Eukaryotic Cells: Cellular Organelles & Structure

Eukaryotic Cells Cellular Organelles & Structure: Two main types of cells, prokaryotic cells (do not have membrane bound nuclei) and eukaryotic cells (do have membrane bound nuclei Peroxisome: lipid destruction and contains oxidative enzymes (helps protect the cell from reactive oxygen species) Lysosome: protein destruction Nucleolus: small subspace found within the nucleus (not membrane bound) and holds DNA with instructions for making ribosomes (rRNA and are even formed inside the nucleus itself). Also, it's a very compact structure Mitochondria: intermembrane space has high pH because ETC is constantly pumping H+ ions into here, they are also self replicating and contain their own DNA (multiple copies and are located in the matrix) Microtubules: small tubes made from the protein tubulin (found in cilia and flagella) and is involved in providing pathways for vesicles to move throughout the cell (even a part of the mitotic spindle where homologous chromosomes are pulled apart) Intermediate Filaments: smaller than microtubules, but larger than microfilaments. These are made up of a variety of proteins such as keratin or neurofilament (very stable and help provide structure to the nuclear envelope and even anchor organelles) don’t contribute to cell motility Microfilaments: thinnest part of the cytoskeleton and are made up of actin (a protein that is the most abundant protein in most eukaryotic cells) and is both flexible and strong, making it a very useful protein in cell movement (such as actin-myosin interaction system in muscle Characteristics of Eukaryotic Cells: Binary Fission: when prokaryotic cells make two copies of everything and split down the middle Prokaryotic RNA Polymerases work faster than eukaryotic ones The Nucleus: Nucleoplasm: the fluid found within the nucleus Nuclear Pore: spans both the inner and outer membrane, allowing proteins and such to exit or enter the nucleus (very selective and recognizes specific signals on proteins wanting to exit/enter The endoplasmic reticulum has a continuous membrane with the nucleus (outer membrane of the nucleus specifically) Mitochondria: While the outer membrane of the mitochondria is permeable to small molecules, the inner membrane is impermeable to small molecules Crista: folds in the inner membrane of a mitochondria (increases surface area and more room to work with) Cellular Respiration: 1. Glycolysis: glucose is converted to 2 pyruvates (occurs in the cytoplasm) 2. Pyruvate Dehydrogenase Complex: pyruvate is converted to acetyl-CoA (occurs in the matrix) 3. Krebs Cycle: acetyl-CoA undergoes a series of reactions producing electron carrier known as FADH (uses NADH dehydrogenase - I) and FADH2 (uses succinate dehydrogenase - II) (occurs in the matrix) 4. Electron Transport Chain: oxygen is the final electron acceptor of the ETC (occurs in the inner membrane) and produces ATP via ATP synthase (energy released from the membrane proteins is used in order to pump H+ ions into the intermembrane space) Chemiosmosis: used by ATP synthase when H+ ions pass through down their concentration gradient in order to generate ATP Oxidative Phosphorylation: refers to ADP being phosphorylated and the oxidation because all of the enzymes (and NADH and FADH2) in the ETC end up being oxidized Endoplasmic Reticulum & Golgi Apparatus: ER has two portions (smooth and rough) to its entire structure The sarcoplasmic reticulum found in muscle cells is a modified version of the smooth endoplasmic reticulum Proteins made in the RER are meant to secreted into the extracellular environment, integrated into the cell membrane, or even become integrated into the ER, golgi, or lysosomes Proteins made in the cytoplasm have destinations within the nucleus, mitochondria, peroxisomes, and cytoplasm All polypeptides begin to be translated in the cytoplasm and if it has a signal sequence it will be pushed into the RER in order to finish translation Cis Stack: portion of the golgi apparatus that is closest to the endoplasmic reticulum Medial Stack: portion of the golgi apparatus that is in the middle Trans Stack: portion of the golgi apparatus that is furthest from the RER and is where vesicles finally bud off from the golgi Lysosomes & Peroxisomes: Lysosomes: membrane bound organelles that break/digest various molecules/substances (typically proteins) Autophagy: when the lysosomes digests parts of the cell or other cells (i.e. organelles that are no longer functional) Crinophagy: when the lysosomes digest excess secretory products (if the cell makes too many secretory products) The broken down things can be reused (such as amino acids) Acid Hydrolases: found in lysosomes and require a low pH (specifically a pH of 5) Peroxisomes: responsible for lipid breakdown and breakdown of reactive oxygen species (such as various peroxides including hydrogen peroxide - H2O2) Epithelial & Connective Tissue: 4 types of animal tissue that are all made up of eukaryotic cells (muscle, nervous, epithelial, and connective tissue) Epithelial Tissue: works as a lining (outer or inner) and even makes up glands (both exocrine glands (which release substances directly to the target organ) and endocrine glands (release hormones into the bloodstream indirectly to their target organs)) Simple is one layer (found in areas where substances need to diffuse, i.e. alveoli of the lungs, CO2 and O2) or stratified is two or more layers (places that need to resist mechanical or chemical stress, i.e. esophagus because food can come through as hot or cold and such needs to be protected from it) Basement Membrane: not made up of cells but made up of fibers and is attached to epithelial cells. This is pretty permeable and this is important because epithelial tissue is avascular (no blood vessel, no nutrients) and therefore gets it from underlying tissue to the epithelial cells Endothelium: epithelial tissue lining blood and lymphatic vessels Connective Tissue: supports tissues, connects tissues, and separates different tissues from each other (i.e. bone, cartilage, blood, lymph, adipose, etc.) Typically contains cells, ground substance, and fibers (the matrix is what contains the fibers and ground substance) Areolar Tissue: is a type of connective tissue that binds together different tissues and provides flexibility/cushioning Adipose Tissues: provides cushioning, stores energy, and has no fibers present Fibrous Connective Tissue: strong (provides support and shock absorption for bones and organs) and is found in the dermis (middle layer of the skin), tendon, and ligaments Blood: no fibers present and the matrix of the blood is known as the plasma Osseous-Bone: contains osteocytes and the matrix contains bone minerals/hydroxyapatite Hyaline Cartilage: chondrocytes and are found in surfaces of joints