Podcast
Questions and Answers
Which of the following is the most accurate description of the cytoskeleton's function?
Which of the following is the most accurate description of the cytoskeleton's function?
- It is a dynamic network of protein fibers that supports cell shape, intracellular transport, and cell movement. (correct)
- It provides a rigid, permanent structure that protects the cell from external forces.
- It is primarily involved in energy production through the synthesis of ATP.
- It facilitates the separation of sister chromatids during mitosis.
In the context of protein sorting, what is the role of chaperone proteins during post-translational import?
In the context of protein sorting, what is the role of chaperone proteins during post-translational import?
- They cleave the matrix targeting sequence once the protein reaches its destination.
- They add a signal sequence to the protein, directing it to the endoplasmic reticulum.
- They bind to the protein in the cytosol, preventing it from folding prematurely as it travels to the target organelle. (correct)
- They directly transport the protein across the target organelle's membrane.
How does alternative splicing contribute to the variation observed in a cell's proteome?
How does alternative splicing contribute to the variation observed in a cell's proteome?
- By permanently altering the DNA sequence of a gene.
- By causing mutations during post-translational modification.
- By allowing different combinations of exons to be included in the final mRNA molecule. (correct)
- By changing the stability of mRNA molecules.
A scientist observes that a particular protein is found in high concentrations in the liver cells of mice but is barely detectable in their brain cells. Both cell types contain the gene for this protein. Which mechanism could best explain this difference?
A scientist observes that a particular protein is found in high concentrations in the liver cells of mice but is barely detectable in their brain cells. Both cell types contain the gene for this protein. Which mechanism could best explain this difference?
What is the primary distinction between the endomembrane system and the secretory system in a eukaryotic cell?
What is the primary distinction between the endomembrane system and the secretory system in a eukaryotic cell?
Upon entering a cell, where would a protein synthesized on free-floating ribosomes most likely be directed for final modification and sorting?
Upon entering a cell, where would a protein synthesized on free-floating ribosomes most likely be directed for final modification and sorting?
A researcher is investigating a cell line with a defect in glycosylation. Which organelle is most likely malfunctioning in these cells?
A researcher is investigating a cell line with a defect in glycosylation. Which organelle is most likely malfunctioning in these cells?
A malfunction in the catalase enzyme within peroxisomes would most directly affect what cellular process?
A malfunction in the catalase enzyme within peroxisomes would most directly affect what cellular process?
Which of the following statements best describes the energy requirements for the movement of lipids within a cell membrane?
Which of the following statements best describes the energy requirements for the movement of lipids within a cell membrane?
What is the immediate consequence of a cell's inability to produce a functional signal peptidase enzyme?
What is the immediate consequence of a cell's inability to produce a functional signal peptidase enzyme?
Which of the following accurately describes how cholesterol contributes to maintaining cell membrane fluidity?
Which of the following accurately describes how cholesterol contributes to maintaining cell membrane fluidity?
What is a primary function of transmembrane proteins located in the plasma membrane?
What is a primary function of transmembrane proteins located in the plasma membrane?
A cell is placed in a hypotonic solution. Which transport mechanism would be crucial for the cell to prevent osmotic lysis?
A cell is placed in a hypotonic solution. Which transport mechanism would be crucial for the cell to prevent osmotic lysis?
The sodium-potassium ($Na^+/K^+$) ATPase pump transports sodium ions out of the cell and potassium ions into the cell, both against their concentration gradients. What type of transport is this, and what is the direct source of energy for this pump?
The sodium-potassium ($Na^+/K^+$) ATPase pump transports sodium ions out of the cell and potassium ions into the cell, both against their concentration gradients. What type of transport is this, and what is the direct source of energy for this pump?
Which of the following is the most direct function of V-SNARE proteins during cellular transport?
Which of the following is the most direct function of V-SNARE proteins during cellular transport?
What is the energetic relationship between catabolic and anabolic pathways in metabolism?
What is the energetic relationship between catabolic and anabolic pathways in metabolism?
