Exam #1 Flashcards
What are the different stages of a growth curve model? (population dynamics)
lag phase, exponential phase, stationary phase, death phase
As of January 2024, what is the human population?
8 billion
What is an exponential growth chart?
“J” curve; displays rapid, nonlinear growth
what is a sigmoidal growth chart?
“S” curve; displays growth that eventually levels off, stabilizing due to availability of resources
What are 4 key factors of population growth (explain them)?
birth, death, immigration, emigration
What does N mean in a growth curve?
size of the population
Carrying capacity
max population a particular environment can support
Likely carrying capacity for Earth
ultimately unknown, China and India surpassed 1 billion, not expected that other countries will reach that
How has the annual global growth rate changed over time?
projections show a decline from 1980 - 2100, indicating reduced fertility rates
Replacement Level Fertility (RLF)
the level of fertility at which a couple has enough children to replace themselves; ~2 children per couple (accounting for infant death) - 2.1 to 2.5 children
How has the total fertility rate (TFR) changed?
it is declining, showing that people are having fewer children
Current projections of population
population expected to peak around 10 - 11 billion around 2090, 2084, and then level off and eventually decline
Correlation between poverty, contraception, and education and fertility rates?
high poverty, poor contraception, and minimal education, especially for girls correlates to higher fertility rates; vice vera
Biology
the study of life; study of the living condition
What are the natural sciences?
Physics, Chemistry, and Biology; they all build off of each other/intertwine
How does a population pyramid work?
males on one side, females on the other; shows percentage of ages in a country
wider on the bottom indicates high fertility and rapid growth, smaller on the bottom indicates decline in population growth, about the same shape throughout indicates stable growth
What strategies can control population growth?
universal access to contraception, birth control, and abortion
eradication of gender bias
guaranteed secondary education for everyone (especially girls)
proper sex education for everyone
ending financial rewards for having children (tax reductions)
increasing economic status of general population
shifting age ranges of fertility so that people are having kids when they are older
What does biology try to understand?
How inanimate molecules built a highly ordered and complex interactive system that exhibits emergent properties
Emergent Properties
characterize life within a cell
Aim of modern biology
interpret the properties of living things within the structure of their molecules → large focus on molecular and chemical structure and how that impacts cell functions
Core tenets established by Biology
all life is carbon-based, shares carbon-based chemistry
life NEEDS water to survive
life is capable of self-replication (“spontaneous generation” is false, as life cannot be created from nothing; all cells comes from preexisting cells)
Independent variable
what is being manipulated/changed and applied as a treatment
Framework of Scientific Method
- ask a question/make an observation
- conduct background research on prior literature
- develop a hypothesis
- conduct an experiment under controlled conditions
- record results
- analyze results and data
- conclusion determines if hypothesis was supported or falsified (disproven)
- communicate results to the public (publish) or perish
Dependent variable
what is being measured → want to see how the manipulation of the independent variable impacts the dependent variable; modified by treatment
Control variable
stays the same; does not change, serves as a baseline
Experimental controls
set of experimental conditions where everything is identical except for one variable
Hypothesis
an educated guess; a formal, tentative, testable explanation based on observations and assumptions
Inductive reasoning
specific to general; taking a specific example and applying it to a general idea or theory
hypothetico-deductive model
involves forming a hypothesis that is conceivably falsifiable by a test of observable data, experiments can help one deduce a general answer to hypothesis
Deductive reasoning
general to the specific (if… then logic); taking a broad theory or idea and applying it to a specific case or scenario
What are some ways to present data?
figures, pictures, tables, graphs (bar charts, line graphs), etc.
Ironic Science
non-testable hypothesis that appears scientifically based
examples of ironic science
nuclear winter and a meteor that caused dinosaur extinction
When did Earth form?
around 4.6 billion years ago
nuclear winter
proposed by carl sagan, posited that explosions of nuclear weapons would lead to build-up of soot, smoke, and debris in the atmosphere that would block sunlight, reduce the temperature significantly, and destroy life on Earth
Meteor extinction of dinosaurs
Chicxulub crater; impact crater near Yucatan Peninsula believed to be responsible for mass extinction of ~75% of life on Earth
When does the first evidence of life date back to?
around 3.5 - 3.7 billion years ago
How old is the universe?
