bio b.1.2 proteins

proteins how much of the dry mass of a cell

2/3

amine group component

-NH2

amine group description

interacts with the carboxyl group of another amino acid by releasing a molecule of H2O when a dipeptide forms

side group symbol

R

side group description

an exchangeable chemical group which defines the properties of an amino acid, with 20 different types

how many types of amino acids can be made

20

-NH2

amine group

R

side group

Carboxyl group symbol

-COOH

-COOH

carboxyl group

carboxyl group description

the terminal that usually connects with the amino terminal of another amino acid in a condensation reaction

what does the r group determine

the properties of the amino acid, its polarity, charge, interactions with other parts of a protein

do all organisms use the same 20 amino acids to build their proteins

yes

what does every amino acid have

amine group, carboxyl group, hydrogen atom, r group

peptide bond formation

two amino acids join through a condensation reaction to form a dipeptide in the ribosome of a cell

process of peptide formation

An OH from the carboxyl group of one animo acid and an H from the amine group of the other are removed, forming one molecule of water

where does the peptide bond from between

the carbon of the carboxyl group and the nitrogen of the amine group

zwitterion

ionized form in water

ionized form in water carboxyl group

-COO^-

ionized form in water amine group

-NH3^+

why does the carboxyl group donate H^+ when ionizes in water

oxygen pulls electron strongly so the H^+ easily detaches

why does the amine group receive H^+ when ionizes in water?

nitrogen had a lone pair of electrons that attracts H^+

why do r groups alternate in polypeptides

to avoid steric hinderance, and keep the polypeptide backbone stable and linear

what is the n terminal

amine group

what is the c terminal

carboxyl group

other ways of n terminal

n terminus, n terminal end, amino terminus, amino end

other ways of c terminal

c terminus, c terminal end, carboxyl terminus, carboxyl end

amino acids

the monomer of proteins consisting of a central carbon bonded to an amine group, a carboxyl group, a hydrogen atom, and a variable R group

the monomer of proteins consisting of a central carbon bonded to an amine group, a carboxyl group, a hydrogen atom, and a variable R group

amino acids

dipeptides

a molecule of 2 amino acids synthesized in the ribosome via a condensation reaction, forming a peptide bond and releasing H2O

a molecule of 2 amino acids synthesized in the ribosome via a condensation reaction, forming a peptide bond and releasing H2O

dipeptides

oligopeptides

a short chain of 2 - 20 amino acids (including dipeptides) synthesized in the ribosome via condensation reactions (forming peptide bonds and releasing n-1 water molecules) that typically acts as a signaling molecule

a short chain of 2 - 20 amino acids (including dipeptides) synthesized in the ribosome via condensation reactions (forming peptide bonds and releasing n-1 water molecules) that typically acts as a signaling molecule

oligopeptides

polypeptides

a long linear chain of 21+ amino acids synthesized in the ribosome via condensation reactions (forming peptide bonds and releasing n-1 water molecules) the folds into a protein

a long linear chain of 21+ amino acids synthesized in the ribosome via condensation reactions (forming peptide bonds and releasing n-1 water molecules) the folds into a protein

polypeptides

proteins

a functional macromolecule made of one or more polypeptide chains folded into a specific 3D structure (determined by R-group interactions) to perform biological functions

eg of proteins

insulin, titin

smallest protein

insulin

insulin no of peptide chains and amino acids

1, 21 and 30

largest protein

titin

titin no of polypeptide chains and amino acids

1, 34350

ribosomes location

located either freely in the cytoplasm of a cell or membrane bound and associated with the rough endoplasmic reticulum (rough ER)

located either freely in the cytoplasm of a cell or membrane bound and associated with the rough endoplasmic reticulum (rough ER)

ribosomes

no of peptide bonds equal

no of released water molecules

no of released water molecules equal

no of peptide bonds formed

no of peptide bonds in a single polypeptide chain

n - 1

why is there only n-1 peptide bonds in a single polypeptide chain

the two ends remain unbranched

no of peptide bonds in a multiple polypeptide chain

(n1 - 1) + (n2 - 1) + …

why is there only (n1 - 1) + (n2 - 1) + … peptide bonds in a multiple polypeptide chain

each separate chain has its own two unbranched ends

what can plants do and animals can’t do

synthesize all 20 amino acid themselves

essential amino acids

these cannot be synthesized by the human body in sufficient quantities and must be obtained from the diet

these cannot be synthesized by the human body in sufficient quantities and must be obtained from the diet

essential amino acids

non essential amino acids

these can be synthesized by the body from other molecules, including other amino acids and metabolic intermediates

these can be synthesized by the body from other molecules, including other amino acids and metabolic intermediates

non essential amino acids

why are both essential amino acids and non essential amino acids needed

they are used to synthesize protein

how many essential amino acids

9

how many non essential amino acids

4

how many conditionally essential amino acids

7

essential amino acids list

histidine, lysine, methionine, phenylalanine, threonine, tryptophan, isoleucine, leucine, valine

conditionally essential amino acids

arginine, cysteine, glutamine, tyrosine, glycine, proline, serine

non essential amino acids

alanine, asparagine, aspartic acid, glutamic acid

classify: histidine

essential

classify: lysine

essential

classify: methionine

essential

classify: phenylalanine

essential

classify: threonine

essential

classify: tryptophan

essential

isoleucine

essential

classify: leucine

essential

classify: valine

essential

classify: arginine

conditionally essential

classify: cysteine

conditionally essential

classify: glutamine

conditionally essential

classify: tyrosine

conditionally essential

classify: glycine

conditionally essential

classify: proline

conditionally essential

classify: serine

conditionally essential

classify: alanine

non essential

classify: asparagine

non essential

classify: aspartic acid

non essential

classify: glutamic acid

non essential

where are most essential amino acids found

animal and dairy products

what do vegan people do

eat plant based alternatives or take supplements

alternatives: histidine

rice, wheat, potatoes

alternatives: lysine

beans, pistachios

alternatives: methionine

sunflower seeds, chia seeds

alternatives: phenylalanine

beans, pumpkins

alternatives: threonine

pumpkin, chia seeds

alternatives: tryptophan

sweet potatoes, oats

alternatives: isoleucine

cabbage, brown rice

alternatives: leucine

seaweed, peas

alternatives: valine

legumes, spinach

can vegan diets supply all essential amino acids?

yes

conditionally essential amino acids

amino acids that are normally non essential except during times of infancy (premature birth), illness, severe stress, or genetic disorders, when they must be obtained from the diet

why do amino acids become conditionally essential?

synthesizing these amino acids from other molecules require specific enzymes while the body lacks enough functional enzymes when they are ill

genetic code

how the amino acid sequence of each polypeptide is stored in a coded form in the base sequence

how the amino acid sequence of each polypeptide is stored in a coded form in the base sequence

genetic code

protein synthesis

how the dna base sequence of a gene is used to generate a polypeptide

how the dna base sequence of a gene is used to generate a polypeptide

protein synthesis

how many main processes do protein synthesis have

2