Biomolecules: Nucleic Acids and Carbohydrates

Prokaryotes vs. Eukaryotes

• Prokaryotes are defined as "before the kernel" and do not have membrane-bound organelles.
• They contain three times less genetic material than the smallest eukaryotic cells and possess DNA in singular circular molecules.
• Eukaryotes, meaning "true kernel," have membrane-bound organelles and larger genomes, with DNA stored in chromosomes.
• Both cell types are surrounded by a plasma membrane and share similar macromolecular components.

Parts of the Cell

• Cell Wall: Composed of cellulose, microfibrils, hemicellulose, pectin, lignin, and soluble proteins. Bacterial cell walls primarily contain peptidoglycan (NAG and NAM).
• Plasma Membrane: A semi-permeable barrier regulating nutrient intake, waste filtration, and cell communication.
• Nucleus: Contains chromosomes within a double membrane structure; the outer membrane connects to the rough endoplasmic reticulum (RER).
• Cytosol: Hosts the cytoskeleton for cell shape and motility; key site for cellular metabolism due to abundant enzymes.
• Endoplasmic Reticulum (ER): Largest membrane system in eukaryotic cells; rough ER synthesizes proteins, while smooth ER synthesizes lipids.
• Golgi Bodies: Act as traffic controllers for sorting proteins, modifying secretory proteins within the Golgi lumen.
• Secretory Vesicles: Transport modified proteins and release contents through exocytosis; can fuse for storage.
• Small Vesicles: Coated with clathrin, guiding fusion with target membranes to deliver contents.
• Nucleic Acids: Store genetic information and regulate gene expression through protein synthesis instructions.
• Lipids: Integral structural components of biomembranes.
• Carbohydrates: Primary energy source (glucose) and significant in nucleic acid composition (ribose and deoxyribose). Types include monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

Omega Fatty Acids

• Omega-3: Essential for heart, brain, and metabolism; often under-consumed.
• Omega-6: Energy-providing, abundant in the diet.
• Omega-9: Non-essential fats produced by the body.

Amino Acids Structure

• Primary Structure: Sequence of amino acids in a polypeptide chain.
• Secondary Structure: Folding into patterns like alpha-helices.
• Tertiary Structure: Further folding and organization of secondary structures.
• Quaternary Structure: Assembly of multiple polypeptide chains into a functional protein.

Nucleic Acids Characteristics

• Comprised of phosphate groups, five-carbon sugars (pentose), and organic bases.
• Purines include adenine and guanine; pyrimidines consist of cytosine, thymine, and uracil.
• Leading strand synthesizes from 5' to 3'; lagging strand runs from 3' to 5'.

The Cell Cycle

• The cell cycle consists of G1 (transcription and translation), S (DNA replication), and G2 (preparation for mitosis).
• Mitosis occurs in somatic cells; meiosis occurs in sex cells and involves stages like prophase, metaphase, anaphase, and telophase.

Meiosis and Mitosis Processes

• Prophase 1 features synapsis and crossing over.
• Chromosomes condense, the nuclear envelope fragments, and spindle fibers attach during prophase's later stages.
• Telophase 1 involves partial assembly of the nuclear envelope and cytokinesis.

Cyclins and Cell Cycle Regulation

• Cyclin D responds to mitogenic stimuli, binds to cyclin-dependent kinases (Cdks) (4 and 6) in G1 phase, triggering transcription that synthesizes Cyclins A and E for S phase.
• Following S phase, mitotic cyclins (A and B) interact with CDK1 to initiate M phase, regulated by checkpoints on cell size, nutrient availability, and DNA damage.

RNA Transcription and Processing

• RNA polymerase catalyzes transcription by binding to the promoter region, indicating where transcription begins (often contains a TATA box).
• Pre-mRNA undergoes splicing, removing introns with the aid of spliceosomes forming mature mRNA.
• Processing involves 5' capping and 3' polyadenylation to stabilize and protect the mRNA.

Translation Process

• mRNA is translated into proteins within the ribosome; each tRNA carries specific amino acids and matches codons in mRNA.
• The initiation site for translation involves the attachment of the mRNA and the first tRNA, with ribosomes facilitating the formation of polypeptide chains.

This quiz explores essential biomolecules, focusing on nucleic acids and carbohydrates. Learn about their roles in genetic information storage, energy sources, and cell membrane composition. Test your understanding of these vital components of life.