Chapter 2 Basic Components Of living systems Flashcards
What is an organelle
A membrane bound compartment with varying functions
By providing distinct environments and conditions for different cellular reactions
Uses of membranes
Serve as barriers
Allow molecules to diffuse across lipid bilayer
Cell signaling
Nucleus
Contains genetic material - which directs the synthesis of all proteins
Controls metabolic activities of cells
Nuclear envelope
Surrounds the nucleus
Contains nuclear pores - movement in and out
Nucleolus
Produces ribosomes
Composed of proteins and RNA
RNA used to make rRNA which combines with proteins to form ribosomes for protein synthesis
Cell wall
Supports the plant
Made of cellulose
Gives shape
Protects from pathogens
Mitochondria
Structure (matrix crista)
The site of aerobic respiration
Where atp is produced
Double membrane
Inner membrane folds to form crista
Inside crista is matrix
Matrix has enzymes for respiration
Vesicles
Storage
Transport materials inside cell
Fluid filled, membrane bound sacs
Lysosomes
Membrane bound
Contain hydrolytic enzymes (digestive)
Break down waste material in cells
Break down pathogens, dead organelles
Cytoskeleton
Network of fibres necessary for the shape and stability of a cell
Controls movement of organelles
What are the three main components of cytoskeleton
Micro filaments
Microtubules
Intermediate fibres
Centrioles
Microfilaments
Contractile filaments formed by actin
Responsible for cell movement and cell contractions
During cytokinesis
Microtubules
Globular tubular proteins polymerise to form tubes to form structure that determines the shape of the cell
Act as tracks for the organelles go follow (spindle fibres)
Intermediate fibres
Provide mechanical strength to cells
Help maintain integrity
Centrioles
Involved in the separation of chromosomes
Hollow cylinders of microtubules
Star shape
2 make centrosome
Flagellum
Microtubules contract to make flagellum move
Help swim
Detect chemical changes
2 microtubules in middle
9 pairs outside in circle
Cilia
Beat to cause fluid or objects to move
Smooth endoplasmic reticulum
Produces and stores
Lipids and carbohydrates
No ribosomes
Fluid filled, membrane bound, flattened sacs
Rough endoplasmic reticulum
Transfers, synthesises, folds and processes proteins made from attached ribosomes
Fluid filled, membrane bound, flattened sacs
Membrane enclosing fluid filled space - cisternae
Surface has ribosomes
Ribosomes
Site of protein synthesis
No membrane
2 sub units
Made from RNA
Golgi apparatus
Processes and packages new lipids and proteins
Makes lysosomes
Modifying proteins and packages them into vesicles
Fluid filled, membrane bound, flattened sacs
Protein production
- proteins formed on ribosomes on ER
- transported into ER cisternae and are packaged into transport vesicles
- vesicles move to Golgi apparatus via the cytoskeleton transport system
- vesicles fuse with cis face of Golgi apparatus and the protein enters
- proteins are structurally modified before leaving Golgi in vesicles from trans face
Different types of vesicles that secretory vesicles make
Secretory vesicles fuse with cell surface membrane - exocytosis
Lysosomes - stay in cell
Vacuoles
Maintain turgid and maintain rigid framework
Membrane lined sacs filled with sap
Chloroplasts
Responsible for photosynthesis
Reactions driven by daylight
Double membrane Stroma = fluid in chloroplast Thylakoids = flattened sacs Granum = stacked thylakoids - contain chlorophyll pigment Lamelle = joins stacks of granum / grana Has starch grains
Similarities between plant and animal cells
- eukaryotic
- have organelles : Golgi, nucleus, ER, mitochondria, ribosomes, membranes
- obtain energy from cellular respiration
Differences between plant and animal cells
- Plant cells are larger
- organelles: chloroplast, vacuole, cell wall, animal = centrioles
- different shape: animal= round irregular, plant = rectangular
- store energy: animal = glycogen, plant = starch
Similarities between eukaryotic and prokaryotic
- have: membranes, cytoplasm, ribosomes, DNA
- cellular respiration
- undergo cell division
- require energy
Differences between eukaryotic and prokaryotic
- eukaryotic are membrane bound
- eukaryotic is bigger
- prokaryotic cells undergo cell division by binary fission
- prokaryotic has one large coiled chromosome
- prokaryotic no nucleus
- cell walls: p= peptigoglycan, e = chitin, cellulose
- ribosomes : p= 70s, e= 80s
