Biology - Exam 1

Biology

The study of life

How can you differentiate living and non-living things?

By using the principles of biology

10 Principles of Biology

1. Cells are the simplest unit of life
2. All organisms require energy from their environment
3. All organisms interact with their environment
4. Although life is a dynamic process, all organisms maintain relatively stable internal conditions
5. All organism change during their lifespan
6. All living organisms have genetic material composed of DNA
7. All living organisms evolve from one generation to the next
8. All organisms at some point share a common ancestor
9. Structure determines function
10. Emergent properties arise from the interaction of smaller components or from the interaction with the environment

What are the levels of organization?

Atoms, molecules and macromolecules, cells, tissues, organs, organism, population, community,
ecosystem, and biosphere

What is vertical descent?

The progression of changes in a lineage. New species evolve from pre existing species by accumulation of heritable changes in their genetic code defined as Mutations. Natural selection takes advantage of beneficial mutations.

What is horizontal gene transfer?

Horizontal gene transfer is genetic exchange between different species, not directly from a shared ancestor. It is rare and more common in bacteria and mostly occurred at the beginning of life on Earth.

What are the three domains of life?

Bacteria, Eukarya, Archaea

What is science?

It's the observation, identification, experimental investigation and theoretical explanation of natural phenomena.

What is discovery-based science?

A scientific methodology which aims to find new patterns, correlations, and form hypotheses through the analysis of large-scale experimental data.

What is hypothesis-driven research?

One of the main methods for using data to test and, ultimately, prove (or disprove) assertions. To do that, researchers collect a sufficient amount of data on the subject and then approach it with a specific hypothesis in mind.

Which types of data are used by scientists?

Qualitative data
Quantitative data

What is a hypothesis?

A proposed explanation for a natural phenomenon.

What is a theory?

A broad explanation of some aspect of the natural world that is substantiated by a large body of evidence.

Hypothesis vs. Theory

Theory allows you to make correct predictions, hypothesis allows you to make predictions that can be right or wrong.

What is the age of our planet?

4.5 billion years old

What is the age of the universe?

13.7 billion years old

When did life start?

3.5-3.8 billion years ago.

What evidence do we have for when life started?

Fossil Prokaryote and
Modern cyanobacteria.

What are the 4 stages that gave rise to life?

Stage 1 - Production of nucleotides and amino acids
Stage 2 - Polymerization
Stage 3 - Polymers became enclosed in membranes
Stage 4 - Polymers enclosed in membranes acquired cellular properties

What are the hypotheses that explain where and how organic molecules originated?

Extraterrestrial source
Reducing atmosphere
Deep sea vents

What is the Miller-Urey experiment?

A simulation of conditions on the early Earth testing the
idea that life, or more specifically organic molecules, could have formed by nothing
more than simple chemical reactions.

What is the panspermia hypothesis?

he theory that life on the earth originated from microorganisms or chemical precursors of life present in outer space and able to initiate life on reaching a suitable environment.

What is the sea-vent hypothesis?

By creating protocells in hot, alkaline seawater, a UCL-led research team has added to evidence that the origin of life could have been in deep-sea hydrothermal vents rather than shallow pools.

What are protobionts?

Self-organized, spherical collection of polymers and macromolecules within a membrane, proposed as a stepping-stone toward the origin of life.

What are the characteristics of protobionts?

1. Boundary (e.g., membrane) separated external environment from internal contents
2. Polymers that contained information
3. Polymers that had enzymatic functions
4. Protobionts capable of self-replication

What is the RNA world?

An early Earth period when both information and catalytic activities
were done only by RNA

RNA vs. DNA vs. Proteins

DNA contains the information necessary for encoding proteins, although it does not produce proteins directly. RNA carries the information from the DNA and transforms that information into proteins that perform most cellular functions.

What is chemical selection?

