Chapter 1: The Facts of Life Flashcards
__ are lifeless. Yet, the properties of living things derive from the properties of __.
Molecules; molecules
Who said, “Living things are composed of lifeless molecules.”
Albert Lehninger
Who said,“…everything that living things do can be understood in terms of the jigglings and wigglings of atoms.”
Richard P. Feynman
Distinctive properties of living systems
1) Organisms are complicated and highly organized
2) Biological structures serve functional purposes
3) Living systems are actively engaged in energy transformations
4) Living systems have a remarkable capacity for self-replication
Living systems are distinct from the inanimate world because they have certain extraordinary properties. They can grow, move, and perform the incredible chemistry of:
- metabolism
- respond to stimuli from the environment
- replicate
organisms are composed of many __, typically of many types. In turn, these possess subcellular structures, called __, which are complex assemblies of very large polymeric molecules, called __.
- cells
- organelles
- macromolecules
macromolecules themselves show an exquisite degree of organization in their intricate __, even though they are composed of simple sets of chemical building blocks, such as __ and __.
- three-dimensional architecture
- sugars
- amino acids
- the complex three-dimensional structure of macromolecules is __
- a consequence of interactions between the __, according to their individual chemical properties.
- conformation
- monomeric units
it is this __ that separates the science of biology from studies of the inanimate world such as chemistry, physics, and geology.
functional characteristic of biological structures
In biology, it is always meaningful to seek the __ of observed structures, organizations, or patterns; that is, to ask what __ they serve within the organism.
- purpose
- functional role
- Made of long chains of 20 amino acids
- Most of the structure and function of living things
Proteins
- Made of long and short chains of nucleic acid bases form DNA, RNA, also ATP, GTP…
- Informational storage (RNA, DNA), structure, enzymes, energy transfer
Nucleic Acid
- Made of phosphate or other charged “head” with a long hydrocarbon tail
- Energy Storage, insulation, cushioning, membranes
Lipids
- Made of long and short chains of sugar molecules like glucose, fructose
- Energy source, energy storage, structure
Carbohydrates
- Made of various molecules such as hormones, vitamins, neurotransmitters, porphyrins
- mostly sending signals
small molecules
Maintenance of the highly organized structure and activity of living systems depends on their ability to __ from the environment.
extract energy
The ultimate source of energy
sun
Solar energy flows from __ (organisms able to capture light energy by the process of photosynthesis) through food chains to __ and ultimately to __ at the apex of the food pyramid. The biosphere is thus a system through which __.
- photosynthetic organisms
- herbivores
- carnivorous predators
- energy flows
Organisms capture some of this energy, be it from photosynthesis or the metabolism of food, by forming special energized biomolecules, of which __ and __ are the two most prominent examples
- ATP
- NADPH
energized biomolecules because they represent chemically useful forms of stored energy.
- Adenosine triphosphate (ATP)
- Nicotinamide adenosine dinucleotide phosphate hydrogen (NADPH)
when ATP and NADPH molecules react with other molecules in the cell, the energy released can be used to drive energetically unfavorable processes. That is, ATP, NADPH, and related compounds are the power sources that drive the energy-requiring activities of the cell, including:
- biosynthesis
- movement
- osmotic work against concentration gradients
- light emissions (bioluminescence) *in special instances
Only upon __ does an organism reach equilibrium with its inanimate environment
death
At the expense of this energy flow, the organism can maintain its intricate order and activity far removed from equilibrium with its surroundings, yet exist in a state of apparent constancy over time. This state of apparent constancy, or so-called __, is actually a very dynamic condition: Energy and material are consumed by the organism and used to maintain its stability and order.
steady state
A thermodynamic term used to designate
that amount of energy in a system that is unavailable to do work.
entropy
__, as exemplified by the universe in totality, is moving to a condition of increasing disorder or, in thermodynamic terms, __
- inanimate matter
- maximum entropy
Self-replication can proceed by a variety of mechanisms, ranging from __ in bacteria to __ in plants and animals; but in every case, it is characterized by an astounding __
- simple division
- sexual reproduction
- degree of fidelity
the degree of exactness with which something is copied or reproduced
fidelity
Energy and material are consumed by the organism and used to maintain its __. Living organisms are able to extract free energy from the environment and export entropy (in the form of __).
- stability and order
- heat
The fidelity of self-replication resides ultimately in the chemical nature of the __. This substance consists of __ of deoxyribonucleic acid, or DNA, which are structurally complementary to one another
- genetic material
- polymeric chains
These molecules can generate new copies of themselves in a rigorously executed __ that ensures a faithful reproduction of the original __.
- polymerization process
- DNA strands
the molecules of the inanimate world lack the capacity to __. A crude mechanism of __ must have existed at life’s origin.