- flagella does not have 9+2 arrangement, motor causes hook to rotate
Magnification
How much bigger the image is than the specimen
Magnification equation
Magnification = image size/ actual size
Resolution
Smallest distance between two points on a specimen that can be distinguished as two separate entities
Dry mount
Cut into thin slices - sectioning
Place on slide
Cover slip
Used to view pollen, dust,hair, plant
Wet mount
Suspended in liquid
Coverslip placed on at angle
Squash slide
Wet mount
Lens tissue used to press down on cover slip
For soft samples
Root tip
Smear slide
Smear sample onto slide using another slide
Cover slip
Used for blood cells
What is resolution in a light microscope limited by
Wavelength of light
De fraction of light
What does staining do
Increases contrast to see better
As different components take up different stains
How to prepare for staining
Sample is air dried
Heat fixed - passed through flame
Specimen will adhere to microscope and take up stain
Positively charged dyes
Crystal violet
Eosin
Methylene blue
Bacteria
Cytoplasm
DNA
Attracted to negatively charged cytosol
Stains cell components
Negatively charged dyes
Nigrosin
Congored
Repelled by negatively charge cytosol
Stain background
Stay outside cell
Electron microscope stain
Specimen dipped in solution or heavy metals
Metal ions scatter electrons
Creates contrast
Places turn darker than others
What is differential staining
Can distinguish between 2 types of organisms
And different organelles
Gram staining technique
Separates bacteria into gram positive and negative
Crystal violet applied
Then iodine - fixes stain
Slide washed with alcohol
Gram positive stay BLUE - retain the dye
Gram negative have thinner cell walls - lose the dye
Stained with safranin
Gram negative - RED
Why is gram negative bacteria not susceptible to penicillin
Has protein layer around cell wall that prevents penicillin from attacking
What is acid fast technique used to separate
Different species of mycobacterium from other bacteria
How does acid fast technique work
Lipid solvent carries carbolfuchsin dye into cells
Washed with dilute acid alcohol
Mycobacterium is not affected by alcohol and stays RED
Other bacterium turned BLUE
What are artefacts
Visible structural detail caused by processing the specimen and not a feature of the specimen
Artefacts of light microscope
Air bubbles
Artefact of electron microscope
Loss of continuity of membrane
Empty spaces in cytoplasm
Distortion of organelle
Mesosomes - membrane folds - produced by chemicals used in fixing
How is resolution limited by diffraction of light
Tendency of light waves to spread as they pass close to physical structures
Light waves overlap - not seen as separate entities
How to increase resolution
Using beams of electrons
With shorter wavelengths
Less overlapping
1000 nanometres nm =
1000 micrometres um =
1000 mm =
1 um
1mm
1m
How to calibrate an epg and sm
1000sm divisions = 1mm
1 sm d = 10um
- put stage micrometre in place
- focus
- align sm and EPG
- find magnification factor
Light microscope
Uses light to magnify
Wavelengths are filtered to produce an image
Whole cells/ tissues
TEM electron microscope
Transmission
Uses electromagnets to focus a beam of electrons and transmit them through specimen
Denser parts absorb more = darker
Ultrastructure / organelles
Resolving power = 0.5
SEM
Scanning electron microscope
Scan a beam of electrons across specimen
Reflected electrons gathered in cathode ray tube to produce 3D image
Only see surface
Resolving power of 3-10nm
Factors of light microscope
Lower resolution Cheaper No vacuum needed Colour Living specimens Small
Laser confocal microscopes
Uses laser beams to scan specimen - tagged with fluorescent dye
Fluorescent light in focused through pinhole onto détecter is hooked to computer
Only light focused close to pinhole is detected
Uses of laser confocal microscopes
Look at different depths of thick specimens
Diagnosis of eye disease
Distribution of molecules within cells
Development of drugs
Maximum resolution
Light
TEM
SEM
- 2 um
- 0002um
- 002um
Maximum magnification of
Light
TEM
SEM
1500 x
1,000,000 x
500,000 x
How to use a light microscope
Selected lowest powered magnification
Use coarse adjustment knob to bring stage up
Looked down
Use coarse adjustment until focused
Use fine adjustment to get better focused
Use higher magnification
How to find uncertainty
Uncertainty = ( percentage error / 100 ) x reading
