Lecture 3 Cell Biology Flashcards
What are the size ranges for Prokaryotes and Eukaryotes?
Prokaryotes -0.2 um to 700+ um
Eukaryotes -10 um to 200+ um
Why is the small cell size so significant?
Surface to area volume
- smaller size = greater SA:Vol
- bigger size = smaller SA:Vol = can’t take in as much nutrients
Growth Rates
-High Growth Rate = High Evolution Rate
What are the main cell morphological shapes?
- Coccus = sphere
- Bacillus = cylindrical
- Spirillum = spiraled
- Spirochete = cork-screw
- Appendaged = with a stalk or hypha
- Filamentous = clusters
What are the types of cell filamentous cluster types?
Diplo = pairs of only 2 cells
Strepto = Chains of 3+
Staphylo = Grouped together in clump not chain
What is the structure of a cytoplasmic membrane composed of and what is its function?
Structure composed of phospholipid bilayer Function is selective permeability and to separate the inside cytoplasm from the environment outside.
What are the types and characteristics of membrane proteins?
Types are integral and peripheral They are anchored in cytoplasmic membrane and have hydrophobic and hydrophylic regions
How are Archaeal membranes different from Bacteria membranes?
Linkage of glycerol head to fatty acids
- Archaea have ether bond, Bacteria have ester Fatty Acid Composition
- Archaea have more unsaturated Isoprene bonds Monolayer membranes only in Archaea
- Monolayer membranes have FA’s connected
What are the functions of the cytoplasmic membrane?
Permeability barrier
Protein anchor
Energy conservation (proton motive force)
What are the types of transport proteins?
Simple
Group Translocation
Periplasmic (ABC)
Why are transport proteins so important?
They enhance the rate of uptake of needed solutes
-much greater than simple diffusion
What are the types of transport mechanisms?
Uniport
Symport
Antiport
What is an example of a simple transport protein?
Lac Permease (E. coli) -Symport transports lactose against its concentration gradient along with H+ Protons into the cell
-Uses energy of protons moving with concentration gradient to transport lactose against its concentration gradient
What is group translocation?
Transport mechanism where the substance transported is chemically modified
- Uses the phosphotransferase system
- Uses 5 proteins which gives more control of system
- Energy driven using phosphoenolpyruvate (PEP) to phosphorylate the 1st protein which phosphorylates each one down the cascade
What is Periplasmic (ABC) transport protein?
ABC = ATP-Binding Cassette System Occurs in Periplasm
- Between cytoplasmic and outer membranes Requires multiple proteins
- protein binds substrate which the binds to membrane transporter to transport substrate
What is Protein export?
Transport large molecules either:
- across membrane inside-to-outside
- inserts into membrane Translocase proteins do this
- Ex. Sec System
What do cell walls provide for bacteria and archaea?
Structure
-Bacteria have Gram (+) or Gram (-)
What are the functions of cell walls in bacteria?
Prevent osmolytic lysis (cell explosion) Give shape and rigidity to cell
What is peptidoglycan?
Only present in bacteria
- Both Gram (+) and Gram (-)
- Not found in Archaea or Eukarya
Polysaccharide made of 2 sugar derivatives
- Connected by B-1-4 Glycosidic Linkages
- For long chains (sheets) around cell
- Chains are linked by amino acid branches (peptide bonds)
How does peptidoglycan differ?
Many different types that differ structurally
- Same Sugar backbone
- Different Peptide cross-linked branches
How is peptidoglycan targeted/destroyed?
Lysozymes destroy peptidoglycan Penicillin prevents synthesis
-breaks a bigger and bigger hole until cell is lysed
What are the similarities between Gram (+) and Gram (-) bacteria?
Both have peptidoglycan Gram (+)
- cytoplasmic membrane
- THICK wall of peptidoglycan Gram (-)
- cytoplasmic membrane
- THIN wall of peptidoglycan
How do Gram (+) and Gram (-) bacteria differ?
Gram (+)
- THICK peptidoglycan and NO outer membrane
- Looks smooth under scanning electron microscope
Gram (-) bacteria
- THIN wall of peptidoglycan and outer membrane
- Looks rough under scanning electron microscope
What are the characteristics of Gram (+) bacteria?
Have Teichoic Acids
- Embedded in cell wall
- Negatively charged so attracts cations Negative charge of cell surface transports cations like Mg 2+ or Ca 2+
What are the characteristics of Gram (-) bacteria?
Outer membrane has second Lipid Bilayer (Outer membrane) Outer membrane has: 1. Lipopolysaccharide (LPS)
- Lipoproteins
- Porins
