Organisation of life - from atoms to the biosphere Flashcards
organization
life is composed of one or more cells - basic units of life
homeostasis
maintenance of a constant state
metabolism
conversion of chemicals to obtain energy and cellular building blocks
growth
cells grow and divide
adaptation
ability to change
responsiveness
ability to respond to stimuli
reproduction
ability to produce new individual organisms
organization of life
atoms ▶️ molecules ▶️tissues ▶️organs ▶️organism
atom
basic unit of matter, consists of:
- dense central nucleus
- cloud of electrons
they can make covalent, ionic and hydrogen bonds
covalent bonds
the sharing of a pair of valence electrons by two atoms
hydrogen bonds
a primary electrostatic force of attraction between a partially negatively charged atom and a partially positively charged atom
ionic bonds
transfer of electron between two atoms
neutron
- charge = 0
- mass = 1 atomic mass unit [amu]
proton
- charge = +
- mass = 1 atomic mass unit [amu]
electron
- charge = -
- mass = ~0
orbitals (shells, energy levels)
- depending on the number of electrons of an atom, it can have multiple orbitals
- each orbital can carry a different maximal number of electrons
- orbital 1 can hold 2 electrons
- orbital 2 can hold 8 electrons
- orbital 3 can hold 8 electrons
how are atoms / elements classified?
on the basis of the number of protons - ATOMIC NUMBER (Z)
in a neutral atom, the atomic number = number of electrons
number of protons (Z) plus neutrons (N) equals mass number (A) of an atom
A = Z + N
valency
chemical behavior of an atom depends mostly on the number of electrons in the outermost shell, called the VALENCE SHELL (valence electrons)
an atom with a full valence shell is unreactive = it will not interact with other atoms
atoms with incomplete valence shells can interact with other atoms, so that each partner atom completes its valence shell, these atoms either share or transfer valence electrons
biomolecules
most important biomolecules are nucleic acids, proteins, carbohydrates and lipids
main elements of biomolecules
Hydrogen, Carbon, Nitrogen, Oxygen, Phosphorus, Sulfur
C = 4 bonds
N = 3 bonds
O = 2 bonds
S = 2 bonds
H = 1 bond
P = 5 bonds
elements of the biosphere
populations ▶️communities ▶️ecosystems ▶️biomes ▶️the biosphere
- individuals of the same species form populations, while various populations form communities
- ecosystems include communities as well as abiotic environmental factors
- the biosphere is divided in various biomes, each holding multiple ecosystems
macromolecules
huge molecules (polymers) consisting of a variable number of coupled building blocks (units, residues, monomers)
- carbohydrates (sugars): monosaccharides and polysaccharides
- nucleic acids (DNA & RNA): consisting of 4 different monomers (nucleotides)
- proteins: consisting of 20 different monomers (amino acids)