Module 1: Introduction to Biology Flashcards
What are the 10 steps of the scientific method?
- Observation
- Question
- Hypothesis
- Null hypothesis
- Prediction
- Methods (includes establishing a control)
- Results
- Discussion
- Conclusions
- Future work
What are the 6 characteristics that distinguish living from non-living things?
- They have a structure that is ordered (they are not just random collections of matter).
- They can reproduce.
- They can grow and develop.
- They can maintain a consistent internal environment (Homeostasis).
- They can respond to changes in the environment (through long-term evolutionary or short-term environmental changes).
- They require energy.
Robert Hook
Anton van Leeuwenhoek
Robert Brown
MJ Schleiden
Theodor Schwann
Robert Hook: English scientist who first penned the term “cells.”
-His microscopes used light and 2 lenses.
Anton van Leeuwenhoek: Dutch lens maker who was the first person to describe bacteria.
-His microscopes used light and 1 lens.
Robert Brown: Scottish botanist who was the first to describe a cell’s nucleus.
MJ Schleiden: German scientist who described the nucleus as the most important part of plant cells.
Theodor Schwann: German scientist who published the “Cell Theory.”
What are the 3 basic ideas of the Cell Theory?
- All living organisms are made up of one or more cells.
- The cell is the basic organizational unit of life.
- All cells come from other cells.
Organism
A living entity made up on one or more cells.
Which 3 ideas laid the groundwork for modern biology?
- The cell theory
- The theory of evolution
- The chromosome theory of inheritance
Theory
An explanation for a very general class of phenomena or observations that is supported by a wide body of evidence.
Null hypothesis
Specifies what the results of an experiment will be if the main hypothesis being tested is wrong.
Often states that there will be no difference between experimental groups.
Rudolf Virchow
German scientist who proposed that all cells arise from cells already in existence.
Spontaneous generation
Prior to the cell theory, the explanation that cells could arise spontaneously under certain conditions.
Hypothesis
A testable statement to explain a phenomenon or a set of observations.
A theory serves as a framework for developing new hypotheses.
Experimental prediction
Describes a measurable or observable result that must be correct if a hypothesis is valid.
Louis Pasteur
French scientist who used experiments to test the cell theory.
His experiment proved the all-cells-from-cells hypothesis.
Chemical evolution
The theory that simple chemical compounds in the early atmosphere and ocean combined to form larger, more complex substances, eventually leading to the origin of life and the start of biological evolution.
Who originally formulated the idea that all distinct, identifiable types of organisms are connected by common ancestry?
Charles Darwin and Alfred Russel Wallace (1959)
Theory of Evolution by Natural Selection
The theory that similarities among types of organisms are mostly due to the fact that they are related to one another.
It was developed over a 20-year period.
What are the two claims of Darwin & Wallace’s theory concerning patterns that exist in the natural world?
- Species are related by common ancestry.
- The characteristics of species can be modified from generation to generation (“descent with modification”).
Evolution
A change in the characteristics of a population over time.
Population
A group of individuals of the same species living in the same area at the same time.
Natural selection
The process by which individuals with certain heritable traits tend to produce more offspring than individuals without those traits.
Often leads to a change in the genetic makeup of a population.
Natural selection occurs whenever which two characteristics are met?
- Individuals within a population vary in characteristics that are heritable (can be passed onto an offspring).
- In a particular environment, certain versions of these heritable traits help individuals survive better or reproduce more than other versions.
Natural selection acts on _________ but evolutionary change occurs in _________.
Natural selection acts on individuals but evolutionary change occurs in populations.
Speciation
The evolution of two or more distinct species from a single ancestral species.
When populations of one species diverge and form new species.
Fitness (in biology)
An individual’s ability to produce viable offspring.
Adaptation (in biology)
A trait that increases the fitness of an individual in a particular environment.
The chromosome theory of inheritance
The principle that genes are located on chromosomes and that patterns of inheritance are determined by the behaviour of chromosomes during meiosis.
Chromosome
Gene-carrying structure consisting of a single long molecule of double-stranded DNA and associated proteins.
