Basic Biological Principles
Characteristics of Life, Cells,
Organization of Life
7 Characteristics of Life
• Living things MUST exhibit these 7
characteristics to be considered living:
1.
2.
3.
4.
5.
6.
7.
Order
Metabolism
Response to a Stimulus
Reproduction
Homeostasis
Growth and Development
Evolutionary Adaptation
7 Characteristics of Life
• Order
– Organized arrangement of parts in a living thing or
group of living things
• Smallest to largest
–
–
–
–
–
–
–
Atom
Molecules
Cell
Tissue
Organ
Organ system
Organism
• Single-celled organisms stop at the cell level and most
multi-celled organisms exhibit all levels
(1) Order
7 Characteristics of Life
• Metabolism
– All of the chemical reactions that take place in an
organism
– Chemical reactions either break down molecules
or build up molecules in the body
– Organisms must be able to perform chemical
reactions
(4) Energy processing
7 Characteristics of Life
• Response to a Stimulus
– Must be able to react to the environment
– Running away from a prey or a plant growing towards
light
• Reproduction
– Produce more of your own kind
– Asexual-only ONE parent and make a genetically
identical clone to the parent
– Sexual-usually more than one parent and make
genetically different offspring from the parents
(5) Response to the environment
(6) Reproduction
7 Characteristics of Life
• Homeostasis
– Maintain stable internal conditions
• Temperature, water, salts, gases and even cell number
– If our temperature increases, humans sweat
– If water levels drop too low, we get thirsty and our
kidneys save water
• Growth and development
– Increase in size and mature/change from embryo
to adult
(2) Regulation
(3) Growth and development
7 Characteristics of Life
• Evolutionary Adaptation
– Ability of an entire species to change genetically
over generations to survive in a changing
environment
– Species that do not adapt will become extinct
(7) Evolutionary adaptation
Cells
• Cells
– Basic unit of structure and function in a living
thing (first level where life appears)
– Two types of cells:
• Prokaryotic cells-cells that do NOT have a nucleus or
membrane-bound organelles
• Eukaryotic cells-cells that HAVE a nucleus and
membrane-bound organelles
Cells
• Cell Size
– Cells are small to be efficient
• Being small allows them to maximize their ability to
exchange nutrients and waste with the environment
• Cells can become larger by:
– Increasing surface area (flat shape and folds in membranes)
– Dividing up labor
• Prokaryotic cells remain small to maintain efficiency
• Eukaryotic cells can be larger because labor is divided
into compartments
Cells
• Similarities between prokaryotic and
eukaryotic cells (every cell has these
structures):
– Cell membranes
– Genetic material (DNA)
– Ribosomes
– Cytoplasm
Differences between Prokaryotic and
Eukaryotic Cells
Prokaryotic Cells
Eukaryotic Cells
• No nucleus
• No membrane-bound
organelles
• Smaller in size
• Circular chromosomes
• Nucleus
• Membrane-bound
organelles
• Larger in size
• Linear chromosomes
Prokaryotic cell
DNA
(no nucleus)
Membrane
Nucleus
(contains DNA)
Organelles
Eukaryotic cell
Prokaryotic Cell Structure
External Structures
• Pili
• Flagellum
• Capsule
• Cell wall
• Cell membrane
Internal Structures
• Ribosome
• Cytoplasm
• Nucleiod
• Plasmid
• Chromosome
Pili
Nucleoid
Ribosomes
Plasma membrane
Bacterial
chromosome
Cell wall
Capsule
Flagella
Eukaryotic Cell Structure (found in
both plant and animal cells)
• Flagellum
• Cilia
• Cell (plasma)
membrane
• Cytoskeleton
• Nucleus
• Nucleolus
•
•
•
•
•
•
•
Endoplasmic reticulum
Golgi apparatus
Lysosome
Mitochondrion
Centrosome
Food vacuole
Vesicle
NUCLEUS:
Nuclear envelope
Smooth endoplasmic
reticulum
Chromosomes
Nucleolus
Rough
endoplasmic
reticulum
Lysosome
Centriole
Peroxisome
CYTOSKELETON:
Microtubule
Intermediate
filament
Microfilament
Ribosomes
Golgi
apparatus
Plasma membrane
Mitochondrion
Eukaryotic Cell Structure
• Plant cells only
– Cell wall
– Central vacuole
– Chloroplast
NUCLEUS:
Nuclear envelope
Chromosome
Rough endoplasmic
reticulum
Ribosomes
Nucleolus
Smooth
endoplasmic
reticulum
Golgi
apparatus
CYTOSKELETON:
Central vacuole
Microtubule
Chloroplast
Cell wall
Intermediate
filament
Plasmodesmata
Microfilament
Mitochondrion
Peroxisome
Plasma membrane
Cell wall of
adjacent cell