PRE FI: LAB SHEETS (PROTEIN STRUCTURE)

Question 1

ELEMENTS (ATOMS) PRESENT IN PROTEINS

Answer 1

• NITROGEN
• CARBON
• OXYGEN
• HYDROGEN

Question 2

Amino acids found in proteins are always ________ amino acids

Answer 2

ALPHA

Question 3

an amino acid in which the amino group and the carboxyl group are attached to the 𝛼 carbon

Answer 3

𝛼-amino acid

Question 4

what distinguishes one amino acid from another?

Answer 4

R GROUP OR SIDE CHAIN

Question 5

What types of food are rich in protein?

Answer 5

• MEAT (beef, pork)
• POULTRY (chicken, duck, lamb)
• FISH AND SEAFOOD (pawn, crab, lobsters, scallops)
• DAIRY PRODUCTS (milk, cheese)
• NUTS & SEEDS (almonds, walnuts, cashew, sunflower seeds
• LEGUMES & BEANS (chickpeas, split peas, tofu)

Question 6

What are the building blocks (monomers) of proteins?

Answer 6

AMINO ACIDS

Question 7

How many different building blocks are there in total?

Answer 7

20 DIFFERENT AMINO ACIDS
- 11 are non - essential since they can be synthesized by our body
- 9 are essential since they cannot be synthesized by our body

Question 8

What types of bonds connect these building blocks?

Answer 8

PEPTIDE BOND - a covalent link with another amino acid

Question 9

What is a byproduct of forming the bonds?

Answer 9

H2O (WATER)

Question 10

What is a chain of amino acids called?

Answer 10

POLYPEPTIDE

Question 11

Why are there so many different shapes of proteins?

Answer 11

THE POLYPEPTIDE CHAINS’ AMINO ACID SEQUENCE DETERMINE THE SHAPE OF A PROTEIN.
- the similar characteristics of amino acid side chain and their interactions with the surroundings cause proteins to fold

• DIFFERENT AMINO ACIDS

Question 12

What type of catalyst is made of proteins?

Answer 12

ENZYMES -speed up biochemical reactions

Question 13

_________ are made of proteins and help fight disease.

Answer 13

ANTIBODIES

Question 14

__________ are made of proteins and help you feel emotions.

Answer 14

HORMONES

Question 15

Give three functions of proteins. Briefly discuss each.

Answer 15

PROTEIN FUNCTION AS:

~ ENZYMES - it speeds up biochemical reaction
~ HORMONES - chemical signals an organism secretes and affect how the body work
~ CELL RECEPTORS - folded protein structures that is attached to the signaling molecules on the cell surface to receive or transmit signals.

• It is used to build muscles and organs, to make hormones and antibodies, to be stored as fat, and to be burned as energy.

Question 16

What is the structure of a protein?

Answer 16

A SEQUENCE OF AMINO ACIDS LINKED TOGETHER TO FORM POLYPEPTIDE CHAIN

Question 17

What can we do to separate individual amino acids in a protein?

Answer 17

Amino acids can be separated CHROMATOGRAPHY

Question 18

peptide bonds or disulfide bridges
- covalent bond between the amino and carboxyl groups of 2 different amino acids

Answer 18

PEPTIDE BONDS

Question 19

peptide bonds or disulfide bridges
- covalent bond that forms when 2 CYSTEINES combines to generate CYSTINE
- the covalent bond formed between the sulfur atoms of two cysteines in a protein to form a cystine - oxidation

Answer 19

DISULFIDE BRIDGES

Question 20

an unbranched chain of amino acids

Answer 20

PEPTIDE

Question 21

Amino acids are a class of chemical compounds containing 2 functional groups:

Answer 21

● a carboxyl group – COOH
● an amine – NH2

Question 22

Amino acids are classified according to the charge of their
residue:

Answer 22

● HYDROPHOBIC AMINO ACIDS
Gly, Ala, Val, Leu, Ile, Met, Phe, Trp, Pro
● NEUTRAL AMINO ACIDS (NON-CHARGED but polar)
No ionisable groups in the residue
Ser, Thr, Cys, Asn, Gln, Tyr
● ACIDIC AMINO ACIDS (NEGATIVELY charged at a
physiological pH)
–COOH group in the residue, ionised in into –COO- at
a cellular pH
Asp, Glu
● BASIC AMINO ACIDS (POSITIVELY charged at a
physiological pH)
–NH2 group in the residue, ionised into –NH3 + at a
cellular pH
Lys, Arg, His

Question 23

Two main categories of proteins are formed:
- the protein folds into a compact structure

Answer 23

GLOBULAR PROTEINS

Question 24

Two main categories of proteins are formed:

• the protein forms a long, narrow, and often very rigid structure

Answer 24

FIBROUS PROTEINS

Question 25

Foldings
Proteins spontaneously fold, always in the same manner.
The optimal spatial arrangement is determined by ________ and by ________ & _________ charges on the amino acids.

Answer 25

• steric hindrance
• positive and
  negative

Question 26

Some proteins are made up of several independent chains of amino acids, called ________, that are co-assembled.

Answer 26

subunits

Question 27

• Some proteins are made up of several independent chains of amino acids, called
  subunits, that are co-assembled.
• This association often forms a symmetrical complex consisting of 2 to 4 identical
  lsubunits.
  Example: a hemoglobin molecule is assembled from 2 α subunits, and 2 β
  subunits.

Answer 27

Oligomeric proteins

Question 28

CELLULAR FUNCTION
they allow a cell to maintain its spatial organization. Example: collagen

Answer 28

STRUCTURAL PROTEINS

Question 29

CELLULAR FUNCTION
they modulate the activity of other proteins. Example: transcription factors

Answer 29

REGULATORY PROTEINS

Question 30

BIOCHEMICAL FUNCTIONS OF PROTEINS

Answer 30

● Proteins with enzymatic activity. Example: DNA polymerase
● Ribonucleoprotein complexes, composed of RNA and proteins. Example: a ribosome

Question 31

defining the role of a given protein in a cell or organism

Answer 31

CELLULAR FUNCTION

Question 32

defining the activity of proteins at the
molecular level.

Answer 32

BIOCHEMICAL FUNCTIONS