Cell Biology - Principles of Biology - Review Sheet | BIO 101, Study notes of Biology

Download Cell Biology - Principles of Biology - Review Sheet | BIO 101 and more Study notes Biology in PDF only on Docsity! Cell Biology • Cell biology is the study of cells • Cells are the fundamental unit of life • The smallest unit of an organism considered living; “the building block of life” Biosphere Ecosystem Florida coast Community All organisms on the Florida coast Population Group of brown pelicans Nucleus Nerve Spinal cord Cell Nerve cell Tissue Nervous tissue Organ Brain Organelle Nucleus Molecule DNA Atom Organism Brown pelican Organ system Nervous system Brain Cell Biology • In 1665, Robert Hooke (“the father of microscopy”) used a crude microscope to examine a piece of cork and saw “little rooms” or cells • In the late 1600’s, Antoni van Leeuwenhoek described “very little animacules” using a refined lens he crafted; what he saw were bacteria! Light microscope image of a Paramecium Electron microscope image of a Paramecium 100 mm 10 mm U n ai d ed e ye Human height Length of some nerve and muscle cells 10 m Frog egg Chicken egg 1 m (10 cm) (1 cm) 1 mm Li gh t m ic ro sc o p e100 µm 10 µm 1 µm Most plant and animal cells Nucleus Most bacteria Mitochondrion Mycoplasmas (smallest bacteria) El ec tr o n m ic ro sc o p e 100 nm Viruses 10 nm Lipids Ribosome Proteins 1 nm Small molecules 0.1 nm Atoms • Most cells are microscopic, but some can be visible to the naked eye • Internal architecture restricts the size of any cell from being too small – A cell must house enough DNA, protein molecules and internal structures to survive and reproduce Cell Biology • Most cells measure between 1-100µm (remember: there are 1,000,000 µm in 1 meter) • Prokaryote cells (bacteria and Archaea) are small; 1-10 µm • Eukaryote cells are slightly larger; 10-100 µm • The maximum size of a cell is limited by the amount of surface area needed to obtain nutrients and exchange gases with the environment Cell Biology • There are 2 types of cells: – Prokaryotic – Eukaryotic • All cells, however, share several basic features in common: • All are bounded by a plasma membrane • All have chromosomes carrying genes made of DNA • All contain ribosomes, which make proteins according to instructions from the genes Prokaryote cells • Prokaryote cells are structurally simpler than eukaryote cells (and smaller) • They lack a nucleus containing DNA • Instead, their DNA is coiled into a region called the nucleoid (“nucleus-like”), and no membrane surrounds their DNA • Most antibiotics target prokaryotic cells for their smaller, structurally-different ribosomes Prokaryotic cell Pili Nucleoid Ribosomes Plasma membrane Cell wall Capsule Flagella Bacterial chromosome A typical rod-shaped bacterium A thin section through the bacterium Bacillus coagulans (TEM) Eukaryotic cells • The structures and organelles of eukaryotic cells can be organized into 4 basic functional groups: 1. Manufacturing: the nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus 2. Hydrolysis: lysosomes, vacuoles, and peroxisomes 3. Energy processing: mitochondria (all cells) and chloroplasts (plant cells only) 4. Structural support, movement and communication: cytoskeleton, plasma membrane and cell wall (plant cells only) NUCLEUS: Nuclear envelope Plasma membrane Mitochondrion Intermediate filament Microfilament Smooth endoplasmic reticulum Rough endoplasmic reticulum CYTOSKELETON: Chromosomes Nucleolus Ribosomes Golgi apparatus Peroxisome Centriole Lysosome Microtubule An animal cell Nuclear envelope Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum CYTOSKELETON: NUCLEUS: Nuclear envelope Chromosome Nucleolus Ribosomes Golgi apparatus Plasma membrane Mitochondrion Peroxisome Cell wall Central vacuole Microtubule Intermediate filament Microfilament Cell wall of adjacent cell Chloroplast Plasmodesmata A plant cell Hydrophilic heads Hydrophobic tails Proteins Hydrophobic region of protein Inside cell Hydrophilic region of protein Outside cell The plasma membrane • Proteins form channels that allow specific ions and other hydrophilic molecules to cross the membrane The nucleus • The nucleus is the cell’s genetic control center • The nucleus contains most of the cell’s DNA and controls the cell’s activities by directing protein synthesis • Eukaryotic chromosomes are made up of chromatin, a complex of proteins and DNA • Chromatin packages DNA into a smaller volume to fit into the cell and contains genetic material-instructions to direct cell functions Chromatin • In Chromatin, DNA wraps around the proteins forming a “beads-on-a-string” structure • Chromatin has various levels of condensation, which varies during different stages