Lecture3 Peptidoglycan synthesis and Eukaryotic Cell structure Flashcards
Gram-postive bacteria stain ____
purple
Gam-negative bacteria stain ____
pink
Giemsa staining is due to
cell wall structure
What two alternating sugars for peptidoglycan backbone
- N-acetylglucosamine (NAG)
- N-acetylmuramic acid (NAM)
Peptidoglycan chains have alternating ___ and ____ amino acids attached to ____
D-, L-, attached to NAM
Peptidoglycan is joined by crosslinks between the _____
peptides
E. coli peptidoglycan exhibits _____ cross-linking
direct
Staphylococcus aureus peptidoglycan exhibits _______ linking
Peptide interbridge
Peptidoglycan synthesis is a complex process involving _____ derivatives
UDP
Peptidoglycan synthesis uses ____ to transport NAG-NAM- pentapeptide units across the cell membrane
bactoprenol
Function of Bacitracin
Does not allow bactroprenol carrier to lose one phosphate (bactoprenol phosphate) and move back to the cytoplasmic side of the membrane
The final step in peptidoglycan synthesis is _____which creates the peptide cross-links between the peptidoglycan chains
transpeptidation
Amino acids are added to NAM one at a time, except for the last _____ ____, which are added in the same reaction
D-alanines
What are the two carriers involved in peptidoglycan biosynthesis
- Bactoprenol
- Uridine diphosphate
A 55-carbon alcohol that attaches to NAM by a pyrophosphate group and moves peptidoglycan units through membrane
Bactoprenol
Bactoprenol is a ___- carbon alcohol that attaches to NAM by a _____ group
55, pyrophosphate group
Bactoprenol function
moves peptidoglycan units through hydrophobic membrane
Uridine diphosphate is an activated ______ carrier, except in the case of peptidoglycan synthesis it carries _____ or ____ instead of glucose
sugar, NAM or NAG
Cycloserine inhibits
Blocks formation of D-Ala-D-Ala
______ inhibits transpeptidation by binding to D-Ala-D-Ala
Vancomycin
Penicillin inhibits the ______ reaction
transpeptidation
_____ blocks the dephosphorylation of bactoprenol pyrophosphate
Bacitracin
The 8 stages of peptidoglycan synthesis
- UDP derivatives of NAM and NAG are synthesized in the cytoplasm
- Amino Acids are added sequentially to UDP-NAM to form the pentapeptide chain
- The 2 terminal D-alanines are added as a dipeptide
- No ribosomes involved - NAM-Pentapeptide is transferred from UDP to a bactoprenol phosphate at the membrane surface
- UDP-NAG adds NAG to the NAM-pentapeptide
- Glycine interbridge, if present, is added - The completed unit is transported across the membrane to its outer surface by the bactoprenol pyrophosphate carrier
- The peptidoglycan unit is attached to the growing end of a peptidoglycan chain
- Bactoprenol returns to inside of membrane. A phosphate is released; bactoprenol phosphate can now accept another NAM-pentapeptide
- Transpeptidation occurs
How does a bacterial cell add new peptidoglycan units to its existing cell wall
- Autolysis carry out limited digestion of peptidoglycan
- This provides acceptor ends for addition of new peptidoglycan units
are ribosomes involved in the amino acids being added sequentially to UDP-NAm to form the pentapeptide chain
No!
Gram-positive bacteria stain
purple
Gram-negative bacteria stain
pink
The gram staining reaction is due to
cell wall structure
Inventor of gram stain
Danish physician Hans christian Gram
The gram stain was invented in ____ and published in
1883 and published in 1884
Hans Christian Gram studied ____ tissue sections form patients who died of ____
lung, pneumonia
Han Christian Gram discovered that _____ and a solution of ___ and ____ formed a water soluble precipitate that could be removed from host tissues and some microbial cells by an alcohol rinse. Many other microbes retained the stain
Gentian (crystal) violet, iodine, and potassium iodide
Hans Cristian Gram did not originally use ____ in his stain
safranin
Gram stain primary stain is _____ in combination with ___.
