M2C2 - Basic Components of Living Systems Flashcards
Equation for magnification
Magnification = Image Size / Actual Size
Components of a microscope
Eye piece lens, Course focus knob, fine focus knob, turret, object lens, stage, light source
Name 3 stains and their function
1) Iodine - stains starch blue/black
2) Methyl blue - stains nuclei blue/purple
3) Eosin - stains cytoplasm pink
Magnification
The degree to which the size of an image is larger then the object itself
Resolution
The degree to which it is possible to distinguish between two separate points
Name the different types of microscopes
Compound light microscope, laser scanning confocal microscope, transmission electron microscope and scanning electron microscope
Compound light microscope
Up to 2,000X
Uses visible light to illuminate a thin section of sample
Looks at living things
Looks at cells and tissues
Low resolution compared to other microscopes
Laser scanning confocal microscope
Up to 2,000X
Lets you look at thin ‘slices’ in a sample while keeping sample intact.
Looks at living cells
Highlighting individual components of a cell
Fluorescent can cause artefacts.
Transmission electron microscope
Up to 5,000,000X
Looks at internal structures
High resolution
Can’t look at living things
Costly to run
Scanning electron microscope
Up to 500,000X
Looks at objects in 3D
Resolution greater then light and scanning, but not as high as TEM.
Can’t look at living things.
Cell walls
Found in plants but not in animal cells.
Formed outside of the cell membrane and offers structural support to the cell.
Polysaccharide cellulose in plants, and peptidoglycan in bacterial cells.
Narrow threads of cytoplasm called plasmodesmata connect the cytoplasm to neighbouring plant cells
Nucleus
Present in all eukaryotic cells and is relatively large.
Separated from the cytoplasm by a double membrane (nuclear envelope)
Contains chromatin which makes up chromosomes.
Mitochondria
Site of aerobic respiration within all eukaryotic cells.
Surrounded by a double membrane with the inner membrane folded to form cristae
Matrix formed around the cristae containing enzymes needed for aerobic respiration.
Small circular DNA and ribosomes found in the matrix.
Chloroplasts
Found in plants.
Surrounded by a double-membrane.
Contains thylakoids and lamellae.
Small circular pieces of DNA and ribosomes used to synthesis proteins needed in chloroplast replication and photosynthesis.
Ribosomes
Found freely in all cells or part of the rough endoplasmic reticulum.
Complex of ribosomal RNA (rRNA) and proteins.
Site of translation.
Rough Endoplasmic reticulum
Found in plant and animal cells
Surface covered in ribosomes
Formed from continuous folds of membrane continuous with the nuclear envelope.
Processes proteins made by the ribosomes
Smooth Endoplasmic Reticulum
Found in plant and animal cells
Doesn’t have ribosomes on the surface
Involved in the production, processing and storage of lipids, carbohydrates and steroids.
Golgi apparatus
Found in plant and animal cells
Flattened sacs of membrane (similar to SER)
Modifies proteins and lipids before packaging them into vesicles.
Permanent vacuoles
A sac in plant cells surrounded by the tonoplast.
Vacuoles in animal cells are not permanent
Vesicles
Found in plant and animal cells
Membrane-bound sac for transport and storage
Lysosome
Specialist forms of vesicles with contain hydrolytic enzymes
Break down waste materials such as worn-out organelles
Used extensively by cells of the immune system
Centrioles
Hollow fibres made of microtubules
Two centrioles at right angles to each other from a centrosome, which organises the spindle fibres during cell division
Not found in flowering plants and fungi.
Microtubules
Found in all eukaryotic cells
Makes up the cytoskeleton of the cell
Made of alpha and beta tubulin combined to form dimers (which join to form protofilaments)
The cytoskeleton is used to provide support and movement of the cell.
Microvilli
Found in specialised animal cells
Cell membrane projections.
Used to increase the surface area of the cell surface membrane.
Cilia
Hair like projections made from microtubules
Allows the movement of substances over the cell surface
Flagella
Found in specialised cells
Similar structure to cilia but longer microtubules.
Contract to provide cell movement (e.g. sperm cells)
Protein synthesis
1) The protein are synthesised on the ribosomes bound to the RER
2) They then pass through into the cisternae and are packaged into transport vesicles
3) Vesicles move towards the Golgi apparatus via the cytoskeleton
4) The vesicles fuse with the cis face of the Golgi apparatus and the proteins enter. The proteins are modified before leaving the Golgi apparatus in vesicles from the trans face
5) Secretory vesicles carry proteins that are to be released from the cell. The vesicles move towards and fuse with the cell-surface membrane, releasing their content by exocytosis.
What is the Cytoskeleton
Network of protein threads that run through the cytoplasm.
Difference between eukaryotic and prokaryotic cells
Prokaryotes have no membrane-bound organelles.
Prokaryotes have smaller ribosomes (70S) compared to eukaryotic ribosomes (80S)
Eukaryotes like plants and fungi have cells walls made of cellulose and chitin. Bacterial cell walls are made of murein.
Prokaryotic cells are much smaller than eukaryotic cells.
Both prokaryotes and eukaryotes have flagella but those found in prokaryotes are made of flagellin whereas in eukaryotes they’re formed from microtubules.
Organelles in prokaryotes that aren’t in eukaryotes
Pili - hair like structures which are used to communicate with other cells.
Plasmids - Small circular rings of DNA which are separate from the main chromosomes
Slime capsule - Protect bacterium against a immune system attack.
