Download TandT Group work

Stage 02 – Colonization and Infection: Our Story, Continued…. Building a cell!
For prokaryotic cells to grow by binary fission in order to colonize or infect a host they need to
1. adhere to the host, get past the normal microbiota, and subvert the immune system (that’s Stage 03),
2. have the right environment, and
3. transport in the nutrients they need to harvest energy and make precursor metabolites
a. that will allow them to build amino acid, nucleotide, lipid, and carbohydrate subunits,
i. which will allow them to build protein, nucleic acid, lipid, and polysaccharide
macromolecules through the processes of
1. DNA Replication,
2. Transcription,
3. Translation, and
4. Enzyme-mediated chemical reactions
a. Which will allow them to make the cellular structures needed to produce
a new generation of cells.
During metabolism we:
• Broke down our chemical energy source (example: glucose) to make precursor metabolites
• Harvested and stored the energy from our chemical energy source in
o ATP
o Proton motive force
o Reducing power
• Used our precursor metabolites to make subunits (amino acids, nucleotides, fatty acids, glycerol, and
monosaccharides)
Now we a store of energy AND we have subunit building blocks that we need to build the macromolecules that
make up our bacteria’s cellular structures. So let’s build them and make a whole new cell!
DNA Replication
The bacterial cell needs to replicate its chromosome to make sure the new daughter cell has a complete copy for
the genome. Using the key words below, draw a diagram and supplement with explanation where needed, that
shows how DNA Replication occurs:
•
•
•
•
•
•
•
•
Circular chromosome
Origin of replication
Replication forks
Helicase
DNA polymerase (5’  3’ direction)
Template strand
DNA nucleotides (deoxyribonucleotides)
DNA base pairing (A-T, G-C)
•
•
•
•
•
•
•
Leading strand
Lagging strand
Primase
RNA nucleotides (ribonucleotides)
Okazaki fragments
DNA ligase
Semiconservative replication
Gene Expression
Now that our bacterial cell has replicated its chromosome, now it needs to make another set of structural and
functional proteins for our new cell. The cell does this through a process called “gene expression.” In order to
make a new protein (ie, to express a gene),
o First, we have transcribe the gene into an RNA messenger (mRNA),
o Then, we have to translate the mRNA code into amino acids, and string them together to make a
protein.
Let’s transcribe our gene (DNA language  RNA language):
Transcription
Using the key words below, draw a diagram and supplement with explanation where needed, that shows how
Transcription occurs:
•
•
•
•
•
•
•
DNA
G
A
T
C
•
•
DNA
Gene
Promoter
RNA polymerase (5’  3’ direction)
Minus (-) strand DNA template
RNA nucleotides (ribonucleotides)
DNA-RNA base pairing:
RNA
C
U
A
G
Terminator
mRNA
Now that we have our mRNA, let’s translate our gene (RNA language  amino acid language):
Translation
Using the key words below, draw a diagram and supplement with explanation where needed, that shows how
Translation occurs:
•
•
•
•
•
•
mRNA
tRNA
amino acids
ribosome
P-site
A-site
•
•
•
•
•
AUG start codon
Codons
Anticodons
Genetic code
STOP codons
Now that we’ve made DNA and proteins, let’s also make lipids and polysaccharides!
Remember:
Fatty acids + glycerol connected together make lipids (fatty acids + glycerol  lipids)
Monosaccharides connected together make polysaccharides (monosaccharides  polysaccharides)
Enzymes are what connect the subunits together to make the macromolecules! We’ve already seen the
enzymes DNA polymerase and RNA polymerase at work. Use the following key words and concepts to explain
how enzymes work:
•
•
•
•
•
•
•
•
•
Enzymes are made out of protein that are folded into a very specific shape
Active site
Substrates
Can break down a substrate (as seen in catabolism) or connect substrates (as seen in anabolism)
Lowers activation energy needed for a chemical reaction to proceed
Catalyst – speeds up a chemical reaction without being used up, so it can work over and over again.
pH and temperature dependence
Competitive inhibitor
Noncompetitive inhibitor