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What is an atom?
smallest chem. unit of matter which can partake in a chemical reaction
What is an element? State some examples.
matter composed of one type of atom
ex: carbon (C), nitrogen (N), oxygen (O), sodium (Na)
What is a molecule?
two or more atoms combined
What are the diff. types of molecules?
either same type of atom N2
or different CO2
called a compound
Describe what a nucleus is made up of
every atom has a central located (atomic) nucleus
nucleus is made up of
protons (+)
neutrons (neutral charge)
results in nucleus having a net positive charge
stable + does NOT participate in chemical reactions
What are electrons?
exist outside of the nucleus in specialized regions of space called orbitals & are (-) charged
What happens when an atom loses an electron?
It will have a net positive charge
What happens when an atom gains an electron?
It will have a negative charge
What is the electron ratio to protons?
equal # of electrons & protons ⇒ a net charge equal to neutral
What are electron shells? What do they correspond to?
densely packed in nucleus (compared to protons & neutrons), lighter electrons orbit nucleus in “shells”
(e-) shells correspond to different energy levels
How do chemical bonds form?
Chemical bonds form between atoms through interactions of (e-) in outer shells with one another
What is the goal of every atom?
goal of every atom is to become chemically stable and do so by filling their outermost shell with electrons
How do atoms achieve their goal of filling their outermost shells?
achieved by filling its outermost shell with electrons
1st = 2e-
2nd = 8e-
3rd = 8e-
atoms achieve a full complement of electrons by combining together to form molecules
What is an ion?
When an atom has an overall positive or an overall negative charge it is no longer neutral and is referred to as an ion
What is a cation?
atoms loses an electron, overall (+) charge
ex: NA+
What is an anion?
atom gains an electron, overall (-) charge
ex: Cl-
What are chemical bonds?
Chemical bonds form in between atoms when electrons in their outer shells interact with one another
Every atom wants to achieve chemical stability and they do this by filling their outermost shell with electrons
Atoms achieve a full complement of electrons (8) by combining to form molecules
What are 3 kinds of chemical bonds?
ionic, covalent, hydrogen bonds
What is an ionic bond?
results from attraction between ions of opposite charges
What holds ionic bonds?
anions & cations(attractive force) form ionic bonds → neutralize their charges
What forms from an ionic bond?
attraction holds the ions together to form a compound
ex: NaCl
Na requires the loss of an electron to achieve stability and Cl requires the gain of an electron to achieve stability
Cl receives the electron from Na rather than sharing it : Cl becomes Cl- and Na becomes Na
What are covalent bonds?
Formed when two atoms come together and share electrons within their outer shell
→ strongest bond
Ex: Water is formed as a result of covalent bonds in between Hydrogen & Oxygen
Where are covalent bonds found?
Found in many compounds ⇒ especially those containing carbon
What is formed with covalent bonds?
almost all organic matter formed with carbon
Are covalent bonds strong or weak?
very strong bonds
How many covalent bonds can carbon atoms form?
4 covalent bonds
ex: methane CH4
What is the difference between ionic & covalent bonds?
depends on conditions (pH, temp.) / covalent bonds are typically stronger ⇒ require more energy to be broken
How do hydrogen bonds occur? State an example
occur when hydrogen is covalently bound to oxygen or another electron loving molecule such as nitrogen
since the atom bound to hydrogen is ‘electron loving; it holds the shared electrons closer to its nucleus than hydrogen
ex: when two hydrogens are bonded to oxygen, the larger oxygen atom tends to pull the electrons closer to itself
Compare the electronegativity of H & C to H & O
H : C
Carbon is not more electron loving than Hydrogen, thus the electrons are equally shared in between the two atoms
(partial positive)H : O(partial negative)
Oxygen is more electron loving than Hydrogen, thus the electrons are not equally shared in between the two atoms and are held more closely to the oxygen nucleus
What do hydrogen bonds result in?
Because the electrons are not equally shared in between the two atoms there is a resulting partial positive charge on the hydrogen atom (d+ )and a partial negative charge (d- )on the electron loving atom (oxygen in this case)
Unequal sharing leads to:
creates a region w/ partial negative charge (O)
and partial positive charge (H)
ex: H2O
on the electron loving atom (oxygen in this case)
regions can now participate in hydrogen bonding
→displays polarity
What are polar molecules?
Molecules that contain unequal sharing of electrons
Which elements have the most electronegativity?
Oxygen & Nitrogen
→Electron greedy
Highly electronegative!
C & H are non polar covalent bonds
(lipid) non soluble because of its equal charge and not partial charge
O & H
polar(unequal charge)
What type of attraction is between oppositely charged regions of different molecules (hydrogen bonds)?
loose attraction between oppositely charged regions of different molecules
partial positive charge on hydrogen atom is attracted to partial negative charge on atoms within other molecules
Are hydrogen bonds stronger than ionic & covalent bonds?
weaker than ionic & covalent bonds
Covalent bonds → ionic bonds → hydrogen bonds
How do hydrogen bonds form?