How do enzymes increase the rate of a reaction?
How do enzymes increase the rate of a reaction?
Which of the following scenarios would most likely result in a decrease in enzyme activity?
Which of the following scenarios would most likely result in a decrease in enzyme activity?
How does feedback inhibition regulate metabolic pathways?
How does feedback inhibition regulate metabolic pathways?
What is the role of ubiquitin in protein degradation?
What is the role of ubiquitin in protein degradation?
In mRNA degradation, what is the purpose of removing the Poly-A tail?
In mRNA degradation, what is the purpose of removing the Poly-A tail?
Which of the following is the net gain of ATP, NADH, and FADH2 from a single glucose molecule after glycolysis and the Krebs cycle?
Which of the following is the net gain of ATP, NADH, and FADH2 from a single glucose molecule after glycolysis and the Krebs cycle?
What is the significance of de-energized electrons during cellular respiration?
What is the significance of de-energized electrons during cellular respiration?
Under anaerobic conditions, what is the primary purpose of fermentation?
Under anaerobic conditions, what is the primary purpose of fermentation?
Which of the following is a key difference observed between cilia and flagella?
Which of the following is a key difference observed between cilia and flagella?
Which component of the endomembrane system is directly involved in the synthesis of proteins that are destined for secretion from the cell?
Which component of the endomembrane system is directly involved in the synthesis of proteins that are destined for secretion from the cell?
What characteristic defines the inner membrane of the mitochondria?
What characteristic defines the inner membrane of the mitochondria?
In the context of cellular structures, what is the role of the basal body associated with cilia and flagella?
In the context of cellular structures, what is the role of the basal body associated with cilia and flagella?
The intermembrane space of the mitochondria is critical to ATP production because:
The intermembrane space of the mitochondria is critical to ATP production because:
In eukaryotic cells, which structure is responsible for ribosome assembly?
In eukaryotic cells, which structure is responsible for ribosome assembly?
What process do both mitochondria and chloroplasts use that supports the endosymbiotic theory?
What process do both mitochondria and chloroplasts use that supports the endosymbiotic theory?
Flashcards
Cytosol
Cytosol
The region of eukaryotic cell outside organelles but inside the plasma membrane, contains complexes like ribosomes.
Cytoplasm
Cytoplasm
Everything inside the plasma membrane, including cytosol and all organelles.
Translation
Translation
Process of polypeptide synthesis where gene info is translated into amino acid sequence, Endergonic.
Glycolysis
Glycolysis
Process where sugars are broken down, can occur with or without oxygen, produces energy.
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Cytoskeleton
Cytoskeleton
Network of three protein filaments (microtubules, intermediate filaments, and actin microfilaments).
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Motor Proteins
Motor Proteins
Cellular proteins that use ATP to promote movement, composed of head, hinge, and tail.
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Flagella and Cilia
Flagella and Cilia
Cellular structures projecting from cell membrane; flagella longer and fewer, cilia shorter and numerous.
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Endomembrane System
Endomembrane System
Membrane network enclosing the nucleus, endoplasmic reticulum, Golgi, lysosomes, and vacuoles.
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Nucleus
Nucleus
Organelle in eukaryotic cells housing genetic material, location of DNA transcription.
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Chromosomes
Chromosomes
Structures in the nucleus that are composed of chromatin.
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Ribosomes
Ribosomes
Complexes of RNA and proteins assembled in the nucleolus responsible for protein synthesis.
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Golgi Apparatus
Golgi Apparatus
Organelle near the ER, a stack of sacs called cisternae; the packaging and transport center.
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Lysosomes
Lysosomes
Organelles in animal cells with hydrolytic enzymes for breaking down macromolecules.
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Autophagy
Autophagy
Process of recycling old, worn-out organelles in the lysosome.
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Vacuoles
Vacuoles
Organelles in plant cells, the membrane of which (tonoplast) can expand and contract.
