I.Characteristics of Organisms

A. Characteristics of Living Organisms

1. obtain nutrients & energy from surrounding environment

2. synthesize organic molecules

3. use free energy to complete chemical reactions

B. Energy and Nutrients

1. Energy � capacity to do work or cause change

2. chemical energy � org. store energy in the organic mol. from which the org. are made.which the org. are made.

a. Free energy � portion of chemical energy available to do work (useable energy)

EX:) energy we use for exercise and thinkingexercise and thinking

3. heterotrophs ���� obtain energy & nutrients from other organisms-living or dead (consumers)

ex:) animals, fungi and most bacteriabacteria

4. autotrophs � obtain energy & nutrients from non living sourcessuch as sun, minerals & air(producers)

ex:) plants, certain bacteria& some protists (euglena)

ex:) plants, certain bacteria& some protists (euglena)

a. Use the energy to synthesize organic

compounds from inorganic materials

5. photoautotrophs � org. that capture energy from sun & use it to synthesize organic compounds from C02 & H20

6. chemosynthesis� can obtain freeenergy from inorganic chemicals

6. chemosynthesis� can obtain freeenergy from inorganic chemicalsin the env. (chemoautotrophs or consumers)

ex:) bacteria

7. cell respiration � autotrophs & heterotrophs carry out reactions that release the free energy of organic compounds

8. nutrients & energy can be obtained from both living & nonliving sources nonliving sources

9. energy passes from autotrophs toheterotrophs.

a. 02 & C02 cycle repeatedly between them

II. Energy & the Ecosystem

A. Producers, Consumers & Decomposers

1. Food Web � Energy & nutrients flow from the env. through the producers to the consumers and finally to the decomposersfinally to the decomposers

2. made up of many food chains

3. abiotic factors� non living things

a. ex:) sunlight, water, temp,soil, wind, severe disturbances

Surprising Carnivores!

4. biotic factors� living things

a. ex:) animals, plants, fungi, bacteria, protists

B. Ecosystem

� the biotic & abiotic components of� the biotic & abiotic components ofa particular place

1. ex:) forest, pond, prairie, coral reef, desert, marshes

2. biosphere� all ecosystems combined

III.III. Energy Conversions Energy Conversions

A. 1st Law of Thermodynamics

� energy cannot be created or destroyed- but can change form.

1. ex:) can NEVER get rid of garbage � burn it � coverts to garbage � burn it � coverts to C02, smoke, ash, water vapor etc.

2. org. cannot create own energy-must obtain it from outside source

3. org. convert chemical energy into free energy & heat energy

4. Law of Conservation of Energy� the total energy of the

universe is constant

a. Chem. Energy in log stored in molecules

b. Log burns – most energy changes to heat energy and

b. Log burns – most energy changes to heat energy andescapes

c. Small amount of chem. energy remains in ash & smoke

d. heat energy eventually spreads out & is no long available to do work

B. Energy & Entropy

1. Entropy � measure of a degreeof disorganization in a system. of disorganization in a system.

a. How much energy in a system has become so dispersed that it is no longerable to do work

2. 2nd Law of Thermodynamics

� systems tend to change in a way that increase disorder

a. World becomes increasingly disordered as free energy isreleasedreleased

b. Burning log releases heat energy from its well ordered mol. � reduced to ash, smoke,& water

c. Mol. in these materials are LESS ordered & contain LESSfree energy

d. As free energy DECREASES, entropy INCREASES

1. Organisms must be well organized to live& grow

2. Key to maintaining organization is ENERGY

IV. Metabolism & Energy Transfer

A. Enzymes & Energy

1. Enzymes � specialized proteins thatlower the activation energy requiredto make a reaction proceed.

a. Activation energy = energy a. Activation energy = energy needed to start a reaction

2. Characteristics of Enzymes:

a. speed up reactions that would otherwise occur slowly

b. are REUSABLE

���� several thousand reactions may occur every min. in each cell!

c. catalysts in living organisms(catalyst – lowers activation

c. catalysts in living organisms(catalyst – lowers activation energies)

d. Catalyses only 1 or a few specificreactions

e. Only work under certain temp. & pH specific to each enzyme

3. How enzymes work:

a. Substrate � where the enzyme binds to

� may change shape after binds

b. active site� site where b. active site� site where substrate binds

� only allows specific molecules to bind

c. Enzyme-substrate complex �enzyme binding to substrate at active site

Enzyme

Active SiteSubstrate

Enzyme substrate complex

4. Metabolism � all chem. act. & changes that take place in a cell or org.

5. 2 Types of Metabolism:

