Cell Biology Organelles and Membrane Structure PDF

Chapter 3 Study Outline: 1.​ Identify the organelles of the cell as well as their function. Organelle Main Function(s) Nucleus a.​ Stores genetic material (DNA)...

Chapter 3 Study Outline: 1.​ Identify the organelles of the cell as well as their function. Organelle Main Function(s) Nucleus a.​ Stores genetic material (DNA) and regulates gene expression. b.​ Nucleolus Region - Produces ribosomal RNA (rRNA) and assembles ribosome subunits. Mitochondria Produces ATP through cellular respiration, powers cellular activities. Golgi Apparatus Modifies, packages, and sorts proteins and lipids for transport or secretion. Smooth ER Synthesizes lipids, detoxifies substances, and metabolizes carbohydrates. Rough ER Synthesizes and processes proteins; ribosomes attached to the surface. Plasma Membrane a.​ regulates what goes in cell b.​ regulates what leaves cell c.​ provides structure d.​ aids in cell signaling Cytoskeleton Maintains cell shape, provides mechanical support, and aids in intracellular transport. Centrioles Centrioles organize microtubules. This is especially important prophase and anaphase phases of mitosis because they help form the spindle apparatus Lysosomes Digest and recycle cellular waste, damaged organelles, and foreign substances. Peroxisomes Break down fatty acids and detoxify harmful substances like hydrogen peroxide. 1.​ Recognize the structure and function of a cell membrane. Molecule Function Membrane Lipids a.​ Phospholipids – Form the bilayer structure with hydrophilic heads and hydrophobic tails. b.​ Steroid Hormones – Serve as signaling molecules; some are synthesized using cholesterol. c.​ Cholesterol - Maintains fluidity and stability of the membrane under varying temperatures. Membrane Proteins a.​ responsible for transporting substances across the membrane b.​ Catalyze specific reactions on the surface of the membrane (e.g., ATPases, kinases). c.​ Bind to signaling molecules (e.g., hormones, neurotransmitters) to initiate cellular responses. d.​ Attach the membrane to the cytoskeleton or extracellular matrix, providing structural support. e.​ Help the cell recognize other cells (e.g., glycoproteins that identify self vs. non-self). f.​ g.​ Membrane Carbohydrates a.​ Membrane Carbs – Serve as signaling molecules and recognition sites. b.​ Glycolipids & Glycoproteins – Contribute to the glycocalyx, aiding in protection and cell communication. Cell Membrane Structure and Function Molecule Function Membrane Lipids Phospholipids Form the bilayer structure with hydrophilic heads and hydrophobic tails. Steroid Hormones Serve as signaling molecules; some are synthesized using cholesterol. Cholesterol Maintains fluidity and stability of the membrane under varying temperatures. Membrane Proteins Transport Proteins Responsible for transporting substances across the membrane. Enzymes Catalyze specific reactions on the surface of the membrane. Membrane Carbohydrates Membrane Carbs Serve as signaling molecules and recognition sites. Glycolipids & Contribute to the glycocalyx, aiding in protection and cell Glycoproteins communication. Active vs. Passive Membrane Transport Passive Transport Mechanisms: Type of What Kind of How Does It Occur? From Where to Picture Transport Molecules are Where? (Basic Transported? Diagram)  Simple Small, nonpolar Molecules move From high Diffusion molecules (e.g., down their concentration to O₂, CO₂) concentration low concentration gradient Osmosis Water molecules Water moves through From low solute semipermeable concentration to membrane high solute concentration Facilitated Larger or polar Use of transport From high Diffusion molecules (e.g., proteins to move concentration to glucose) molecules down their low concentration gradient Define the following terms: Solution Type Definition Picture Which Direction Does Water Osmose? Hypertonic A solution with higher solute Water moves out of the Solution concentration than the cell cell. Isotonic A solution with the same solute No net movement of Solution concentration as the cell water. Hypotonic A solution with lower solute Water moves into the cell. Solution concentration than the cell What happens to a red blood cell in these solutions? ​ Hypertonic: The