 - 2,000,000), high resolving power

• Can only see dead material, lengthy and complex prep can cause artefacts, can’t see true color

Scanning electron microscope (SEM)

• High magnification (x100,000-500,000), high resolving power (3-10nm), 3d images of surface

• Can only see dead material,lengthy and complex prep can cause artefacts, can’t see true col9r

Magnification

The degree to which the size of a image is larger than the object itself

Resoultion

The degree to which it is possibr to distinguish between two separate points

Equation for magnification

Mag = Image/Actual

Dry mount

• Thin slice

• Specimin in centre of slide + cover slip

• Observing: hair, pollen, dust

Wet mount

• Specimen suspended in liquid

• Cover slip placed - no air bubbles

• Observing: water-bound organisms

Smear slide

• Carefully smearing thin layer specimen across slide

• Observing: blood

Squash slide

• Used for soft samples

• Wet mount, the cover slip pressed down to squash

• Obersving: mitosis in root tips

Organelle

Cells inside structure with its own specific role

Nucleus

• Large organelle - surrounded by nuclear envelope

• Contains genetic information and chromatin

• Dense nucleolus - makes ribosomes

Ribosomes

• Site of protein synthesis

• Made of rRNA and proteins

• Found floating in cytoplasm or attached to rough ER

Rough Endoplasmic Reticulum (ER)

• Made of flattened membrane bound sacs

• Covered in ribosomes

• Modifies proteins by folding

Smooth Endoplasmic Reticulum (ER)

• Synthesised +processes lipids

• Detoxification of harmful substances

Golgi apparatus

• Stacks of membrane bound sacs

• Further Modifies proteins and lipids (packages into vesicles)

• Makes lysosomes

Vesicles

• Membrane bounds sacs

• Storage and transport role

• E. G. Proteins/hormones from golgi to plasma membrane

Lysosomes

• special vesicles containing hydrolytic enzymes (disgestive)

• Used to break down materials

Mitochondria

• Double membrane

• Contains small amount of dna

• Produces ATP via aerobic respiration

• Folds called crista - inside is called matrix

Plasma membrane

• Regulates movement of substance into/out of cell

• Contains receptor molecules allowing to respond to chemicals (e. g. Hormones)

• 7 nanometers thick

Cytoskeleton

• Provides mechanical strength + stability through internal network

• Holds organelles in place

• Transports vesicles via microtubles

• Changes shape of cell

Centriole

• Component of cytoskeleton

• Small hallow cylinders - ring of microtubles

• Involved in separating chromosomes during cell division

Flagella

• Like cilia but longer

• Allows cells like sperm to swim

• In eukaryotes: 9+2 arrangement

Cilia

• Hair like structures + increase surface area

• Contain microtubles allowing them to move

Cell wall (plants)

• Made of cellulose in plants

• Freely permeable

• Supports + maintainsl cell shape

• Allows turgidity - prevents bursting

• Contains plasmodesmata (holes for substance exchange)

Chloroplasts

• Double membrane

• Contains flattened membrane sacs called thylakoids

• Stack is called granum (linked by lamella)

• Site of photosynthesis as filled with chlorophyll which absorbs light

Large permanent vacuole

• Membrane bound organelle

• Filled with cell sap to keep turgid

• Cell membrane called the tonoplast

What do thylakoids do in chloroplasts?

Store the chlorophyll

• responsible for the light-dependant reactions of photosynthesis