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Microbiology
Exam 01 - Cell Structure
| Question | Answer |
|---|---|
| What 3 components of a cell are we expected to know? | 1. composition 2. structure 3. function |
| Compare prokaryotic and eukaryotic cell size | 1. P: 0.2-2.0 micro meter in diamter 2. E: typically 10-100 micrometer in diameter |
| Compare prokaryotic and eukaryotic nucleus | 1. P: No nuclear membrane or nucleoli 2. E: true nucleus, consisting of nuclear membrane and nucleoli |
| Compare prokaryotic and eukaryotic membrane-enclosed organelles | 1. P: None 2. E: Present (includes lysosomes, Golgi complex, endoplasmic reticulum, mitochondria, chloroplasts) |
| Compare prokaryotic and eukaryotic flagella | 1. P: consist of 2 protein building blocks 2. E: complex - consist of multiple microtubules |
| Compare prokaryotic and eukaryotic glycoclayx | 1. P: present as a capsule or slime layer 2. E: present in some cells that lack a cell wall |
| Compare prokaryotic and eukaryotic plasma membrane | 1. P: No carbohydrates and generally lacks sterols 2. E: sterols and carbohydrates that serve as receptors |
| Compare prokaryotic and eukaryotic cytoplasm | 1. P: no cytoskeleton or cytoplasmic streaming 2. E: cytoskeleton; cytoplasmic streaming |
| Compare prokaryotic and eukaryotic ribosomes | 1. P: smaller size (70S) 2. E: Larger size (80S); smaller size (70S) in organelles |
| Compare prokaryotic and eukaryotic chromosome (DNA) | 1. P: usually single circular chromosome; typically lacks histones 2. E: multiple linear chromosomes with histones |
| Compare prokaryotic and eukaryotic cell division | 1. P: Binary fission 2. E: involves mitosis |
| Compare prokaryotic and eukaryotic sexual recombination | 1. P: none, transfer of DNA only 2. E: involves meiosis |
| T/F All bacteria have cell walls | False, there are a few wall-less bacteria |
| What is a protoplast? | Wall-less bacteria produced artificially in lab and GRAM POSITIVE |
| What is a GRAM NEGATIVE protoplast called? | Spheroplast, no cell wall but some outer membrane left |
| Give an example of a bacteria that lacks cell walls in nature | Microplasm - have sterols picked up from environment, cause pneumonia-like diseases |
| Describe composition of bacteria cell wall | ALWAYS contain peptidoglycan (unique in bacteria only, not in eukarya or archaea) - makes up rigid/semi-rigid portions of cell wall |
| What does the word peptidoglycan mean? | 1. Peptid - refers to amino acid 2. Glycan - chains of sugars (glucose) |
| T/F Cell wall is thicker than plasma membrane | TRUE |
| What are lysozymes? | 1. an enzyme we produce them in our tears 2. hydrolizes peptidoglycan & breaks the bond in several places 3. use as a form of protection for us against bacteria |
| What is the general function of bacteria cell wall? | Gives bacteria physical shape and structure, prevents osmosis lysis (move dissolved proteins in cells) 2. prevents cell from swelling and bursting |
| T/F Water always moves into bacteria cells, and the cell walls prevents the cell from getting too big and bursting | TRUE |
| The peptidoglycan portion of a cell wall does what? | Gives cell its shape (rod, spiral, etc) |
| What are the two main parts of peptidoglycan? | Amino acids: 1. N-acetylglucosamine (NAG) 2. N-acetylmuramic acid (NAM) |
| What does the NAG and NAM make up? | polysaccharide portion of peptidoglycan |
| What does a peptidoglycan look like? | Alternating chains of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) |
| How are the N-acetylemuramic acids joined? | Joined by tetrapeptide (amino acid) side chains |
| In GRAM POSITIVE (Staphylococcus) bacteria, the N-acetylemuramic acids do not join directly, how are they joined? | By a 5 Pentaglycine bridge |
| T/F In GRAM NEGATIVE (Escherichia coli) bacteria, the N-acetylemuramic acids join directly | True |
| So what's the relationship between peptidoglycan and cell walls? | Cell wall is composed of layers and layers of peptidoglycan |
| T/F Cell wall helps to exclude large molecules from moving in & out of cell | True (but the plasma membrane is the MAIN controller of that) |
| Describe the cell wall of GRAM POSITIVE bacteria | 1. Composed of layers of peptidoglycan (30-70 nm thickness) 2. Has teichoic acid made from glycerol and phosphate |
| What are lipoteichoic acids? | Teichoic acids that are connected to the plasma membrane |
| What are the functions of teichoic acids? | 1. regulates passing of positive ions 2. antigenic functions 3. regulate function of autolysin enzymes (enzymes that break cell walls) |
