Week Two Flashcards
List the 4 major categories of macromolecules in cells
1.
2.
3.
4.
Define protein
The key structural and functional molecules that do the work of the cell, providing structural support and catalyzing chemical reactions. The term “protein” is often used as a synonym for “polypeptide.”
Define nucleic acid
A polymer of nucleotides that encodes and transmits genetic information.
Define carbohydrate
An organic molecule containing C, H, and O atoms that provides a source of energy for metabolism and that forms the starting point for the synthesis of all other organic molecules.
Define lipids
An organic molecule that stores energy, acts as a signaling molecule, and is a component of cell membranes.
Define polymer
A complex organic molecule made up of repeated simpler units connected by covalent bonds.
Define amino acid
An organic molecule containing a central carbon atom, a carboxyl group, an amino group, a hydrogen atom, and a side chain. Amino acids are the building blocks of proteins.
Define nucleotide
A constituent of nucleic acids, consisting of a 5-carbon sugar, a nitrogen-containing base, and one or more phosphate groups.
Define sugar
The simplest carbohydrate molecule; also called a saccharide.
Define fatty acid
A long chain of carbons attached to a carboxyl group
What carbon based molecule makes up the cell wall in bacteria, plants and algae?
carbohydrates
What are the 4 main carbon-based molecules that chemical processes in a cell depend on?
- protein
- nucleic acid
- carbohydrates
- lipids
Proteins, nucleic acids, and carbohydrates are all _____ because they consist of smaller repeating units.
polymers
What are proteins polymers of?
amino acids
What are nucleic acids polymers of?
nucleotides
What are carbohydrates polymers of?
simple sugars (saccharides)
What are lipids defined by?
a property (not chemical structure)
Define functional group
Groups of one or more atoms that have particular chemical properties of their own, regardless of what they are attached to.
Why are functional groups containing N, O, P, and S polar?
because N, O, P, and S are more electronegative than carbon
What is the significance of the polarity of functional groups to cells?
The polarity makes them soluble in the cell’s aqueous environment so they can then disperse in solution throughout the cell. Also because they are polar they are also reactive.
When proteins function as catalysts what are they called?
enzymes
define enzyme
A protein that functions as a catalyst to accelerate the rate of a chemical reaction; enzymes are critical in determining which chemical reactions take place in a cell.
Define alpha carbon
The central carbon atom of each amino acid.
Define carboxyl group
COOH; a carbon atom with a double bond to oxygen and a single bond to a hydroxyl group.
Define amino group
NH2; a nitrogen atom bonded to two hydrogen atoms, covalently linked to the central carbon atom of an amino acid.
Define R group/side chain
A chemical group attached to the central carbon atom of an amino acid, whose structure and composition determine the identity of the amino acid
At the pH commonly found in a cell, the amino and carboxyl groups of an amino acid are _____ with the amino group being _____ charged and the carboxyl group being _____ charged.
ionized
positively
negatively
Define peptide bond
A covalent bond that links the carbon atom in the carboxyl group of one amino acid to the nitrogen atom in the amino group of another amino acid.
What is the bond that covalently links carbon atom in the carboxyl group of one amino acid to the nitrogen atom in the amino group of another amino acid called?
a peptide bond
When peptide bonds are formed what is released in order to make the bonds?
Water
What common molecule is released in the formation of polymers from amino acids, nucleic acids and complex carbohydrates?
water
How many amino acids are cellular proteins composed of?
20
How are amino acids classified?
According to them chemical properties of their R groups (side chains)
Define DNA
A linear polymer of four subunits; the information archive in all organisms.
Define RNA
A molecule chemically related to DNA that is synthesized by proteins from a DNA template.
Define base
A nitrogen-containing compound that makes up part of a nucleotide.
Define pyrimidine
In nucleic acids, any of the bases thymine, cytosine, and uracil, which have a single-ring structure.
Define cytosine (C)
A pyrimidine base.
Define thymine (T)
A pyrimidine base.
