UNIT 1 QUIZ 2 CELL THEORY

Three Unifying Theories of Biology

cell theory genetic theory, theory of evolution. Form the foundation of biology. Do not exist or function independently, rather interact with + influence one another, allowing life to exist

Cell Theory

a three component theory (developed between 1839 and 1858)

First Component of Cell Theory

All living organisms are composed of one or more cells

Second Component of Cell Theory

Cells are the fundamental unit of structure, function, and organization in living organisms

Third Component of Cell Theory

Cells arise only from pre-existing cells

Current (modern) interpretations of Cell theory

include three additional components

4th Component of Cell Theory (current interpretation)

cells contain genetic material DNA and RNA that is passed to new generations of cells through cell division

5th Component of Cell Theory (current interpretation)

all cells essentially same in chemical composition

6th Component of Cell Theory (current interpretation)

metabolism (transfer of energy from chemical bonds of molecules into form that cells can use, ATP) and biochemistry (chemical reactions that sustain life) utilized by living organisms occur only within cells

Genetic Theory (1865-1915)

Using mathematical analysis of offspring of pea plants. Gregor Mendel was able to deduce principles that explain patterns of inheritance (1865). Both Mendel and Darwin independently recognized that:

1 of Genetic Theory

There had to be a “factor” (genes) that determined traits and characteristics

2 of Genetic Theory

These factors (genes) could be passed from parents to offspring

3 of Genetic Theory

These factors (genes) could vary

4 of Genetic Theory

Chromosomes transfer genes from parents to offspring

Genetic Theory additional

Mendel and Darwin predicted existence of genes decades before DNA was isolated. 1915, Thomas Hunt Morgan demonstrated genes carried on chromosomes (chromosome theory of inheritance). These 4 concepts form foundation of genetics

Theory of Evolution (Darwin, 1859)

A five component sequential theory that provides scientific mechanism and explanation for how life evolved from a common ancestor

1st Component of Theory of Evolution - Common Descent

all life arose from single common ancestor that gave rise to ALL life seen today

2nd Component of Theory of Evolution - Variation

individuals within population differ from one another. It is now known these variations are result of random mutations in DNA

3rd Component of Theory of Evolution - Natural Selection/Adaptation

Some variations (mutations) more beneficial in particular environment than others. Individuals possessing beneficial variations more likely to survive in that environment. Those individuals that survive more likely to reproduce and pass their favorable variations (from mutations) on to future generations. This component is highly dependent on environment; a mutation that is beneficial in one environment may be detrimental or even fatal in another.

4th Component of Theory of Evolution - Survival of the Fittest

species produce far more offspring than necessary to maintain the population. Therefore, only individuals that are most fit, and those fortunate enough to survive until reproduction, are likely to reproduce and pass their favorable variations to next generation.

5th Component of Theory of Evolution - Speciation

over thousands of generations (often millions of years), adaptations accumulate within population. As these adaptations accumulate, population gradually changes until it becomes new species. This process is known as speciation.

Integration of the Unifying Theories

Cell theory integrated with Genetic Theory because cells contain genetic material (DNA and RNA) and utilize that genetic information during protein synthesis. Cell Theory also integrated with Theory of Evolution because cells are most basic unit capable of evolving. Theory of Evolution integrated with Genetic Theory because genetic explains what genes are and why different genes (alleles) exist for specific characteristics. This genetic variation provides raw material upon which natural selection acts and is foundation of evolution. 

Population

all of organisms of single species within specific geographical area (environment)

Community

consists of all populations of different species within environment (aquatic, terrestrial, atmospheric, etc.)

Ecosystem

examines relationships among all communities within specifical geographic region (valley, forest, field, etc.)

Biosphere

the sum of all ecosystems on Earth. This is most complex level of ecological organization.