Gen Bio 3rd Quarter

Genetically modified organism (GMO)

an organism whose DNA has been altered through genetic engineering. In this instance, the bacterium has been modified to incorporate a human gene responsible for insulin production, thereby classifying it as a GMO."

Gene Cloning Steps

1. Isolation of desired gene - First, the gene of interest is isolated.
2. Insertion of isolated gene into the vector- The gene is then inserted into a vector (like a plasmid) to carry it into the host.
3. Introduction of recombinant vector to the host - The recombinant vector is introduced into the host organism (e.g., bacteria).
4. Expression of recombinant gene in host - The host organism expresses the recombinant gene.
5. Extraction of recombinant gene product - Finally, the gene product (like a protein) is extracted from the host.

Gene gun

a device used to transfer genetic material (such as DNA) into cells, particularly eukaryotic cells, by shooting microscopic particles coated with the DNA into the cells.

Golden rice

a genetically modified organism (GMO) that has been engineered to produce vitamin A (in the form of beta-carotene) in its grains. This was achieved through genetic modification, where genes responsible for producing the vitamin were inserted into the rice genome.

Cambrian Explosion

an evolutionary event that occurred approximately 541 million years ago, during which there was a rapid increase in the diversity of animal life. Many major animal phyla appeared during this relatively short geological period, marking a significant milestone in the history of life on Earth.

Mutation

a change in the DNA sequence of an organism's genome. These changes can occur due to errors in DNA replication, exposure to radiation, chemicals, or viruses. Mutations can be beneficial, harmful, or neutral and are a key driver of genetic variation and evolution.

Geologic time scale

Epoch - The smallest unit of geologic time.
Period - A longer timespan that includes multiple epochs.
Era - A larger division that includes multiple periods.
Eon - The largest division of geologic time, encompassing multiple eras.

Natural Selection

The process by which individuals with advantageous traits are more likely to survive and reproduce, passing those traits to future generations, while less adapted individuals may not survive as effectively.

Speciation

the process by which new species arise. The best measure of this process is reproductive success, which refers to the ability of individuals to survive and produce fertile offspring.

Example of Natural Selection

On a small Galapagos Island, a species of finch was studied over many generations. Some finches inherited stronger, thicker beaks that allowed them to crack tough seeds during a drought. These finches survived and reproduced, while others with smaller, weaker beaks struggled to find food and their populations declined. Over time, the population of finches with strong beaks increased, demonstrating natural selection.

Geographic isolation

occurs when a population of a species is physically separated by a barrier (such as lakes, mountains, or distance), preventing gene flow between groups. Over time, these isolated populations experience different selective pressures and genetic changes, leading to the formation of new species through the process of allopatric speciation.

Earth's catastrophic changes

Earth has experienced multiple mass extinctions due to catastrophic events like asteroid impacts, volcanic eruptions, and climate shifts. However, life continued because biodiversity provided resilience.

Having a wide variety of species increases the likelihood that some organisms can survive and adapt to new environmental conditions. This ensures that ecosystems can recover and evolve over time, even after major disasters.

Gene flow

the transfer of genetic material (alleles) between populations. In this case, pollen from purple flowers is reaching the yellow flowers across the river, introducing new genetic material into the population. This can increase genetic diversity and potentially lead to evolutionary changes over time.

Gene flow is an important mechanism in evolution because it helps prevent populations from becoming too genetically distinct, reducing the chances of inbreeding and increasing adaptability

Thomas Malthus

wrote about how populations tend to grow exponentially but are ultimately limited by factors like disease, competition, and limited resources (such as food). Darwin was inspired by this concept and applied it to his theory of natural selection. He recognized that in a struggle for survival, only individuals with advantageous traits would be more likely to survive, reproduce, and pass on those traits to the next generation. This idea of limited resources and competition was a key factor in Darwin's formulation of how evolution works.

Dolly the sheep

was the first mammal to be cloned using somatic cell nuclear transfer. This process involved taking a somatic (body) cell from a donor sheep, removing its nucleus, and inserting it into an egg cell from another sheep. The egg's nucleus was then replaced with the donor cell's diploid nucleus, making Dolly's genotype identical to that of the donor sheep's somatic cells.

James Hutton

Known for his theory of gradualism, which suggests that geological changes occur slowly over long periods of time, shaping the Earth in a gradual manner rather than through sudden, catastrophic events.

Ecological isolation

occurs when species live in the same geographic area (range) but occupy different habitats and therefore do not interact or breed with each other.
For example, two bird species might live in the same forest, but one prefers the canopy, while the other lives on the forest floor. Even though they share a range, their habitat preferences prevent interbreeding, leading to isolation.

