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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. Order2. Metabolism3. Response to a Stimulus4. Reproduction5. Homeostasis6. Growth and Development7. 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
• 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
7 Characteristics of Life
(5) Response to the environment
(6) Reproduction
• 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
7 Characteristics of Life
(2) Regulation
(3) Growth and development
• 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 Characteristics of Life
(7) Evolutionary adaptation
• 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
Cells
Eukaryotic Cells
• Nucleus• Membrane-bound
organelles• Larger in size• Linear chromosomes
Prokaryotic Cells
• No nucleus• No membrane-bound
organelles• Smaller in size• Circular chromosomes
Differences between Prokaryotic and Eukaryotic Cells
DNA(no nucleus)
Prokaryotic cell
Membrane
Eukaryotic cell
Nucleus(contains DNA)
Organelles
Prokaryotic Cell Structure
External Structures• Pili• Flagellum• Capsule• Cell wall• Cell membrane
Internal Structures• Ribosome• Cytoplasm• Nucleiod• Plasmid• Chromosome
Nucleoid
Ribosomes
Plasma membrane
Cell wall
Capsule
Flagella
Bacterialchromosome
Pili
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
Smooth endoplasmicreticulum
Roughendoplasmicreticulum
CYTOSKELETON:
NUCLEUS:
Nuclear envelope
Chromosomes
Nucleolus
Ribosomes
Golgiapparatus
Plasma membrane
Mitochondrion
Peroxisome
Centriole
Lysosome
Microtubule
Intermediatefilament
Microfilament
Eukaryotic Cell Structure
• Plant cells only– Cell wall– Central vacuole– Chloroplast
Smooth endoplasmicreticulum
Rough endoplasmicreticulum
CYTOSKELETON:
NUCLEUS:
Nuclear envelope
Chromosome
NucleolusRibosomes
Golgiapparatus
Plasma membrane
Mitochondrion
Peroxisome
Cell wall
Central vacuoleMicrotubule
Intermediatefilament
Microfilament
Cell wall ofadjacent cell
Chloroplast
Plasmodesmata