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Peroxisomes
Peroxisomes
Small organelles in eukaryotic cells that are not part of the secretory system.
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Endoplasmic Reticulum (ER)
Endoplasmic Reticulum (ER)
Membrane network forming tubules called cisternae, divided into smooth and rough regions.
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Rough ER Function
Rough ER Function
Synthesizes and distributes proteins.
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Smooth ER Function
Smooth ER Function
Does detoxification, carbohydrate catabolism, lipid synthesis, and calcium reservation.
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Plasma Membrane
Plasma Membrane
Cell boundary composed of phospholipids providing semi-permeability.
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Mitochondria and Chloroplasts
Mitochondria and Chloroplasts
Contain DNA, RNA, and ribosomes.
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Endosymbiotic Theory
Endosymbiotic Theory
Theory stating chloroplasts and mitochondria descend from symbiotic relationships.
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Mitochondria
Mitochondria
Organelle that makes ATP also involved in synthesis and breakdown; has outer and inner membranes.
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Chloroplasts
Chloroplasts
Organelles used for capturing light energy, containing outer and inner membranes with intermembrane space.
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Signal Recognition Particle (SRP)
Signal Recognition Particle (SRP)
ER signal sequence is picked up by this.
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Biological Membranes
Biological Membranes
Keeps the cell interior separated from the extracellular region; are formidable and flexible.
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ER Signal Sequence
ER Signal Sequence
Cause the ribosome to be docked onto the ER membrane.
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Fluid Mosaic Model
Fluid Mosaic Model
Membranes are fluid because molecules can move laterally and are a mosaic of molecules.
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Fluidity
Fluidity
The ability of molecules to readily move within a membrane while remaining associated.
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Transmission Electron Microscopy (TEM)
Transmission Electron Microscopy (TEM)
These types of electron microscopes use a biological sample that is thin-sectioned and stained with heavy metal dyes.
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Glycosylation
Glycosylation
Attaching a carbohydrate to a protein or lipid.
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Selective Permeability
Selective Permeability
Ensures essential molecules enter, metabolites stay within, and waste exits the cell.
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Passive Transport (Diffusion)
Passive Transport (Diffusion)
Move solutes from high to low concentration without energy.
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Ligand-gated Channels
Ligand-gated Channels
Opens when a signal binds to the channel in a noncovalent manner.
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Pumps
Pumps
Movement of a solute from low to high concentration expending energy.
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Chapter 4: General Features of Cells
- DNA sequences are the same in every cell of the body with the exception of germ-line cells.
- Despite identical DNA sequences, cells structures vary depending on the structure and function of proteins they contain, this is caused by mechanisms of differential protein expression.
Mechanisms of Variation in the Proteome:
- Differential Gene Regulation varies expression based on environment.
- Epigenetic molecules can up-regulate or down-regulate genes.
- Concentration and Stability affect protein levels and stability to change protein composition.
- Alternative Splicing modify pre-mRNA to final mRNA with introns and exons spliced out.
- Depending on which exons are spliced out, different amino acid sequences are created, leading to different proteins and cell structures.
- Covalent Modifications alter protein function and location post polypeptide synthesis and folding.
- Methylation of amino acids at the N-terminal and glycosylation are examples.
Cytosol, Cytoplasm, and Metabolism
- Cytosol is the region of a eukaryotic cell outside organelles but inside the plasma membrane.
- Cytosol contains complexes like ribosomes without membranes.
- Cytoplasm is within plasma membrane including cytosol and organelles.
- Cytosol is the central coordinating region for metabolic activities like Translation.
- Translation occurs in the cytosol at ribosome complexes.
- Transcription occurs in the nucleus.
- Translation is the anabolic process of polypeptide synthesis.
- Information translates into amino acid sequence.
- It requires significant energy, making it a highly endergonic process.
- Glycolysis is a catabolic process that breaks down sugars.
- It can occur with or without oxygen.
The Cytoskeleton
- Composed of a network of three protein structures called filaments.
