The Cell PDF

THE CELL Cell Composition: Endomembrane System: Cell Membrane NUCLEUS Control center of the cell...

THE CELL Cell Composition: Endomembrane System: Cell Membrane NUCLEUS Control center of the cell Separated from cytoplasm by NUCLEAR MEMBRANE/NUCLEAR ENVELOPE Contains genetic material (DNA) arranged in PLASMA MEMBRANE thread-like structures called CHROMATIN also known as the plasmalemma, is the outer boundary of the cell. It's composed of a lipid NUCLEAR ENVELOPE bilayer, which consists of two layers of phospholipids. This structure gives the Part of the ENDOMEMBRANE SYSTEM membrane a selectively permeable property, Double membrane enclosing the nucleus allowing certain molecules to pass through Perforated by PORES for transport while blocking others. Continuous with the ENDOPLASMIC The plasma membrane serves as a barrier RETICULUM (ER) between the outside environment and the Each membrane is a LIPID BILAYER inside environment of the cell, maintaining separated by 20–40 nm space the internal balance, or homeostasis. Additionally, it controls the movement of NUCLEOLUS substances in and out of the cell, such as nutrients, waste, and signaling molecules, Non-membranous structure within the playing a crucial role in cellular nucleus communication and transport. PHOSPHOLIPIDS DNA/CHROMOSOMES Are the most abundant lipid in the plasma membrane Within the nucleus, DNA is organized into Are amphipathic, containing both discrete units called CHROMOSOMES hydrophobic and hydrophilic regions Chromosomes are structures that carry genetic information Cell Membrane: Protein Structures DNA/CHROMOSOMES: PROTEIN INTEGRAL PROTEINS STRUCTURES Penetrate the hydrophobic core of the lipid bilayer Each chromosome contains one long DNA often transmembrane proteins, completely molecule associated with many proteins spanning the membrane Histones are proteins that help coil the DNA molecule, reducing its length and allowing it PERIPHERAL PROTEINS to fit into the nucleus appendages loosely bound to the surface of the membrane Rough Endoplasmic Reticulum Cell Composition: Organelle: Nucleus Ribosomes attached to its surface Manufactures proteins  Not all ribosomes are attached to the rough Maintains cell shape ER Aids in movement and transport May modify proteins produced by ribosomes Includes microfilaments, intermediate Involved in membrane synthesis filaments, and microtubules RIBOSOMES Ribosomes are not membrane-bounded and Cell Composition: Extracellular thus are not considered organelles Components Essential for protein synthesis CILIA AND FLAGELLA CELL COMPOSITION Provide motility Cilia: Short, used to move substances outside human cells Flagella: Whip-like extensions, found on sperm cells CELL WALLS Found in plants, fungi, and many protists Surround the plasma membrane Plants: Made of cellulose Fungi: Made of chitin Archaebacteria: Made of pseudomurein Maintain cell shape and protect from mechanical damage SMOOTH ENDOPLASMIC RETICULUM (ER) Cell Composition: Organelle No attached ribosomes Builds lipids, including cholesterol and steroid hormones MITOCHONDRIA Detoxification Calcium storage Powerhouse of the cell Produces energy by breaking down fats and GOLGI BODIES carbohydrates Double membrane structure Processes and packages proteins from the Cristae: Inner folds of the membrane Rough ER Matrix: Fluid-filled space inside Vesicles transport proteins to the cell membrane for exocytosis PLASTIDS Modifies proteins and lipids Carbohydrate metabolism Chloroplast: Specialized plastid for photosynthesis, converts sunlight to LYSOSOMES chemical energy in sugar molecules Amyloplast: Colorless, stores starch (amylose) Contain digestive enzymes in roots and tubers Functions: Chromoplast: Contains pigments for orange ○ Aid in cell renewal and yellow hues in fruits and flowers ○ Break down old cell parts Elaioplast: Stores lipids ○ Digest invaders Proteinoplast: Stores proteins Believed to have evolved from VACUOLES photosynthetic bacteria, hence their two membranes Prominent in older plant cells Functions: MITOCHONDRIA ○ Storage ○ Breakdown of waste products Powerhouse of the cell ○ Hydrolysis of macromolecules Produces energy (ATP) through the breakdown of fats and carbohydrates CYTOSKELETON Double membrane structure Network of protein fibers Provides structural support CHLOROPLASTS Photosynthetic organelles in plant cells Convert sunlight into chemical energy stored in sugars Double membrane structure Stroma: Fluid-filled space surrounding thylakoids, where the Calvin cycle occurs Believed to have originated from photosynthetic bacteria (endosymbiosis) Prokaryotes vs. Eukaryotes PROKARYOTES No nucleus: DNA is in the nucleoid region No membrane-bound organelles Smaller and simpler structure Ribosomes are smaller EUKARYOTES Nucleus: DNA is enclosed within a nuclear membrane Membrane-bound organelles (e.g., mitochondria, chloroplasts, Golgi apparatus) Larger and more complex structure Ribosomes are larger