Define uracil (U)
A pyrimidine base in RNA, where it replaces the thymine found in DNA.
Define guanine (G)
A purine base.
Define adenine (A)
A purine base.
Define phosphodiester bond
A bond that forms when a phosphate group in one nucleotide is covalently joined to the sugar unit in another nucleotide. Phosophodiester bonds are relatively stable and form the backbone of a DNA strand.
Define double helix
The structure formed by two strands of complementary nucleotides that coil around each other.
Define Complementary
Describes the relationship of purine and pyrimidine bases, in which the base A pairs only with T and G pairs only with C.
Define Complementary
Describes the relationship of purine and pyrimidine bases, in which the base A pairs only with T and G pairs only with C.
DNA and RNA are long molecules consisting of _____ bonded covalently.
nucleotides
What are the 3 components of nucleotides?
- 5-carbon sugar
- a nitrogen containing base
- one or more phosphate groups
What is the sugar in RNA?
ribose
What is the sugar in DNA?
deoxyribose
What is the difference between ribose and deoxyribose?
ribose has a hydroxyl (OH) group on the second carbon (designated the 2′ carbon), whereas deoxyribose has a hydrogen atom at this position (hence, deoxyribose)
What is the difference between pyrimidine’s and purine’s structure?
pyrimidine has a single ring structure and purine a double ring structure
What bases does DNA contain?
A, T, G and C
What bases does RNA contain?
A, U, G, and C
What is the name of the bond which connects nucleotides?
phosphodiester bond
What base is complementary to adenine?
thymine
What base is complementary to thymine?
adenine
What base is complementary to guanine?
cytosine
What base is complementary to cytosine?
guanine
Define carbohydrate
An organic molecule containing C, H, and O atoms that provides a source of energy for metabolism and that forms the starting point for the synthesis of all other organic molecules.
What is another name for sugars?
saccharides
Define saccharide
The simplest carbohydrate molecule, also called a sugar.
What are the two shapes sugars are and which one occurs more commonly?
sugars are linear or cyclic.
Cyclic sugars are much more common
A simple sugar is also called a _____, and two simple sugars linked together by a _____ bond is called a _____.
monosaccharide
covalent
disaccharide
What are the polymers simple sugars combine to make called?
polysaccharides
What are two functions of polysaccharides?
- provides long term energy storage (starch or glycogen)
2. structural support (cellulose in plant cell walls)
What are long, branched chains of monosaccharides called?
complex carbohydrates
Define complex carbohydrates
A long, branched chain of monosaccharides.
Monosaccharides are _____ carbon chains with either an _____ or a _____ group
unbranched
aldehyde
ketone
Monosaccharides with an aldehyde group are called _____ and those with a ketone group are known as _____
aldoses
ketoses
In aldoses and ketoses what is each carbon bonded to if it is not bonded to the functional group?
hydroxyl (-OH) and a hydrogen atom (-H)
How do you number the carbons in a monosaccharide?
By starting at the top (where the aldehyde or ketone is) and numbering down the carbons.
Define glycosidic bond
A covalent bond that attaches one monosaccharide to another.
When glycosidic bonds are formed what molecule is released?
water
When rings are formed from a aldose what happens to the aldhyde?
the aldehyde oxygen becomes part of a hydroxyl group
What is the reason sugar rings (cyclic saccharides) are highly soluble in water?
The presence of polar hydroxyl groups
Complex carbohydrates are composed of…
a single type of monosaccharides or a mix of different types of monosaccharides
Why are lipids a chemically diverse group of molecules?
because they share a property not a structure
Define triacylglycerol
A lipid composed of a glycerol backbone and three fatty acids.
What is triaclyglycerol used for?
for energy storage
What is a fatty acid?
a long chain of carbon atoms attached to a carboxyl group (-COOH) at one end
Define glycerol
A 3-carbon molecule with OH groups attached to each carbon.
