WEEK 2 - BIOREACTION.pptx interaksi ion dan molekul dalam sel

WEEK 2 - BIOREACTION.pptx

1. PREVIOUS WEEK QUESTION HOW IS THE GOLGI BODIES SORTING THE PROTEINS AFTER THE SYNTHESIS ON ROUGH ER? FOLDING PROTEINS MOLECULES TAG ADDING (e.g glycosilation, sulfation) Folding perfectly --> fuses outside the cells Misfolded --> broken and unused The receptors match with the tag --> fuses outside the cells The receptors do not match --> the protein can not fuses outside temporary

2. Interaction of Ions and Molecules in Molecular Parts of Cells WEEK 2 - BIOREACTION

3. What will we learn today? Able to apply chemical concepts and interactions of ions and molecules OBJECTIVES Interaction of ions, molecules in the molecular parts of cells LECTURE Evaluation of lecture suitability and discussion outcomes by topic OUTCOME

4. INTRODUCTION Some organelles can be seen through the macromolecules and monomeric units The monomeric units have their own chemical structure depends on their types The activity inside the cells would not be happened without the interaction of the monomeric units

5. INTERACTION OF IONS Ionic interactions are the result of electrostatic attraction between oppositely charged ions. GENERAL ILLUSTRATIONS MOLECULAR ILLUSTRATIONS

6. a. Ion Channels b. Ion Pumps Ionic Interactions in Cell Membranes TYPES OF IONIC INTERACTIONS 2. Ionic Interactions in Proteins a. Salt Bridges 3. Ionic Interactions in Nucleic Acid a. DNA and RNA

7. Do you remember? IONIC INTERACTIONS IN CELL MEMBRANES Larged polar and charged ions can not cross the membranes due to their polarity Need a help from channel protein Amino acids have both negative and positive charged from their amine and carboxylic groups

8. IONIC INTERACTIONS IN CELL MEMBRANES Charged ions cross the protein membranes in two ways PASSIVE TRANSPORT ACTIVE TRANSPORT Do not required the energy. Charged ions move from higher to lower concentration Requires the energy. Charged ions moved against the gradients ION CHANNELS ION PUMPS

9. ION CHANNELS DEFINITION : Ion channels are transmembrane proteins that form pores or channels in the lipid bilayer of cell membranes, permitting the selective flow of ions across the membrane KEY CHARACTERISTICS : Ion channels are often selective for specific ions Ion channels can open or close in response to specific stimuli TYPES : Leak Channels (always open) Ligand-gated Channels Voltage-gated Channels

10. ION CHANNELS LEAK CHANNELS (always open) Potassium Leak Channels (K⁺ Leak Channels): Allow K⁺ ions to move out of the cell. Sodium Leak Channels (Na⁺ Leak Channels): Allow Na⁺ ions to move into the cell. PHYSIOLOGICAL IMPORTANCE : Leak channels help maintain the ion gradients across the membrane Leak channels play a critical role in neuronal excitability. In addition to neurons, cardiac and smooth muscle cells also rely on leak channels to regulate their membrane potential

11. ION CHANNELS 2. LIGAND-GATED CHANNELS (depend on the existence of ligand) MECHANISMS : Ligand Binding: A ligand (e.g., a neurotransmitter) binds to the extracellular domain of the ion channel. Conformational Change: The binding of the ligand induces a structural change in the ion channel protein. Channel Opening : This structural change opens the channel, allowing specific ions (such as Na⁺, K⁺, Ca²⁺, or Cl⁻) to flow through the membrane. Ion Flux and Cellular Response : The flow of ions leads to changes in the membrane potential or intracellular ionic concentration TYPES OF LIGAND : Gamma-Aminobutyric Acid (GABA) Glutamate Purienergic

12. ION CHANNELS 3. VOLTAGE-GATED CHANNELS DEFINITION : Ion-selective transmembrane proteins that open or close in response to changes in the electrical potential difference across the cell membrane MECHANISM : Resting State: The membrane potential is at its resting level, voltage-gated channels are typically closed. Depolarization: A change in membrane potential occurs when the inside of the cell becomes less negative Conformational Change and Channel Opening: Depolarization leads to a change in the voltage-sensing domain of the channel protein, causing it to open. Ion Flux: Once open, ions such as Na⁺, K⁺, Ca²⁺, or Cl⁻ flow through the channel according to their electrochemical gradients Inactivation and Repolarization: The channel cannot be reopened until the membrane potential returns to the resting state (repolarization).

13. ION PUMPS DEFINITION: Ion pumps are transmembrane proteins that use energy (typically derived from ATP hydrolysis) to move ions across the cell membrane against their concentration or electrochemical gradients

14. ION CHANNELS VS ION PUMPS

15. IONIC INTERACTIONS IN PROTEIN DEFINITION : Salt bridges are non-covalent interactions that occur between oppositely charged amino acid side chains in proteins or other macromolecules SALT-BRIDGE INTERACTIONS Components of Salt Bridges: Positively Charged Residues: Lysine (Lys, K), Arginine (Arg, R), and sometimes Histidine (His, H) when it is protonated. Negatively Charged Residues: Aspartate (Asp, D) and Glutamate (Glu, E). Importance of Salt-Bridge: Salt bridges are particularly important in stabilizing the tertiary and quaternary structures of proteins. In enzymes, salt bridges can also play a role in the active site to help bind substrates or stabilize transition states.

16. Ionic interactions in nucleic acids, such as DNA and RNA, are crucial for their stability, structure, and function. These interactions occur between the negatively charged phosphate groups in the backbone of nucleic acids and positively charged ions or molecules in the surrounding environment. They help in neutralizing the negative charges of the phosphate backbone and facilitate the formation of stable structures like double-stranded DNA (dsDNA) and RNA secondary structures. IONIC INTERACTIONS IN NUCLEIC ACID Monovalent ions Divalent ions

17. Interaction of Molecules The role of water in biological process NEXT MEETING