- The Spindle Apparatus used in mitosis/meiosis is not part of the cytoskeleton because it is not a permanent structure
Motor Proteins
- Use ATP to promote movements with Head(ATP hydrolysis), Hinge, and Tail domains.
- Walking Movement involves protein movement while cytoskeleton remains in place.
- Like walking, filament is the ground and protein-head is the leg
- Filament Movement is where the protein stays still.
- ATP energy is used to push the cytoskeleton along.
- Whiplash Movement is where neither move.
- Energy transfers from head to tail, bending Molecule.
Cilia and Flagella
- Both project outward from the cell membrane.
- Flagella are longer, found singly or in pairs.
- Cilia are shorter, cover cell surface.
- Axonemal Structure is a shared structure of microtubules and dynein.
- Nine microtubule doublets and two central microtubules (9+2)
- Basal Body- directly under the Axoneme containing microtubule triplets.
The Endomembrane System
- Network membranes surrounding nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles.
- Includes the plasma membrane.
- Constituent parts connect directly or through vesicles.
- Peroxisome is not a component of the Secretory System.
The Nucleus
- Organelle in eukaryotic cells housing/protecting genetic material and location of DNA transcription.
- Nucleolus synthesizes rRNA and ribosomal subunits.
- Surrounded by Nuclear Envelope with Nuclear Pores.
- Gatekeeper Proteins keep DNA inside while allowing molecule passage.
- Nuclear Lamina supports envelope with lamin filaments.
- Contains DNA in Chromosomes.
- Chromatin composition: DNA tightly wrapped around Histone proteins.
Ribosomes
- Complexes of RNA and Protein formed at the nucleolus.
- Contains one large and one small subunit.
- rRNA makes up biggest portion of both.
- RNA portion consists of three RNA types.
- rRNA is the primary structural component.
- mRNA carries information of the amino acid sequence.
- tRNA assembles the amino acid sequence based on information.
- Responsible for polypeptide and protein synthesis.
- In translation, mRNA molecule attaches to small ribosome subunit.
Golgi Apparatus
- Organelle close to and facing the ER.
- Structure: stack of membrane-bound sacs called Cisternae (same as ER tubules).
- The Golgi is a packaging and transport center, part of the cell's endomembrane and secretory systems.
- Secretory Vesicles pass substances through sacs (no diffusion).
- They are "stamped" with carbohydrates, shipped along the cytoskeleton.
- Three subdivisions are oriented in the cell.
- Cis Golgi is near ER membrane.
- Trans Golgi is close to the plasma membrane
- Medial Golgi is in the middle: site of Glycosylation and Proteolysis. Substances are packaged and sent out of the cell (Exocytosis) in trans Golgi.
Lysosomes
- Organelles found in animal cells containing Hydrolytic Enzymes
- Acid Hydrolases break down macromolecules, organelles, and various substances at pH 4.8.
- Substance breakdown: Primary Lysosome stage (pH > 4.8), then transitions to Secondary Lysosome stage (pH drops to 4.8) for breakdown.
- Autophagy: recycling of old, worn-out organelles, forms Phagosomes.
Vacuoles
- Organelles found only in plant cells and some protists.
- Tonoplast is capable of expanding and contracting.
- Central Vacuoles found in all plants.
- Store H2O, nutrients, and waste; Enough H2O creates Turgor Pressure that becomes Hydrostatic Skeleton.
- Contractile Vacuoles are found in some protists.
- Expand and contract for cell volume maintenance.
- Phagocytic Vacuoles are found in protists and white blood cells.
- Used for engulfing and digesting foreign materials.
Peroxisomes
- Small organelles, not part of secretory system, found in eukaryotic cells.
- Formed when vesicles bud from the ER and combine.
- Catalyze reactions that break down molecules.
- Reactions remove/add hydrogen/oxygen, producing hydrogen peroxide (H2O2).
- Catalase enzyme breaks down H2O2 into H2O + O.
- Microbody classification includes Glyoxisomes (in plants).
