Week 3: Cell Functions

The central dogma refers to the process by which cells ensure survival using genetic material.
It includes three main processes: DNA replication, transcription, and translation.
Cellular respiration is crucial as it metabolizes glucose using oxygen, producing carbon dioxide, water, and energy (ATP).
The cell cycle involves DNA replication, development, and mitosis, resulting in two identical daughter cells through cytokinesis.
Apoptosis is the programmed cell death linked to cellular processes.

Every cell contains a complete copy of all DNA, allowing for the expression of specific proteins.
Genes are segments of DNA encoding specific proteins interspersed with non-coding regions regulating gene expression.
Transcription: RNA is synthesized from a DNA template in the nucleus.
Cellular Respiration: Biochemical pathways for ATP creation, starting with glycolysis and leading to the citric acid cycle (Krebs cycle).
The electron transport chain forms ATP using energy from oxidation-reduction reactions, with cristae in mitochondria facilitating this process.

Cells exhibit diversity through selective gene expression: different cells read different chapters of the genetic code.
Transcription involves creating mRNA from DNA templates.
Translation uses mRNA to synthesize polypeptides in ribosomes; this process changes the 'language' from nucleotides to amino acids.
Key RNA types involved:
- mRNA: Encodes genetic information.
- tRNA: Carries amino acids to the ribosome.
- rRNA: Forms ribosomal structures.

The ribosome, made of ribosomal RNA and proteins, synthesizes proteins using mRNA as a template.
Initiation: Ribosome assembly occurs, starting with mRNA and initiator tRNA.
Elongation: tRNA enters the ribosome, transferring amino acids to the growing polypeptide chain.
Termination: A stop codon signals the ribosome to release the synthesized protein. Stop codons include UGA, UAA, and UAG.

Cellular Respiration: Using oxygen and nutrients to produce energy, with carbon dioxide as waste.
ATP Production: ATP acts as the energy currency of cells, produced mainly during cellular respiration.
Balanced Chemical Equation for Cellular Respiration:
- C6H12O6 + 6O2 + ADP + Pi → 6CO2 + 6H2O + ATP
Critical molecules involved:
- Reactants: Glucose (C6H12O6), Oxygen (O2), ADP, and Pi.
- Products: Carbon dioxide (CO2), water (H2O), and ATP.

Metabolic Pathway in cytoplasm called 'sugar cutting'.
Glucose is split into two pyruvic acid (pyruvate) molecules, generating ATP and NADH.

Pyruvate is transformed into acetyl-CoA, which enters the cycle.
Each cycle turn generates NADH and FADH2; two turns are needed for each glucose molecule.
Carbon is oxidized to CO2, and energy carriers are produced as a result.

NADH and FADH2 contribute electrons to the ETC, creating a proton gradient in mitochondria.
ATP synthase uses this gradient to generate ATP through chemiosmosis. Without oxygen, ATP production ceases.

Chemiosmosis: The process using the proton gradient to synthesize ATP.
High-energy electrons from NADH/FADH2 cause protons to be pumped into the intermembrane space, creating an electrochemical gradient.

Includes G1 Phase, S Phase (DNA replication), G2 Phase, and M-phase (mitosis).
checkpoints: G1, G2, and M phase monitor DNA integrity and cell readiness for division.

Mitosis: One division producing two diploid daughter cells identical to the parent cell.
Meiosis: Two divisions producing four haploid daughter cells with genetic diversity.

Meiosis produces unique haploid cells, promoting genetic diversity through crossing-over and random assortment during gamete formation.

End products of aerobic respiration: 6 CO2, 6 H2O, and 32-38 ATP.
Glycolysis (anaerobic) yields 2 ATP, while Krebs cycle and ETC (aerobic) yield 30+ ATP total.
The importance of checkpoints in preventing cancer through control mechanisms of the cell cycle.