Charles Lyell

Associated with uniformitarianism, the idea that geological processes occurring today have been constant over Earth's history.

Jean-Baptiste Lamarck

Proposed the theory of inheritance of acquired characteristics, suggesting that organisms could pass traits acquired during their lifetime to their offspring.

Biological species concept

proposed by Ernst Mayr, defines a species as a group of organisms that can interbreed and produce viable, fertile offspring under natural conditions.

Scientific name

Made up of two parts: the genus (the first part) and the species (the second part).

EXAMPLE: Arenicola cristata and Arenicola marina share the same genus name (Arenicola), which means they are more closely related to each other than to animals in different genera.

Alfred Russel Wallace

Known for independently conceiving the theory of evolution by natural selection, contributing significantly alongside Charles Darwin. Wallace is not associated with uniformitarianism.

Pre-zygotic barriers

mechanisms that prevent fertilization from occurring in the first place, often through behavioral, mechanical, or gametic isolation, such as the sperm not being able to recognize or bind with the egg of a different species.

Antibiotic resistance

in bacteria is a clear and observable example of natural selection within a short time frame. Bacteria can rapidly evolve resistance to antibiotics due to mutations and the selective pressure created by the use of antibiotics. These resistant bacteria survive and reproduce, passing on their resistant traits to future generations.

Bindin protein

Plays a role in sperm-egg recognition before fertilization occurs.

Charles Darwin

During his voyage on the HMS Beagle, Charles Darwin observed that organisms had traits that were well-suited to their environments. These adaptive characteristics helped them survive and reproduce in specific habitats. This observation laid the foundation for his theory of natural selection, where individuals with advantageous traits are more likely to survive and pass those traits on to future generations.

Homologous structures

are anatomical features that are similar in different species because they were inherited from a common ancestor.

EXAMPLE:
The flipper of a cetacean (like a whale or dolphin) and the wing of a bird are both modified forelimbs with similar bone structures, indicating they share a common evolutionary origin. This makes them homologous.

Allopatric speciation

focuses on geographical isolation as the primary driver for the divergence of populations. Over time, these isolated populations adapt to different environments, leading to changes in traits and eventually reproductive isolation as a by-product of these adaptations.

Evidence for evolution

Scientists use multiple lines of evidence for evolution, including fossil records, genetic similarities, and experimental tests. However, the functional similarity between insect wings and bird wings is an example of analogous structures, not homologous ones.

Organisms that are more closely related

share a more recent common ancestor

Organisms that are more closely related share a more recent common ancestor

Mushroom and tree: Fungi (mushrooms) and plants (trees) are both eukaryotic organisms. Interestingly, fungi are actually more closely related to animals than to plants, but a tree (plant) is still closer to a mushroom than bacteria or tapeworms

Biogeography

The study of how species are distributed across different geographical locations and how their evolution is influenced by their environment

Vertebrate embryos

The similarity in early embryonic development among vertebrates, such as the presence of tails and gill slits in fish, turtles, chickens, mice, and humans, suggests that these species share a common evolutionary ancestor. The genes responsible for the development of these features are likely inherited from this ancestor. Over time, these features may be modified or become vestigial, but the presence of similar embryonic stages across these diverse vertebrates provides evidence of common ancestry and the retention of genetic instructions from that ancestor.

Cave fish

evolved from ancestors that had functional eyes, but because they live in total darkness, eyes became useless and eventually lost their function.

Directional selection

occurs when environmental conditions favor individuals at one extreme of a trait distribution. This causes the population's trait distribution to shift toward that extreme over time.

Similar DNA sequences

While fossils, body structures, and embryological similarities all provide strong evidence for evolution, DNA sequence similarity is the strongest evidence for a common ancestor.

Homologous structures

are anatomical features that share a similar structure but may have different functions, indicating that they were inherited from a common ancestor.

Species

In biological classification, the species is considered the basic unit or the smallest taxon. It represents a group of organisms that can interbreed and produce viable, fertile offspring under natural conditions.

Modification of habitats

can lead to species being unable to find food, shelter, or mates, causing population declines and extinctions.

taxonomic hierarchy

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Phylogenetic tree

is a diagram that shows the evolutionary relationships among various species or groups based on their shared common ancestors. The base of the tree represents the most recent common ancestor of all taxa depicted.

Binomial nomenclature

is the system of naming organisms developed by Carl Linnaeus. It gives each organism a two-part name (Genus and species), such as Homo sapiens for humans.