1.5 Proteins & Nucleic acids Flashcards
Protein definition
A large molecule that consists of many amino acid subunits that are joined together by peptide bonds folded into a specific 3D shape
Nucleic acid definition
A blueprint for proteins that are synthesized in cells; stores hereditary information
All proteins are _________ that are composed of amino acid ________.
polymers; monomers
Amino acid definition
A molecule that contains a carboxyl group and an amino group; serves as the monomer subunit of proteins
Attached to the central carbon atom (beside the amino acid) is a variable side group, called an ___ ______, which gives each amino acid its distinct _____________.
R group; characteristics
There are __ different amino acid side groups, or ___ _____, ranging from a single hydrogen atom to complex carbon chains or rings
20; R groups
The one exception to the 20 different amino acid groups is the amino acid ______, which has a ring structure that includes the ______ and central carbon atoms.
proline; nitrogen
Among the polar side groups in amino acids, some carry a positive or negative _______ and
others act as _____ or _____.
charge; acids; bases
Many of the amino acid side groups contain a _______ functional group, such as -NH2, -OH,
-COOH, or -SH, which may interact with atoms located elsewhere in the same protein or with molecules and ions located ______ the protein.
reactive; outside
With few exceptions, all proteins in living things are an assembly of various numbers and
_________ of 20 different amino acids.
combinations
___ of these amino acids are considered
essential for humans because they can only be obtained from our ____. The rest can
be synthesized by the _____.
8; diet; cells
________ proteins provide much of the supportive framework of the cells
Structural
Defensive proteins called _________, which are found in the human body, help to fight off ________.
antibodies; infections
Hormones and other messenger chemicals in the cell are ______ proteins.
signal
Special proteins called ________ are largely responsible for making almost every __________ reaction possible. They _______ up the rate of chemical reactions.
enzymes; biochemical; speed
Structural protein function and example
Framework support
e.g. hair, tendons, and ligaments
Defensive protein function and example
Infection fighters
e.g. antibodies
Signal protein function and example
Messenger
e.g. hormones
Carrier protein function and example
Transport of materials
e.g. hemoglobin
Recognition and receptor protein function and example
Cellular markers
e.g. major histocompatibility complex
Enzyme protein function and example
Catalyst
e.g. amylase
Motile protein function and example
Movement
e.g. actin and myosin
Peptide bond definition
A covalent bond that links many amino acids into chains of subunits that make proteins.
Peptide bonds are formed by a ________ _______ reaction between the -NH2 group of one amino acid and the -COOH group of a second amino acid
dehydration; synthesis
An amino acid chain always has an group
at one end, called the __________, and a -COOH group at the other end, called the ____________
N-terminal end; C-terminal end
In cells, amino acids are added only to the
_____ end of the growing peptide strand.
-COOH
Peptide definition
A chain of amino acid subunits that are connected by peptide bonds
Polypeptide definition
A peptide with more than 50 amino acids
Protein definition
A protein is one or more polypeptides that are folded into a precise 3D shape.
True or false:
A protein can function without folding.
False
Only after folding occurs is the protein able to function.
The primary structure of a protein is the unique _______ sequence of its amino acids in
each __________ chain
linear; polypeptide
Changing even a single amino acid
in the primary structure will _____ the overall structure of the protein to some degree.
A single change can alter or even destroy the __________ function of the protein.
alter; biological
The possible combinations of lengthy primary structures are virtually _________.
limitless
Most polypeptides have portions that repeatedly _____ or fold into patterns and contribute to the overall _____ of a protein.
coil; shape
This secondary structure is the result of __________ bonding between different parts of the same amino acid _________.
hydrogen; backbone
Two common secondary structures are the _____-pleated (or ß-pleated) sheet and the ______-helix (or a-helix)
beta; alpha
A B-pleated sheet forms by a side-by-side _________ of the amino acid chain. B-pleated sheets play an important role in the strength of ______.
alignment; silk
An a-helix is a delicate ____ that is held together by ________ bonds between every _____ amino acid.
coil; hydrogen; fourth
An a-helix is found in ____ proteins and _______________ proteins, and it provides the necessary _________ for their functions.
thin; transmembrane; structure
The secondary structure of a protein is the result of _________ between atoms in the _________.
interactions; backbone
The tertiary structure of a protein is the overall ___ _______ of a protein due to a range of interactions among the amino acid _________
3D shape; R groups
It is in the tertiary structure that the interactions of the R groups determine the 3D _____ of the __________ chain.
shape; polypeptide
Hydrophobic interactions definition
Hydrophobic interactions are the interaction of non-polar side groups that cluster together as a
result of other amino acid R groups interacting with water.
Disulfide bridge definition
A disulfide bridge is the bond that is formed when the -SH groups of two cysteine amino acids line up and react to form an S-S covalent bond.