These bonds form when Hydrogen is covalently bound to oxygen or another
electron loving molecule such as nitrogen
1 water molecule will be attracted through covalent bonds
4 charges (2 partial negative & 2 partial positive)
What do hydrogen bonds do?
serves to bridge separate molecules together
ex: in H2O the H’s of one molecules are attracted to the O’s of the other molecule
What do hydrogen bonds result in?
Networks of molecules of different molecules
What are organic compounds?
Organic compounds are compounds which contain Carbon
Carbonic acid, Carbon dioxide, & Carbon monoxide (inorganic - exception)
What are inorganic compounds?
Inorganic compounds are compounds which do not contain Carbon
What kind of compounds do organisms require?
Organisms require a wide variety of inorganic compounds in order to live & reproduce
What is the most inorganic molecules found in living systems?
Water accounts for approximately for 75% of cell weight
Since water is used to dissolve materials it is a solvent and because electrons are not shared equally in between the hydrogen and the oxygen atoms, it is a polar solvent
Like dissolves like (polar & polar: yes/polar & non-polar: no)
How is water an excellent solvent?
Can dissolve many ionic compounds such as NaCl
Not covalent because its polar (like dissolves like)
Ions (Na+, Cl-) remain dissolved in water to form a solution
This solution forms because the partial + regions within the water molecules surround the (-) ions Cl- & the partial (-) regions within the water molecules surround the positive ions (Na+) holding them in solution
Does water have an equal charge distribution, why or why not? In relation to temperature?
has an unequal charge distribution
each water molecule can form up to four hydrogen bonds with other water molecules → excellent ability to hydrogen bond allows water to form networks of interconnected water molecules which gives water:
a high boiling point (100°C)
makes water resist rapid changes in temp. (keeps it in liquid state in most of the places found on Earth
great temp. buffer because of its strong hydrogen bonds
Can water be easily split into its component ions?
Yes it can be easily split into its component ions H+ & OH-
This characteristic allows water to play key roles in many chemical reactions
What kind of solvent is water & why?
water ⇒ universal solvent (reach 4 degrees - highest density of water, closer to each other) (polar solvent)
What does water allow due to its unequal charge of distribution?
unequal charge of distribution allows it to dissolve many ionic compounds
What does the (+) region of water do?
(+) region of water molecules surround (-) ions
holds ion in solution
ex: NaCl easily dissolves into Na+ & Cl- in water
What does water’s polarity facilitate?
water’s polarity facilitates the splitting & joining of hydrogen ions H+ & hydroxide ions OH-
makes these ions available for chemical reactions
What does the pH scale describe?
pH scale describes the concentration of $H^+$ ions in a solution
measures of acidity
What does a ph of 7 mean? below 7? above 7?
pH 7 = neutral (pure water)
pH below 7 = acidic
pH above 7 = basic or alkaline
What are organic molecules? Why is it so?
any molecule that contains both carbon & hydrogen
reason: each C atom can participate in 4 covalent bonds, carbon can be used to build an enormous variety of compounds
What are the four major classes of organic molecules?
Carbohydrates, Lipids, Proteins, Nucleic Acids
What is a carbohydrate?
large group of compounds including sugars & starches
What do Carbohydrates contain? State an example of a compound using this ratio
all contain the elements C, H, & O and ratio is C1 H2 O1
C6 H12 O6
Are carbohydrates polar?
generally polar (so they dissolve in water)
What is carbohydrates used for?
ready source of energy for cells
unsaturated = healthy
What is the organ that is given glucose(prioritized) in a fight or flight response?
The brain
Can carbohydrates be insoluble?
Yes and it is dependent on size (smaller-soluble; larger: not soluble)
What are the diff. types of carbohydrates?
monosaccharides
disaccharides
polysaccharides
What are monosaccharides? Example?
mono = one
simple sugars, ex: glucose
more stable - least amount of repulsion
What are disaccharides? Example?
di = two
two monosaccharides come together to form a disaccharide
ex: glucose + fructose = sucrose (table sugar)
covalently bonded together through a dehydration reaction
What are polysaccharides? Solubility? Examples?
poly = many
hundreds of monosaccharides
often not soluble in water (too large)
ex: glycogen, starch, cellulose (cannot digest)
What are lipids & their importance?
includes fats, complex lipids (ex: phospholipids) & steroids
essential to the structure & function of membranes
comprises the lipid portion of the phospholipid bilayer
What are lipids used for?
used for energy storage
Are lipids polar or non-polar?
non-polar molecules: hydrophobic ⇒ water hating
Non-polar (equal sharing) which means no regions of partial (+) or (-) →not attracted to water molecules (polar-unequal sharing)
What are fats made from?
made from a glycerol backbone +1 or more fatty acids(non-polar; hydrophobic)(function: holds heat in body):
monoacylglycerides: glycerol + 1 fatty acid
diacylglycerides: glycerol + 2 fatty acids
triacylglycerides: glycerol + 3 fatty acids
What can fatty acids be?
fatty acids can be:
saturated ⇒ no double bonds, saturated with hydrogen atoms
pack closer together - forms more bonds (more solid)
or unsaturated ⇒ at least one double bond, fewer hydrogen atoms
has “kinks” therefore influences its fluidity
What makes up a phospholipid?
in complex lipids
contain glycerol, 2 fatty acids, & a phosphate group
Where are phospholipids found?