In this process, a chemical within a mixture has an advantage that results in an increase in its number in comparison to other chemicals in the mixture.
First, polymers of RNA acquired auto-replication properties using one RNA molecule as template
Then, polymers of RNA acquired catalytic properties to synthesize ribonucleotides (building blocks) of RNA. This results in an RNA world.

What are fossils?

preserved remains of past life on Earth. Examples: Bones, shells, leaves, amber

Who studies fossils?

Paleontologists

What is radiometric dating?

This method uses the decay rate of radioactive material to date objects.

Why is the fossil record incomplete?

Because few individuals have fossilized, and even fewer have been discovered.

What is continental drift?

the gradual movement of the continents across the earth's surface through geological time.

Are we in the midst of a 6th mass extinction?

Yes

What is systematics?

The study of biological diversity and the evolutionary relationships among organisms, both extinct and modern.

What is taxonomy?

The science of describing, naming, and classifying living (extant) and extinct organisms and viruses

What is the most significant contribution of Carolus Linnaeus?

The publication of a system of taxonomy based on resemblances and similarities

How can we name a species?

The first letter of the genus is capitalized, and the entire species name is italicized
Both parts together name the species (not only the specific epithet). This binomial name
is used by convention when talking about the same species

What are the taxonomic levels?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

What is a phylogenetic tree?

A simple diagram that depicts the origin and evolution of a group of species.

How are phylogenetic trees inferred?

Morphology and molecular data

What is evolution?

Heritable change in one or more characteristics of a population from one generation to the next

What is microevolution?

Changes in a single gene in a population over time

What is macroevolution?

Evolutionary changes that result in the formation of new species.

What was the early thinking about evolution before Darwin?

Classifications were made by many different people including Aristotle

What is catastrophism?

The belief that the Earth's past geological changes were caused by sudden, violent changes in the Earth's surface.

What is uniformitarianism?

The belief that the Earth's past geological changes can be fully explained by current processes.

What was Thomas Malthus' insight about population growth?

Human population might grow in size, at best, linearly (i.e., one to one). However, human's reproductive potential is exponential (i.e., can double each cycle of reproduction)

What is variation?

Differences in the characteristics of individuals in a population

What is natural selection?

the process through which populations of living organisms adapt and change.

What is artificial selection?

modifying other species by selecting and breeding individuals with desired traits

What are the 5 most important inferences of Darwin's book: On the Origin of Species?

Inference 1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment, tend to leave more offspring than other individuals
Inference 2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations
Inference 3: Natural selection increases the adaptation of organisms to their environment over time
Inference 4: If an environment changes, natural selection may result in the adaptation of these populations to these new conditions and may give rise to new species
Inference 5: Complex structures such as eyes, wings and intelligence can emerge from the accumulation of small changes through natural selection

How is it possible that. complex traits, like eyes, evolve in natural systems?

Traits are passed down, we don't all have the same vision or eye shape, but overtime it can change

What is homology?

similarity resulting from common ancestry

What is the smallest unit of evolution?

A population

What is a gene pool?

all the alleles in a population

What are alleles?

Different forms of a gene

Monomorphic

Predominately single allele

Polymorphic

two or more alleles

What is the nomenclature of alleles?

A capital letter, a subscript, allele is a combination of both.

Homozygous

The presence of two identical alleles at a particular gene locus. A homozygous
genotype may include two normal alleles or two alleles that have the same variant.

Heterozygous

Having two different alleles of a particular gene or genes.

What are single nucleotide polymorphisms (SNPs)?

Smallest type of genetic change in a gene

What is the Hardy-Weinberg equilibrium equation?

A mathematical function that describes the relationship between allele frequencies and genotype frequencies.
p^2 + 2pq + q^2 \= 1
p \= dominant, q \= recessive

What are the conditions to maintain the predications under the. Hardy-Weinberg equilibrium equation?

The population is not evolving.
The population has random mating.
The population does not go through natural selection.

What are random mutations?

Changes in the genetic code that are responsible for the variety of life

What is gene duplication?

multiple copies of the same gene