Gateway High school biology EOC review

THEORY OF EVOLUTION

-Proposed by Charles Darwin.

-Process by which organism that are best suited to environment survive and pass genetic traits on to offspring.

Adaption - organism with the most suited traits will survive.

Evolution - Change in a species over time (not a single individual, but the group)

EVIDENCE OF EVOLUTION:

Fossils - May appear in rocks, ice, and amber; when fossils are arranged in order of their age, the fossil record provides a series of changes that occurred over time; comparison of anatomical characteristics reveals shared ancestry/common ancestry.

Molecular Biology - Comparing DNA/gene or protein sequences from organisms (closely-related organisms will have similar DNA, RNA, and Protein (amino acid) sequences). This also gives evidence of a common ancestor.

Embryology - Embryos of different vertebrates look alike in their early stages, giving the superficial appearance of a relationship.

Comparative Anatomy - Homologous structures - structures (body parts/anatomy) which are similar in different species because the species have common descent. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales. Vestigial structures are anatomical features that are still present in an organism (although often reduced in size) even though they no longer serve a function. Whales, which evolved from land mammals, have vestigial hind leg bones in their bodies.

Biogeography - patterns of past evolution are found in the natural geographic distribution of related species, similarity of endemic island species to nearby mainland species.


The traits that help an organism survive in a particular environment are “selected” in natural selection. Overtime, natural selection results in changes i n the inherited characteristics of a population. These changes increase species fitness (survival rate)

Conditions required for natural selection:

There is variation in traits.

For example, some beetles are green and some are brown.

There is differential reproduction.

Since the environment cant support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown (camouflage with the bark of trees) beetles do.

There is heredity.

The surviving brown beetles have brown baby beetles because this trait has genetic basis.

End result

The advantageous trait, brown coloration, which allows th beetle to have mor offspring, becomes more common in the population. Eventually, all individuals in the population will be brown.

Hominids are the family or organisms that includes humans

Trends in Hominid Evolution:

  • Bipedalism (walk on two legs)

  • Increase in brains size

  • Smaller teeth and jaw

  • Tool usage

  • Langugae development

Mechanisms of Evolutionary Change

  • Mutation is the change in DNA. Since all cells in our body contain DNA, there are lots of places for mutation to occur; However, not all mutations matter for evolution. Somatic mutations occur in non-reproductive cells and wont be passed onto offspring only those in germ cells/Gametes.

  • Gene flow/migration is any movement of genes from one population to another. Gene flow includes lots of different kinds of events. such as pollen being blowen to a new destination or people moving to new cities or countries. If genes are carried to a population where those genes previously did not exist, gene flow can be a very important source of genetic variation which could potentially lead tot he evolution of the species in that population.

  • Genetic drift along with natural selection, mutation, and migration - is one of the basic mechanisms of evolution. In each generation, some individuals may, just by chance, eave behind a few more descendants (and genes, of course!) Than other individuals. The genes of the next generation will be the genes of the “lucky” individual, not necessarily the healthier or “better” individuals.

  • Nonrandom mating mating that has not occurred due to chance (arranged marriages) - sexual selection

  • Natural selction

Conditions contributing to the origin of life on Earht:

  • Presence of liquid water

  • Moderate temperature

  • Free oxygen

  • Sunlight

  • Formation of the ozone layer using oxygen

  • Absence of toxin from the atmospere

  • Absence of radiation]

Scientific Explanation of the Origin of Life

  1. Simple organic molecules were formed (primordial soup)

  2. Replicating molecules evolved and began to undergo natural selection.

  3. Replicating molecules became enclosed within the cell membrane

  4. Formation of prokaryote. some cells began to evolve modern metabolic processes and out-competed those with older forms of metabolism (endosymbiotic theory)

  5. Multicellularity evolved.

Miller/Urey Experiment showed that amino acids (organic molecules) could be formed from matter present on early Earth (inorganic molecules: ammonia, hydrogen)

Endosymbiotic Theory states tat several key organelles of eukaryotes originated as symbiosis between separate single-celled prokaryotic organism.

Origin of Life on Earth

Chemical Evolution - Inorganic meolecules formed coplex organic molecules(building blocks of life)

Biological Evolution - Prokaryotes engulfed each other to for eukaryotes.

Classification:

-Process in understanding how organisms are related and how they are different.

-It also follows the evolutionary trends.

-Taxonomy - branch of biology that studies grouping and naming of organisms.

History of classification systems-

- early 1700s, Carolus Linnaeus developed a system based on physical characteristics; two kingdom (plants and animals)

- developed “genus” and “species”

- designed system of naming called binomial nomenclature "(“two names”) which gave each organism two names, a genus and a specie, Genus always capitalized, both should be underlined or italicized.

- One of the new reasons why species are being reevaluated is because DNA analysis. Basic genetic analysis information can change our ideas of how closely two species are related and so their classification can change.

Organisms are classified into three domains and into one of six Kingdoms of life. Organisms are placed into these categories based on similarities or common characteristics. Some of the characteristics that are used to determine placement are cell type, metabolism, and reproduction.

Domain: archaea, bacteria and Eukarya.

Six kingdoms: Archaea/Archaebacteria, bacteria/Eubacteria, Protista, Fungi, Plantae, and Animalia.

Levels Of Classification:

- Kingdom

- Phylum

- Class

- Order

-Family

- Genus

- Species

Classification of humans:

Kingdom: Animalia (multicellular organisms that eat food

Phylum: Chordata (dorsal hollow nerve cord, notochord, pharyngeal slits)

Class: Mammalia (hair, mammary glands, endothermic, and four-chambered hear)

Order: Primates (nails, clavicle, orbits encircled with bone, enlarged cerebrum, and opposable digits)

Family: Homidae (bipedal - walk erect on two feet, advanced tool use)

Genus: Homo (“human” like)

Autotrophs- are organisms that can produce their own food from the substances available in their surroundings using light (“Photosynthesis”) or chemical energy (chemosynthesis); producers.

Heterotrophs- are organisms that cannot produce their own food and rely on other organisms for energy/food; consumers.