bio tek 2 protein

7/24/2019 Bio Tek 2 Protein

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AP Biology

Proteins


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Proteins

Most structurally & functionally diversegroup of biomolecules

Function:

involved in almost everything enzymes structure (keratin collagen!

carriers & transport (membrane channels!

receptors & binding (defense!

contraction (actin & myosin!

signaling (hormones!

storage (bean seed proteins!


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AP Biology

Proteins

"tructure: monomer # amino acids

$% different amino acids

polymer # polypeptide protein can be or more polypeptide chains

folded & bonded together

large & comple' molecules

comple' )* shape


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Amino acids

"tructure: central carbon amino group

carbo'yl group (acid! + group (side chain! variable group

confers uni,ue

chemical propertiesof the amino acid -.-/

/

/

0-1-

01-2/00

2

+


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.onpolar amino acids

nonpolar & hydrophobic

3hy are these nonpolar & hydrophobic4


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Polar amino acids

polar or charged & hydrophilic

3hy are these polar & hydrophillic4


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"ulfur containing amino acids

*isulfide bridges cysteines form cross links


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Building proteins

Peptide bonds: dehydration synthesis linking ./$of amino acid to

122/ of another

15. bond

peptidebond


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AP Biology

Building proteins

Polypeptide chains .)terminal # ./$end

1)terminal # 122/ end

repeated se,uence (.)1)1! is thepolypeptide backbone gro6 in one direction


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Protein structure & function

hemoglobin

function depends on structure )* structure

t6isted folded coiled into uni,ue shape

collagen

pepsin


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AP Biology

Protein structure & function

function depends on structure all starts 6ith the

order of amino acids 6hat determines that order of

amino acids4

78et9s go to the video tape;(play movie here!

lysozyme: enzyme in tears & mucus that kills bacteria

the % glycolytic enzymes

used to breakdo6n glucoseto make A


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Primary (=! structure

2rderof amino acids in chain amino acid se,uence

determined by *.A

slight change in amino acidse,uence can affect protein9s

structure & it9s function even >ust one amino acid change

can make all the difference


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"ickle cell anemia


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"econdary ($=! structure

78ocal folding; Ffolding along

short sections of

polypeptide interaction bet6eenad>acent amino

acids

/ bonds bet6een+ groups

)heli'

)pleated sheet


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"econdary ($=! structure


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AP Biology


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?uaternary (@=! structure

oins together more than polypeptide chain only then is it a functional protein

hemoglobin

collagen #

skin & tendons


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Protein structure (revie6!

=

$=

=

@=

aa se,uencepeptide bonds

+ groups

/ bonds

+ groupshydrophobic interactions

disulfide bridges

determinedby *.A

multiplepolypeptideshydrophobic

interactions


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AP Biology

1haperonin proteins

uide protein folding provide shelter for folding polypeptides

keep the ne6 protein segregated fromcytoplasmic influences


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Protein models

Protein structure visualized by C)ray crystallography

e'trapolating from amino acid se,uence

computer modelling

lysozyme


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*enature a protein

*isrupt = structure p/ salt

temperature

unravel or denatureprotein

disrupts / bonds ionic bonds &

disulfide bridges

"ome proteins can

return to theirfunctional shape

after denaturation

many cannot


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AP Biology

8et9s build some

Proteins


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Any ?uestions44

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