a. Synthesis �build up or make moleculesmolecules

ex:) making starch from glucose

ex:) builds DNA from nucleotides, proteins from A.A

ex:) Plants: sugars from CO2 & H2O

� called biosynthesis

SubstrateProduct

Enzyme Enzyme-substrate complex

b. Decomposition� break down molecules

ex:) lactase (enzyme) breaks downmilk sugar (substrate) �simple sugar (product)

ex:) breakdown of glycogen to glucose in a muscle cell

ex:) breakdown of glycogen to glucose in a muscle cell

ex:) glucose to CO2 & H2O during cell respiration

SubstrateProduct

Active site Enzyme

V. Energy Transfer & ATP

A. Decomposition Releases Free Energy

1. Oxidation� removal of electrons from a molecule.

a. certain bonds are broken & rearranged rearranged

b. Energy of original mol. in living cells are released as heat & free energy

c. Free energy released throughoxidation is available as ATP

2. ATP (adenosine triphosphate) is a nucleotide � adenine & ribose joined with 3 phosphates

a. Energy in ATP released whenbond between 2nd & 3rd

phosphate are broken � free energy energy

b. 1 phosphate released = ADP

c. To form ATP again- need 1phosphate from free energyof broken down food

d. ATP NOT long term storage!

e. ATP forms & is consumed rapidly

� 10 mill. Mol. of ATP are consumed & regenerated per second per cellper second per cell

VI. Digestion Inside & Outside Cell

A. Digestion

1. Consists of 2 parts:

a. physical (chewing, grinding) =increases surface area of food for easier breakdown food for easier breakdown

b. chemical (enzymes) to breakdown food

2. extracellular digestion� digestionthat takes place outside the cells

a. Digestive tract opens to the outside env.

b. humans and most animals

3. Intracellular digestion �

digestion takes place inside the cells

a. Plants digest food they made themselves in their OWN cells

b. protists & single celled organisms

b. protists & single celled organisms

4. Hard to digest food = cellulose

a. Goats & cows � 4 chamberedstomachs to handle hard to digest foods

b. Horses & rabbits � special side pockets where microorganisms live & digest side pockets where microorganisms live & digest cellulose

c. Humans � no special microorg. and cannot digestcellulose

B. Human Digestion Process

1. ingestion � taking in food

2. epiglottis � trapdoor like tissue that normally prevents food & liquids from entering trachea(airway)(airway)

3. food travels to esophagus �muscular tube

4. wavelike contractions of muscles of esophagus move food to stomach� peristalsis

5. food in stomach break up & mix food with secretions � gastric juice (enzymes, mucus & acid)

6. food is soup like

7. muscular ring � pyloric sphinctersquirts partially digested food into small intestine squirts partially digested food into small intestine

8. Small intestine (6 m long) chemical digestion is completed & food mol. are absorbed.

a. Contains villi � mill. of small fingerlike projections that increase S. A

b. Each villi contains capillaries� tiny thin walled blood vessels that serve as entry points into the bloodstreampoints into the bloodstream

9. pancreas & liver contribute digestive juices to S.I. through ducts

10. food absorbed through intestinalwalls into bloodstreamwalls into bloodstream

11. blood carries mol. to all cells & used in metabolism

12. undigested material passes to large intestine where bacteria help produce vitamins & gases

13. water absorbed from food through walls of L.I.

14. dries out waste = feces14. dries out waste = feces

15. feces excreted through anus

C. Carbohydrate Digestion & Absorption

1. carb digestion begins in mouth with enzyme � salivary amylase

Salivary Amylase

STARCH + WATER MALTOSE

2. Saliva pH 6-7.4 amylase 2. Saliva pH 6-7.4� amylase functions best in this range

3. Stomach pH 1-3.5 = NO carb digestion in stomach

5. carb digestion completed in S.I. =final result glucose

E. Protein Digestion & Absorption

1. occurs in stomach & S.I.

2. enzymes that break down large protein mol. require strong acid

3. stomach glands secrete HCL

4. food stimulates the release of a 4. food stimulates the release of a hormone � gastrin. Gastrin + HCL starts secretion

5. protein digesting enzyme in stomach � pepsin

6. pepsin secreted by stomach gland in an inactive form �pepsinogen

7. HCL changes pepsinogen to pepsin

8. further protein digestion in S.I.

9. S.I enzyme trypsin only works inbasic pH- pancreatic juices shift basic pH- pancreatic juices shift the pH

F. Fat Digestion & Absorption

1. digested in S. I.

2. bile secreted from liver & stored in gallbladder can digest fats

3. fat digesting enzyme � lipasesecreted from pancreas & secreted from pancreas & intestinal juices splits fats

G. End Results:

1. End products of digestion �A.A, simple sugars, fatty acids and glycerol

2. cells absorb these molecules2. cells absorb these molecules

3. small enough to pass through cells lining the S.I