applied biochemistry

what are proteins made up of?

amino acids

all amino acids are chiral except:

glycine

a protein structure is categorized by

alpha carbon linked to: hydrogen, amino group, carboxylic acid, and r-side chain

chiral molecules

mirror images of each other but not superosed

all amino acids in proteins are:

L-stereomers

a smaller r-group means the AA is

more hydrophillic

glycine; nonpolar

alanine; nonpolar

proline; nonpolar

valine; nonpolar

leucine; nonpolar

isoleucine; nonpolar

methionine; nonpolar

serine; polar

threonine; polar

cysteine; polar

asparagine; polar

glutamine; polar

phenylalanine; aromatic

tyrosine; aromatic

tryptophan; aromatic

lysine; positively charged

arginine; positively charged

histidine; positively charged

aspartate; negatively charged

glutamate; negatively charged

what do disulfide bonds do?

links two parts of the polypeptide chain or two different chains

disulfide bonds of a polypeptide chain make

proteins more stable

insulin protein consists of:

2 polypeptide chains stabilized by 3 disulfide bonds between cysteines

what happens when a disulfide in within the same chain?

folding

proline is categorized as being the

only amino acid with cyclized sidechain

what neurotransmitters are derived from tryptophan?

melatonin and serotonin

how do antidepressants increase serotonin levels?

they inhibit proteins that reuptake serotonin

what neurotransmitters are derivatives of tyrosine?

catecholamine neurotransmitters: DOPA→ Dopamine → norepinephrine → epinephrine

what is DOPA is used to treat?

dystonia

dopamine deficiency associated with

depression and ADHD

high levels of dopamine associated with

psychosis and schizophrenia

low norepinephrine associated with

depression

depression can be treated by inhibiting the reuptake of which catecholamine transmitter?

norepinephrine

epinephrine is used to

treat cardiac arrest by boosting the supply of oxygen and glucose to the brain and muscles

creatinine levels will show

kidney function

how are amino acids linked through peptide bonds?

condensation or a dehydration reaction

one peptide bonds links

two amino acids

tertiary structures are

multiple secondary structures

what is the structure around an alpha carbon?

tetrahedral

Gly

glycine

G

glycine

Ala

alanine

A

alanine

Val

valine

Leu

leucine

L

leucine

V

valine

Ile

isoleucine

I

isoleucine

Met

methionine

M

methionine

Pro

proline

P

proline

Ser

serine

S

serine

Thr

threonine

T

threonine

Cys

cysteine

C

cysteine

Asn

asparagine

N

asparagine

Gln

glutamine

Q

glutamine

Phe

phenylalanine

F

phenylalanine

Trp

tryptophan

W

tryptophan

Tyr

tyrosine

Y

tyrosine

Asp

aspartic acid

D

aspartic acid

Glu

glutamic acid

E

glutamic acid

Lys

lysine

K

lysine

Arg

arginine

R

arginine

His

histidine

H

histidine

amino acid are read from

n-terminal to c-terminal

alpha helix is how many residuals long?

3.6 residues

what amino acid is a helix breaker?

proline

what form of beta sheet is more stable?

anti-parallel

what AA are often found in beta sheet?

glycine and proline

fibrous proteins

simple structures made of polypeptide chain arranged in long strands and sheets

what type of proteins provide support, shape and external protection to vertebrates?

fibrous proteins

what are examples of fibrous proteins?

collagen, keratin, elastin

what type of proteins consist of a single type of secondary structure and their tertiary?

fibrous proteins

what type of proteins are polypeptide chains folded into a spherical or globular shape?

globular proteins

what are examples of globular proteins?

enzymes, hemoglobin, and myoglobin

what is fibrous protein that is a left handed helix with 3 amino acids per turn?

collagen

Which statement correctly describes the structure and chirality of amino acids found in proteins?

The central carbon is attached to H, H₃N⁺, COO⁻, and a variable R group; all amino acids are chiral except glycine, and protein amino acids are L-stereomers

Which statement about peptide bonds and the structure of peptides is correct?

Peptide bonds are formed through a condensation (dehydration) reaction, and amino acid sequences are read from the C-terminus to the N-terminus.

Which of the following correctly distinguishes fibrous proteins from globular proteins

Fibrous proteins are arranged in long strands or sheets and generally provide structural support, while globular proteins fold into a compact shape and often perform functional roles such as enzymatic activity