Lecture 2. Atoms and Energy. Water, Carbon, and the foundations of life From the Sun to your body

Transcription

1 Lecture 2 Atoms and Energy Water, Carbon, and the foundations of life From the Sun to your body

2 Atoms of Gold each: 174 picometers m Basic unit of matter Made of smaller particles Atoms Argonne National Labs Nucleus (protons +, neutrons) PhysicalScience/atom-with-electrons.gif Electron shell: outside the nucleus (electrons -) Atoms form molecules through two chemical bonds Ionic bonds (charged atoms) Covalent bond (uncharged)

3 Ionic bonds 2 or more atoms into a molecule Stealing of electrons, which cause each atom to have a charge (+, -) Difference in charge causes the atoms to stay together (opposites attract!) Rare in biological molecules

4 Covalent bonds 2 or more atoms into a molecule Sharing of electrons (no charge) Sharing stabilizes the atoms (sharing is fun!) Common in biological molecules

5 Polarity Covalent bonds (two atoms of unequal size): the resulting bond can produce polar (+, -) molecules /images/polar_molecules-h2o.gif

6 Water Polar molecule: cohesion (stick to each other) adhesion (stick to surfaces) Universal solvent: dissolves substances Interactions with other molecules Key to life /images/polar_molecules-h2o.gif

7 Hydrological cycle Water cycle Evaporation and Transpiration (atmosphere) Precipitation (returns) Runoff, groundwater, organisms (storage) Where is the water? 97% salt water 2% polar regions 1% Freshwater

8 Carbon All life (as we know it) is carbon based (organic) Four covalent bonds Wide array of biological molecules lipid uesc_02_img0113.jpg

9 Carbon Carbohydrates (sugars): energy source for organisms 1:2:1 carbon:hydrogen:oxygen Lipids (fats, waxes, steroids): energy storage, structure, signaling polar head with fatty acid tail (hydrophobic) Proteins: made of amino acids: cellular function, enzymes carbon + amino group + carboxylic group + R (variable) Nucleic acids (DNA, RNA): molecules of heredity chains of nucleotides (5 carbon + phosphate + nitrogen base)

10 Carbon cycle CO 2 captured by plants and turned into material Animals and others eat tissue Animal release that CO 2 back into atmosphere Other release of CO 2 Fossil fuels Storage of CO 2 Dead organisms Fossil fuels Limestone

11 E=mc 2 What is the meaning of this equation? What does it have to do with Biology?

12 The Sun Compared to Earth 110 times the diameter Can accommodate 1.3 million 100 million miles away Light takes 8 minutes to reach 92% hydrogen and 8% helium Core temperature is 28 million o F Surface temperature is 10,000 o F

13 Power of the Sun How long will our Sun last? Sun age: about 5 billion years Another 5 billion years Answer: E=mc 2 speed of light (670,000,000 mph) Energy mass A tiny change in mass will give off enormous amount of energy

14 Applications of E=mc 2 Nuclear fission Splitting uranium Atomic bombs Nuclear power plant Nuclear fusion Hydrogen fusion Hydrogen bombs Solar furnace (Sun)

15 Photosynthesis In General Carbon Dioxide + Water + Sunlight Chemical energy + Oxygen Overall Equation n CO 2 + 2n H 2 O + light energy (CH 2 O)n + n O 2 Glucose Synthesis 6 CO H 2 O + light energy C 6 H 12 O O 2

16 Light Glucose Synthesis 6 CO H 2 O + light energy C 6 H 12 O O 2 Competition for light, plants are not passive

17 Water Glucose Synthesis 6 CO H 2 O + light energy C 6 H 12 O O 2 Transpiration: transport of water from roots to leaves Cells: Xylem

18 Energy and Ecosystems Feeding relationships obey the 10% law Energy pyramid: Only 10% of the energy is transferred to the next higher level

19 Calorie Energy Unit calorie: The amount of energy (heat) that is needed to raise a 1 g of water by 1 o C (energy Calorie = kilocalorie (1,000 calories) Combustion in the presence of oxygen Measured using a Calorimeter Different molecules have different caloric values carbohydrates: 5 calories per gram proteins: 4 c/g fats: 9 c/g

20 Obesity in America What state has the highest obesity rate? A. West Virginia (3): 33.8% B. Colorado (50): 20.5% C. Massachusetts (49): 22.9% D. Mississippi (2): 34.6% E. Louisiana (1): 34.7% For children (K-5): Mississippi (1): 37.3%! (was 43% in 2008)

21 Obesity in America 72% (men) and 64% (women) overweight or obese Worldwide, 1.6 billion (2005), double by in 7 children is obese Mississippi: lead the nation in obesity ( ) + Type I, II Diabetes CDC 2009

22 Obesity Trends* Among U.S. Adults BRFSS, 1990, 2000, 2010 (*BMI 30, or about 30 lbs. overweight for 5 4 person) No Data <10% 10% 14% 15% 19% 20% 24% 25% 29% 30%

23 Health Consequences of Obesity Heart diseases Diabetes Stroke High cholesterol Osteoarthritis Certain types of cancer Shorter life span (6-20 years) extra 40 calories a day, for year = 1 lb Over 10 years = 10 lbs Age = 30 lbs (obese!)

24 Body Mass Index (BMI) BMI = Weight in lbs * Height in inches * Height in inches BMI = BMI = 180 lbs * in * 70 in 130 lbs * in * 60 in = = 25.44

25 Body Mass Index (BMI) BMI = Weight in lbs * Height in inches * Height in inches Healthy: BMI < 25 Overweight : BMI Obese: BMI 30

26 What else? What s the difference between Glycogen and Triglyceride? What s the difference between saturated and unsaturated fat? How many hours of sitting would it take to burn off 1 slice of thick crust pizza?

27 For Next time: Chemistry