Biology - Chapter 15: Origins of Life

Stromatolites

layered rocks that form when certain prokaryotes bind thin films of sediment together.

our whole universe was in a hot dense state, then nearly 14 billion years ago expansion started, wait.

Stromatolites were the first objects to prove that...

Spontaneous generation

Idea that life arose from inanimate objects. Ex: mud and meat.

Louis Pasteur

Spontaneous generation was proven false in 1862 by this scientist. He concluded that life only forms from other life.

1. Synthesis of abiotic/nonliving organic molecules.

2. Polymerization.

3. Packaging into "protocells".

4. Origins of self-replicating molecules.

4 Steps of the beginning of life.

Protocells

A form of synthesized membrane.

Oparin and Haldane

Two scientists who independently hypothesized that the Earth's early atmosphere with the help of lightning and intense UV light created the first organic molecules.

Miller and Urey

Two scientists that tested Oparin and Haldane's hypothesis by mixing methane, ammonia, and hydrogen gas and gave it energy which created simple carbohydrates.

Electricity

Since lightning couldn't be controlled at the time, what did Miller and Urey use to simulate it?

Volcanic vents on the ocean floor.

A meteorite that carried organic life to Earth.

Two examples of Alternative hypotheses for the origin of life.

RNA

The first life. It served as both basic genes and catalytic molecules.

Short RNA molecules assembled spontaneously from nucleotide monomers.

How was a polymer of RNA made?

RNA monomers adhered to clay.

How was the protocell of RNA made?

Ribozymes

The catalytic molecules that RNA monomers joined to.

Mutations

Variations in RNA that occurred which allowed for natural selection.

It is simplistic and single stranded. It also has the least mutations throughout history compared to the other macromolecules.

Why is it believed that RNA is first life?

Macroevolution

Evolution above the species level. Causes the diversity of life.

Anaerobic prokaryotes - Oxygen in atmosphere - unicellular eukaryotes - multicellular eukaryotes - colonization of land - life today.

Order of the evolution of early life.

Endosymbiotic hypothesis. Created by Margolius.

The hypothesis that states that membraned organelles might have been prokaryotes engulfed by one another to form a eukaryote.

Radiometric dating

Used to measure aging of rocks and fossils. Uses radioisotopes.

Radioisotopes

Isotopes that give off radiation as they decay.

Half-life (T 1/2)

The amount of time it takes for half a sample to decay.

T 1/2 \= 5,730 years.

Carbon-14's half-life.

Classification

The arrangement of organisms into the orderly groups based on their similarities.

Taxonomy

The branch of biology that works with classification.

1. Accurate and uniform names amongst organisms.

2. Prevents misnomers like starfish or killer whale.

3. Uses the same language (Latin or Greek) for all names.

Benefits of classification.

Aristotle

The first taxonomist who divided organisms into plants or animals.

Plants were determined to be herbs, shrubs, and trees by their stem, and animals were determined by location: sea, air, land.

Linnaeus

Father of modern taxonomy who, like Aristotle, classified using observable structures, or morphology.

Binomial nomenclature

The modern naming system of organisms developed by Linnaeus.

Taxon (taxa plural)

A category into which related organisms are placed.

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

The hierarchy of groups of taxa from broadest to the most specific.

Division

Phylum for plants.

Woese

Scientist that added Domain to the hierarchy.

Subspecies

Members of a species that is geologically isolated.

Phylogeny

Evolutionary history of a species or a group of related species.

Phylogenetic tree

A diagram that biologists use to predict the evolutionary relationships of organisms.

-Morphology

-Homologous structures

-Analogous structures

-Embryology

-Molecular Structure

Evidence to infer phylogeny.

Analogous structures

Features with the same function but different structure.

Embryology

Branch of biology that studies embryonic development.

Molecular structure

Structure used to compare DNA and amino acids between species.

Cladistics

Branch of modern taxonomy under systematics that focuses on one branch of phylogeny.

Hennig

Scientist that introduced cladistics.

Clad

A group of related organisms.

Shared or derived characteristics of clads.

The only things studied by cladistics.

Shared characteristics

Common traits to all members of a clad.

Derived characteristics

The unique feature of a species that not all groups have. Causes the branching of new species.

Cladogram

An illustration of how organisms are related based on shared and derived characteristics.

Out-group

The organism on a cladogram that has no shared or derived characteristics with the others. Used as a constant staring point.

Molecular cladistics

Compares amino acid sequences and based on similarities and differences infers relatedness to a common ancestor.

Molecular clock hypothesis

Suggests the greater the differences between the two organisms, the greater the time of divergent from common ancestor.

Fossil records made it possible to assign exact times to when characteristics arose.

What does interpreting fossil records contribute to molecular cladistics? Radiometric dating also helped with this.

Chromosomes can infer relatedness by comparing organisms' karyotypes.

How can chromosomes contribute to molecular cladistics?

Domain

The most inclusive taxon in the modern organism taxon hierarchy.

Archaea, Bacteria, and Eukarya

The three types of domains.

Archaea and Bacteria

The two domains that contain prokaryotes.

Bacteria, Eubacteria

What domain and kingdom do bacteria fall under?

Autotrophs: Photosynthesis and Chemosynthesis

Heterotrophs: causes diseases

The ways bacteria absorb energy (food).

P.m: fatty acids

C.w: peptidoglycan

Composition of the plasma membrane (p.m) and cell wall (c.w) of a bacteria.

Unicellular

Are bacteria multicellular or unicellular?

Archaea, Archaebacteria

What domain and kingdom do archaea fall under?

P.m: hydrocarbons

C.w: no peptidoglycan

Composition of the plasma membrane (p.m) and cell wall (c.w) of an archaea.

Autotrophic: only chemosynthesis

Heterotrophic

The ways archaea absorb energy (food).

Unicellular

Are archaea multicellular or unicellular?

Protista, Fungi, Plantae, and Animalia

The four kingdoms that belong to the Eukarya domain.

P.m: fatty acids

C.w: cellulose

Composition of the plasma membrane (p.m) and cell wall (c.w) of Protista.

Autotrophs: only photosynthesis

Heterotrophs: phagocytosis and absorption

The ways Protista absorb energy (food).

Unicellular and multicellular

Are Protista multicellular or unicellular?

P.m: fatty acids

C.w: chitin

Composition of the plasma membrane (p.m) and cell wall (c.w) of Fungi.

Only heterotrophic by absorption

The ways Fungi absorb energy (food).

Unicellular and multicellular

Are Fungi multicellular or unicellular?

P.m: fatty acids

C.w: cellulose

Composition of the plasma membrane (p.m) and cell wall (c.w) of Plantae.

Only autotrophic by photosynthesis

The ways Plantae absorb energy (food).

Multicellular

Are Plantae multicellular or unicellular?

P.m: fatty acids

Composition of the plasma membrane (p.m) of Animalia.

Only heterotrophic by ingestion

The ways Animalia absorb energy (food).

Multicellular

Are Animalia multicellular or unicellular?

Methanogens

Type of Archean who like sewage treatment plants.

Thermophilies

Types of Archean that like thermal volcanic vents.

Halophiles

Types of Archean that like very salty water.

Hot spring ones

Types of Archean that like hot springs or geysers that have acid.

Systematics

Branch of biology that includes taxonomy and phylogeny.