| Starting from the center of a GRAM POSITIVE bacteria cell, list the components of the cell that lead to the cell wall | 1. Cytoplasm 2. Plasma membrane 3. Cell Wall (layers of peptidoglycan) |
| Describe peptidoglycan in GRAM NEGATIVE bacterial cells | Single layer of peptidoglycan |
| What is the E.coli strain that causes gastrointeritis? | E. coli O157:H7 |
| In E. coli O157:H7, what does 0157 and H7 mean? | 1. O157 - O Side chain 2. H7 - flagella |
| How thick is the peptidoglycan layer in GRAM NEGATIVE bacteria? | Between 2-3 nm thick and is a single layer |
| How is the cell wall in GRAM NEGATIVE bacterial cells different from GRAM POSITIVE cell walls? | Cell wall has thin layer of peptidoglycan and also an OUTER MEMBRANE, no teichoic acids |
| What is the outer membrane in gram negative bacterial cell walls composed of? | 1. phospholipids 2. lipoproteins 3. lipopolysaccharide 4. porins |
| Is the outer membrane a semi-permeable membrane? | Yes |
| What are porins? | Proteins in outer membrane that regulates what moves in & out |
| What is the function of the outer membrane in GRAM NEGATIVE bacterial cells? | protects cells, keeps harmful substances out (ex: protects against some antibiotics such as penicillin) |
| What does penicillen do? | prevents cell from building new cells walls, prevents formation of peptidoglycan |
| What are the components of a lipopolysaccharide? | 1. Base: Lipid A 2. Middle: Core polysaccharide 3. Head: O polysaccharide |
| What is Lipid A? | 1. toxic to vertebrates - causes fevers, infections, inflammation, etc 2. Also known as endotoxins 3. located in membrane area |
| What are O-polysaccharides? | Located on outer membrane - has antigenic functions |
| What is Lipid A made up of? | Hydrophobic fatty acids |
| What is the core polysaccharide made up of? | sugars |
| What is the O-polysaccharide (O side chain) made up of? | Sugar molecules |
| What are some of the substances that are important in cell wall that defends against diseases? | 1. Antiobiotics 2. Lysozymes |
| What are antibiotics? | created originally by microorganisms (bacteria/fungi), we do not produce them |
| How does bacteria grow? | Cell walls broken to allow cells to grow larger (during growth & cell division) |
| Describe the characteristics of the plasma membrane | 1. ~7nm in thickness 2. encloses cytoplasm 3. typically the ONLY membrane in bacteria cell How thick is the plasma membrane of bacterial cell? |
| T/F The plasma membrane is the only membrane on all bacteria | TRUE |
| What is function of plasma membrane? | 1. regulates what moves in & out of cell through selective permeability 2. location of electron transport sys that produce energy for bacteria 3. DNA replication |
| What is a non-function of plasma membrane? | No pinocytosis and no phagocytosis (can't consume/engulf small molecules) |
| What is active mechanism? | Energy is required for movement across bilayer |
| What is passive mechanism? | No energy is required for movement across bilayer |
| What is selective permeability? | It's passive mechanism - Some molecules can get across, some can't |
| What are the types of passive mechanism? | 1. Diffusion 2. Osmosis 3. Facilitative diffusion |
| What is diffusion? | molecules move from high to low concentration until equilibrium is reached |
| What is osmosis? | diffusion of solvent (water) from the side with more pure water to the side with more solutes |
| T/F In cells, water is highly likely to move INTO the cell | True |
| What is facilitative diffusion? | protein channel help certain molecules diffuse/travel - has transporter protein (positively charged ion) |
| What type of energy is use in active mechanism? | Phosphate bond energy (ATP), ion-driven transport H+ (hydrogen ions are readily available from water H2O |
| What is group translocation? | Uses phosphate bond energy - the pumping of sugar into cell; substance being transported is altered during transport (attachment of phosphate group) |
| Give an example of group translocation | Glucose goes into cell, comes out as glucose phosphate |
| T/F group translocation occurs only in eukarya | False - group translocation is only in bacteria and not in eukarya |
| What is the composition of plasma membrane? | 60% protein, 40% phospholipid, no sterol |
| In prokaryotic cells' plasma membrane, the absence of sterols helps do what? | Helps membrane be more fluid |
| Describe lipids in prokaryotic cells' plasma membrane | Lipids tend to not have double bonds - makes it more brittle |