red blood cell shrinks (Crenation). ​ Isotonic: The red blood cell remains normal. ​ Hypotonic: The red blood cell swells and may burst (Hemolysis). Active Transport  Mechanism How It Works Active Transport Movement of molecules against their concentration gradient, requiring energy (ATP). Vesicular Involves bulk transport of substances via vesicles. Transport Endocytosis Cell takes in substances by engulfing them in a vesicle. Pinocytosis A type of endocytosis where the cell ingests extracellular fluid and dissolved substances. Exocytosis Expulsion of materials from the cell via vesicles that fuse with the membrane. DNA Structure and Replication 1.​ Which enzyme builds DNA in the process of DNA replication? ○​ DNA Polymerase 2.​ Which enzyme has NOTHING to do with cell replication but is used in transcription to make mRNA for protein synthesis? ○​ RNA Polymerase 3.​ During what phase of the cell cycle is DNA replicated using the enzyme in (a)? ○​ S-phase (Synthesis phase) of Interphase. 4.​ Define “mutation”: ○​ A mutation is a change in the DNA sequence, which can lead to different traits or conditions. 5.​ Which nucleotides pair with each other? ○​ Adenine (A) pairs with Thymine (T) (in DNA) ○​ Cytosine (C) pairs with Guanine (G) 6.​ What makes DNA different from RNA? ○​ DNA has deoxyribose sugar and is double-stranded. ○​ RNA has ribose sugar and is single-stranded. 7.​ Does DNA replication technically happen in mitosis? When does it happen? ○​ No, DNA replication happens during the S-phase of Interphase, not during mitosis. Cell Cycle Phases Phase of Cell Full Name Major Events Draw Cycle It G0, G1 Growth 0, Cells grow, perform their functions, and prepare Growth 1 for DNA replication. S-phase Synthesis Phase DNA replication occurs. M-phase Mitosis Cell division (prophase, metaphase, anaphase, telophase) and cytokinesis. Protein Synthesis mRNA Structure: ​ mRNA is a single strand of nucleotides with codons that correspond to specific amino acids. mRNA Processing: ​ mRNA is modified in the nucleus by adding a 5' cap and poly-A tail, and removing introns through splicing. Triplets and Codons: ​ Codons are triplets of nucleotides in mRNA that code for amino acids. tRNA Function: ​ tRNA brings amino acids to the ribosome to form proteins. Each tRNA has an anticodon that pairs with a corresponding codon on the mRNA. rRNA/Polyribosome: ​ rRNA is part of the ribosome structure, facilitating protein synthesis. Polyribosomes allow multiple proteins to be synthesized simultaneously. Practice Questions 1.​ Put the following events in order and identify where in the cell each stage occurs: ○​ Order: Transcription (nucleus) → mRNA Processing & Editing (nucleus) → Translation (cytoplasm) 2.​ For the following mRNA sequences, fill in the complementary codon on the tRNA: mRNA Codon tRNA Anticodon AAA UUU UUU AAA UAG AUC CGU GCA UUC AAG 3.​ ​ If the (unmodified) mRNA produced by a gene was: AUG GGG AAA CCC UUU UGA, what was the original DNA sequence? ○​ Original DNA sequence: TAC CCC TTT GGG AAA ACT ○​ tRNA Anticodons: UAC, GGG, UUU, CCC, UUU, ACU 4.​ Diagram the process of protein synthesis: ○​ Transcription (DNA → mRNA in the nucleus) → mRNA processing (splicing, capping) → Translation (mRNA → polypeptide at the ribosome) 5.​ How does translation relate to the structure of a polypeptide? ○​ Translation links amino acids in the order specified by the mRNA codons to form a polypeptide, which folds into primary, secondary, tertiary, and sometimes quaternary structures. 6.​ Clarify the difference between transcription & translation: ○​ Transcription makes mRNA from a DNA template. ○​ Translation makes proteins from an mRNA template. ○​ Transcription comes first. 7.​ What is the difference between mRNA, tRNA, and rRNA? ○​ mRNA carries genetic information.  ○​ tRNA brings amino acids to the ribosome. ○​ rRNA is part of the ribosome and helps in protein synthesis. 8.​ Where is the codon located? Where is the anticodon located? ○​ Codons are found in mRNA, and anticodons are found in tRNA. 9.​ What is the purpose of transcription/translation? ○​ Transcription makes mRNA to carry genetic information from DNA. ○​ Translation makes proteins based on mRNA instructions. ○​ DNA replication is separate and only copies DNA.