13.7 billion years
Common elements for life
carbon, nitrogen, oxygen, hydrogen
Supernova
a collapse of a dying star, releases energy
Light year
distance it takes for light to travel in a year
3 domains
bacteria, archaea, eukarya
hierarchical classification
kingdom, phylum, class, order, family, genus, species
Ribosomes
macromolecular complexes that synthesize biological proteins and have 2 major components: small and large ribosomal subunits, each composed of ribosomal RNA and a number of proteins; found in all prokaryotic and eukaryotic cells → universal organelle
4 kingdoms of eukarya
protista, fungi, animalia, plantae
NASA definition of Life
a self-sustaining chemical system capable of Darwinian evolution
Can we define life?
No, we can only characterize it and identify common traits, because no one definition can apply to all forms of life
Common traits of cells
All cells derived from single, primordial cell
Cells obey laws of thermodynamics; transform energy to perform metabolic processes (cellular respiration produces ATP, photosynthesis produces glucose)
Highly structured and exhibit emergent properties
Cells metabolize: produce metabolic pathways, process nutrients, self-adjust to environment through metabolic regulation
Self-replication: mitosis (cell divides into two identical daughter cells → skin cell producing two identical skin cells) and meiosis (cell division for sexual reproduction, sex cells, produces 4 daughter cells that are not genetically identical but contain 50% DNA from each parent)
Maintain homeostasis
Communicate through molecular and electrical signals
Show animation; are in constant motion → cyclosis deals with assembly/disassembly
Divide, grow, and differentiate to perform different functions
Die
Common characteristics of life
Living things:
contain nucleic acids (DNA and RNA), proteins, carbohydrates, and lipids
are composed of cells
Reproduce
Use energy and raw materials
Respond to stimuli
Maintain homeostasis (biological equilibrium)
Evolve and have adaptive traits
Main elements within the body (and necessary for life)
oxygen (O), carbon (C), hydrogen (H), nitrogen (N)
Other important elements
calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), sulfur (S), chlorine (Cl)
3 potential hypotheses for life
divine creation (supreme being, not scientifically testable)
astrobiological (Big Bang)
chemical evolution (organic molecules came together to form complex compounds)
Cosmology
study of the origin of the universe
Big Bang Theory
universe was created through a massive expansion; began as a small, dense, very hot ball of energy, eventually expanded to create everything
Two major eras of universe
Radiation (dominance of radiation, first element He formed) and Matter (dominance of matter, H formed as universe cooled down)
Nucleosynthesis
elements formed by nuclear fusion
How did stars produce the elements?
Advanced nuclear burning occurs in multiple shells of a star; temp and pressure increase towards center of the star, creating ripe conditions for nuclear fusion (different elements fusing together) depending on distance from core
How do planets form?
accretion and differentiation
Differentiation
geologic process of separating out different constituents of a planetary body, form compositionally distinct layers
Accretion
the coming together and cohesion of matter under the influence of gravitation to form larger bodies; rocks and debris get pulled in, amassing to eventually form a planet
What are two other Earth-like planets?
Gliese 12-b and Jupiter-size exoplanet containing hydrogen sulfide and metal-enriched atmosphere
Why is Earth likely the only planet in the Milky Way that can support life?
“Goldilocks Zone” - not too hot, not too cold, right distance from the sun, contains liquid water
Haven’t found other suitable planets
What do interstellar clouds contain?
carbonaceous compounds formed by solar and cosmic radiation; amino acid tryptophan found (vital for growth and development, helps produce proteins, neurotransmitters, enzymes, and muscles)
PAH
polycyclic aromatic hydrocarbons; organic compounds containing only one carbon and hydrogen ring structure; abundant in universe
Asteroid
mass of rock and astronomic debris that crashes into Earth
Comet
frozen mass of ice and rock
Meteorite
part of an asteroid that breaks off
What has been found in asteroids?
organic molecules for life; amino acids, amines (derivatives of ammonia), carboxyls (functional group)
Which of Saturn’s moons contains organic compounds?