Endoplasmic Reticulum
- Network of membranes.
- Forms flattened tubules called Cisternae.
- Divided into 2 regions: Smooth ER and Rough ER.
- Region between them is the ER Lumen.
- Rough Endoplasmic Reticulum synthesizes/distributes proteins.
- Inserts proteins (Glycosylation )into organelle membranes.
- Smooth Endoplasmic Reticulum detoxifies (barbiturates).
- Functions: Carbohydrate catabolism, lipid synthesis/modification, calcium reservation.
- Carbohydrate Catabolism starts with Phosphorylation.
- Phosphate added to starch end, forming Glucose 6-Phosphate.
- SER acts as a Calcium Reservoir.
Plasma Membrane
- Boundary between cell and extracellular environment.
- Largely Phospholipids for Semi-Permeability for hydrophobic molecules, blocking hydrophilic ones.
- Contains 3 protein types.
- Transport Proteins for Selective Permeability.
- Receptor Proteins for cell communication.
- Adhesive Proteins allowing temporary attachment of cells in different tissues
Endosymbiotic Theory
- Mitochondria and Chloroplasts are semiautonomous: contain DNA, RNA, and ribosomes.
- Cannot properly without proteins from the rest of the cell.
- Cannot divide without nucleus.
- Chloroplasts/mitochondria are from an Endosymbiotic relationship with eukaryotic cells.
- Cell gets energy, organelles get nutrients and place to live
- Theory explains why organelles contain DNA
Mitochondria
- Primary role is to make ATP.
- Involved in synthesis, modification, and breakdown of cellular molecules.
- Generate heat in brown fat cells (bears and babies).
- Divide through binary fission.
- Possess Outer and Inner Membranes, the latter is folded.
- Space between is Intermembrane Space with protons.
- Inside: Mitochondrial Matrix, filled with synthesized ATP.
- Along inner membrane's Cristae: Electron Transport Chains and ATP protein molecules
Chloroplasts and Other Plastids
- Chloroplasts are only in plants and algae.
- Capture light energy and synthesize organic molecules like glucose.
- Divide using binary fission.
- Chloroplasts possess Outer and Inner Membranes.
- Intermembrane Space between them
- Stroma fills inner: Calvin Cycle
- Grana are stacks of Thylakoid Membranes (flattened tubules) connected by Lamella.
- Pigments are along thylakoid membrane; oxygen produced in Thylakoid Lumen
- Plastids are a small organelle class where Chloroplasts are involved in photosynthesis (chlorophyll).
- Chromoplasts store pigments.
- Amyloplasts colorless: store root starch.
Mechanisms of Protein Sorting
- Co-translational Import starts with ER Signal Sequence picked by Signal Recognition Particle (SRP).
- SRP binds to the ribosome, stops translation, transfers to ER, docks on ER Membrane
- Amino acid sequence threaded in ER Membrane, ER Signal Sequence cleaved by Signal Peptidase enzyme. Presence/absence of Retention Signal dictates if protein stays or goes to Glycosylation.
- Post-translational Import requires Matrix Targeting Sequence at C-terminal,
- Chaperone Proteins prevent folding as it travels to the target organelle.
- Proteins pulled into organelle by chaperone protein set.
- Signal Peptidase removes the targeting sequence allowing it to fold.
Chapter 5: Membrane Structure, Synthesis, and Transport
- Biological Membranes
- Protein Insertion
- Fluid-Mosaic Model
- Types of Membrane Proteins
- Semifluidity
- Factors Affecting Fluidity
- Lateral Transport Experiment
- Exceptions to Protein Movement
- Electron Microscopy
- Phospholipid Synthesis
- Glycosylation
- Selective Permeability
- Cell Gradients
- Passive Transport
- Channels
- Carriers
- Aquaporin
- Pumps
- ATP-Driven lon Pumps
- Endocytosis and Exocytosis
Biological Membranes
- Membranes serve as formidable and flexible cell boundaries separating the interior from extracellular region.
