6 Characteristics of Living Things

• Made up of cells

• Reproduce (sexually or asexually)

• Have DNA (genetic code)

• Grow and develop

• Metabolism -Use materials and energy

• Respond to stimuli

Cont.

• Homeostasis – maintain a stable internal environment

• All living things are carbon based – organic compounds

• Carbon is the most diverse element and can form millions of compounds

• Macromolecules-giant molecules formed from monomers (smaller molecules) that form polymers (larger molecules)

Four groups of Organic Compounds

• Carbohydrates – (carbon-hydrogen-oxygen) in a 1:2:1 ratio (C6H12O6)

• Carbohydrates are the main source of energy for living things

• Carbohydrates are sugars that break down for immediate energy and the balance is stored as starch (monomer is sugar, polymer is starch)

Cont.

• Lipids – mostly carbon and hydrogen• Common lipids are fats (solid), oils (liquid) and waxes• Lipids are made of glycerol and fatty acid molecule chains

• The molecule chain determines saturated (solids) or unsaturated fats

Cont.

• Nucleic acids – contain hydrogen, oxygen, nitrogen, carbon, phosphorus

• Formed from monomers called nucleotides: 3 parts– 5-carbon sugar– Phosphate group– Nitrogenous base

• Sugar, base, phosphate group

Cont.

Cont.

• Nucleic acids store and transmit genetic information (the blue print of life)

• DNA-deoxyribonucleic acid (contains sugar group deoxyribose)

• RNA-ribonucleic acid (contains sugar group ribose)

Cont.

• Proteins-macromolecules made of nitrogen, carbon, hydrogen, oxygen

• Polymers of molecules called amino acids (monomers)

• Contain an amino groups (NH2-) and a carboxyl group (-COOH) at each end with an R-group in the middle

• The R-group determines the amino acids

Cont.

• Some acidic some are basic

• Instructions for arranging amino acids into different proteins is stored in DNA

• Each protein has a specific role in an organism

Chemistry of Life

• All living things are constantly undergoing chemical reactions

• Reactions always involve the breaking and making of new bonds

• All reactions involve a reactant and a product

• CO2 + H2O → H2CO3 (CO2 is taken up)

• H2CO3 → CO2 + H2O (CO2 is released)

Cont.• Some reactions release energy

(exothermic) (spontaneously)• Some absorb energy (endothermic)

(requires energy to complete)• Importance of this: all living things must

have a source of energy to allow for chemical reactions to take place(metabolism)

• Activation energy-minimum energy need to start a reaction

Enzymes

• Catalyst-speeds up a reaction

• In living things, some reactions are very slow or require extreme energy to happen, catalyst work to lower the activation energy need for the reaction

• Enzymes are proteins that act as biological catalysts

Cont.• CO2 + H2O → H2CO3 (carbonic acid)

• Very slow reaction that by itself would allow CO2 to build up in bloodstream

• Bloodstream contains an enzyme called carbonic anhydrase that speeds the reaction by a factor of 10 million

• Enzymes are very specific only catalyzing one type of reaction (in name of enzyme that catalyzes a specific reaction)

Viruses

• Viruses are not living organisms, do not contain all of the 6 requirements of living things (cannot reproduce)

• Contain a core DNA or RNA surrounded by a protein coat (capsid)

• Highly specific to a particular type of cell• Plant virus infects plants, bacteria virus

infects bacteria and animal virus infects animal

Cont.

• 4 shapes of virus: spacecraft, spheres, crystals, cylinders

• Lytic infection – virus enters cell, makes copies of self, and cell bursts spreading the virus

• Lysogenic infection – virus integrates DNA into the host DNA and viral genetic material replicates along with host cell’s DNA

Cont.

• Viruses can lay dormant for many generations, however, it will eventually become active

• Retrovirus – produce a DNA copy of their RNA (backward)

• AIDS is a retrovirus• Viruses were not the first living organisms,

however, have been around for billions of years

Bacteria

• Prokaryotes – single-celled organisms lacking a nucleus (commonly referred to as bacteria)

• Monera divided into eubacteria and archaebacteria

• Identified by shape, chemical nature of cell walls, movement and how they obtain energy

Shapes

• bacilli – rod shaped• Cocci – spherical• Spirilla – spiral• Bacteria can be heterotrophs or autotrophs• Reproduction:• Binary fission (divides in half)• Conjugation – genetic material is exchange by

way of “bridge” between two cells• Spore formation – structure of stored genetic

material which will germinate when conditions are right

Importance of bacteria

• Necessary to maintaining life:

• Nitrogen fixation – converting nitrogen into usable material (plants)

• Humans – contain trillions of bacteria good and bad (outnumber cells 10:1) most found in intestines; digestion, removal of waste

Germ Theory

• Disease – produced by agents: bacteria, viruses, fungi – environmental, genetic

• Pathogen – any disease causing agent

• Late 1800’s Louis Pasteur and Robert Koch theorized that diseases were caused by germs

Koch’s Postulate

• 1. pathogen should always be found in the body of a sick organism and not in healthy organism

• 2. pathogen must be isolated and grown in controlled environment (lab) in pure culture

• 3. when cultured pathogens are place in new host, should cause the same disease as the original host

• 4. injected pathogen should be isolated from second host and should be identical to the original pathogen

Agents of disease

• Virus – flu, polio, HIV, smallpox, warts

Bacteria – anthrax, streptococcus, botulism, diphtheria

Protists – malaria, typanosoma (African sleeping sickness), dysentery

Worms – tapeworm, hook worm,

Spread

• Physical contact (STD) or by indirect contact (sneeze)

• Food or water – contaminated source (cholera)

• Infected animals – vectors (carrier), rabies, Lyme disease, West Nile

• pigs, cows, birds

Prevention and treatment

• Vaccinations – MMR, polio, flu

• Antibotics – kill bacteria but don’t damage cells: – penicillin (accident), Cipro, vancomycin – do not effect viruses

• Antivirals – inhibit the ability of viruses to invade cells and multiply