This is a strong bond that holds 2 parts of the
polypeptide strand together, stabilizing its shape.
The tertiary structure is critical to
the ________ of proteins, especially _______.
functions; enzymes
Extreme conditions (such as temperature and pH) can _______ a protein, causing _______
unfold; denaturation
Denaturation definition
The loss of both the structure and function of a protein
Many proteins are composed of ____ polypeptides that come together to form the final functional proteins. This quaternary structure, which forms _______, exists
in many proteins.
2+; subunits
The same bonds and forces that fold _____ polypeptide chains into tertiary structures (including hydrogen bonds, polar and non-polar attractions and disulfide linkages) also hold the ______ polypeptide chains together.
single; multiple
Besides properly folded polypeptide chains, many proteins require _________ components, called ________ groups, to function.
non-protein; prosthetic
Prosthetic group example
One example is found in hemoglobin, the major protein that is involved in transport in vertebrates.
In hemoglobin, the 4 polypeptides don’t bind the oxygen (it’s bound to heme groups, surrounded and held by polypeptides)
Each polypeptide chain contains 1 heme ring, in which there is a single iron (Fe2+) ion.
Therefore, there are 4 heme groups per hemoglobin, and 4 are carried.
Many enzymes require prosthetic groups that contain ______ ions in order to function.
For example, some enzymes that are involved the process of cellular respiration require ______ ions.
metal; Mg2+
The _______ of a protein influences and enables its _________.
shape; function
Give an example of how shape influences a protein’s function
For example, long linear proteins align to form the strong fibres of silk, collagen, and keratin. This long linear formation provides the strength.
Compact globular proteins, such as the hemo
globin protein, are good for transport. Their shape enables them to be carried efficiently through red blood cells and the body.
Enzymes and antibodies have special _______ that _____ specific molecules, allowing these proteins to carry out their ________.
pockets; bind; function
DNA
stores hereditary information responsible for inherited traits in all eukaryotes, prokaryotes and many viruses.
RNA
-hereditary molecule of some viruses
-several different forms of RNA involved in
protein synthesis in all cells.
All nucleic acids are ________ of units called ___________.
polymers; nucleotides
Nucleotide definition
Building block of nucleic acids; consists of a 5- carbon sugar, a nitrogenous base, and one to three phosphate groups linked together by covalent bonds
In a nucleotide, each nitrogenous base links covalently to a 5- carbon sugar, either ________ or ________.
The two sugars differ only in the chemical group that is bound to the 2’-carbon: deoxyribose has an ___, and ribose has an ____ group.
deoxyribose; ribose; -H; -OH
What are the 2 types of nitrogenous bases?
Pyrimidines and purines
Pyrimidines
-single organic rings
-high nitrogen content
uracil (U), thymine (T), and cytosine (C)
Purines
-two-ringed organic structures
-high nitrogen content
adenine (A) and guanine (G)
DNA and RNA consist of chains of nucleotides, called __________ chains, with one nucleotide linked to the next by a single bridging ________ group between the 5’- carbon of one sugar and the 3’-carbon of the next sugar in line.
This type of linkage is called a _________ bond.
polynucleotide; phosphate; phosphodiester
Phosphodiester bond definition
A link formed between nucleotides by a
phosphate bridge
The arrangement of the alternating sugar and phosphate groups forms the ________ of a ______ ____ chain.
backbone; nucleic acid
In a ___ chain, each nucleotide contains _________, a phosphate group, and one of the four bases A, T, G, or C.
DNA; deoxyribose
In an ___ chain, each nucleotide contains _______, a phosphate, and one ofthe four bases A, U, G, or C.
RNA; ribose
DNA is a double-stranded molecule in which the two strands of DNA run _________
to each other.
This means that they are oriented in the ________ direction relative to the sugar-phosphate backbone.
antiparallel; opposite
In a sugar phosphate backbone, the end with the phosphate group is referred to as the
___ end, and the opposite end of the same strand, with the deoxyribose sugar, is referred to
as the ___ end.
5’; 3’
Bases on _________ strands of DNA hydrogen bond to one another to form ______________ DNA molecule
opposite; double-stranded
G (guanine) forms __ hydrogen bonds
with C (cytosine), and A (adenine) forms __ hydrogen bonds with T (thymine).
3; 2
As base pairs form between two strands of DNA, the molecule is twisted into a double ____
helix
RNA takes on a greater _______ of structures. RNA structures include relatively short _____ forms, as well as structures that ____ back on themselves in clover or hairpin formations.
variety; linear; fold
Nucleotides perform many functions in cells, in addition to serving as the _______ ______ of nucleic acids.
building blocks
Two nucleotides in particular, adenosine triphosphate (ATP) and guanosine triphosphate (GTP), are the primary molecules that ________ chemical energy from one ________ system to another. These nucleotides also regulate and adjust _______ activity.
transport; reaction; cellular
4 major types of biological molecules:
carbohydrates, lipids, proteins, and
nucleic acids.
