Lecture 4/5 Flashcards
Ways of energy transformation. 2
- Cellular respiration
- converts chemical energy into cellular - Photosynthesis
- converts light energy to chemical energy
Characteristics of prokaryotic cells
Size
Metabolic rate
How cell grows- benefits and disadvantages of cell size
- size depends on rate of growth
- high metabolic rate- constant supply of nutrients
- as cell grows in size. Volume increases much more fast than surface area
- cell remains small — so cytoplasm always near membrane; where nutrients enter and waste exist.
- generates ATP in membrane. If cell grows too large- ATP cannot move across cell fast enough
Why are eukaryotic larger
- sub compartments
- internal and external environment make up for larger size
How are mircrobes and viruses measured
Micro organisms. Micrometer. One millionth of m (10-6)
Viruses. Much smaller. Nanometer. One billionth (10-9)
Resolution.
Can see object more clearly. Can distinguish close spaced objects
- oil immersion. Provides greater resolution. More light
- short wavelength. Provides more resolution
SEM- scanning electron microscope
Staining process.
Simple vs negative.
- provides contrast. Can see the cells better
- all cells need to be dead
Simple—- Cation dye. Bind to negativity charged cells
Negative—- anion dye. Repelled by cells
Differential staining process
2 contrasting colour dyes
- GRAM STAIN used to classify bacteria species based on cell wall structure
Gram positives— have thick multilayered cell wall ++
Gram negative— thin porous cell wall -
ACID FAST TECHNIQUE
- normally difficult to stain- because of the very waxy walls repel the dye used
Light microscopy techniques that enhance contrast (3)
- Phase contrast microscopy
- light condenser and objective lenses
- provides contract cause throws light out of phase
- ray pass through slightly different densities
- can study living organisms. - Dark field microscopy
- scatters light
- only light from specimen enters - Fluorescence
- uv light source.
- fluorescence dye
- major immunological, tool
Two electron microscopes
- TEM
- SEM
TEM- transmission electron microscope
- uses a magnet
- cut specimen into several sections
- after cut. Stain with heavy metal to provide contrast.
SEM. Scanning electron microscope
- whole species covered in gold
- dead specimens
- less magnification than. TEM
Who helped uses nomenclature to identify organisms
Binomial.
System of rules.
Carolous linnaeus
How to name
First word. = genus name (capitalized)
Second word. = specific epithet (not capitalized)
Prokaryotic cells shape 3 types of
Bacillus. Prokaryotic cell with short or long chains
- many species remain attached to another after cell division
Coccus. Short and long chains/ small and large cluster
Spiral. Curved. Wavey corkscrew
- do not remain attached after cell division
- Inhance mobility
How does a bacteria cell sense and respond to surrounding environment
Pilli. Sense and respond to stimuli (thin protein fibres that extend from surface-enable adhesion to surfaces)
Flagella.
Protein fibres that rotate and enable the cell to move through liquids
(Long tails)
Glycocalyx.
- thick or thin layer of carbohydrate providing protection and helping cell adhesion to surfaces
What makes a COMPARTMENT for bacteria metabolism
“ compartment of metabolism “
Protection from osmotic forces - cell metabolism separated from external environment.
Cell wall. Shape and structure
Cell membrane. Lipid by layer with protein control movement in and out of the cell
What is responsible for bacteria cell growth and reproduction
Ribosome. RNA/ manufacture proteins
Cytoplasm. Semifluid substance inside. Where cell metabolism occurs
Nucleotide. Bacteria chromosomes essential genes. Growth and metabolism .
Plasmid. Closed loop of DNA. Containing non essential genetic info
Three types of pili and functions.
Type 1. Attach and bind to objects
Type 2. Locomotion. Know where is
Conjugation pil. Allow for exchange of dna between bacteria
Types of flagellation movement
Flagella function. Rotate allow cells to move through liquids. Cell movement and attachement.
Hook. Anchored into cell envelope
Basal body. Motor. Generates rotation
Random walking.
- no attraction
- run- rotation of flagella counterclockwise
Biased- random walking
- chemotoxis to an attractant
- longer runs- counterclockwise
- fewer tumbles- clockwise
Bias movement towards attractant as a result
Tumble.
Unbundled. Uncoordinated. Random change in direction
** when looking for nutrients. Flagellated bacteria cells manipulates. Runs and tumbles towards nutrient. Attractant.
Chemotaxis
Movement towards a stimulus or away from repellant
What is glycocalyx
Layer of polysaccharides surrounding cells
- capsule when firmly bound to cell
- may contain small proteins
Thinner layer- slime layer- water soluble
Sticky layer.
PROTECT CELL AND STICK TO SURFACES
Bio film
- antibiotic resistance- less exposed to host immune response- less prone/ susceptible to antibodies
- many wound and chronic infections are caused by bio films
Bio-film cells communicate chemically
Quorum sensing
- when chemical reaches threshold- sense their population numbers through exchange of extracellular chemicals. Causes altered gene expression. And causes behaviour response
- provides protection to bacteria and makes them more suitable for external environment under certain conditions
Use of the bacterial cell wall.
Structure integrity
- osmotic forces push against cell membrane
- water diffuses into cell. And cell walls prevent from rupturing
- hypertonic. More solutes in the call. Water wants to move in
Peptidoglycan
Gram positive and gram negative
Bacterial wall is made up of. Long disaccharide strands linked short elastic peptides
Can occur in multiple layers connected by amino acid side chains or peptide cross bridges
Gram positive.
Layers of peptidoglycan
No outer membrane
Gram negative.
Thin peptidoglycan
Outer member
Gram positive wall vs gram negative
Thick. Rigid.
Multiple layer of glycan strands cross linked
Plasma membrane composition
- selectivity permeable barrier
- fluid in nature. Can move laterally in membrane
25% phospholipid
75% protein (by weight);
Hydorphobic tails
Hydrophilic heads
2 types of transporters
