Types Of Proteins Flashcards
what are the two main types of protein?
- globular
- fibrous
what are some features of globular proteins?
- compact
- water soluble
- roughly spherical in shape.
how are globular proteins formed?
when proteins fold into their tertiary structure in a way whereby hydrophobic R groups of the amino acids are kept away from the aqeuous environment. hydrophilic R groups are on the outside so they are soluble in water.
what are globular proteins useful for?
- chemical reactions.
- immunity.
- muscle contractions.
what is an example of a globular protein?
insulin
what is the role of insulin?
involved in the regulation of blood glucose concentration.
why do hormones (insulin) need to be soluble?
they are transported in the bloodstream.
why do hormones need to have a specific shape?
they have to fit into the specific receptors on cell-surface membranes to have their effect.
what are conjugated proteins?
they are globular proteins that contain a non-protein component called a prosthetic group.
what is an example of a prosthetic group?
haem groups. catalase and haemoglobin both contain haem groups.
what is haemoglobin?
the red, oxygen carrying pigment found in red blood cells. It is a quaternary protein made up of two alpha and two beta subunits (haem group with each subunit.)
how does haemoglobin transport oxygen around the body?
iron 2 ions present in haem groups are able to combine reversibly with an oxygen molecule.
what is catalase?
an enzyme; a quaternary protein containing four haem groups
how many haem prosthetic groups does catalase contain?
4
what are some examples of fibrous proteins?
- keratin
- collagen
- elastin
how are fibrous proteins formed?
formed from long, insoluble molecules. this is due to the high proportion of amino acids with hydrophobic R-groups in their primary structure. amino acid structure quite repetitive.
what are features of fibrous proteins?
- strong
- long
- insoluble
- not folded into complex three dimensional shapes.
where is keratin present?
hair, skin, nails.
do more or less disulphide bonds make it more or less flexible?
less bonds - more flexible.
are disulphide bonds strong?
yes.
why does burnt skin/hair smell bad?
large presence of sulfur.
where are elastic fibres found?
walls of blood vessels and alveoli.
what is elastin?
a quaternary protein made from any stretchy molecules called tropoelastin.
