Lecture 9: Biosynthesis and Cell Growth Flashcards
(21 cards)
What is the purpose of catabolic metabolisms?
To break down complex molecules into simpler ones, releasing energy in the process, which is then used to power cellular processes and build new molecules
What is the purpose of anabolic metabolisms?
To build complex molecules from simpler ones, using energy, to support growth, tissue maintenance, and energy storage.
What are the building blocks for the primary macromolecules?
proteins - amino acids
nucleic acids - nucleotides
lipids - fatty acids, glycerol
polysaccharides - monosaccharides
What is gluconeogenesis?
Some cells don’t have access to glucose so it will take the carbons it has (C2-C5) and feed it into the citric acid cycle. It will become oxalacetate and then decarboxylated into PEP. Then the process can be reversed to get the glucose needed (glucose-6-P)
PEP -phosphoenolpyruvate
C5 - pentose
C6 - hexose
What form of nitrogen is commonly used to form the amino group for amino acids?
Nitrite (NO2-)
How are fatty acids biosynthesized?
Acyl Carrier Proteins will hold onto carbons as they are put together. Acetyl-ACP (C2) is combined with malonyl-ACP(C3) through decarboxylation which will make acetoacetyl-CoA (C4) since you lose a carbon in the process. Then to get rid of the uneeded oxygen, NADPH will reduce the intermediate to create a 4 carbon chain molecule. The carbons are added two at a time from C3 malonyl-ACP
fatty acids are long carbon chains
What is the difference between lipids in Bacteria, Eukarya and Archaea
- fatty acids chains substituted to glycerol via esther linkages in bacteri and eukarya
- phytanyl side chains instead in archaea
How are polysaccharides synthesized?
UDPG or ADPG will supply glucose one at a time to the growing polymer chain and it is then ends up as ADP.
Example of polysaccharide - peptidoglycan, glycogen
UDPG/ADPG - urinin/adenosine diphosphoglucose
How are pentoses used nucleic acid synthesis?
- need 5 carbon sugars to make up nucleotides
- Glucose-6-P –> decarboxylation –> ribulose-5-P (shift around)–> ribose-5-P –> ribonucelotides –> RNA
- DNA: NADPH + ribonucleotide reductase –> deoxyribonucleotide –> DNA
What are the catabolic pathways that can provide intermediates for the production of amino acids?
Citric acid cycle - alpha-ketoglutarate, oxalacetate
Glycolysis - pyruvate, phosphophynol pruvate –> 3-phoshpoglycerate
What are the precursors for purines and pyrimindines ring stuctures for the synthesis of nucleotides?
Purines are made from inosine and pyrimindines are made orotate.
What are the steps in prokaryotic binary fission?
DNA replication –> cell elongation –> septum formation –> completion of septum with formation of distinct walls –> cell separation
What is the divisome?
a complex, dynamic protein machine in bacteria that orchestrates cell division, constricting the inner and outer membranes and synthesizing the septal peptidoglycan (sPG) at the division site.
What are the components of a divisome and their function?
The divisome includes FtsZ protein, a bacterial tubulin homologue, which forms a ring-like structure called the Z-ring at the cell’s midpoint. FtsZ rings depolymerize, constricting the membrane at the center.
Fts - filamentous temperature sensitive
tubullin mutants- analog of ftsZ
What is Fts?
They stand filamentous temperature sensitive mutants are temperature dependent so they will not segregate the cell correctly if the temperature is too high
What is the experimental discovery of FtsZ?
FtsZ was studied in Fts mutants using the immunogold labeling. The protein was labeled antibodies and conjugated to gold particles.
What is the role of FtsK, FtsA and ZipA?
FtsA and ZipA act as membrane anchors for FtsZ, while ZipA also helps recruit downstream cell division proteins, and FtsK is recruited after FtsZ, FtsA and ZipA, and is required for the recruitment of other divisome components. FtsK help chromosomes segregate.
What is the role of Min proteins?
MinC proteins prevent cell division and formation of Z-rings until the cell center has been located by FtsZ.
MinE proteins inhibit MinC, localize the center, and recruit FtsZ.
What is the role of Mre B proteins?
MreB forms polymers similar to the actin filaments that make up the cytoskeleton of eukaryotic cells.
MreB (along with peptidoglycan) dictates cell shape. Cocci have not MreB.
How is peptidoglycan being broken down in cell division?
Autolysins will break the glycosidic bonds and is highly regulated.
How is peptidoglycan being synthesized during cell division?
Monomers are made inside the cell. Bactoprenol (hydrophobic lipid) is the molecule that shuttles the intermediate across the membrane. It also helps with assembly by interacting with other proteins to catalyze the bonds. Once the monomers are transported outside the cell membrane, they are assembled and cross-linked by peptidoglycan transpeptidase (target of penicillin).
