Amino Acids & Peptide bonds

Question 1

pH

Answer 1

a measure of hydrogen ion concentration; a measure of the acidity or alkalinity of a solution.

• 0-14 scale
• 7 is neutral
• 14 is very basic

Question 2

Acid

Answer 2

• have a sour taste

* have a pH of less than 7.

Question 3

base

Answer 3

substances that accept protons from acids

Question 4

alkaline

Answer 4

basic, if its hydrogen ion concentration is less than its hydroxyl ion concentration.

Question 5

macromolecule

Answer 5

A large complex molecule, such as nucleic acids, proteins, carbohydrates, and lipids, with relatively large molecular weight

Question 6

polymer

Answer 6

made from monomers linked by chemical bonds.

Carbohydrates - composed of sugar monomers and necessary for energy storage.

Lipids - include fats, phospholipids and steroids. Lipids help to store energy, cushion and protect organs, insulate the body and form cell membranes.

Proteins - composed of amino acid monomers and have a wide variety of functions including molecular transport and muscle movement.

Nucleic Acids - include DNA and RNA. Nucleic acids contain instructions for protein synthesis and allow organisms to transfer genetic information from one generation to the next.

Question 7

monomer

Answer 7

molecule that forms the basic unit for polymers. Monomers may bind to other monomers to form a repeating chain molecule.

Question 8

amino acid

Answer 8

the building blocks of proteins.

Question 9

amino group

Answer 9

amines

Question 10

carboxyl group

Answer 10

consisting of a carbon atom double bonded to an oxygen atom and single bonded to a hydroxyl group…has a hydroxyl group (O-H) attached to the carbon atom.

The carboxyl group is commonly written as -C(=O)OH or -COOH.

Question 11

side group

Answer 11

R chain

Question 12

polar covalent bond

Answer 12

Bonds that are partly ionic

Question 13

nonpolar covalent bond

Answer 13

equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.

Question 14

polypeptide

Answer 14

large number of amino-acid residues bonded together in a chain, forming part of (or the whole of) a protein molecule.

Question 15

peptide bond

Answer 15

a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). This is a dehydration synthesis reaction (also known as a condensation reaction), and usually occurs between amino acids.

Question 16

N-terminal end

Answer 16

the start of a protein or polypeptide terminated by an amino acid with a free amine group (left side)

Question 17

C-terminal end

Answer 17

the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH)

Question 18

Difference between an acidic and basic solution

Answer 18

Acidic solutions have a low pH, under 7.0, while basic solutions have a pH of over 7.0

Question 19

Why are the amino group and carboxyl group on an amino acid are charged at pH 7?

Answer 19

neutral pH and are therefore strongly hydrophilic

Question 20

Explain what pH means and what is happening to a solution as its pH changes?

Answer 20

The pH scale measures how acidic or basic a substance is. pH is defined as the negative logarithm of the hydrogen ion concentration

Question 21

The difference between a polar and nonpolar amino acid.

Answer 21

Polar amino acids can again classify as positively charged and negatively charged amino acids.Non Polar Amino Acids have equal number of amino and carboxyl groups and are neutral. These amino acids are hydrophobic and have no charge on the ‘R’ group. The amino acids in this group are alanine, valine, leucine, isoleucine, phenyl alanine, glycine, tryptophan, methionine and proline.

Question 22

The relationship between an amino acids, proteins, polypeptides, and peptide bonds.

Answer 22

Amino acids are the basic unit of proteins.
Amino acids linked together by a peptide bond forms a chain of amino acids called a polypeptide. When the amino acids from different parts of the chain interact with each other and form hydrogen bonds, the polypeptide chain takes on a unique shape, forming a protein.

Question 23

Why a protein has one Amino(N)-terminus and one Carboxyl(C)-terminus

Answer 23

Amino acids link to one another by peptide bonds which form through a dehydration reaction that joins the carboxyl group of one amino acid to the amine group of the next in a head-to-tail manner to form a polypeptide chain.
5’ to 3’

Question 24

How changing one or more amino acids in human CFTR can cause cystic fibrosis

Answer 24

Mutations affect the composition of the mucus layer lining the epithelial surfaces in the lungs and pancreas. The disruption of ion transport affects the salt concentration in sweat which is used in the CF “sweat test.”

Question 25

How changing one or more amino acids in human CFTR can cause it to transport a completely different
molecule, transforming CFTR into some other member of the ABC transporter family

Answer 25

Gene encodes a member of the ATP-binding cassette (ABC) transporter superfamily. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies. This protein is a member of the MRP subfamily that is involved in multi-drug resistance. The encoded protein functions as a chloride channel and controls the regulation of other transport pathways. Mutations in this gene are associated with the autosomal recessive disorders cystic fibrosis and congenital bilateral aplasia of the vas deferens.

Question 26

Why the CFTR proteins in other animals have slightly different amino acid sequences when compared to each
other and to humans.

Answer 26

Different number of amino sequence.

Question 27

What are the 9 “Essential” amino acids? What is special

about them?

Answer 27

Essential amino acids cannot be made by the body. As a result, they must come from food. The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.