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cations
atoms carrying a positive charge
anions
atoms carrying a negative charge
three types of chemical bonds found in living systems
covalent
ionic
hydrogen
covalent bonds
very strong bonds
formed when two atoms come together and share electrons within their outer shell
water is formed as a result of covalent bonds between H and O
ionic bonds
form as a result of the attractive force between ions of opposite charge (cation or ion)
weaker than covalent bonds
attractive force holds the two atoms together in the bond
example of ionic bonds
NaCl
Na requires the loss of an electron to achieve stability and Cl requires and electron to achieve stability
Cl received electron from Na rather than sharing
Cl- and Na+
Hydrogen bonds
hydrogen covalently bound to oxygen or another electron loving molecule such as nitrogen
atom bound to hydrogen is ‘electron loving’ so it holds the shared electrons closer to its nucleus than hydrogen
UNEQUAL SHARING OF ELECTRONS ARE POLAR MOLECULES
partial positive on hydrogen, partial negative on electron loving atom
weakest of the bonds
result in networks of molecules of different molecules
H:C
carbon is not more electron loving than hydrogen, electrons shared equally between two atoms.
non-polar covalent bonds
δ+ H—-:O δ-
oxygen more electron loving than hydrogen, electrons not being shared equally. held more closely to the oxygen atom
polar covalent bond
organisms require a wide variety of __________ in order to live and reproduce
inorganic compounds
whats the most important inorganic molecule found in living systems?
water H2O
75% of cell weight
water is used to dissolve materials, it is a solvent.
because electrons are not shared equally it is POLAR SOLVENT
3 exceptions to inorganic molecules
carbon dioxide
carbon monoxide
carboxylic acid
why is water an excellent solvent?
dissolve many ionic compounds like NaCl
ions Na+, Cl- remain dissolved in the water and from a solution
solution forms due to partial positive regions within the water molecules surround the negative ions cl-. partial negative regions within the water molecule surround the positive ions na+ holding them in solution
forms sodium chloride crystal
how to break down a sodium chloride crystal?
adding heat
mechanically break it apart
water molecule can from four hydrogen bonds with other molecules
hydrogen bonds allow water to from networks of interconnected water molecules which gives water a very high BP
high BP 100 degrees C keeps water in liquid state in most places on Earth
solid, 4 H bonds (freezing/melting) liquid, 3.4 H bonds (boiling/evaporating) gas
why is water a great temperature buffer?
because of its strong hydrogen bonds
water can easily split into its component ions ____
H+ and OH-
plays key role in many chemical rxns
four major classes or organic compounds found in living things
carbohydrates
proteins
lipids
nucleic acids
carbohydrates
energy source immediately utilizable by cells
polar covalent compounds - dissolve easily in water (only if they are small enough)
contain the elements C, H, O (CnH2nOn)
three major groups of carbohydrates
monosaccharides
disaccharides
polysaccharides
monosaccharides
one sugar
glucose, fructose
disaccharide
two monosaccharides form a disaccharide
glucose + fructose = sucrose
polysaccharides
hundreds of monosaccharides come together
often too large to be water soluble
starch, cellulose (plants use to cage themselves, dietary fiber — clears u out)
glycogen is a storage method
lipids
fats, complex lipids (phospholipids), and steroids
essential to the structure and function of membranes (phospholipid bilayer)
used as means of energy storage
molecules are non-polar therefore don’t interact well with water HYDROPHOBIC
fat stores 2x more energy than sugar, we store as fat because its better for us but we still store some as sugar i.e in liver
lipids - Fats
composed of a glycerol molecule plus one to three fatty acids
monoglycerides
diglycerides
triglycerides (stored in adipose tissue)
lipids - fatty acids
saturated or unsaturated
complex lipids include phospholipid which are found in the membrane of living cells — primary component of prokaryotic and eukaryotic plasma membrane
saturates fatty acid
no double bonds
saturated with H atoms
unsaturated fatty acids
has at least one double bonds
fewer H atoms
less saturated because double bond takes space for a H
more fluid at given temp.
heavy group placements
cis - both on same side
trans - on opposite sides (favourable)
steroids
structurally distinct from other lipids
four ring structure
found mainly in eukaryotes
ex. cholesterol and vitamin D
proteins
composed of individual units of amino acids
individual AA are joined by peptide bonds which are covalent bonds
AA sequence important for determining shape of protein
proteins required in all aspects of cell structure and function — membrane channels
ex. hair — different textures come from AA
amino acids
all amino acids and thus proteins are composed of C, O, H, N (some have S)
20 known
side group -r determines chemical properties of AA
NH2 and COOCH (n and c terminus)
peptide
short chain of amino acids
polypeptide
long chain of amino acids
(proteins)
enzyme
increase the rate of chemical reactions that occur within the cell
nucleic acids
made of nucleotides
each nucleotide has three components
nitrogenous base
pentose sugar
phosphate group
nitrogenous base
purines: contain 2 rings
two types: Adenine (A), Guanine (G)
silver is very pure and makes nice rings Ag double rings
pyrimidines: contain 1 ring
three types: Cytosine (C), Thymine (T) DNA option, Uracil (U) RNA option
pentose sugar
five carbon sugar
two types: ribose and deoxyribose
phosphate group
phosphate group is attached to the nucleotide and serves as the site of attachment for the next nucleotide
enzyme specificity
two types of nucleic acid
deoxyribonucleic acid DNA and ribonucleic acid RNA
deoxyribonucleic acid (DNA)
always the genome
composed of deoxyribose sugar
double stranded, each strand held by h-bonds (virus can be single stranded)
DNA is what genes composed of
“recipe book“
order of nucleotide sequence is very specific and forming the genetic instructors for the organisms
made of nucleotides A, C, T, G
ribonucleic acid (RNA)
composed of ribose sugar
single stranded (virus can have double stranded RNA)
involved in communicating the instructions of DNA
made of nucleotides A, C, U,G