Cellular Structure Lecture 6 PDF

Lecture 6 Cellular Structure Which of the following molecules would likely diffuse through the lipid bilayer of a plasma membrane most rapidly? A) sucrose B) an amino acid C) O2 D) Na+  Cellular Structure A: Prokaryotes versus Eukaryotes B:Cellular structures and their functions ...

Lecture 6 Cellular Structure Which of the following molecules would likely diffuse through the lipid bilayer of a plasma membrane most rapidly? A) sucrose B) an amino acid C) O2 D) Na+  Cellular Structure A: Prokaryotes versus Eukaryotes B:Cellular structures and their functions  Cellular Structure Prokaryotes versus Eukaryotes Cellular structures and their functions Plant or animal? Elysia chlorotica Prokaryotes vs. Eukaryotes Prokaryotes vs. Eukaryotes Green = Listeria (prokaryote) Red = animal host cell (eukaryote) Listeria Prokaryotic vs. Eukaryotic Cells Bacteria Plants, animals & protists Prokaryotic vs. Eukaryotic Cells Bacteria Plants, animals & protists BOTH Plasma membrane Genetic information = DNA (chromosomes) Ribosomes for translation Prokaryotic vs. Eukaryotic Cells Bacteria Plants, animals & protists Differences Prokaryotes: Lack a nucleus Eukaryotic cells- Posses a nucleus Prokaryotic vs. Eukaryotic Cells Bacteria Plants, animals & protists Differences Prokaryotes: 1 – 5 microns in length Eukaryotic cells- 10 - 100 microns  Prokaryotic vs. Eukaryotic Cells Bacteria Plants, animals & protists Differences Prokaryotes: No membrane-bound organelles Eukaryotic cells- Possess membrane-bound organelles  Cells – Part by Part nucleus, nucleolus ribosomes endomembrane system endoplasmic reticulum Golgi apparatus lysosomes peroxisomes vacuoles (central vacuole in plants) mitochondria chloroplasts  Structure of a typical plant cell (Assembly line) (House of photosynthesis) (Control center) (Powerhouse) (tunnel) (Assembly line) (Workbench) (Distribution center)  Cells – Part by Part nucleus, nucleolus Enclosed by two Bi-layers -Genetic information (DNA) stored in nucleus, transcription occurs in nucleus. -Ribosomal RNA is synthesized in the nucleolus  Chromosome –Chromatin- Nucleolus Chromosome DNA carries genetic information in the form of genes and is located in the nucleus of eukaryotic cells. It is associated with proteins (mainly histones) and is organized into thread-like structures called chromosomes. Chromatin Chromatin is the uncondensed, less organized form of DNA and proteins found in the nucleus during interphase. It exists in two forms: Euchromatin: Loosely packed, transcriptionally active regions. Heterochromatin: Tightly packed, transcriptionally inactive regions. Nucleolus The nucleolus is a region within the nucleus responsible for producing and assembling ribosomal RNA (rRNA) and ribosome subunits, which are essential for protein synthesis in the cell. RNA vs. DNA: DNA: Double-stranded helix. RNA: Single-stranded. Sugar: DNA: Deoxyribose (lacks one oxygen atom).RNA: Ribose (contains an extra oxygen atom). Bases: DNA: Thymine (T), Adenine (A), Cytosine (C), Guanine (G). RNA: Uracil (U) replaces Thymine, along with A, C, and G. Function: DNA: Stores genetic information. RNA: Transfers genetic information (mRNA), helps in protein synthesis (tRNA, rRNA), and regulates gene expression (e.g., miRNA). Stability: DNA: More stable, due to its double-stranded structure. RNA: Less stable, more prone to degradation. If one strand of a DNA molecule has the sequence of bases 5′-ATTGCA-3′, the mRNA synthesized following the template will be ________. A) 5′-TAACGT-3′ B) 5′-TGCAAT-3′ C) 3′-UAACGU-5′ D) 5′-UGCAAU-3  Ribosome In the nucleolus, proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes. These subunits then exit the nucleus through the nuclear pores to the cytoplasm, where a large and a small subunit can assemble into a ribosome. ribosomes –Carry out the process of translation.  ribosomes –Carry out the process of translation. * * –Ribosomes can be found either free in the cytosol, or they can be bound to the cytosolic face of the endoplasmic reticulum (ER).  The Endomembrane System nuclear membrane ER vesicles move Golgi apparatus substances Plasma membrane among these lysosomes Smooth ER: membrane lipid synthesis &carbohydrate metabolism Rough ER: gateway to other membranes & outside the cell secretory and membrane proteins get into ER by rough ER, then sent to other locations  Golgi Apparatus cis face (“receiving” side of Golgi 0.1 µm apparatus) Cisternae trans face (“shipping” side of Golgi apparatus) packaging center: ‘tagging’ of products TEM of Golgi apparatus and/or vesicles Covalent modification of proteins vesicles can go to the plasma membrane Integration of biological process for cellular function Insulin Synthesis Gene Activation: The insulin gene in the DNA of beta cells provides instructions for making insulin. Preproinsulin Formation: The initial product, called preproinsulin, is made in the ribosomes of the beta cells. Proinsulin: Preproinsulin is modified in the endoplasmic reticulum to become proinsulin, a longer, inactive precursor of insulin. Mature Insulin Formation: In the Golgi apparatus, proinsulin is further processed and cut into two parts: Active insulin (the hormone itself) C-peptide, which is a byproduct released along with insulin.  insulin synthesis and secretion (an example of modification of a secreted protein) synthesis in ER  transport to Golgi for modification  secretory vesicle  fusion with plasma membrane