Lecture 2 Flashcards
what are the four steps of protein formation?
- primary
- secondary
- tertiary
- quaternary
what are proteins made of?
amino acids
what is the part that varies within amino acid structures?
the R group
what are the four main categories of amino acids?
acidic, basic, nonpolar, and uncharged polar amino acids
which type of amino acids makes disulphide bonds?
cysteine
how are peptide bonds formed?
when the oxygen of a carboxyl group of one amino acid reactions with the hydrogen of the amino group of an adjacent amino acid
what are the ends of polypeptide chains like?
an N terminus or amino group on one end and a C terminus or carboxyl group on the other end
why does the difference in primary amino acid sequences matter?
the unique sequence determines the unique structure and function of a protein
what is an alpha helix?
a spiral staircase protein structure
how are the hydrogen bonds in the alpha helix formed in terms of carbon number?
between every four amino acids
what are beta pleated sheets?
a flat arrangement of amino acids
how are hydrogen bonds formed in alpha helixes?
the hydrogen of one amino acid reacts with the oxygen in the carbonyl of an adjacent amino acid on the same strand
what are the R groups like in beta pleated sheets?
they alternate pointing up and down
what does antiparallel mean?
when the amino acids on one strand run in one direction and the amino acids on another strand run in the opposite direction
what are the two types of beta-pleated sheets?
- anti parallel
- parallel
what does parallel mean?
amino acids on both strands run in the same direction
how are hydrogen bonds formed in beta-pleated sheets?
the hydrogen of one amino acid reacts with the oxygen in the carbonyl of an adjacent amino acid on the opposite strands
what is the coiled coil?
when structures of alpha helixes wind around one another
what is the property of coiled coils?
amphipathic
what does amphipathic mean?
a molecule that has both hydrophobic and hydrophilic parts
what is the tertiary stage of protein formation?
a 3D folded structure of a protein
what forces hold the tertiary structure together?
- hydrophobic forces
- non-covalent parts
- disulphide bonds
what are non-covalent bonds?
bonds within a protein formed by weak attractions
what are hydrophobic interactions?
part of the protein that fears water
what are disulphide bonds?
a bond that forms between the sulphur of two cysteine groups in two different amino acids
why do proteins fold in a certain way in terms of energy?
they fold in a certain way that makes them most energetically stable
what proteins help in the shaping process of making proteins?
chaperone proteins
how many domains do eukaryotic proteins have?
two or more
what are protein domains?
a specialized part of the tertiary structure that is semi-independent
what are domains in eukaryotic proteins connected by?
intrinsically disordered sequences
what are protein families?
proteins that have similar amino acid sequences and 3D structures
how do protein domains play a role in protein evolution?
protein domains can be rearranged and altered during protein evolution
what do proteins in protein famlies do in terms of evolution?
evolve to have different structures
how are proteins in protein families similar in terms of domain structure?
they have similar domain structures even though they might have different overall structures
what is hemoglobin made of?
two subunits, 2 alpha and 2 beta
what are examples of different multiprotein complexes?
- actin filament;; structure with the same subunits
- viruses and ribosomes: structures made from different protein and DNA
- molecular machines; structures made of many different proteins to perform complex tasks
What is each subunit like in hemoglobin?
the subunits function independently
what are ways to study a protein in terms of purification?
electrophoresis and chromatography
what is a way to study the protein in terms of amino acid sequences?
mass spectroscopy
