A2.1 HL only Flashcards
Prebiotic age
hypothetical set of conditions present on the Earth around 3.7 to 4.0 billion years ago
Proto-Earth
encompassing Earth in its first one billion years
Extraplanetary objects
an astronomical object that exists outside the Solar System.
Hadean Eon
the oldest eon and dates from 4.5–4.0 billion years ago. This time represents Earth’s earliest history, during which the planet was characterized by a partially molten surface, volcanism, and asteroid impacts
inorganic molecules
Inorganic molecules are generally simple and are not normally found in living things. Although all organic substances contain carbon , some substances containing carbon, such as diamonds, are considered inorganic
organic molecules
a complex molecule that is primarily made of carbon atoms bonded with other elements and/or other carbon atoms. All living things on Earth are composed of organic molecules
unicellular
composed of a single cell
multicellular
an organism that is made of many cells, such as plants, animals or fungi
organelles
a subcellular structure that has one or more specific jobs to perform in the cell
compartmentalization
the separation of the cell interior in distinct compartments with specific local conditions that allow the simultaneous occurrence of diverse metabolic reactions and processes
Subcellular components
specific structures that take on sets of tasks within the cell, or they can be local regions of the cell defined by the concentration of molecules or distinct physical characteristics and proportions
binary fission
the process of one cell simply dividing into two. It is most commonly used in archaea and bacteria, which are both prokaryotic organisms
mitosis
the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division.
gametes
a reproductive cell of an animal or plant. In animals, female gametes are called ova or egg cells, and male gametes are called sperm
paradox
contradictory-yet-interrelated elements that exist simultaneously and persist over time
proto-cell
self-organized, endogenously ordered, spherical collection of lipidsproposed as a rudimentary precursor to cells
Spontaneous generation theory
hypothetical process by which living organisms develop from nonliving matter
LUCA
the hypothesized common ancestral cell from which thethree domains of life, the Bacteria, the Archaea, and the Eukarya originated
Primordial Soup Theory
if energy is added to the gases that made up Earth’s early atmosphere, the building blocks of life would be created
Polymerization
any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer
Miller-Urey experiment
experimentalsimulationconducted in 1953 that attempted to replicate the conditions ofEarth’s earlyatmosphereandoceansto test whetherorganicmoleculescould be created abiogenically, that is, formed fromchemical reactionsoccurring betweeninorganicmolecules thought to be present at the time
Scientific models
a physical and/or mathematical and/or conceptual representation of a system of ideas, events or processes
Extraplanetary carbon compounds
organic compounds found on meteorites
Panspermia theory
the concept that life may have originated elsewhere in the universe and reached Earth through space travel, potentially by microorganisms or even advanced extraterrestrial beings
Monomers
atoms or small molecules that bond together to form more complex structures such as polymers
Polymers
any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, that are multiples of simpler chemical units called monomers
covalent bonds
a chemical bond that involves the sharing of electrons to form electron pairs between atoms
activation energy
The minimum energy required for a reaction to occur
“RNA World” hypothesis
suggests that life on Earth began with a simple RNA molecule that could copy itself. The RNA world hypothesis suggests that life on Earth began with a simple RNA molecule that could copy itself without help from other molecules
Phospholipids
a group of polar lipids that consist of two fatty acids, a glycerol unit and a phosphate group
Hydrophilic head
phosphate group of a phospholipid
Hydrophobic tails
fatty acid tails of a phospholipid
Micelle
a collection ofamphiphilicsurfactant molecules that spontaneously aggregate in water in a concentration-dependent manner to produce a metastable aggregate
Liposome
a tiny bubbled vesicle made up of similar material to a cell membrane and phospholipids, which are essential to the cell membrane
lipid bilayers
a continuous double layer of lipid molecules in which membrane proteins are embedded
Murchison meteorite
a meteorite that fell in Australia in 1969 near Murchison, Victoria. It belongs to a group of meteorites rich in organic compounds
Ribozymes
catalytically active RNA molecules or RNA–protein complexes, in which solely the RNA provides catalytic activity
Inferred evolutionary intermediate
steps in an evolutionary pathway that are assumed but there is no direct evidence of
Prokaryotes
any organism that lacks a distinct nucleus and other organellesdue to the absence of internal membranes
Bacteria
single-celled microorganisms that lack a nuclear membrane, are metabolically active and divide by binary fission
Archaea
single-celled microorganisms with structure similar to bacteria. They are evolutionarily distinct from bacteria and eukaryotes and form the thirddomain of life
Extremophiles
an organism that thrives inextreme environments. Extremophiles are organisms that live in “extreme environments,” under high pressure and temperature
sedimentary rock
formed from pre-existing rocks or pieces of once-living organisms
isotope
A form of a chemical element in which the atoms have the same number of protons (part of the nucleus of an atom) but with a different number of neutrons (part of the nucleus of an atom)
half-life
The time required for a biological system, such as that of a human, to eliminate, by natural processes, half of the amount of a substance (such as a radioactive material) that has entered it
Biomarkers
A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease
Stromatolites
mineral structures built by microorganisms
Hydrothermal vents
the result of seawater percolating down through fissures in the ocean crust in the vicinity of spreading centers or subduction zones
mutation
a change in a DNA sequence
Carcinogens
a substance, organism or agent capable of causing cancer
Molecular clock
DNA and protein sequences evolve at a rate that is relatively constant over timeand among different organisms
obligate anaerobe
organisms that can grow and survive only in the absence of oxygen
chemoautotroph
an organism that takes inorganic chemicals and transforms it into energy