Inside cells, hereditary or genetic information is encoded on ___________, the units located on ___________.
A chromosome consists of a molecule of ___________.
Inside cells, hereditary or genetic information is encoded on genes, the units located on chromosomes.
A chromosome consists of a molecule of DNA.
Central dogma
The scheme for information flow in the cell:
DNA»_space; RNA»_space; protein.
First penned by Francis Crick.
Deoxyribonucleic acid (DNA)
A nucleic acid that carries genetic information.
Generally occurs as a double helix with two intertwined strands held together by non-covalent bonds.
Ribonucleic acid (RNA)
A usually single stranded nucleic acid that transports messages of the DNA code required for protein synthesis (mRNA).
What are the 2 fundamental nutritional needs of organisms?
- Acquiring chemical energy in the form of ATP.
- Obtaining molecules that can be used for the synthesis of complex compounds such as DNA, proteins, etc.
Tree of life
A family tree of all organisms.
Carl Wose
An American biologist who analyzed the molecular components of organisms as a way to understand their phylogeny.
Phylogeny
The evolutionary history of a group of organisms.
Translates to “tribe-source”
Ribosomal RNA (rRNA)
An RNA molecule that forms part of the ribosome.
Ribonucleotides
The 4 smaller chemical components of an rRNA molecule.
They are symbolized by the letters A, U, C, and G.
What are the nucleobases of DNA?
What are the nucleobases of RNA?
DNA: Thymine - Adenine, Cytosine - Guanine.
RNA: Uracil - Adenine, Cytosine - Guanine.
Phylogenetic tree
A branching diagram that shows the evolutionary relationships among species.
Last universal common ancestor of cells (LUCA)
A theoretical entity proposed to be the product of chemical evolution and provided characteristics of life that are shared by all living organisms on earth today.
What are the 3 fundamental groups or lineages of organisms established by the tree of life?
[Prokaryotes]
1. The Bacteria
2. The Archaea
[Eukaryote]
3. The Eukarya
Eukaryote
Prokaryote
Eukaryote: an organism whose cells contain a nucleus, numerous membrane-bound organelles, and an extensive cytoplasm.
Prokaryote: a unicellular organism lacking a nucleus and containing relatively few organelles or cytoskeletal components.
Taxonomy
Taxon
Taxonomy: the effort to name and classify organisms.
Taxon: Any named group.
Domain
A taxonomic category, based on similarities in basic cellular biochemistry, above the kingdom level.
The 3 recognized domains are bacteria, archaea and eukarya.
Phylum / Phyla
Major lineages within each domain.
Each is considered a major branch on the tree of life.
Carolus Linnaeus
Swedish botanist who developed the scientific naming system for naming species. (1735)
He created a 2-part name unique to each type of organism.
Genus
Species
Genus: fist part of the name made up of a closely related group of species.
Species: the second part of the name identifies the organism’s species.
Artificial selection
Changes in a population that occur when humans select certain individuals to produce the most offspring.
Example: domestic animal domestication.
What does a prediction specify?
What we should observe if the hypothesis is correct.
Which 4 atoms make up 96% of all matter found in organisms today?
- Hydrogen
- Carbon
- Nitrogen
- Oxygen
Protons have a ______ charge.
Neutrons have a ______ charge.
Electrons have a ______ charge.
Protons have a positive charge.
Neutrons have a neutral charge.
Electrons have a negative charge.
Element
A substance consisting of atoms with a specific number of protons.
Elements preserve their identity in chemical reactions
Atomic number
Mass number
Atomic weight
Atomic number: the number of protons in the nucleus of an atom, giving the atom its identity as a particular chemical element.
Mass number: the total number of protons and neutrons in the nucleus of an atom. The mass of an atom.
Atomic weight: The average mass of an element based on the relative proportions of all its naturally occurring isotopes. (Often slightly different from mass numbers)
Dalton (Da)
Unit of mass approximately equal to the mass of one proton or one neutron.
Named after John Dalton, an English scientist who formulated the atomic theory.
Isotopes
Radioactive isotope
Isotope: Any of several forms of an element that differ in the number of neutrons contained in their nuclei.
