0079c82a-60e9-4e89-bcd2-4e81915deb11-66c49b93deb10536bfc461f7-1724160934-THE CELL.pdf

BIOCHEMISTRY LECTURE (PRELIM) ◼ Attached carbohydrates (glycolipids and glycoproteins) THE CELL Membrane Function:...

BIOCHEMISTRY LECTURE (PRELIM) ◼ Attached carbohydrates (glycolipids and glycoproteins) THE CELL Membrane Function: Barrier between inside and outside of cell It is the smallest unit that is capable of Controls entry of materials: transport performing life functions. Receives chemical and mechanical signals The structural and functional unit of all living Transmits signals between intra- and extra- cellular spaces organisms The building block of life Cell Connections and Communications Vital functions of an organism occur within cells 1. GAP JUNCTION All cells contain hereditary information When two cells are right next to each other, necessary for regulating cell functions and for their cell membranes may actually be transmitting necessary information to the next touching cell generation 2. DESMOSOME They physically connect cells like the gap Two types of cells junction, but no opening is created 1. PROKARYOTIC 3. TIGHT JUNCTION Do not have structures surrounded by Happens when two membranes actually membranes bond into one Few internal structures \ One-celled organisms bacteria, archae 2. EUKARYOTIC Contain organelles surrounded by membranes Most living organisms multicellular organisms such as plants and animal cell Terminology: Body Fluid Pools 1. Intracellular (ICF) Within cells: 2/3 of total 2. Extracellular (ECF) Between cells = Interstitial In blood vessels = Plasma In lymphatic vessels = Lymphatic Terminology: Solutions Cell Structure 1. Solvent: the liquid doing the dissolving (usually Plasma membrane water) Cytoplasm: cytosol + organelles 2. Solute: Nucleus the dissolved material (particles or gas) 3. Concentration Plasma/Cell Membrane Amount of solute in a given amount of ◼ Outer membrane of cell that controls movement in solvent and out of the cell 4. Concentration gradient ◼ Double layer Difference in concentration between 2 ◼ Phospholipid bilayer areas of solution ◼ Proteins (integral and peripheral) ◼ Cholesterol Transport 1. PASSIVE  - Diffusion (simple and facilitated) Diffusion of water across selectively permeable - Osmosis membrane: 2. ACTIVE Permeable to solvent - Endocytosis Impermeable to solute - Exocytosis Types of solutions surrounding human RBCs PRINCIPLE: Isotonic: solution outside RBC has same the process by which molecules spread from areas concentration of solute as RBC: 0.9% NaCl of high concentration, to areas of low concentration Hypotonic: solution outside of RBC has When the molecules are even throughout a space - it lower concentration: 0% NaCl → hemolysis is called equilibrium Hypertonic: solution outside of RBC has higher concentration: 4% NaCl → crenation Facilitated Diffusion is the passage of molecules or ions across a biological membrane through specific transport proteins and requires no energy input Requires a carrier in membrane but not ATP Solute goes down concentration gradient Maximum transport speed depends on number of carriers insulin increases number of carriers for glucose in plasma membrane Active Transport Requires a carrier (called a pump) and energy (ATP) Can transport up a concentration gradient from an area of lower concentration to an area of higher concentration Critical for moving important ions Major active transport in most cells is (Na+/K+) pump Reabsorption of glucose, amino acids and salts by the proximal convoluted tubule of the nephron in the kidney Endocytosis Taking “in” large molecules by the cell importing materials into cell Phagocytosis = “phood”, taking in food particles Pinocytosis = liquid substances Exocytosis Removing large particles (waste) from the cell Exporting materials out of the cell Osmosis  Two centrioles arranged perpendicular to each other Composed of microtubules: 9 clusters of 3 (triplets) Pericentriolar material: Composed of tubulin that grows the mitotic spindle Function: moves chromosomes to ends of cell during cell division Ribosomes Made within the nucleus (in nucleolus) Inside the Cell Cytoplasm Sites of protein synthesis is the fluid that fills a cell Consist of ribosomal RNA (rRNA) + proteins Cell contents Contain large and small subunits Gel-like mixture Can be attached to endoplasmic reticulum Surrounded by cell membrane or free in cytosol Contains hereditary material Cilia and Flagella Includes organelles and cytosol Specialized for motion Excludes nucleus Flagellum: single tail like structure on sperm Cytoskeleton Propels sperm forward in reproductive tract Maintains shape of cell Cilia: Positions organelles in groups Changes cell shape Found in respiratory system: move mucus Includes: microfilaments, intermediate Endoplasmic Reticulum filaments, microtubules Structure: network of folded membranes Functions: synthesis, intracellular transport The double membranes of smooth and rough ER form sacs called cisternae Two types: o Rough ER - studded with ribosomes (sites of protein synthesis) o Smooth ER - lacks ribosomes Functions: ▪ lipid synthesis ▪ release of glucose in liver cells into