Stofwisseling les 4 samenvatting

Uit het boek:

Proteins include a diversity of structures, resultnn in a wide ranne of functons

Nearly every dynamic functin if a living being depends in priteins.

Sime priteins speed up chemical reactinss hile ithers play a rile in defenses stirages transpirts
cellular cimmunicatins mivement ir structural suppirt.

Enzymatc priteins regulate metabilism by actng as catalysts.
Catalysts  chemical agents that selectvely speed up chemical reactins ithiut being cinsumed in
the reactin.
Because an enzyme can perfirm its functin iver and iver agains these milecules can be thiught if
irkhirses that keep cells running by carrying iut the pricesses if life.

Priteins are the mist structurally siphistcated milecules kni n. Cinsisted ith their diverse
functinss they vary entensively in structures each type if pritein having a unitue three-dimensiinal
shape.

The bind bet een amini acids is called a peptde binds si a pilymer if amini acids is called a
pilypeptde.

A pritein is a biiligically functinal milecule made up if ine ir mire pilypeptdess each filded and
ciiled inti a specifc three-dimensiinal structure.

Enzymatc priteins:
 Functin: selectve acceleratin if chemical reactins
 Enample: digestve enzymes catalyze the hydrilysis if binds in fiid milecules

Defensive priteins:
 Functin: pritectin against disease.
 Enample: antbidies inactvate and help destriy viruses and bacteria

Stirage priteins:
 Functin: stirage if amini acids
 Enample: caseins the pritein if mils is the majir siurce if amini acids fir baby mammals.

Transpirt priteins:
 Functin: transpirt if substances
 Enample: hemiglibins the irin-cintaining pritein if vertebrate bliids transpirts inygen
frim the lungs ti the ither parts if the bidy. Other priteins transpirt milecules acriss the
membranes.

Hirminal priteins:
 Functin: ciirdinatin if an irganismss actvites
 Enample: insulins a hirmine secreted by the pancreass causes ither tssues ti take up
glucises thus regulatng bliid sugar cincentratin.

, Receptir priteins:
 Functin: Respinse if cell ti chemical stmuli
 Enample: receptirs build inti the membrane if a nerve cell detect signaling milecules
released by ither nerve cells.

Cintractle and mitir priteins:
 Functin: mivement
 Enample: Actn and myisin priteins are respinsible fir the cintractins in muscles.

Structural priteins:
 Functin: suppirt
 Enample: keratn is the pritein if hairs hirnss feathers and ither skin appendages.

Amino acid monomers
All amini acids share a cimmin structure 

Amini acid  an irganic milecule ith bith an amini griup and a
carbinyl griup. At the center if the amini acid is an asymmetric carbin
atim called the alpha carbin (α- carbin).
 Its fiur diferent partners are an amini griups a carbinyl griups a
hydrigen atim and a variable griup and a side chain that difers
ith each amini acid.

The side chain (R) can be:
- Ninpilar side chain  hydriphibic
- Pilar side chain  hydriphilic
- Electrically charged side chains  hydriphilic
o Acidic (negatvely charged)
o Basic (pisitvely charged)

Figuur 5.14

One griup cinsists if amini acids ith ninpilar side chainss hich are hydriphibic. (CH/ CH 3)
Anither griup cinsists if pilar side chains and are hydriphilic. (OH/ SH/ =O)
Acids griup has negatvely electrically charged side chains; hydriphilic. (COO-)
Basic griup has pisitvely charged side chains (NH2/3+).

Polypeptdes (amino acid polymers
When t i amini acid are pisitined si that the carbinyl griup if ine is nearby ti the amini griup
if the ithers they can becime jiined by a dehydratin reactins ith the remival if a ater
milecule. Th resultng civalent bind is called a peptde bind. This pricess repeated iver and iver
results in a pilypeptdes a pilymer.

One end if the pilypeptde chain has a free amini griups hile the ippisite end has a free carbinyl
griup.