Chemistry is life • Molecules make up components of cells • Four major organic molecule types: 1. 2. 3. 4. Carbohydrates (sugars, starches) Lipids (fatty acids) Proteins Nucleic acids (DNA, RNA, ATP) 1. Carbohydrates •Carbon + Hydrogen + Oxygen •Ex. sugars/starches •composed of single sugar units called monosaccharides, ex. glucose. •can bond to form more complex compounds like table sugar, ex. sucrose (1 glucose + 1 fructose); 2 sugar units=disaccharide. C C C C C C glucose C C C C C Carbohydrates •Some important CHO’s are: –glycogen (how animals store food) –starch (how plants store food) –cellulose (plant cell wall compound)—most common CHO on planet –chitin (shells of bugs and some cells in fungi) 2. Lipids (Fats) •Usually made of fatty acids and a molecule called glycerol •fats are either saturated or unsaturated •saturated fats, like lard, are the worst for humans •unsaturated fats, like fish oils and plant oils, are better, and can be bonded together to make more complex fats called polyunsaturated fats. Lipids/Fats (cont.) •Lipids are extremely important: cell membranes •lipids make other molecules like hormones (estrogen, testosterone) •Ex.cholesterol is a lipid byproduct used to make hormones The cell membrane is a fluid mosaic of phospholipids and proteins Fibers of the extracellular matrix Carbohydrate (of glycoprotein) Glycoprotein Glycolipid Plasma membrane Figure 5.12 Phospholipid Microfilaments of cytoskeleton Cholesterol Proteins Cytoplasm 3. Proteins •Composed of units called amino acids •only 22 amino acids exist, with 20 used for amino acids •all share a similar structure •amino acids form a peptide bond or sulfur bond with others •as these chains of peptides form, they either form a spiral or a flattened sheet. Amino acid 3. Proteins •protein spirals or sheets form complicated compounds •Ex. hemoglobin in your red blood cells that carry oxygen: Hemoglobin How proteins fold to become more complex proteins: Modified proteins: enzymes •Enzymes are amazing! •Modified proteins •Names end in –ase ex. Glucose is sugar, glucase is enzyme that breaks it down ex. Amylose is starch, amylase is enzyme •Speed up chemical reactions •Break compounds apart •Put compounds together Enzymes can break apart molecules OR put them together! How enzymes work •Two models: lock&key or induced fit •Lock&key: exact fit of compounds to enzyme •Induced fit: enzyme can “wrap” around compounds 4. Nucleotides •3 parts •1. phosphate OH molecules (phosphorus + O P oxygens) O Phosphate •2. a sugar group •3. a base that contains nitrogen H H N N N H N O CH2 Nitrogenous base (A) O H H H H OH Sugar N H H Examples of Nucleotides: •DNA (deoxyribonucleic acid)—holds genetic information •RNA (ribonucleic acid)—takes information from DNA and makes proteins •ATP (adenosine triphosphate) is important in transferring electrons; major energy carrier for cells ATP uses Electrons to store/release energy – In living organisms, chemical energy is stored by using it to move electrons to more distant orbits. – ATP powers nearly all forms of cellular work – The energy in an ATP molecule lies in the bonds between its phosphate groups Adenosine Adenosine diphosphate Triphosphate Phosphate groups P Adenine P H2O P P Hydrolysis Ribose ATP Figure 5.4A ADP P + P + Energy Structure of DNA Nucleotide = N-containing base, a pentose sugar, and a phosphate group Five nitrogen base types – adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U) Figure 2.21a Molecules make Cells possible: • • • • • Sugars for energy Proteins for building structures Lipids for cell membranes DNA/RNA for making more cells ATP for making energy possible Molecules make Cells possible: • • • • • Sugars for energy Proteins for building structures Lipids for cell membranes DNA/RNA for making more cells ATP for making energy possible Prokaryotes vs. Eukaryotes •DNA in single loop •Very small •No organelles •Live in all environments •DNA in chromosomes in nucleus •Much larger •Organelles handle complex cell tasks •Live in restricted environments Prokaryotic cells are structurally simpler than eukaryotic cells Prokaryotic cell Colorized TEM 15,000 Nucleoid region Nucleus Figure 4.3A Eukaryotic cell Organelles Surface Area to Volume Ratio A small cell has a greater ratio of surface area to volume than a large cell of the same shape 10 m 30 m 30 m Figure 4.2B Surface area of one large cube 5,400 m2 10 m Total surface area of 27 small cubes 16,200 m2 Eukaryotic cells—plants, fungi, animals, protists • Nucleus present • Membrane surrounds cell • Cell wall may be present (plants, fungi, but NOT animals) Plasma membrane • Surrounds entire cell • Made of two lipid layers • Allows certain molecules in/out = “selectively permeable” Nucleus—control center Cytoskeleton—internal ‘skeleton’ Internal membrane system 3 important membranes: 1. Rough endoplasmic reticulum 2. Smooth endoplasmic reticulum 3. Golgi complex •Smooth endoplasmic reticulum has a variety of functions: 1. Synthesizes lipids 2. Processes toxins and drugs in liver cells 3. Stores and releases calcium ions in muscle cells Rough endoplasmic reticulum makes membrane and proteins Ribosomes on the sur face of the rough ER produce proteins that are secreted, inserted into membranes, or transported in vesicles to other organelles •Lysosomes are sacs of enzymes that function in digestion within a cell •Lysosomes in white blood cells destroy bacteria that have been ingested •Lysosomes also recycle damaged organelles The various organelles of the endomembrane system are interconnected structurally and functionally Moving the cells around 3 ways: 1. Flagellum—cell extends cytoplasm into tail-like structure 2. Cilia—cell extends small hair-like structures 3. Pseudopodia—cell extends itself to move around Human cells move too! 1. Lung cells & fallopian tube cells use cilia to move things around. 2. Male sperm cells use a flagellum to get to the egg. 3. White blood cells use pseudopodia to move between other cells and get to where they need to be. Lecture Assignment 2 • Pages 485-511 in back of textbook • Topic is cancer • 1 page summary, handwritten, in your own words, due Thursday, April 17, at the beginning of class Organelles • Membrane surrounds them • Important organelles: • • • • • • • Nucleus Cell membrane Lysosomes/peroxisomes Rough endoplasmic reticulum Smooth endoplasmic reticulum Golgi apparatus Special organelles involved in energy: • Mitochondrion—produces ATP (in all eukaryotes) • In plants and some algae: Chloroplast—produces sugar from light energy Mitochondria Chloroplast Can human diseases result from organelles? Yes! •Lysosomes •Mitochondria •Peroxisomes (in plants) •Even Cell Membranes! •Aging? •Chronic Fatigue Syndrome? Quick Review! • What are 5 organelles in the cell? • In order, what organelles are responsible for moving the products of DNA to the Golgi Complex? • What 3 things make up the cell membrane? • What are the 4 foundational theories of biology? • What are the 4 groups of biologicallyimportant molecules?