In membranes of living cells & they are the primary component of prokaryotic & eukaryotic plasma membranes
What makes up a phospholipid?
Included in complex lipids
glycerol & phosphate group
hydrophilic - likes water
fatty acid tails are non-polar
hydrophobic - hates water
has two fatty acid tails
has permeability to enable certain ions to travel through cell membrane (small non polar material; polar material can’t because of the lack of charges in phospholipid tails(repelled))
What does the fatty acid tails allow the phospholipids to do?
allows phospholipids to form membranes in water
saturated fatty acids tend to form membranes that are more solid
unsaturated fatty acids - more fluid
What are biological membranes made from?
are made from a phospholipid bilayer
What are biological membranes?
are semi-fluid (contain a mix of saturated & unsaturated fatty acids)
What are biological membranes function?
separate the watery inside of the cell from the watery environment
one saturated & unsaturated, this is what enables the entrance of certain elements through the cell membrane
What is the difference between steroids & other lipids?
structurally different from other lipids
What are steroids built on?
built on a hydrophobic 4 ring structure
on exam, portrayed as true or false
Where are steroids found in?
generally found in eukaryotes (more complex organism) not in prokaryotes(bacteria)
ex: Cholesterol ergosterol(thermostability) & vitamin D
What are proteins made up of?
made up of building blocks: amino acids (individual units)
What do proteins contain?
all contain: C, H, O, N (& some have S)
proteins typically contain: 20 different amino acids
have at least one amino -NH2 & one carboxyl (-COOH) group
side groups(different on each amino acid) determine properties of amino acid
What are functions of proteins?
required in all aspects of cell structure & function
some are structural
but most act as enzymes - increase the rate at which chemical reactions take place in living organisms
What bonds turn amino acids to proteins?
amino acids are joined to make proteins by covalent peptide bonds
What is a chain of amino acids?
protein= polypeptide = chain of amino acids
short chain of amino acids are called peptides
What is the shape & function of protein determined by?
shape & functions of the protein is determined by the sequence of amino acids
How is protein required in all aspects of cell structure & function?
Structural components of the cell:
Membrane channels
Enzymes
Increase the rate of chemical reactions that occur within the cell
What are the 9 amino acids essential for life?
needs to obtain from other sources
histidine, isoleucine, leucine, lysine, methionine (AUG is the starting column), phenylalanine, threonine, tryptophan, and valine
What are types of nucleic acids?
(double strands)DNA transcribes to RNA then to (single strand) RNA become translated to amino acids (series of amino acids)→ proteins (enzymes or structural)
DNA = deoxyribonucleic acid
RNA = ribonucleic acid
What are nucleotides made up of? Describe the 3 building blocks.
built of building blocks called nucleotides
each nucleotide has 3 parts
Nitrogenous Base:
Purine → 2 rings = Guanine (G) & Adenine (A)
Pyrimidine →1 ring = Cytosine (C), Thymine (T) or Uracil (U)
Uracil is the change due to evolutionary change to increase genetic stability
Pentose sugar → 5 carbon sugar
ribose or deoxyribose
deoxyribose - no oxygen therefore “dehydrated”
Phosphate group
A phosphate group is attached to the nucleotide and serves as the site of attachment for the next nucleotide
What is DNA made up of?
nucleotides: A, G, T, & C
sugar deoxyribose
double stranded with each strand together by hydrogen bonds
What does DNA do?
stores the genetic info of all cellular organisms (what genes are composed of)
What is the direction of DNA?
forms a double helix
5 prime to 3 prime
The order of the nucleotide sequence is very specific and forming the genetic instructions for the organism
there are viruses that contain DNA
How many base pairs in DNA?
3 billion base pairs in DNA
What is RNA made up of?
A, G, U, & C
sugar ribose
single stranded
except in viruses; can be double stranded
What is RNA involved in?
involved in communicating the instructions stored in DNA(transcription)
What is the direction of RNA?
3 prime to 5 prime
SARS covid 2(viruses that contain RNA)
What is the DNA structure composed of?
each strand is built from a sugar phosphate backbone
2 strands are held together by hydrogen bonds between nitrogenous bases
forms the double helix
What nitrogenous base pairs are paired in DNA?
A pairs w/ T
G pairs w/ C
order of bases is specific & forms the genetic instructions for the organisms
ex: genes