2.2 Proteins Flashcards
Protein facts
- make up 50% of organic material in cell
- Made of carbon, oxygen, hydrogen and nitrogen (sulphur=some)
-used in many structural reasons
-used as carriers
used as enzymes
-used s hormones
-used as antibodies
collagen
-used in skin and ligaments
keratin
found in nails
monomers of proteins
amino acids
amino acid structure
- amine group which is NH2
- carboxyl group which is COOH
- C in centre and H
-variable R group- different for each amino acid- make it what it is
condensation reaction in proteins
- 2 molecules join together
- create a new bond called a peptide bond
- release water
peptide bond
primary structure
made out of OH group of a carboxyl group and H of an Amine group
primary structure
the specific sequence of amino acids in a protein
hydrolysis
-water is added and bond is broken
secondary structure
the coiling and pleating of parts of the polypeptide make alpha helixes and beta-pleated sheets
-this occurs because of hydrogen bonds
tertiary structure
the overall 3D structure of the protein
4 types of bonding affecting shape of protein (tertiary structure
- Disulphide bonds/bridges
- hydrogen bonds
- Ionic bonds
- hydrophilic/hydrophobic interactions
Disulphide bonds/bridges
- occurs between amine groups that have sulphur in (e.g. cysteine)
- double bond between 2 sulfurs
hydrogen bonds
-between delta negative and delta positive R’s
Ionic bonds
-between completely ionic R groups
difference between hydrophobic and hydrophilic
- hydrophobic away from water
- hydrophilic towards water
globular proteins
- rolled into balls
- usually soluble
- metabolic roles
- Enzymes, antibodies, haemoglobin
fibrous proteins
- Form fibres
- usually insoluble
- structural roles
- Collagen, Keratin
Quaternary structure
- proteins made of more than one polypeptide
- (e.g. haemoglobin, collagen)
haemoglobin
- globular
- Soluble
- Many amino acids
- Prosthetic group (haem)
- alpha helix
-2 alpha 2 beta polypeptide chains
collagen
- fibrous
- insoluble
- 35% glycine
- no prosthetic group
- left-handed helix structures
prosthetic group
-group that helps the molecule work
-non-protein element
protein can function without it
haem
- prosthetic group in haemoglobin
- conatisn iron which binds with oxygen as haemoglobin carries oxygen
collagen structure
- 3 polypeptide chains coiled
- provides tensile strength
- hydrogen bonds form between them
- covalent cross links between different collagen molecules
- flexible
fibril
lots of protein molecules covalently bonded together
how 2 amino acids join together?
peptide bonds form between H (from amine) and OH from a different carboxyl group in a condensation reaction where water is released
how R groups interact to form tertiary structure of a protein?
-Some R groups attract/repel
- Disulphide bonds (S=S) between cysteine
- Hydrogen bonds
- Ionic bonds
- Hydrophobic R groups, inside
- Hydrophilic R groups, outside
properties of collagen that make it suitable for its purpose
- high tensile strength
- not elastic
- insoluble
- flexible
cations:
- calcium ions (Ca2+)
- sodium ions (Na+)
- potassium ions (K+)
- hydrogen ions (H+)
- ammonium ions (NH4+)
anions:
- nitrate (NO3–)
- hydrogencarbonate (HCO3–)
- chloride (Cl –)
- phosphate (PO43–)
- hydroxide (OH–)