Radioactive isotope: A version of an element that has an unstable nucleus, which will release radiation energy as it decays into a more stable form.
Orbital
Region of space around an atomic nucleus in which an electron is present most of the time.
Electron shell
Valence shell
Electron shell: A group of electron orbitals with similar energies.
Valence shell: The outermost electron shell of an atom.
Valence electron
An electron in the outermost electron shell (valence shell) of an atom.
These tend to be involved in chemical bonding.
Valence
The number of unpaired electrons found in an atom’s valence shell.
Chemical bond
Covalent bond
Chemical bond: an attractive force binding two atoms together.
Covalent bond: A type of chemical bond in which two atoms share one or more pairs of electrons.
Molecule
A substance made up of two or more atoms held together by covalent bonds.
Nonpolar covalent bond
Polar covalent bond
Nonpolar covalent bond: type of covalent bond where electrons are shared equally between two atoms of the same or similar electronegativity.
Polar covalent bond: type of covalent bond where electrons are shared unequally between atoms differing in electronegativity.
-Results in the more electronegative atom having a partial negative charge and the other having a partial positive charge.
Compound
Any substance that consists of more than one element chemically bonded together.
Electronegativity
A measure of how strongly an atom pulls its shared electrons toward itself in a bond.
An atom’s electronegativity is due to a combination of what two things?
- The number of protons in the nucleus.
- The distance between the nucleus and the valence shell.
𝛿+
𝛿-
𝛿+ : partial positive charge
𝛿- : partial negative charge
Ionic bond
Chemical bond that is formed when an electron is completely transferred from one atom to another.
Ion
An atom or molecule that has lost or gained electrons and now carries a full electric charge, either positive (cation) or negative (anion).
Molecular formulas
Structural formulas
Molecular formulas: one way of representing a molecule that is compact and doesn’t contain much information.
-Example: H2O
Structural formulas: one way of representing a molecule that indicates which atoms are bonded together in 2-dimensions.
-Example: O
/ \
H H
What are 4 ways of representing molecules?
- Molecular formulas
- Structural formulas
- Ball-and-stick models
- Space-filling models
What are 2 ways we can use radioisotopes in biology?
- Dating organic material via carbon dating (measuring the amount of decay).
- Radioactive tracers for the diagnosis and treatment of diseases.
What are 2 strong types of chemical bonds?
What are 2 weak types of chemical bonds?
Strong: Covalent and ionic bonds
Weak: Hydrogen bonds and Van der Waals interactions.
Hydrogen bond
Van der Waals interaction
Hydrogen bond: a weak bond between 2 molecules or different parts of the same molecule resulting from the attraction between a hydrogen atom with a partial positive charge and another atom with a partial negative charge.
Van der Waals interaction: a weak electrical attraction between two nonpolar molecules that have been brought together through hydrophobic interactions.
Solvent
Solution
Solute
Solvent: any liquid in which one or more solids or gases can dissolve.
Solution:a liquid containing one or more dissolved solids or gases in a homogenous mixture.
Solute: any substance that is dissolved in a liquid.
Polar
Carrying a partial positive charge on one side of a molecule and a partial negative charge on the other.
Polar molecules are generally hydrophilic.
Hydrophobic interactions
Very weak interactions between nonpolar molecules, or nonpolar regions of the same molecule, when exposed to an aqueous substance.
Cohesion
Adhesion
Cohesion: The tendency of certain like molecules to cling together due to attractive forces.
-Water is cohesive.
Adhesion: The tendency of certain dissimilar molecules to cling together due to attractive forces.
Surface tension
The cohesive force that causes molecules at the surface of a liquid to stick together, thereby resisting deformation of the liquid’s surface and minimizing its surface area.
Why does water expand when frozen?
It is denser as a liquid than a solid.
This is also why ice floats.
Chemical reaction
Any process in which substances combine or are broken down into other substances.
Involves the creation/breaking of chemical bonds.
Hydrogen ion (H+)
Hydroxide ion (OH-)
Hydrogen ion (H+): A single proton with a positive electric charge of +1.
