Quiz 2 - Micro
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How are Amino Acids linked and what do they form?
Linked by peptide bonds and form polypeptides (PROs)
Describe Nucleotide Structure.
- Nitrogenous Base ( A, C, G, T, U)
- Linked by phosphodiester bonds
Which nitrogenous bases are purines and which are pyrimidines?
- Purines: Adenine and Guanine
- Pyrimidines: Thymine, Cytosine, and Uracil
What is the structure of DNA?
- Usually double stranded
- Strong Covalent Bonds
- Base Pairing
- H-bonds between bases form helixs
- Phosphodiester bonds
What are the functions of Nucleic Acids?
- Passes parent to offspring as genetic info
- Information for protein synthesis (DNA - long term storage info, RNA - ss info storage during protein synthesis)
All cells contain both DNA and RNA. ___________ contain ________ DNA or RNA. ATP energy currency.
ATP has a _______ structure.
What is anabolism?
Synthesis, bond formation, requires energy
What is catabolism?
Bonds broken, energy released
What are reduced molecules?
Contain electrons and potential energy (e.g. CHO, lipids)
What are oxidized molecules?
Contain fewer electrons and less energy
What are prokaryotic cells?
- Cell wall
- Bacteria (no small organelles)
- High Surface area : volume ratio, allows for survival without specialized organelles
What is Eukaryotic cells?
- Animals, plants, fungi, and protozoa
- Large nucleus, other organelles
What are the typical prokaryotic morphologies?
- Coccus - Sphere
- Coccobacillus - elongated sphere
- Vibrio - banana
- Bacillus - Rod
- Spirillum - wave
- Spirochete (corkscrew, almost always motile)
Describe bacterial arrangements.
- Single-celled arrangement very common
- Diplo: Two joined
- Strepto: Chains
- Staphylo: Clusters
- Tetrads: Four Cells
Describe the cell membrane of a prokaryotic cell.
- Exterior to cell membrane, complex, semi-rigid
- Borders cytoplasm
- Composed of phospholipid bilayer + proteins(act as bilayer in and out)
- No sterols (e.g. cholesterol)
What are the functions of the cell wall?
- Determines shape
- Protects cell membrane from osmotic pressure changes
- Composed of peptidoglycan lattic
What is the structure of peptidoglycan lattice?
- Carbohydrate, backbone of NAG-NAM disaccharide repeats
- Peptide chains + cross-bridges (4 AA)- cross-link and strengthen CHO backbone
- CHO backbones can be 30-40 thick
Describe the peptidoglycam in gram positive and in gram negative.
- Gm (+): Thick layer of peptidoglycam, Teichioic acids , no outer membrane
- Gram (-): Thin peptidoglycam, Outer membrane contains LPS or endotoxin(which stimulate immune response), periplasmic space - between cell membrane and cell wall, metabolically active, hydrolysis of organic nutrients
How are AA linked in peptidoglycan lattice?
AA linked together by stable peptide bonds
What can inhibit cross-link formation?
Cell wall synthesis inhibitors (e.g. penicillin)
What is gram stain procedure?
Based on cell wall differences, is critical to bacterial identification
What is the importance of the nuclear region of the cell?
- Contain a singular chromosome
- Other nucleic acid: Plasmids
What are plasmids?
- Small circular extrachromosomal DNA molecules
- Common location of antibiotic resistance genes
What are ribosomes?
- Structurally distinct from eukaryotic
- Antibiotic target
What are endospores?
- Resistant structures produced by some (not all) bacteria
- Can survive in extreme conditions
- Dehydrated, metabolically inert, comped of core, cortex, spore coat layers
- Not for reproduction (1 per bacteria)
How are endospores produced?
Vegetative (active) cell produced endospore under stress
How is an endospore activated?
Germination: Endospore activates, enters vegetative cycle
What are the layers of an endospore?
- Spore Coat
During endospore formation, what occurs during "good times" and what occurs during "bad times" or stress?
- Vegitative cycle: Good times
- Sporulation: Bad times
What are the external structures located outside of the cell?
- Flagella: Motility
- Basal Body: Anchors flagella to plasma membrane/cell wall
- Taxis: Response to stimuli
What are the different kinds of taxis>
- Chemo: Attracted to or away from a chemical
- Phototaxis: Maintain themselves in the upper layer of the water / ability to move towards a light source
What is Pili? What are the two types?
- Pili: Attachment, not motility
- Attachment pili: Allow attachment to surfaces (key virulence factor for some pathogens)
- Conjugation pili (sex pili): Allow transfer of DNA (conjugation), Usually a plasmid from one cell to the next
What is the Glycocalyx?
- Enternal to cell wall
- Usually composed of polysaccharides, provides 'slippery' outer layer
- Prevents desiccation, acts as virulence factor by protecting cell from phagocytosis, can also aid in attachment
- Not thick
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