Levels of organization

Transcription

1 The Cell 1.The cell the basic structural and functional unit of living organisms 2.Prokaryotic and Eukaryotic Cells 3.Cellular organization: external morphology cell size, shape and color internal structure cell compartments 4.Chemical composition of living cells

2 Levels of organization Levels of organization: cell tissue organ organ system organism The cell: the basic structural and functional unit of all known living organisms the smallest unit of life the building block of body Major cell abilities: reproduction by cell division the functioning of a cell depends upon its ability to extract and use chemical energy stored in organic molecules response to stimuli such as changes in temperature, ph or levels of nutrients cell contents are contained within a cell surface membrane 2

3 The cell evolutionary levels The biological universe consists of two cell types: Prokaryotic cells (Gr. πρό- (pro-) "before" + καρυόν (karyon) nut or kernel", referring to the cell nucleus) bacteria and archaea Eukaryotic cells "true nucleus" (Gr. eυ- (eu), "good", "true") multicellular organisms internal compartmentalization 3

4 Prokaryotes and Eukaryotes 4

5 200 different cell types that come in an astounding assortment of shapes and sizes: size µm The cell external morphology small-sized up to 10 µm medium-sized µm large-sized > 20 µm shape related to their function: spherical spindle-shaped squamous, cuboidal... color: colorless pigmented 5

6 Basic cellular architecture nucleus (Lat., nux, nut) cytoplasm (Gr. kytos, cell + plasma, thing formed) organelles ( little organs ) universal and specialized membranous (membrane-limited) nonmembranous cytoplasmic inclusions deposits of carbohydrates, lipids, and pigments cytosol (cytoplasmic matrix) 6

7 Cell components cytosol (intracellular fluid, cytoplasmic matrix), Lat. mold ~70 % of the cell volume final supernatant produced by differential centrifugation translucent fluid, ph 6.8 delicate 3D microtrabecular lattice (cytoskeleton) intermediate and filaments of actin, microtubules substratum for cytoplasmic functions water (up to 90%) macromolecules: proteins (20-25%), incl. soluble enzymes all machinery to synthesize proteins (rrna, mrna, trna, enzymes) carbohydrates salts and electrolytes 7

8 The cell chemical composition essential elements: macroelements 98-99% of the cell mass - C, N, O, H microelements up to % - Cu, Zn, Mg ultra trace elements % - Hg, Ag, U, Ra water 70-80% exogenous ⅔ endogenous ⅓ inorganic molecules: free ions bound with organic molecules organic compounds: carbohydrates lipids proteins nucleic acids 8

9 The cell water composition Water features: essential for all life to exist 99% of the molecules inside living cells are water molecules 70-80% of the total wet-weight of the cell functions: a matrix of life solvent for nutrients helps the body maintain a constant temperature eliminate waste products from the cell water channels: aquaporins Peter Agre 9

10 The cell organic compounds saccharide (Gr. sakchar, sugar) Carbohydrates: monosaccharides pentoses hexoses disaccharides polysaccharides 10

11 Lipids (Gr. lipos, fat) The cell organic compounds 11

12 The cell organic compounds Proteins (Gr. πρώτος (prótos), first, original) general features: very large molecules of linked subunits called amino acids 60% of cell dry mass (15% on a wet-weight basis) determine the shape and structure of the cell serve as main instruments of molecular recognition and catalysis classification ~10000 different types: structurally: simple proteins albumins, globulins, histones, collagen compound proteins glycoproteins lipoproteins nucleoproteins metalloproteins functional classes: structural proteins enzymes transport proteins storage proteins defense proteins contractile proteins 12

13 Building blocks of proteins amino acids: 20 different amino acids: essential nonessential major function: protein building blocks smallest units of proteins non-protein functions: precursors for the biosynthesis of some biological molecules forming parts of coenzymes metabolic intermediates neurotransmitters: excitatory inhibitory 13

14 Protein structure Four levels of structural organization: Primary structure: the amino acid sequence Secondary structure: regularly repeating local structures stabilized by hydrogen bonds Tertiary structure: formation of protein subunits by folding Quaternary structure: the assembly of subunits the structure formed by several protein molecules (polypeptide chains) 14

15 The cell organic compounds Nucleic acids: DNA RNA ribosomal RNA (rrna) transfer RNA (trna) messenger RNA (mrna) 15

16 Thank you 16