- replicate
- replication
The elemental composition of living matter differs markedly from the relative abundance of elements in the __. __, __, __, and __ constitute more than 99% of the atoms in the human body, with most of the __ and __ occurring as __.
- earth’s crust
- Hydrogen, oxygen, carbon, nitrogen
- H, O, H2O
the predominant gas in the atmosphere
Nitrogen as dinitrogen (N2)
abundant in the atmosphere and in the oceans
oxygen
present at a level of 0.04% in the atmosphere, a small but critical amount
carbon dioxide
What property unites H, O, C, and N and renders these atoms so suitable to the chemistry of life?
- It is their ability to form covalent bonds by electron-pair sharing.
- H, C, N, and O are among the lightest elements of the periodic table capable of forming such bonds. Because the strength of covalent bonds is inversely proportional to the atomic weights of the atoms involved, H, C, N, and O form the strongest covalent bonds
Two other covalent bond-forming elements, ___ , also play important roles in biomolecules.
- phosphorus (as phosphate derivatives)
- sulfur
can share two electron pairs to form double bonds with one another within biomolecules, a property that enhances their __.
- Carbon, Nitrogen, Oxygen
- chemical versatility
can form covalent bonds with itself and __ shape; these broperties hold the potential for an incredible variety of __, __, and __compounds of __
- Carbon
- tetrahedral
- linear , branched, cyclic
- Carbon
Carbon can form as many as __ such bonds by sharing each of the __ in its __ with electrons contributed by other atoms. Atoms commonly found in covalent linkage to C are C itself, H, O, and N. Hydrogen can form __ such bond by contributing its __ to the formation of an __. Oxygen, with __ unpaired electrons in its outer shell, can participate in __ covalent bonds, and nitrogen, which has __ unshared electrons, can form __ such covalent bonds.
- four
- four electrons
- outer shell
- one
- single electron
- electron pair
- two; two
- three; three
Two properties of carbon covalent bonds that merit particular attention
- the ability of carbon to form covalent bonds with itself
- the tetrahedral nature of the four covalent bonds when carbon atoms form only single bonds
biomolecules are classified according to the __ and __, an organizational pattern emerges.
- similarities of their sizes ; chemical properties
The biomolecules are built according to a __: Simple molecules are the units for building __.
- structural hierarchy
- complex structures
The major inorganic precursors for the formation of biomolecules
▪ Water (H2O)
▪ carbon dioxide (CO2)
▪ ammonium (NH4+)
▪ nitrate (NO3-)
▪ dinitrogen (N2)
In the first step, the major inorganic precursors are converted into __, simple organic compounds that are intermediates in cellular energy transformation and in the biosynthesis of various sets of building blocks: __
- metabolites
- amino acids
- sugars
- nucleotides
- fatty acids
- glycerol
Through the covalent linkage of the building blocks, the __ are constructed: __(4)
- macromolecules
- proteins
- polysaccharides
- polynucleotides (DNA and RNA)
- lipids
- contain relatively few building blocks and are therefore not really polymeric like other macromolecules
- important contributors to higher levels of complexity
lipids
Interactions among macromolecules lead to the next level of structural organization, __.
supramolecular complexes
Here, various members of one or more of the classes of macromolecules come together to form specific assemblies that serve important sub-cellular functions.
supramolecular complexes
Examples of supramolecular assemblies
- multifunctional enzyme complexes
- ribosomes
- chromosomes
- cytoskeletal elements
supramolecular assemblies are an interesting contrast to their components because their structural integrity is maintained by __, not by __. These forces include __, __, __, and __ between macromolecules. Such forces maintain these __ in a __.
- noncovalent forces; covalent bonds
- hydrogen bonds
- ionic attractions
- van der Waals forces
- hydrophobic interactions
- supramolecular assemblies; highly ordered functional state
- entities of considerable dimensions compared with the cell itself
- found only in eukaryotic cells, that is, the cells of “higher” organisms
organelles
Organelles
- Nucleus
- Mitochondria
- Chloroplasts
- endoplasmic reticulum
- Golgi apparatus
- Vacuoles
- other relatively small cellular inclusions such as peroxisomes, lysosomes, and chromoplasts
Two attributes of organelles
- They are cellular inclusions, usually membrane-bounded
- They are dedicated to important cellular tasks.
the repository of genetic information as contained within the linear sequences of nucleotides in the DNA of chromosomes.
nucleus
the “power plants” of cells by virtue of their ability to carry out the energy-releasing aerobic metabolism of carbohydrates and fatty acids, capturing the energy in metabolically useful forms such as ATP
mitochondria
endow cells with the ability to carry out photosynthesis. They are the biological agents for harvesting light energy and transforming it into metabolically useful chemical forms
Chloroplasts