b1.2 proteins Flashcards
what are proteins
complex macromolecules composed of one or more chains of amino acids
what roles do proteins have
structural support, catalysis and signalling pathways
what are amino acids
monomers that are used to make proteins.
how many unique amino acids are there
20
structure of a amino acid
central carbon= alpha carbon
covalently bonded with a
carboxyl group (-COOH)
an amino group (-NH2)
a hydrogen atom (-H)
a unique organic side chain (R-group)
how do amino acids join together
condensation reaction
a peptide bond is formed when (-COOH) of one amino acid and the amino group (-NH2) of another amino acid join) forming dipeptide (C-N) releasing water
is the covalent bond strong
yes
what does the N terminal represent
free amino group
what does the C terminal represent
carboxyl group
polypeptides
a chain of amino acids that is linked together by peptide bonds
what is a essential amino acid
amino acids that your body cannot produce and therfore must be obtained by the food that you eat
what are essential amino acids used for
maintenance and repair of body tissues
non essential amino acids
Amino acids that can be produced by the body from other amino acids or by the breakdown of proteins.
why is there an infinite variety of possible peptide chains
ability to combine the 20 different amino acids in any sequence. This allows for creation of an almost limitless number of unique proteins with different structures and functions.
what is a protein
complex, three-dimensional structure that is made up of one or more polypeptide chains
n protein composed of only 1 polypeptide chain
the amino acids will interact with each other, folding the chain into a functional protein.
In proteins composed of more than one polypeptide,
the polypeptide chains can additionally interact with each other, contributing to the overall structure of the protein.
denaturation
A process in which the structure of a protein is altered, causing it to lose function, usually permanently.
2 factors that cause denaturation of proteins
proteins and PH
what are all enzyme
proteins
what happens with extreme changes in pH
in pH can affect protein solubility and shape by altering the protein’s charge. This can lead to irreversible changes in protein structure, causing inactivity.
what do high temperatures cause for proteins
High temperatures can break the weak hydrogen bonds holding the protein structure together, causing the protein to unfold and lose function.
what is the r group
R-group is what gives each amino acid its unique characteristics.
Hydrophobic R-groups
are non-polar and tend to repel water molecules.
Hydrophilic R-groups
are polar or charged, acidic or basic, and tend to attract water molecules.
4 levels of protein structure
primary structure
secondary structure
tertiary structure
quaternary structure.
primary structure of proteins
Structure of a protein that refers to the specific sequence of amino acids that are joined together to form a polypeptide chain.change in the sequence of amino acids may result in significant changes to the protein’s structure and function
secondary structure of proteins
Structure of a protein that refers to the local folding patterns that occur within the polypeptide chain.
either:
alpha helices or beta pleates sheets
This is achieved through hydrogen bonding between the carboxyl group of one amino acid and the amino group of another amino acid in a different part of the polypeptide chain.
hydrogen bonds on their own are weak but become strong
alpha helix
the hydrogen bond forms between the amine hydrogen of one amino acid and the carboxyl oxygen of another amino acid that is four residues away in the sequence
beta pleated sheet
ections of the polypeptide chain run parallel to each other, and hydrogen bonds form between adjacent strands.
tertiary structure of proteins
Structure that gives rise to the overall three-dimensional shape of the protein.
what is the tertiary structure dependant on
It is dependent on the interaction between R-groups, which may include the formation of hydrogen bonds, ionic bonds, disulfide covalent bonds and hydrophobic interactions
quaternary structure
links polypeptide chains to form a single large complex protein.
protein structure os primary
has peptide bond and is linear
secondary protein structure
peptide bond, hydrogen bond
tertiary protein structure
peptide bond, hydrogen bond, disulfide bridge, ionic bond, hydrophobic interaction
into a fibrilor or globular structure
what are fibrous proteins
structural roles in the body
long molecules
usually insoluble in water
have seconday structure with many a-helices with hydrogen bonds
examples of fibrous proteins
collagen and keratin
globular proteins
complex rounded 3 dimensional shape
either tertiary or quaternary structure
soluble in water
enzymes such as pepsin and antibodies
examples of globular proteins
myglovbin and hemoglobin