- Crystal violet in combination with iodine
What is the function of iodine in the gram stain
it acts as a mordant to enhance crystal violet staining
What is the counter stain used in gram staining
Safranin
What is used to decolorize the gram negative bacteria
Alcohol or acetone removes crystal violet from Gram-negative cells
Gram-positive cell wall has a ___ ring basal body
2
Gram-negative cell wall has a ___ ring basal body
4
Gram-positive cell wall is disrupted by ____ and sensitive to ____
lysozyme, Penicillin
Gram-negative cell wall is _____ sensitive
Tetracycline (because it attacks the ribosomes)
Acid-fast cells resist decolorization with _____
acid alcohol
the basis for acid-fast staining is a ____ cell wall composed of ______
waxy cell wall composed of mycolic acids
examples of cells that stain with acid-fast stain
- Mycobacterium
- Nocardia
The waxy cell wall composed of mycelia acids prevents
water-soluble stains form crossing the cell wall
Acid-fast staining methods use ______, which is a ______ soluble stain
carbolfuchsin, lipid soluble stain
Acid-fast stain ,Carbolfuchsin, contains ____ to help the stain penetrate the cell wall
Phenol
Acid-fast cells often give ____ gram stain results, this is due to
abnormal, poor stain absorption followed by high retention
Acid fast staining is important for identifying bacteria in the genus _____, which can be pathogenic
Mycobacterium
Examples of bacteria in the genus Mycobacterium
- M. leprae
- leprosy
- M. tuberculosis
- Tuberculosis
Acid fast staining can be used to identify opportunistic pathogenic members of the actinomycete genus _____ and oocysts of coccidian parasites, such as _______ and _____
Norcardia, Cryptosporidium, Isospora
bacterial spores are _____, as well as the head of sperm, and certain eukaryotic cellular inclusions (neuronal cytoplasmic inclusion bodies and nuclear inclusion bodies)
acid fast
What is a common counterstain in acid fast staining
methylene blue
Carbolfuchsin stains what color
Red
Mycoplasmas lack
cell walls
Mycoplasmas have what in their plasma membranes
sterols
the cell walls of archaea can be ____ or ____
absent or pseudomurein (lack NAM and D-amino acids)
What two groups of eukaryotes commonly possess microbial members
- protists
- fungi
Prominent members of ecosystem, useful as model systems and industry, and some are major human pathogens
Eukaryotic microorgansims
What are the common features of Eukaryotic cells
- Membrane-delimited nuclei
- Membrane-bound organelles that perform specific functions
- Intracytoplasmic membrane complex serves as transport system
- More structurally complex and generally larger than bacterial or archaeal cells
The intracytoplasmic membrane complex serves as ____ system in eukaryotic cells
transport
Functions of plasma membrane in eukaryotic cells
- mechanical cell boundary
- selectively permeable barrier with transport system
- mediates cell-cell interactions and adhesion to surfaces
- secretion
- signal transduction
Functions of cytoplasm
- Composed of cytosol (liquid portion) and organelles
- location of many metabolic processes
Functions of Cytoskeleton
- Composed of actin filaments, intermediate filaments, and microtubules
- provides cell structures and movements
Functions of endoplasmic reticulum
- Transport of materials
- lipid synthesis
Functions of ribosomes
Protein synthesis
Function of golgi apparatus
- Packaging and secretion of materials for various purposes
- lysosome formation
Function of Mitochondria
- Energy production through use of the tricarboxylic acid cycle, electron transport, oxidative phosphorylation, and other pathways
Function of Chloroplasts
- Photosynthesis (trapping light energy and forming carbohydrate from CO2 and water)
Functions of nucleus
repository for genetic information
Functions of Nucleolus
- Ribosomal RNA synthesis
- Ribosome construction
Functions of Cell wall and pellicle
- Strengthen and give shape to the cell
Functions of cilia and flagella
- cell movement
Functions of vacuole
- Temporary storage and transport
- Digestion (food vacuoles)
- Water balance (contractile vacuole)
Where are free ribosomes located
-cytosol, nucleus, and mitochondria
Where are bound ribosomes located
on the Rough ER
Eukaryotic cell envelopes consist of the _____ and ____
plasma membrane and all coverings external to it
The plasma membrane of eukaryotic cells is a _______
lipid bilayer
What are the major eukaryotic membrane lipids
- phosphoglycerides
- sphingolipids
- cholesterol
all of which contribute to strength of membrane
The plasma membrane of bacteria and eukaryotes both have _____
phospholipids
The plasma membrane of eukaryotic cells have ______ which participate in a variety of cellular processes
microdomains (lipid rafts)
Unlike the ______ in the cell wall of Bacteria and Archaea, many eukaryotes lack or have a chemically distinct cell wall
