PRE FI: LAB SHEETS (PROTEIN STRUCTURE) Flashcards
ELEMENTS (ATOMS) PRESENT IN PROTEINS
- NITROGEN
- CARBON
- OXYGEN
- HYDROGEN
Amino acids found in proteins are always ________ amino acids
ALPHA
an amino acid in which the amino group and the carboxyl group are attached to the 𝛼 carbon
𝛼-amino acid
what distinguishes one amino acid from another?
R GROUP OR SIDE CHAIN
What types of food are rich in protein?
- 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)
What are the building blocks (monomers) of proteins?
AMINO ACIDS
How many different building blocks are there in total?
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
What types of bonds connect these building blocks?
PEPTIDE BOND - a covalent link with another amino acid
What is a byproduct of forming the bonds?
H2O (WATER)
What is a chain of amino acids called?
POLYPEPTIDE
Why are there so many different shapes of proteins?
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
What type of catalyst is made of proteins?
ENZYMES -speed up biochemical reactions
_________ are made of proteins and help fight disease.
ANTIBODIES
__________ are made of proteins and help you feel emotions.
HORMONES
Give three functions of proteins. Briefly discuss each.
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.
What is the structure of a protein?
A SEQUENCE OF AMINO ACIDS LINKED TOGETHER TO FORM POLYPEPTIDE CHAIN
What can we do to separate individual amino acids in a protein?
Amino acids can be separated CHROMATOGRAPHY
peptide bonds or disulfide bridges
- covalent bond between the amino and carboxyl groups of 2 different amino acids
PEPTIDE BONDS
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
DISULFIDE BRIDGES
an unbranched chain of amino acids
PEPTIDE
Amino acids are a class of chemical compounds containing 2 functional groups:
● a carboxyl group – COOH
● an amine – NH2
Amino acids are classified according to the charge of their
residue:
● 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
Two main categories of proteins are formed:
- the protein folds into a compact structure
GLOBULAR PROTEINS
Two main categories of proteins are formed:
- the protein forms a long, narrow, and often very rigid structure
FIBROUS PROTEINS
Foldings
Proteins spontaneously fold, always in the same manner.
The optimal spatial arrangement is determined by ________ and by ________ & _________ charges on the amino acids.
- steric hindrance
- positive and
negative
Some proteins are made up of several independent chains of amino acids, called ________, that are co-assembled.
subunits
- 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.
Oligomeric proteins
CELLULAR FUNCTION
they allow a cell to maintain its spatial organization. Example: collagen
STRUCTURAL PROTEINS
CELLULAR FUNCTION
they modulate the activity of other proteins. Example: transcription factors
REGULATORY PROTEINS
BIOCHEMICAL FUNCTIONS OF PROTEINS
● Proteins with enzymatic activity. Example: DNA polymerase
● Ribonucleoprotein complexes, composed of RNA and proteins. Example: a ribosome
defining the role of a given protein in a cell or organism
CELLULAR FUNCTION
defining the activity of proteins at the
molecular level.
BIOCHEMICAL FUNCTIONS
