Bio sac 1

This area of study focuses on the expression of genetic information encoded in DNA to synthesize proteins.
It involves exploring the genetic code and the proteome.
Students will learn about the structure and function of the DNA molecule.
Application of molecular tools and techniques to manipulate DNA for specific purposes.
Comparison of gene technologies addressing human and agricultural issues.
Consideration of the ethical implications associated with these technologies.

Nucleic Acids: DNA and RNA as information molecules that encode instructions for protein synthesis.
- Structure of DNA: Composed of nucleotides made of a 5-carbon sugar, phosphate group, and nitrogenous base.
- Types of RNA:
- mRNA (messenger RNA): Carries genetic information from DNA to ribosomes.
- rRNA (ribosomal RNA): Forms the core of ribosome's structure.
- tRNA (transfer RNA): Brings amino acids to ribosomes during translation.
Genetic Code: A universal triplet code that is degenerate, meaning multiple codons can code for the same amino acid.
- Gene Expression Steps:
- Transcription: Synthesis of RNA from a DNA template.
- RNA Processing: Modifications before translation.
- Translation: Synthesis of proteins by ribosomes.
Structure of Genes: Composed of coding (exons) and non-coding (introns) regions, and regulatory elements (promoter, operator).

Key chemical elements: Carbon (C), Hydrogen (H), Oxygen (O), Phosphorus (P), and Nitrogen (N).
Biopolymers and macromolecules include nucleic acids (DNA, RNA) and proteins.
Monomers of nucleic acids are nucleotides.
Components of Nucleotides: 5-carbon (pentose) sugar, phosphate group, nitrogenous base (nucleobase).
Nucleotide monomers form a polymer structure via phosphodiester bonds.

Nucleotide Differences:
- DNA has deoxyribose sugar; RNA has ribose sugar.
- DNA contains thymine (T), while RNA has uracil (U).
Base Pairing: A pairs with T (or U in RNA), C pairs with G.
- Structural Features:
- DNA: Double-stranded, anti-parallel, forms a double helix.
- RNA: Single-stranded.

Genes: Sections of DNA that can produce proteins (coding) or RNAs (non-coding).
Gene Expression Regulation: Genes can be activated (expressed) or repressed (turned off).

Regions of Genes:
- Exons: Coding sequences expressed in proteins (~1% of human genome).
- Introns: Non-coding sequences that are spliced out during processing.
- Promoter Region: RNA polymerase binding site.
- Operator Region: Binding site for repressor proteins in prokaryotes.
- Untranslated Regions (UTRs): Regulatory roles at 5’ and 3’ ends.

Initiation:
- RNA polymerase binds to the promoter region; DNA unwinds to expose bases.
Elongation:
- RNA polymerase synthesizes pre-mRNA by adding complementary ribonucleotides. RNA grows in a 5’ to 3’ direction.
Termination:
- RNA polymerase detaches upon reaching the termination sequence; DNA reforms double-helix.
- Pre-mRNA undergoes processing into mature mRNA.

Additions: 5’ methyl-G cap added and a 3’ poly-A tail for stability.
Splicing: Introns removed, exons joined, allowing for alternative splicing (producing various mRNAs from one gene).

Initiation:
- tRNA binds to mRNA, bringing the first amino acid (usually Methionine).
Elongation:
- Polypeptide chain formed as tRNA delivers amino acids; peptide bonds formed via condensation reactions.
Termination:
- Release of polypeptide chain upon reaching a stop codon.

Genetic code is universal, allowing genes to be shared across species.
Codon Example:
- DNA triplet: TAC → mRNA codon: AUG → tRNA anticodon: UAC → Amino acid: Methionine.
- Useful for genetic engineering, as genes from one organism can be inserted into another.

Codons specify one amino acid but multiple codons can code for the same amino acid.

Amino Acids: Monomers forming polypeptide chains, defined by their R groups which influence properties (hydrophobic, hydrophilic, etc.).
Polypeptide Chains: Formed through peptide bonds; may require joining with other chains for functionality.

Primary Structure (1°): Linear sequence of amino acids determined by DNA.
Secondary Structure (2°): Localized folding (alpha-helix, beta-pleated sheet) formed by hydrogen bonding in the polypeptide backbone.
Tertiary Structure (3°): Overall 3D shape of a polypeptide, resulting from interactions among R groups (disulfide bridges, ionic bonds, hydrogen bonds, hydrophobic interactions).
Quaternary Structure (4°): Assembly of multiple polypeptide chains into a functional protein.

Proteins must maintain precise shape to function; environmental factors can alter this (e.g. temperature, pH).
Minor genetic changes can lead to significant functional impacts due to structural alterations.

Endonucleases: Cut DNA at specific recognition sequences (restriction sites); can produce sticky or blunt ends.
DNA Ligase: Joins DNA fragments by catalyzing phosphodiester bonds.
DNA Polymerases: Synthesize DNA and RNA strands from nucleotide building blocks.

Function: CRISPR-Cas9 acts as a bacterial immune system, allowing precise editing of an organism's genome.
Mechanism:
- Guide RNA directs Cas9 endonuclease to target DNA sequence; creates double-strand breaks for gene editing.
Applications: Editing crops for enhanced traits like disease resistance, improving photosynthetic efficiency.

Production: Through recombinant DNA technology, introducing traits for higher yields or disease resistance.
Example: Human insulin production using recombinant plasmids that integrate insulin genes into bacterial systems.

Implications of GMO Usage: Biotechnological advancements have benefits like cost reduction for treatments but also ethical concerns such as potential off-target effects during gene editing.

In summary, nucleic acids and proteins are integral to maintaining life, facilitating essential processes such as genetic information expression, protein synthesis, and genetic engineering applications, all underpinned by ethical considerations in modern biotechnology.