| Do prokaryotic plasma membrane have carbohydrates? | No |
| Describe the structure of prokaryotic plasma membrane | Composed of a phospholipid bi-layer |
| What does a phospholipid bi-layer look like? | Polar heads on top and bottom, non-polar tails in between |
| What flows through the phospholipid bilayer? | Proteins |
| What are the functions of phospholipid tails? | Repels charged particles (Hydrogen ion) |
| Can CO2 and Oxygen get across the phospholipid bilayer? | Yes |
| Can big molecules get across the phospholipid bilayer? | No |
| How do charged molecules and big molecules move through the phospholipid bilayer? | Via proteins |
| How does water move across the phospholipid bilayer? | Via protein channels |
| What are ribosomes used for? | Protein building |
| What is the function of the nucleoid? | 1. Contains bacterial DNA 2. only be seen with transmission electron microscope 3. not a true nucleus because of lack of membrane |
| Are cell capsules found in all bacteria? | No |
| What is glycocalyx? | sugary substance that is released to cover cell |
| What are some types of glycocalyx? | 1. slime layer 2. extracellular polysaccharide "EPS" 3. capsule |
| What is the composition of glycocalyx? | 1. Polypeptide (capsule) or Polysaccharide (slime layer & EPS) or BOTH |
| What is the function of glycocalyx? | 1. attach/adhere to surfaces & objects 2. helpful in causing disease (prevent phagocytosis by immune system) |
| What does extracellular polysaccharide EPS do? | inhibits phagocytosis |
| Give examples of capsules | 1. Streptococcus mutans 2. Klebsiella pneumoniae 3. Streptococcus pneumoniae 4. Bacillus anthracis |
| What does Streptococcus mutans cause? | Tooth decay (Makes a slime layer to glucose and sticks to teeth), hydrolyzes sugar into fructose for energy & glucose to stick to teeth |
| What does Klebsiella pneumoniae do? | Gram negative, causes pneumonia, sticks to epithelial cells |
| What does Streptococcus pneumoniae do? | Causes pneumonia/meningitis - only pathogenic when it makes a capsulbe because it prevents phagocytosis, causing disease |
| What does Bacillus anthracis do? | has a capsule of glutamic acide - causes diseases and prevents lysozyme cell death |
| What is the function of flagella? | causes bacteria to become motile |
| Describe the composition of bacterial flagella | made of globular protein |
| Describe the structure of bacterial flagella | long chains that are coiled to form hollow tube, semi-rigid, wavy |
| What is the "large" portion of the flagella known as? | Filament - normally 20 nanometers |
| How is the flagella powered? | By basal body of flagella - it's the motor of flagella |
| How does the flagella work? | By spinning the filament like a propeller |
| The spinning in flagella is powered by? | movement of hydrogen ions |
| What are the functions of the ring structures in flagella? | Hold flagella to cell wall |
| In gram negative flagella, how many ring structures are on the basal body? | 4 |
| In gram positive flagella, how many ring structures are on the basal body? | 2 |
| What does peritrichous mean? | It's the pattern of flagella all over bacterial cell |
| When flagella is described as polar, what does that mean? | means flagella is on one end of the cell |
| Which bacteria have peritrichous flagella? | E. coli and Salmonella |
| Which bacteria have polar flagella? | Pseudonomas |
| How wide is a typical bacterial cell? | 1 micrometer wide |
| How fast does Pseudonomas move? | 50 micrometer per second |
| Is Cocci motile or non-motile usually? | Non motile |
| What is 'pili' also known as? | Fimbriae or Pilus (eventhough they're 2 totally different things) |
| What is pili? | protein extensions of cells - globular protein arranged in coil to form hollow tube |
| What is the function of pili? | adhesion & attachment (sticks to particular cell structure due to protein) |
| How does Nesseria gonorhoeae use its pili? | N. gonorhoeae is gram negative cocci, uses pili to attach to epithelial cells of cervix & urethra |
| Is the pili shorter or longer than a flagella? | Shorter and more numerous |
| What does conjugation mean? | It's a function of pili, attaching to other cells for DNA transfer |
| In E. coli, the conjugation pilus is also known as? | 1. sex pilus 2. F-pilus (fertility pilus) |
| In conjugation, the donor cell is known as 'male' and the recipient cell is known as 'female' | True |
| What is mainly inside a bacterial cell? | Cytoplasm w/ribosome, inclusions, endospore, and nucleoid(s) |