- Facilitate intercellular communication, transport, and cell division.
- 50% lipids, 50% proteins and carbohydrates
- Phospholipids form bilayer with hydrophobic tails inside and hydrophilic heads on outside.
- Lipid Rafts, found in cell division sites, bind at specific locations that cause cell division.
- Proteins: transport, communication, adhesion and synthesis
- Carbohydrates for protection: 90% glycoproteins; 10% glycolipids.
Protein Insertion in ER Membrane
- ER signal sequences cause docking on the ER membrane.
- Ribosome translates molecules into ER membrane or Lumen.
- Ribosome translates sequence until reaching Stop Transfer Sequence, Signal peptidase removes ER signal sequence.
Fluid Mosaic Model
- Model represents membrane structure as lipids and proteins moving relative to each other.
- Proteins and carbohydrates are in a pattern.
- Asymmetrical phospholipid bilayer
- Most proteins/carbohydrates on Extracellular Leaflet located out of cell.
- Very few on Protoplasmic Leaflet.
Types of Membrane Proteins
- Classified by isolation/analysis breaking apart Intrinsic proteins or keeping intact Extrinsic.
Intrinsic
- Requires membrane fracture.
- Transmembrane Proteins span entire membrane; containing hydrophobic/philic regions.
- Lipid-Anchored Proteins: covalently bonded, located between fatty acid tails
Extrinsic (Peripheral)
- Isolation using opposite charged solution
- Connected to hydrophilic phospholipid heads.
Semifluidity
- Molecules easily move within membrane but stay close, as seen in membrane-bound porteins
- Biological membranes are semifluid, liquids can only move adjacent to their neighbors
- Lateral movement of lipids is energy efficient.
- Lipids can flip-flop with flippase transporter proteins and ATP hydrolysis in cell repair and cancer.
Factors Affecting Fluidity
- Optimal temperature of 37°C helps phospholipids move without assistance.
- Hotter causes moving too fast, colder too slow.
- Cholesterol stabilizes and regulates by binding/cushioning phospholipids.
- Saturated reduces movement and Hydrocarbons, Unsaturated induces double bonds.
- Inducing chain length in plant cells occurs while saturated and unsaturated.
Lateral Transport Experiment
- Frye/Edidin fused mouse and human cells for lateral protein movement verification.
- Chimera resulted in mouse and human cells.
- Experiment with mouse cells that have H-2 Antigen.
- Half cells at 0°C and half incubated at 37°C.
- With antigen stain: frozen antigen was on mouse side, incubated expressed over cell surface.
Exceptions to Protein Movement
- Not all integral membrane proteins move restricting range between 10-70%.
- Attachment/cell-compartmentalizing proteins cannot undergo lateral movement.
- Binding to cytoskeleton or molecules limits movement.
Electron Microscopy
- Transmission Electron Microscopy (TEM)
- Uses thin-sectioned biological sample stained with heavy metal dyes.
- These dyes bind to polar phospholipid heads not nonpolar fatty acid bodies.
- Freeze Fracture Electron Microscopy analyzes nonpolar phospholipid bilayers.
- Freezing sample and using knife-like tool dividing into Extracellular/Protoplasmic halves.
- Halves covered with heavy metal for mold analysis.
- The mold is used because it's fragile.
Phospholipid Synthesis
- Begins in cytosol, proceeds in smooth ER
- Raw materials: Fatty Acid Chains, Glycerol Phosphate, coA, Acyltransferase, Phosphatase, Choline/Serine Phosphotransferase enzymes.
- Five Steps:Activation of Fatty Acids, Formation of Fatty Acyl Glycerol Phosphate, Insertion of Fatty Acyl Glycerol Phosphate into Cytosolic Side, Removing Charged Phosphate, Attaching Choline/Serine Amino Acid. Synthesized phospholipid moves through the membrane.
Glycosylation
- Attaches carbohydrate to protein/lipid.
- Products: Glycoproteins and Glycolipids in self/non-self tissue recognition.