of the cell life cycle; when the cell divides, chromatin forms the chromosmes The nucleus nuclear envelope nucleolus nuclear chromatin Gopyright © 2006 Pearson Prentice Hall, Inc. Ribosomes • Ribosomes are organelles that carry out protein synthesis • A human pancreas cell may contain a few million ribosomes! • Ribosomes are made up of a small subunit and a large subunit made up of RNA and protein (“ribo” comes from ribonucleic acid…) The Endoplasmic Reticulum • Endoplasmic reticulum is differentiated into smooth endoplasmic reticulum and rough endoplasmic reticulum • Rough endoplasmic reticulum (ER) has ribosomes that stud the outer surface, while smooth ER lacks attached ribosomes • The ER is an extensive network of flattened sacs and tubules, which divides the cell into separate compartments The Endoplasmic Reticulum • Rough ER (with ribosomes) makes membranes and proteins – The bound ribosomes produce proteins that enter the ER membrane and are transported to other organelles, or secreted by cell – Insulin is a protein produced by ribosomes but secreted by the cell via the rough ER! Transport vesicle buds off Secretory protein inside trans- port vesicle Glycoprotein Ribosome Sugar chain Polypeptide Rough ER The Golgi Apparatus • After leaving the ER, many transport vessicles travel to the Golgi apparatus • The Golgi apparatus receives, sorts, chemically alters, and packages important molecules manufactured by the ER • One side of a Golgi stack serves as receiving dock, while the other serves as the shipping side, which buds off vesicles to travel elsewhere Lysosomes • Tay-Sachs disease occurs in people who lack one or more lysosomal enzyme • In this case, a lipid-digesting enzyme is missing (genetic defect in a single gene) and brain cells become impaired by an accumulation of lipids • A child with Tay-Sachs disease will die within a few years; no cure or treatment Digestive enzymes Lysosome Plasma membrane Food vacuole Digestion Lysosome fusing with food vacuole Vacuoles • Vacuoles are membrane-bound sacs that have a variety of functions – Food vacuole – cytoplasmic sacs used to engulf food – Central vacuole - in plants; absorbs water and stores chemicals (e.g., toxins or pigments) or waste products – Contractile vacuole - stores or pumps excess water out of cell; common in freshwater protists Engulfing of photosynthetic prokaryote Chloroplast Mitochondrion Some cells Host cell Mitochondrion Host cell Engulfing of aerobic prokaryote Endosymbiosis • Mitochondria are the “power houses” of the cell • A host could benefit from the ability of the mitochondria to use oxygen and release large amounts of energy in cellular respiration • Chloroplasts are the photosynthesizing organelles of photosynthetic eukaryotes (plants and some protists); also have a double membrane The Cytoskeleton • Organelles do not float freely in the cell • Rather, they are supported and transported by a network of protein fibers, the cytoskeleton • The cytoskeleton is made up of 3 main types of filaments – Microfilaments (the thinnest) – Microtubules (the thickest) – Intermediate filaments (in between in thickness0 Fibers of the cytoskeleton as Fig PO ee: *, 4, Tubulin eO subunit Rigor mortis • After death, cellular respiration ceases • ATP is no longer made within the cells • Without ATP, cellular pumps cannot transport Calcium ions, which enable actin and myosin to bind to each other (=contraction state), out of the muscle cells • Without ATP, the actin and myosin fibers remain linked together (until decomposition of the muscle itself) The Cytoskeleton • Cilia are short, numerous appendages that propel many protists (“ciliates’) and generate currents • Flagella are long, singular appendages used for locomotion • Both are composed of a core of microtubules wrapped in an extension of the plasma membrane; a ring of 9 microtubule doublets surround a central pair of microtubules (9+2) Cellular phones? • Neighboring cells communicate with each other through cell phones! • Just kidding… cells adhere, interact, and communicate through special junctions between them – Gap junctions are channels that allow small molecules to flow through protein-lined pores between neighboring cells; essential for chemical communication And what about plant cells? • Plant cells are distinguished from animal cells in having chloroplasts and a cell wall • The cell wall is a rigid extracellular structure that provides ‘skeletal’ support to keep plants upright on land • Cell walls are made of cellulose!!! A plant cell Rough endoplasmic reticulum Nucleus Ribosomes Smooth endoplasmic Golai reticulum Microtubul Intermediate’ Cytoskeleton filament anim E } )\- Microfilament Mitochondrion Peroxisome Figure 4.