| What is in cytoplasm? | water, dissolved materials, enzymes - basically the fluid where all cell structures are found |
| T/F the bacterial nucleoid is separated from cytoplasm by a membrane | False (no membranes involved) |
| How many types of chromosomes are in bacteria? | 1 type |
| What does the bacterial chromosome do? | Carries genetic information |
| How many bacterial chromosomes are there in E. coli? | At least one |
| T/F In bacteria, DNA replication is much faster than cell division | True |
| What is 'gene'? | Section of DNA that carries information to make product (RNA, protein, etc) |
| What do proteins do? | give traits to cells |
| What are plasmids? | additional DNA, circular DNA, much smaller than chromosomes - tightly coiled, contains extra genes that don't have any info on everyday basis |
| What can plasmids do? | self-replicate (genetic info on antibiotic resistance) |
| Are plasmids crucial in a cell? | Nope, not required by cell to grow in lab, can be lost |
| Are plasmids found in all bacteria? | No |
| What are ribosomes? | Granular stuff found in cell ribosomes (ribosome - location for protein synthesis), made of 60% RNA & 40% proteins |
| What is a bacterial ribosome composed of? | Small subunit & large subunit that join when a protein is being built |
| In bacterial, the small subunit and large subunit have what type of ribosomes? | 30S ribosome & 50S ribosome - combine to form 70S ribosome |
| In eukarya, the small subunit and large subunit have what type of ribosomes? | 40S ribosome & 60S ribosome - combine to form 80S ribosome |
| What is protein synthesis? | Main activity of cell for energy use; it's expensive, cost a lot of energy |
| Which organelle in Eukarya have 70S ribosome? | Mitochondria (which is proof that eukarya MIGHT have been bacteria before) |
| What are inclusions? | not found in all bacteria, deposit of non-living substances in cell, may/may not be enclosed by membrane (fluid, gases, energy, solid crystals) |
| What are some types of inclusions | 1. gas vesicles 2. glycogen/fat 3. volutin (granules) 4. magnetic sensing structures |
| What do gas vesicles do? | allow bacteria to flow up to get the right amount of light (photosynthesis) |
| What is glycogen/fats use for? | energy storage |
| What is volutin (granules) use for? | phosphate storage, chains of phosphate |
| What do you call granules that show up in stain? | metachromatic granules |
| What is an example of a metachromatic granule? | Corynebacterium diphtheriae |
| What two major disease-causing bacteria have endospores? | 1. Bacillus 2. Clostridium |
| What are some characteristics of endospores? | 1. non-reproductive 2. the reproductive cells are called vegetative cells 3. heat-resistant (but can be killed @ 250 fahrenheit) 4. metabolically inactive 5. rapid germination |
| How long does sporulation of an endospore normally take? | several hours, maybe a day |
| What is 10-15% of spore weight consist of? | Dipicolinic acid which protects the spores |
| In endospores, what helps protein to not denature from heat? | Calcium ions |
| Describe the layers of the endospore | 1. Core (center) 2. plasma membrane 3. cortex 4. spore coat 5. exosporium |
| What is the "core" of the endospore? | protoplast, has cytoplasm, ribosome, really dried out - gives endospore heat resistance |
| What is the cortex of the endospore? | peptidoglycan, absorbs water from core to make core dryer |
| What is the spore coat of the endospore? | prevents spore from chemicals & invasion |
| What is the exosporium of the endospore? | made of lipid/proteins, loose layers in some spores |
| Describe mitochondria in Eukarya | 1. circular DNA, can't live outside cell, 2 membrane (inner/outer) layers |
| What happens when you take away mitochondria from a eukaryotic cell? | It can't produce anymore |
| How does mitochondria reproduce? | It divides to make more |
| What is the 'matrix' of mitochondria? | cytoplams inside mitochondria |
| What does the inner membrane of mitochondria do? | contains respiratory enzymes. conducts electron transport to produce ATP |
| Can eukaryotes live w/o mitochondria? | YES, but w/o mitochondria, energy generation is less efficient |
| Besides mitochondria, what other organelle might have came from bacteria as well? | Chloroplasts |
| What is the endosymbiotic theory? | evidence that eukarya might have derived from bacteria |
Created by:
lophung
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