- Glycocalyx shields and protects membrane.
- Types: N-linked in the RER and O-linked in medial Golgi
- Oligosaccharide attaches to the N-side in N-linked and attaches to the O side in O-Linked.
- Co-translational import embeds protein ER Lumen with enzyme Oligosaccharide Transferase detecting sequence.
Selective Permeability
- Biological membranes selectively permeable.
- Essential and waste molecules passing through.
- Nonpolar molecules pass easiest through bilayer.
- Polars pass at concentration.
- Transports are necessary when moving through glucose as ions or ATP will never diffuse.
- Cells maintain transmembrane and ion electrochemical gradients.
- Passive transport moves solutes until transmembrane gradient evens out without energy: passive and facilitated diffusion.
Passive Transport (Diffusion)
- Moves high to low concentration without energy.
- Types are Passive Diffusion and Facilitated Diffusion from proteins
- Protein types: rate differs in Channels or Carriers depending on barriers.
Channels
- 5 Types:
- Ligand-gated Channels require molecule binding.
- IRP-gated Channels needs IRP Molecule association.
- Phosphorylation-gated Channels use covalent attachment.
- Voltage-gated Channels and muscle tissue need charge change.
- Mechanosensitive Channels need changes in tension and frequency change.
Carriers
- Known as transporters- for organic molecules like sugars uptake.
- Classification
- Uniporters: carry one molecule.
- Symporters/antiporters: carry multiple molecules in same or different direction
Active Transport (Diffusion)
- Transmmebrane goes from low to high with energy.
- Maintain homeostasis
- Differentiation by energy: primary active transport uses ATP Hydrolysis.
Ion Pumps
- Secondary active transport uses pre-existing Na*/H+ gradient.
- Na+/K+ ATPase pump involves transporting to establish equilibrium.
- Exports 3 Na+ and imports two K+ ions.
Electrochemical Gradients
- The resting membrane potential is -70mV
- Ion Gradients go through channels
- Negative value means it’s more negative inside cell
- Ion Electrochemical Gradients has chemical and electrical gradients.
ATP Driven Lon Pumps
- Na+/K+ ATPase pump moves with ATP: exports three +sodium and imports two +potassium results a +net charge
- It is particularly vital in neuron activity.
Endocytosis and Exocytosis
- Cargo larger than 1 kDa enters and exits. _ Exocytosis: material is carried into vesicles and excreted through the plasma membrane such as collagen and hormones. _ Starts with cargo to transport, coated transfer proteins for membrane. _ Coat proteins are removed along with the vesicle. T-snare proteins fuse to proteins along plasma.
- Endocytosis: plasma membrane invaginates for a vesicle. _ The 3 types: solid-Phagocytosis, liquid-Pinocytosis, specific proteins and receptors-Receptor-Mediated Endocytosis. _ Pinosytosis in intestine and sertoli cells. _foreign bodies contact cell and coat for snare binding with protein.
Chapter 6: Energy, Enzymes, and Metabolism
- Thermodynamics
- Spontaneity of Chemical Reactions
- Metabolism
- Energy Intermediates
- ATP Synthesis
- Regulation
- Enzymes and Ribozymes. Recycling of mRNA and Proteins.
- Influences on Enzyme Activity.
Thermodynamics
- thermodynamics refers to heat changes between different forms of energy
- the ability to promote change.
- Kinetic, Potential, Chemical (energy in the molecular bonds), Piezoelectric (pressure-based), heat transfer.
- Measure random movement
- measured in joules (J), calories (c) and kilocalories.
Laws of Thermodynamics
- Energy cannot be destroyed or created. It can only be transferred (conservation of energy).
- Entropy has a measure to increase disorder (entropy).
- 10%Rule only only 10% energy can move up food chain.
Spontaneity of Chemical Reactions
_ is determined by the change in free energy. _ free energy, temperature, enthalpy, entropy _ H = G =TS, ∆G = ∆H – T∆S
- Types: Spontaneous and NonSpontaneous. _ Exergonic vs _ Endergonic
- Exothermic vs Endothermic _ Reactants and products difference between oxidizing.