bloodstream ▪ drug detoxification (especially in liver cells) ▪ storage and release of Ca2+ in muscle cells (where smooth E.R. is known as sarcoplasmic Centrioles reticulum or SR) is a small set of microtubules arranged in a specific way Golgi Complex centrioles are found in pairs and move Protein 'packaging plant‘ towards the poles (opposite ends) of the was named after Camillo Golgi, an Italian biologist nucleus when it is time for cell division Structure: Flattened membranes (cisternae) with bulging edges (like stacks of pita bread) Centrosome Functions: gathers simple molecules and combines Structure: them to make molecules that are more complex o Move materials within and out of the cell  o Modify proteins → glycoproteins and Round or oval structure surrounded by nuclear lipoproteins that: envelope with nuclear pores ▪ Become parts of plasma Contains nucleolus: makes ribosomes that pass into membranes, Are stored in cytoplasm through nuclear pores lysosomes (cell digestion Store genetic material (DNA) in genes arranged in machines) or are exported by 46 chromosomes exocytosis DNA contains information for directing protein synthesis: Lysosome o In this cell Contains digestive enzymes o In new cells (formed by cell reproduction) Digestive 'plant' for proteins, fats, and carbohydrates Help in final processes of digestion within cells Nucleoplasm Cell breaks down if lysosome explodes is the suspension fluid that holds the cell's chromatin Carry out autophagy (destruction of worn and nucleolus out parts of cell) and death of old cells It is not always present in the nucleus (autolysis) When the cell divides, the nuclear membrane Tay-Sachs: hereditary disorder; one dissolves and the nucleoplasm is released. After the missing lysosomal enzyme leads to nerve cell nucleus has reformed, the nucleoplasm fills the destruction space again Small Bodies Nuclear Membrane or Envelope Peroxisomes: Surrounds nucleus o hold on to enzymes that require oxygen Made of two layers (oxidative enzymes) Openings allow material to enter and leave o break down fatty acids, digest alcohol and nucleus protect cells against hydrogen peroxide o detoxify; abundant in liver Nucleolus Proteasomes: Inside nucleus o digest unneeded or faulty protein (proteolysis) Contains RNA to build proteins o Faulty proteins accumulate in brain cells in persons with Parkinson or Alzheimer Chemical Composition of the Living Matter disease ✓ tissues are made up of 70-90% water ✓ 10-30% solids Mitochondria ✓ 1% is inorganic and the rest are organic substances Structure: Sausage-shaped with many folded Water membranes (cristae) and liquid matrix containing enzymes This is the major component of the cell Have some DNA, ribosomes (can make often referred to as an inert space filter in a proteins) living organism Function: It is a strong dipole and has a high dielectric Nutrient energy is released and trapped in constant ATP; so known as “power houses of cell” It is highly reactive with unusual properties Produces energy through chemical different physically and chemically from reactions – breaking down fats & other common liquids carbohydrates Controls level of water and other materials Water and its ionization products H+ and in cell OH- are important factors in determining the Recycles and decomposes proteins, fats, structure and biological properties of and carbohydrates proteins, nucleic acids, lipids, and other cell components Nucleus Directs cell activities Water Component of the Cell Separated from cytoplasm by nuclear membrane Found partly in free state  governed by the physical laws of osmosis ▪ Ex: capillary action-pulls column of water up and diffusion to the top of a plant any disturbance to water equilibrium leads to an alteration in water distribution ▪ Water is called “Universal solvent ▪ dissolves many other substances due to Fixed State polarity held in a state of hydrophilic colloid system, ▪ Differences in charges pulls/pushes substances thereby forming a constant constituent of apart (Like a magnet attracts or repels other the cell itself magnets) responsible for the maintenance of the shape and size of the cell ▪ Water exhibits evaporative cooling the amount of fixed water in tissues varies ▪ removes heat when it evaporates from a with their functional activities surface (Ex: sweating cools skin) Inorganic Constituents ▪ Water expands during freezing: expands into crystal ✓ Sodium formation releasing heat ✓ Potassium ▪ Ex: ice floating on water ✓ Calcium ✓ Ammonium ✓ Iron ✓ Iodine ✓ Manganese ✓ Cobalt ✓ Zinc Organic Constituents CHONs CHO Lipids Oxygen Carbon dioxide Properties of Water of Biological Importance It is an electron dipole. It is a universal solvent. An ideal medium for the ionization of substances. Freezing point, boiling point, vapor pressure, osmotic pressure are altered by dissolved solutes. High surface tension. High specific heat. High latent heat of vaporization. High latent heat of fusion. Has the capacity to conduct heat readily. Water Properties ▪ Water is cohesive ▪ Cohesion: sticks to itself ▪ Ex: allows some insects & spiders can “walk” on the surface ▪ Water is adhesive ▪ Adhesion: sticks to other things