Microbial Genetics

Knowledge of NADH count is crucial.
- Each NADH generates 3 ATP.
- If there are 10 NADH, the calculation is: 10 NADH x 3 ATP = 30 ATP.
Additionally, there are 2 FADH generated.
- Each FADH generates 2 ATP.
- Calculation: 2 FADH x 2 ATP = 4 ATP.
Total ATP production thus far: 30 ATP (from NADH) + 4 ATP (from FADH) = 34 ATP.

Scenario: Inoculation of growth medium with 50 bacterial cells.
Generation time is 1 hour with a lag phase of 1 hour.
- During the lag phase, cells do not double.
Objective: Determine time required to exceed 10,000 cells.
- Initial count: 50 cells.
- Growth phases follow a doubling process:
- After lag phase (1 hour): still 50 cells.
- Post lag, cells double each hour:
  - Hour 1: 50 → 100
  - Hour 2: 100 → 200
  - Hour 3: 200 → 400
  - Hour 4: 400 → 800
  - Hour 5: 800 → 1600
  - Hour 6: 1600 → 3200
  - Hour 7: 3200 → 6400
  - Hour 8: 6400 → 12800
- Conclusion: Culture exceeds 10,000 cells after 8 hours.

Catabolic reactions typically lead to breakdown via hydrolysis reactions.
Catabolic and condensation reactions represent contrasting biological processes.

Questions surrounding metabolic pathways involving glycolysis, Krebs cycle, and various electron transport chains.
- Importance of different receptors (e.g., nitrate) in anaerobic bacterial respiration to be discussed in further modules.

Gene defined as a sequence, but full meaning requires depth knowledge beyond simple definition.
Large proportion of genome is non-coding sequence; many genes do not encode proteins.
- Microbial genomes are often more efficient in coding.
Classical view of genes has evolved to understand regulatory genes and their implications in heritability.

Genotype: refers to the genetic constitution related to traits.
Phenotype: the observable expression of the genotype (example: eye color).
Expression of genes generates observable characteristics; the challenge is accurately mapping these characteristics to genes.

A nucleotide consists of:
- Nitrogenous base
- Sugar
- Phosphate group
The bonding between these components forms the DNA backbone and dictates molecular directionality (5' to 3').

Double Helix: DNA's characteristic structure.
Antiparallel strands: One runs 5' to 3', the other 3' to 5'.
Major & minor grooves formed by twisting:
- Chemical groups exposed in major grooves facilitate binding of proteins for transcription.

Major groove contains richer information for binding due to varying chemical groups.
Proteins can recognize specific sequences by navigating through these grooves without needing to separate the strands completely.

DNA’s stability compared to RNA is critical for maintaining genetic consistency during replication.
Requirement for stable genetic material to ensure reliable inheritance.

Semiconservative replication: Each daughter cell receives one parental strand and one newly synthesized strand.
Bacteria possess circular DNA with a single origin of replication, whereas eukaryotes have linear chromosomes with multiple origins.

Initiation occurs at origin of replication, typically rich in A-T due to weaker hydrogen bonds, facilitating unwinding.
**Enzymes involved:
- Helicase: Unzips the DNA strands.
- Topoisomerase: Alleviates the twisting tension ahead of the helicase.
- SSB (single-strand binding protein): Stabilizes unwound single-stranded DNA.

DNA polymerase III plays a central role in elongation by adding nucleotides to the growing strand, growing in the 5' to 3' direction.
Replication of the leading strand occurs smoothly, while the lagging strand poses challenges due to its opposite orientation, requiring small fragments (Okazaki fragments).

RNA primase synthesizes short RNA primers enabling DNA polymerase to begin replication.
Primers are needed due to DNA polymerase's inability to initiate nucleic acid synthesis directly.

Understanding these processes is vital not only for genetics but also for practical applications such as biotechnological advancements and medical genetics.