Enceladus; found on hydrothermal vents on the surface
Murchison Meteorite
discovered 1969; contained around 100 amino acids, iron, water, and organic material
Which monomers are essential for life?
amino acids (form proteins), nucleotides (form DNA and RNA), fatty acids, lipids (fats), sugars (provide energy, participate in reactions)
What is believed to be the primordial origin of metabolism?
simple small peptide reaction systems
Oxidoreductases
enzymes that catalyze oxidation reduction reactions
Oxidation reduction reactions
electrons are transferred between atoms; lose electrons, oxidized vs gain electrons, reduced
Why are minerals important for molecules forming larger compounds?
provide scaffolding support; can provide a flat base for concentrating molecules together, allowing for easy assembly; also can provide protection
Feldspar
group of rock-forming aluminum tectosilicate minerals (contain Na, Ca, P, or Ba); compose 60% of Earth’s minerals
microscopic pits may favor concentration by providing protection and cover from external sources (UV radiation and destruction), would concentrate components and create greater reactivity
Magnetite
one of the main iron ore minerals, small grains found in almost all igneous and metamorphic rocks, catalyst for industrial synthesis of ammonia (NH3) by triggering reaction between nitrogen and hydrogen
Clay
layered clay can trap organics between clay sheets, concentrating them; montmorillonite clays can catalyze formation of membranous fluid-filled sacs
Calcite
carbonate mineral, displays selective absorption of D- and L-amino acids
Chirality
2 different configurations that cannot be superimposed (ex: left and right hand); mirror images
Enantiomers
molecules of identical composition, but not superimposable because they are mirror images, exhibit opposite spatial configuration and are known to have different optical activity
Enantiomer Isomer activity
One isomer will rotate plane of polarized light to the right a set number of degrees
Other isomer will rotate plane of polarized light to the left the same set number of degrees
Which form of amino acid is used to make proteins?
L-amino acids; indicates life is homochiral (same amino acid used, not a mixture of D and L)
What are the two optical isomers of amino acids?
D and L - proteins only contain L
Which optical isomer of glucose do cells use?
D-glucose
2 Earth-origin hypotheses of life
hydrothermal vents and land volcanic pools/volcanic landscapes
Hydrothermal vents
provide chemicals and energy for metabolism, supported by dark oxygen (oxygen produced without photosynthesis); found in deep sea
Volcanic landscape
lipid-encapsulated polymers can be synthesized by cycles of hydration and dehydration to form protocells (encapsulated molecules)
Polymerization
formation of polypeptide chains that may have eventually been able to fold and create proteins
Combinatorial Chemistry
complex biological life may be result of similarly long period of random iterations of molecules interacting
Catalytic activity
one RNA molecule recognizes another and catalytically halves it
Ribozyme
RNA molecule w/ enzymatic-like activity; enzymes catalyze chemical reactions
Potential ribozyme activities
Hydrolytic cleavage: adds water, breaks bond
Ligase activity: removes water, forms bond; links RNA nucleotides together
Artificial RNA ligases (synthetically produced) can join two strands of nucleic acid together to form RNA polymers
Assembly and duplication of random RNA
First strand of RNA forms slowly, but once it forms, it can be used as a template to create other complementary strands → much faster process than original strand
Knockout genes technique
Artificially made miRNAs (microRNAs) can be used to silence gene expression → repress protein synthesis by degrading mRNA and thus silencing the gene
Impact of knockout genes
Can create a synthetic genome in which cells are controlled by a chemically synthesized chromosome
Condensation reaction
dehydration synthesis, monomers linked together by removing water molecule
Hydrolytic reaction
hydration synthesis (hydrolysis), bonds between monomers broken by adding a water molecule; releases energy
Cosmic microwave background
immense amount of radiation released from the plasma state expanding, cooling, and converting into neutral gas to form the first atoms; responsible for over 99.999% of radiation in universe
2 theoretical pillars of Big Bang
general relativity and cosmological principle
General relativity
observed gravitational effect between masses results from their warping of spacetime; gravity is a distortion of space and time itself
Cosmological principle
on a large scale, the universe is both homogenous and isotropic; relatively uniform
LUCA
last universal common ancestor; estimated to have lived ~4.2 bya; likely anaerobic acetogen, may have had cellular immunity
evidence for common ancestor
universal genetic code, shared chirality of 20 amino acids, use of ATP as common energy source, common machinery for protein synthesis
5 steps of volcanic landscape theory
- synthesis of biomolecules
- organic compounds in volcanic hydrothermal pools concentrate biomolecules
- polymerization of amino acids
- lipids form protocell-like entities
- metabolic reactions occur
