Cell Structure & Function!

Transcription

1 Cell Structure & Function! Chapter 3! The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny.! -- Isaac Asimov Animal Cell Plant Cell Cell membrane/wall - protective, permeable layer around outer boundary of cell provides structure Bacteria: Cell wall made of peptidoglycan Plants: Cell wall made of cellulose Cytoplasm consists of all cellular structure inside the membrane except the nucleus 2 Components: cytosol and organelles Cytosol intracellular fluid site of many chemical reactions needed for cell existence water, ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, and waste products

2 Organelles specialized structures within cell perform specific functions in cell growth, maintenance, and reproduction Each has own set of enzymes for specific reactions Numbers and types of organelles vary from cell to cell depending on cell s function Enzymes proteins that speed up (catalyze) chemical reactions provide alternate pathway that requires less energy to start reactions Nucleus stores DNA Head Office! Note: all cells have same DNA different genes turned on in different cells enzymes remain unchanged after reactions Within the nucleus: Chromatin a combination of DNA and associated proteins Genes subunits of DNA that control particular hereditary characteristics Chromosomes long threadlike structures a single piece of DNA containing many genes 46 in humans Nucleoplasm semi-fluid surrounding chromosomes Nucleolus location where ribosomal RNA is produced Nuclear envelope membrane surrounding nucleus

3 Ribosomes responsible for synthesis of proteins Found: individually in cytoplasm in groups (polyribosomes) Production! attached to endoplasmic reticulum Rough Endoplasmic Reticulum attached to nuclear envelope responsible for folding, processing, Packaging! and transport of proteins ribosomes! Smooth Endoplasmic Reticulum attached to rough endoplasmic reticulum synthesizes phospholipids in membranes Shipping! forms vesicles to transport products to Golgi apparatus Interoffice Mail! Vesicles membranous sac stores and transports cell products Vacuoles (vesicle) -large membranous sac - most prominent in plants stores & transports cell products Peroxisomes (vesicle) contains enzymes that oxidize (remove H atoms from) organic substances examples: amino acids, fatty acids, alcohol storage of substances water, sugars, salts, pigments (flower color), toxic substances (self-defense) byproduct: hydrogen peroxide (H2O2) enzyme catalase decomposes H2O2 self-replicating

4 Lysosomes (vesicle) Sanitation Workers! membrane-enclosed vesicles formed in the Golgi complex ~60 different kinds of digestive & hydrolytic enzymes Enzymes are created in the RER Breaks down worn cell parts and substances entering cell Most numerous in disease-fighting cells, such as white blood cells Proteasomes Barrel-shaped structures that handle destruction of unneeded, damaged, or faulty proteins Cell contains 1000s of proteasomes Enzymes cut proteins into amino acids, which are recycled into new proteins Plastids (vesicle) manufacture & storage of chemical compounds in plant & algae cells Etioplasts chloroplasts that have not been exposed to light Chloroplasts photosynthesis Chromoplasts pigment synthesis & storage Leucoplasts synthesis of resins Amyloplasts: starch storage & detecting gravity! Elaioplasts: fat storage Proteinoplasts: storing, modifying proteins Golgi apparatus a collection of folded curved sacs collects, sorts, packages and Post Office! distributes goods created by the ribosomes and ER to rest of cell Chloroplasts Power Generator Plants & algae! use solar energy to create organic molecules (in plant cells) ~50 in each cell food producers of cell create sugars from CO 2 & H 2 O need light energy byproduct is oxygen Power Generator Plant & Animal! Mitochondria responsible for generating ATP (energy) 100s to 1000s in each cell self-replicate if increased energy demands Sugar combines with oxygen on surface of cristae (inner membrane) to form ATP contain their own DNA 37 genes only inherited from your mother!

5 Cytoskeleton Network of protein filaments throughout the cytosol Provide strength and shape for the cells 3 different sizes (diameters) Microfilaments found at edges of cell Composed of protein actin Generate movement and provide mechanical support Intermediate filaments exceptionally strong Found in parts of cell that experience mechanical stress Stabilize position of organelles within cell Help attach cells to one another Microtubules created in centrosome Long hollow tubes Composed of protein tubulin Help determine cell shape Centrosome pair of centrioles & pericentriolar material Located near nucleus Replicate in cell division so new cells can also divide Centrioles --Two cylindrical structures 9 clusters of 3 microtubules arranged in circular pattern Pericentriolar material helps in cell division and in microtubule formation Cilia Numerous short hairlike projections that extend from surface of cell Made of microtubules arranged in specific pattern Movement of cilia creates steady flow of fluid across exterior of cell Flagella similar to cilia except larger Propels entire cell Example: sperm cell tail Chapter Objectives Label the structures within the eukaryotic cell Describe the functions of cell structures Compare and contrast prokaryotic and eukaryotic cells give examples of each Know the key differences between plant and animal cells Vocabulary Be able to define the following; describe the functions of bolded items: eukaryotic endomembrane system: cytoskeleton: prokaryotic rough endoplasmic reticulum actin (micro) filaments plasmid smooth endoplasmic reticulum intermediatecytoplasm vesicle(s) filaments cytosol vacuole(s) microtubules nucleus Golgi apparatus cilia Nuclear envelope lysosome flagella nucleolus proteasomes centrioles chromatin energy related structures: ribosome mitochondria peroxisome chloroplast