ATP
- Adenosine Triphosphate _ Electrostaic repulson-living tissue stores energy through ATP. _ energy is stored between phosphate molecules and they are negative. _ Hydrolysis release the high energy, exergonic result. _ ATP -> ADP + iP Δe -7.3kal/mol
- Indirect Synthesis is Chemiosmois
Enzyme and ribozymes
- Are catalysts
- lowers the Energy of Activation.
- bond and stretches.
- Enzyme Activity.
- Active Sites Specific-bind substrate in sites (Induced)
- Prosthetic group
- Cofactors = inorganic enzymes
- coenzymes= organic
- Metabolism
- cellular metabolism
- Enzymes Path ways and multienzyme, Anabolic/Catabolic pathways exgonic and endgoric
Other Influences on Enzyme Activity
- Prosthetic Groups: small molecules that are intertwined in the enzyme
- Isolated through enzyme destruction.
- Cofactors: inorganic compounds forming temporary enzyme association to increases activity.
- Coenzymes: organic/non-proteinaceous molecules participating in catalyzed reaction but unchanged vitamins.
- Metabolism is the reactions in any organanism.
- Reactant energy cannot proceed without specific concentration and catalyst.
- Rate determined by a catalyst.
- Enzyme regulation occurs Metabolic Pathways and Multienzyme saves unwanted enzymes.
- Anabolic/Catabolic requires an exergonic (breakdown) reactions.
Energy Intermediates
- Transport electrons during synthesis.
- Reduced (gain electrons) to form electron carriers from electron receptors such as NADH oxidized during ATP generation.
- Nicotinamide Adenine Dinucleotide: two nucleotides, NMP⁺ and AMP such as coenzymes.
Regulation of Metabolic Pathways
- Environmental Gene Regulation affects genes for growth.
- Cellular Regulation by cell-signaling through hormones indicated by the rate of exocytosis.
- Biochemical Regulation includes inhibitors to restrict enzyme actibity.
- Reversible and Irreversible are how they tempoarily biond.
Recycling in the Cell
- It is crucial to recycle mRNA and protein when not functioning in the needed.
- molecule recycled if made with a defect.
MRNA degradation
- Exonuclease is an enzyme used to remove Poly-A tail
- Exosome is a multiprotein enzyme.
- Protein degradation begins when a ubiquitin protein covalent marks targeted proteins, directed to the protease.
EXTRA extra
- Amalyse breaks saliva down
- 20% proteins are atp optimal temp for enzymes Coenzyme stabilizers atp cycle 10;000
Chapter 7: Respiration, Fermentation, & Secondary Metabolism
Main Topics
- Cellular Respiration
- Glycolysis
- Pyruvate Oxidation
- Krebs Cycle
Cellular Respiration
- Hydrolysis molecules obtaining cells energy.
- Occurring with or without oxygen.
- Four metabolic: glycolysis-break down, 3citric, oxidative.
Stages
- Occurs in the Cytosol
- Without and with energy. Investment, 2 atp is hydrolyzed. Liberlation- gain net 2 ATP NET 2 NADH Is breakdown energy in NADH
Oxidation
- Products from ctosol in Mitocondrial matrix, go in intermem space to to undergo activation.
- Through channel.
- Pyruvate Dehydrogenase: catalyses removes co2-2.
- Dihydrolipoyltransacetylase: catalyses Acetyl COA reaction
- Dihydrolipoyldehydrogenase:: catylaes NAD +1, 2e=
Kreb cycle
- Also AKA acid or tricaorbocyillc acid
- molecole enters and leaves with a orgnaic regenerated
- Glucose 2 acetyle, 1 molecules provides 2 revolts.
Prep
- Acetyl CoA or oxalate - Iso citrate NADH 1 ATP. FAD! Glucose 2 CO2 FAD!!
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