peptidoglycan
Cell walls of photosynthetic algae are composed of
- cellulose
- pectin
- Silica
Cell walls of fungi are composed of
- Cellulose
- Chitin
- Glucan
____ are the most prominent external structures observed on eukaryotic cells
cilia and flagella
how are cilia and flagella of a eukaryotic cell different
- cilia are typically only 5 to 20 micrometers while flagella are 100 to 200 micrometers long
- their patterns of movement are usually distinctive
substance inside plasma and outside nucleus
Cytoplasm membrane
fluid portion of cytoplasm
cytosol
Cytoskeleton is
microfilaments, intermediate filaments, microtubules
movement of cytoplasm through cells
Cytoplasmic streaming
80S ribosomes are found where in eukaryotic cells
- membrane bound: attached to ER
- Free: in cytoplasm
70S ribosomes are found where in eukaryotic cells
- In chloroplasts and mitochondria
bacterial ribosomes are what size
70s
An 80S ribosome are composed of
-a dimer of 60S and 40S subunit
The 60 S subunit is composed of 3 rRNA molecules which are ____, _____, and _____
5S, 28S, and 5.8S rRNAs
The 40S subunit is composed of 1 rRNA (_____), and ____ proteins
18S rRNA and 30 proteins
organelle that contains chromosomes
Nucleus
organelle that is the transport network
ER
Organelle that functions in membrane formation and secretion
Golgi complex
Organelle that functions in digestive enzymes
Lysosome
Organelle that brings food into cells and provides support
Vacuole
Organelle that functions in cellular respiration
Mitochondrion
Organelle that functions in photosynthesis
Chloroplast
Organelle that functions in oxidation of fatty acids and destroys hydrogen peroxides
Peroxisome
Organelle that consists of protein fibers and centrioles
Centromere
_____, ____ and ____ are all thought to have evolved from bacterial cells that invaded or were ingested by early ancestors of eukaryotic cells
- Mitochondria
- Hydrogenosomes
- Chloroplasts
Mitochondria are very similar to extant _____
bacteria
Chloroplasts are very similar to extant _____
cyanobacteria
” the power house of the cell” are found in most eukaryotic cells
Mitochondria
Site of tircarboxylic acid activity
mitochondria
Organelle where ATP is generated by electron transport and oxidative phosphorylation
Mitochondria
The Mitochondria is about the same size as ___ cells
bacterial
Mitochondria reproduce by _____ as do bacterial cells
binary fission
The outer membrane of mitochondria contain ____ similar to the outer membrane of Gram-negative bacteria
porins
The inner membrane of mitochondria are highly fold to form ______ and is the location of enzymes and electron carriers for _____ and _____
cristae, electron transport and oxidative phosphorylation
The mitochondrial matrix is enclosed by ______
inner membrane
The mitochondrial matrix contains ribosomes (_____ the same as _____) mitochondrial DNA (may be _____ like ____ DNA)
70S, same size as bacterial ribosomes, closed circular like bacterial DNA
The mitochondrial matrix contains enzymes of the tricarboxylic acid cycle and enzymes involved in _____ of fatty acids
catabolism
Small energy conservation organelles in some anaerobic protists
Hydrogenosomes
Hydrogenosomes descended form common ____ ancestor
mitochondrial
Hydrogenosomes have a ____ membrane, ____ cristae, and usually ___ DNA
double, no, lack
Hydrogenosomes ATP is generated by _____ process rather than respiration
fermentation
What are the products of ATP production in Hydrogenosomes
CO2, H2, and acetate
What are plastids
cytoplasmic organelles of photosynthetic protists and plants
Pigment containing organelles observed in plants and algae that are the site of photosynthetic reactions
Chloroplasts
Chloroplasts are surrounded by ____ membrane
double
The stroma (matrix) of a chloroplast is within the inner membrane and contains
- DNA
- Ribosomes
- Lipid droplets
- Starch granules
- Thylakoids
What are Thylakoids
- flattened, membrane delimited sacs
- site of light reactions (trapping of light energy to generate ATP, NADPH, and oxygen)
stacks of thylakoids are called
grana
____ is the site of dark reactions of photosynthesis (formation of carbohydrates from water and carbon dioxide)
Stroma
many algal chloroplasts contain a _____, which participates in polysaccharide synthesis
pyrenoid
Molecular unity basic to bacterial, archaeal, and eukaryotic cells
- biochemical processes, metabolic pathways
- genetic code
Differences in eukaryotic cells from bacterial and archaeal
- eukaryotic nucleus (membrane-enclosed nucleus)
- larger, more complex (archaea and bacteria are about the size of mitochondria and chloroplast and have no organelles)
- meiosis, mitosis (archaea and bacteria lack both)
- complex processes (bacteria and archaea cannot perform endocytosis, intracellular digestion, directed cytoplasmic streaming, and ameboid movement)