What groups of atoms are found in amino acids?
All amino acids contain an amine group, carboxylic acid, and an R group.
Describe the difference between the primary and secondary protein structures.
Primary protein structure is linear sequence of order of amino acids.
Secondary protein structure is the result of hydrogen bonding between different parts of the same amino acid backbone.
Explain why it is necessary for a protein to adopt specific tertiary and quaternary arrangements.
For proteins to function properly, they need to fold into very specific 3D shapes (tertiary structure) and may require the assembly of multiple polypeptides (quaternary structure).
Explain the role of hydrogen bonding and disulfide bonds between R groups.
Hydrogen and disulfide bonds help to maintain proper secondary and tertiary structure—i.e., they are responsible for the shape of the polypeptide.
List some of the different types of proteins and their functions. Identify specific applications of these proteins in various living organisms.
Structural proteins provide framework support. Examples in animals are spider web silk proteins and eggshells. Defensive proteins fight off infection. Examples in animals are antibodies. Signal proteins are chemical messengers. Examples in animals are hormones.
Relate the diversity in protein structure to the diversity in its function.
There are 20 different amino acids. They represent an almost limitless number of combinations for different proteins.
This factor and the ability of amino acids along the backbone of a protein molecule to make various combinations of hydrogen, disulfide bonds, and non-polar configurations leads to tremendous diversity of shape of proteins and therefore function.
What is the role of the sugar and phosphate groups in the structure of nucleic acids?
Sugar and phosphate groups form the backbone of a nucleic acid molecule.
Explain the similarities and differences between DNA and RNA.
DNA is double stranded and RNA is a single stranded molecule. Nitrogenous bases in DNA are G (guanine), A (adenine), T (thymine), C (cytosine) Nitrogenous bases in RNA are G, A, U (uracil), and C. DNA almost always forms a double helix while RNA can take on a variety of configurations.
How does the function of nucleic acids differ from that of other types of macromolecules?
Other macromolecules have a large number of structures and functions.
Nucleic acids have only one function – working together to make proteins.
Your biology teacher tells you that nucleic acids, fatty acids, and amino acids can increase the H+ concentration of a solution. Explain how this is possible.
When nucleotides contain at least one phosphate group and they break down, they produce phosphoric acid.
Fatty acids break down and produce ketone bodies that are acidic.
Amino acids containing sulfur in their R group will produce sulfuric acid when they break down.
In each case, there is a change in the concentration of hydrogen ions in solution.
proteins
carry out vital structural and functional roles
what are proteins made of?
proteins are polymers that are made up of amino acid monomers
amino acid
a molecule that consists of a carboxyl group and an amino group; building blocks of proteins.
essential amino acids
amino acids that need
to be acquired through diet (8 amino acids)
Non-Essential Amino Acids
amino acids that can be made in the body (12 amino acids)
protein
large molecules made up of amino acids with a distinct 3D shape
building proteins
Proteins are built by attaching Amino Acids
into chains
Amino acids are connected by attaching a NH2
group to a COOH group by Dehydration
Synthesis
The resulting bond is called a Peptide Bond
peptide
a term used to describe a chain of amino acids
polypeptide
a peptide with more than 50 amino acids
primary structure
chain of amino acids
Changing even ONE
amino acid in the chain
can alter/destroy the
final structure/function
of the protein
second structure
the coiling/folding of
amino acid chains
Occurs because of hydrogen bonding between different amino acids
tertiary structure
folding of protein caused by
R-group interactions
quaternary structure
linking several separate
polypeptide chains
What causes proteins to no longer function?
changes in pH and temp can alter the shape of proteins causing them to no longer function
denaturation
the loss of both the structure and function of a protein
True or false
Proteins can also bond with non-protein structures
true
How does hemoglobin carry oxygen?
Hemoglobin carries oxygen with the help of four Heme Groups
which contain Iron
Nucleic acids
Nucleic Acids serve as the assembly instructions for all proteins in living organisms.
Two types: DNA and RNA
DNA stores hereditary information
RNA is involved in protein synthesis and is the
hereditary molecule of some viruses
Nucleotides
All nucleic acids are
polymers of nucleotides
Nucleotides consists of
a sugar, phosphate
group, and a
nitrogenous base
DNA and RNA are chains of nucleotides, joined together by the ________ and the
______ by _____________
phosphate; sugar; phosphodiester bonds
DNA molecules are _________, contains nitrogen bases A,T,G,C, and _________ sugar
double stranded; deoxyribose
RNA molecules are __________, contains nitrogen bases A,U,G,C, and ______ sugar
single stranded; ribose
Adenosine triphosphate (ATP) and Guanosine triphosphate (GTP) are that _________that transport energy from one ______ system to another
nucleotides; reaction
