1. 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
2. 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)
3. 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)
4. 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
5. 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
7. 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)
8. 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
9. 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
10. 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)
11. 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
12. 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
13. 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)
14. 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
15. 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
16. 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
17. 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
18. 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
19. 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
20. 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
21. 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