Hydroxide ion (OH-): An oxygen atom and a hydrogen atom joined by a single covalent bond and carrying a negative electric charge of -1.
Chemical equilibrium
A dynamic but stable state of a reversible chemical reaction in which the forward and reverse reactions proceed at the same rate so that the concentrations of reactants and products remain constant.
Acid
Base
Acid: Any compound that gives up protons or accepts electrons during a chemical reaction, or that releases hydrogen ions when dissolved in water.
-Increases H+
Base: Any compound that acquires protons or gives up electrons during a chemical reaction,or accepts hydrogen ions when dissolved in water.
-Increases OH-
Acid-base reaction
A chemical reaction that involves a transfer of protons.
Mole
Molecular weight
Mole: The amount of a substance that contains 6.022 x 10²³ of its elemental entities (atoms, ions, molecules).
Molecular weight: mass on one mole of a molecule = sum of the atomic weights of all the atoms in a molecule.
-Example: the molecular weight of H2O would be (1+1+16) = 18.
pH
A measure of the concentration of protons in a solution and thus of how acidic or basic the solution is.
Changing one pH level causes the sample to become how many times more acidic or basic?
10 x
Buffer
A substance that, in solution, acts to minimize changes in the pH of that solution when acid or base is added.
Buffers are important in maintaining homeostasis.
What are the 2 environments that researchers are investigating the origin of life?
- The atmosphere
- Deep-sea hydrothermal vents
System (chemistry)
A defined set of interacting chemical components under observation.
Endothermic
Exothermic
Endothermic: A chemical reaction that absorbs heat.
-Liquid to gas.
Exothermic: A chemical reaction that releases heat.
-Gas to liquid.
Energy
The capacity to do work or to supply heat.
May be stored (potential energy) or available in the form of motion (kinetic energy).
Potential energy
Kinetic energy
Chemical energy
Thermal energy
Potential energy: Energy stored in matter as a result of its position or the position of electrons that form chemical bonds between atoms.
Kinetic energy: The energy of motion.
Chemical energy: The potential energy stored in chemical bonds between atoms.
Thermal energy: The total kinetic energy of a system that includes the motion of matter and is measured in temperature.
Heat
Thermal energy that is transferred from an object at higher temperature to one at lower temperature.
First law of thermodynamics
Second law of thermodynamics
First law of thermodynamics: The principle of physics that energy is conserved in any process. It can be transferred and converted into different forms, but it cannot be created or destroyed.
Second law of thermodynamics: The principle of physics that the entropy of the universe or any closed system always increases.
Chemical reactions are spontaneous if ________.
Chemical reactions are spontaneous if they are able to proceed on their own without any continuous external influence.
What are the 2 factors that determine if a reaction will proceed spontaneously?
- When the product molecules are less ordered than the reactant molecules (increases entropy in the system).
- When the products have lower potential energy than the reactants.
Entropy
A measure of the amount of disorder in any system (such as a group of molecules).
-Example: melting ice.
Organic compounds
A group of molecules that include at least one carbon atom.
Functional group
A small group of atoms bonded together in a precise configuration and exhibiting particular chemical properties that it imparts to any organic molecule in which it occurs.
What are the 6 most important functional groups?
- Amino group - acts as a base and tends to attract a hydrogen ion (proton) when in solution.
- Carboxyl group - acts as an acid and tends to lose a proton in solution.
- Carbonyl group - found in molecules such as aldehydes. Site of reactions that link these molecules into larger, more complex organic compounds.
- Hydroxyl group - highly polar and may act as a weak acid and drop a proton (includes alcohols).
- Phosphate group - carries two negative charges. Phosphates that are bonded together store chemical energy that can be used in chemical reactions.
- Sulfhydryl groups - sulphur atom bonded to hydrogen atom.
Hydrocarbons
Compounds that consist of solely carbon and hydrogen.
Inorganic compounds
Molecules that do not contain both carbon and hydrogen.
Organic compounds differ from each other in which two ways?
- The length and structural arrangement of the carbon chain.
- The atoms attached to the carbon chain.