How do fatty acids differ from one another?
they differ in the length of their hydrocarbon chain (i.e. they differ in the number of carbons they have)
Why do most fatty acids in cells contain an even number of carbon atoms?
beacuse they are synthesized by the stepwise addition of 2-carbon units
Define saturated
Describes fatty acids that do not contain double bonds; the maximum number of hydrogen atoms is attached to each carbon atom, “saturating” the carbons with hydrogen atoms.
Define unsaturated
Describes fatty acids that contain carbon–carbon double bonds.
What is the difference in shape between unsaturated and saturated fatty acids?
Saturated fatty acids are straight and unsaturated fatty acids have a kink at every double bond
Fatty acids do not have polar covalent bonds mean that the electrons are…?
evenly distributed over the entire molecule
Because of the nonpolarity of triaclyglycerols they are extremely hydrophobic which means….
a large number of these molecules can be packed into a small volume because of their exclusion of water
Fatty acids experience temporary dipoles which results in the temporary polarization of other fatty acids and the subsequent _____ of these fatty acids. These van der waal forces ____ the boiling point of these fatty acids
attraction
increase
Why do saturated fatty acids have higher boiling points than unsaturated fatty acids?
The shape of the unsaturated fatty acids inhibits the tight packing of the fatty acids reducing intermolecular forces and therefore the boiling point
Define van der waals forces
The binding of temporarily polarized molecules because of the attraction of opposite charges.
Defien steroid
A type of lipid.
Like other steroids, cholesterol has a core composed of ____ carbon atoms bonded to form…
20
four fused rings, and it is hydrophobic.
What cell membranes is cholesterol a part of? What does it do?
animal cell membranes
it serves a precurser for the synthesis of steroid hormones (such as estrogen and testosterone)
Define phospholipid
A type of lipid and a major component of the cell membrane.
Phospholipids are a major component of….
the cell membrane
Define molecule
A substance made up of two or more atoms.
Define chemical bond
Any form of attraction between atoms that holds them together.
Define valance electrons
The electrons farthest from the nucleus, which are at the highest energy level.
Define molecular orbital
A merged orbital traversed by a pair of shared electrons.
Define covalent bond
A chemical bond formed by a shared pair of electrons holding two different atoms together.
Define double bond
A covalent bond in which covalently joined atoms share two pairs of electrons.
Define electronegativity
The ability of atoms to attract electrons.
Electronegativity increases as you go ____ across a row or ____ a column
right
up
Why does electronegativity increase going to the right across a row?
because the number of protons in the nucleus increases going to the right across a row
Define polar covalent bond
Bonds that do not share electrons equally.
Define nonpolar covalent bond
A covalent bond between atoms that have the same, or nearly the same, electronegativity.
Define ionic bond
The association of two atoms resulting from the attraction of opposite charges.
Define chemical reaction
The process by which molecules are transformed into different molecules.
Define reactants
Any of the starting molecules in a chemical reaction.
Define products
Any one of the transformed molecules that result from a chemical reaction.
What is the single most abundant molecule in cells?
water
Define polar
A molecule that has regions of positive and negative charge.
What two classes do molecules fall into based on their interactions with water?
hydrophilic
hydrophobic
Define hydrophilic
“Water loving”; describes a class of molecules with which water can undergo hydrogen bonding.
Define hydrophobic
“Water fearing”; describes a class of molecules poorly able to undergo hydrogen bonding with water.
hydrophilic compounds are ____; they dissolve readily in water
polar
Water is a good ____ as it is capable of dissolving many substances
solvent
Define aqueous
watery
Define nonpolar
Describes compounds that do not have regions of positive and negative charge.
hydrophobic compounds are _____
nonpolar
Define hydrophobic effect
The exclusion of nonpolar molecules by polar molecules, which drives biological processes such as the formation of cell membranes and the folding of proteins.
Define hydrogen bond
A weak bond between a hydrogen atom in one molecule and an electronegative atom in another molecule.
three fatty acid chains attached to glycerol form a _____, a lipid used for ____ ______.
triacylglycerol
energy storage
