The genetic code

Question 1

What does an amino acid look like?

Answer 1

. R
I
H2+N–C—COO-
I
H

Question 2

What is a peptide bond?

Answer 2

A peptide bond is formed from a condensation reaction between the carboxyl group of one amino acid and the amino group of the adjacent amino acid.

Question 3

What does a peptide bond look like?

Question 4

What is the difference in genetic code from protein to RNA?

Answer 4

RNA consists of four nucleotides - A U G C
Protein consists of 20 amino acids, each made from 3 nucleotides.

Question 5

What is the genetic code?

Answer 5

A triplet code in which three nucleotides in RNA specify one amino acid in protein.

Question 6

What is a triplet?

Answer 6

Each triplet of nucleotides (A,U,G,C) is a codon.

Question 7

What is the start codon?

Answer 7

AUG = (Met)hionine

Question 8

What are the stop codons?

Answer 8

UAA
UAG
UGA

Question 9

How are the amino acids grouped?

Question 10

How do mutations affect amino acids?

Answer 10

Mutations can affect biochemical property and therefore function.
It can lead to loss of the function of a protein in a mechanism that may be essential and has no back up.

Question 11

What are hydrophobic amino acids?

Answer 11

Repels water
Val, Leu, Ile, Met, Pro

Question 12

What are nucleophilic amino acids?

Answer 12

Donates electron pairs to form chemical bonds
Ser, Thr, Cys

Question 13

What are basic amino acids?

Answer 13

The R group at pH 7 is basic.
It contains N2.
Binds protons, positive, and nucleophilic.
His, Lys, Arg

Question 14

What are acidic amino acids?

Answer 14

R group at pH 7 is acidic
Contains carboxylic acid, loses protons, negative.
Asp, Glu

Question 15

What are aromatic amino acids?

Answer 15

Cyclic - very important as they absorb at 280
Phe, Tyr, Trp

Question 16

What are amide amino acids?

Answer 16

The amides are cyclic based on the R group.
Gln, Asn

Question 17

What are small amino acids?

Answer 17

Small in size - Gly, Ala

Question 18

What are essential amino acids?

Answer 18

Need to be provided through diet.
Thr
Phe, Trp
Val, Leu, Ile, Met
His, Lys

Question 19

What are non-essential amino acids?

Answer 19

Made within the body
Cys, Ser
Tyr
Gly, Ala
Gln, Asn
Arg
Asp, Glu

Question 20

What is the structure of Glutamic acid?

Answer 20

CH2 CH2 COOH

Question 21

What is the structure of Glycine?

Answer 21

H

Question 22

What is the structure of Lysine?

Answer 22

(CH2)4 NH2

Question 23

What is the structure of Glutamine?

Answer 23

CH2 CH2 C=O NH2

Question 24

What is the structure of Methionine?

Answer 24

CH2 CH2 S CH3

Question 25

What is the structure of Phenylalanine?

Answer 25

CH2 - aromatic ring

Question 26

What is the structure of Serine?

Answer 26

CH2 OH

Question 27

What is the structure of Tyrosine?

Answer 27

CH2 - phenol ring

Question 28

What is the structure of Valine?

Answer 28

CH (CH3)2

Question 29

What are reading frames?

Answer 29

Once a gene has been sequenced we need to identify the Open Reading Frame. Every region of DNA has 6 possible reading frames - 3 in each direction.

Question 30

What is an Open Reading Frame?

Answer 30

ORF is a run of codons that starts with ATG and ends with a termination codon - TGA, TAA or TAG. It is the frame that produces the longest polypeptide.

Question 31

What does an ORF look like?

Question 32

How should you write an open reading frame?

Answer 32

N-Met amino acid -C

Question 33

What is the triplet code feature of the genetic code?

Answer 33

Each triplet on the DNA codes for a specific amino acid in the RNA when it is translated.

Question 34

What is the degenerate feature of the genetic code?

Answer 34

Most amino acids are coded for by more than one codon.

Question 35

What is partial degeneracy?

Answer 35

The 1st two bases in the codon are the same and the 3rd is one of 3 bases.

Question 36

What is complete degeneracy?

Answer 36

The 1st two bases in the codon are the same and the 3rd is any of the 4 bases.

Question 37

What is the non-overlapping feature of the genetic code?

Answer 37

Adjacent codons do not overlap so no single base can take part in the formation of more than one codon.

Question 38

What is the non-ambiguity feature of the genetic code?

Answer 38

While the same amino acid can be coded by more than one codon (degenerate), the same codon shall not code for two or more different amino acids.

Question 39

What is the universal feature of the genetic code?

Answer 39

The same sequence of 3 bases encode the same amino acids in all life forms.

Question 40

What is the polarity feature of the genetic code?

Answer 40

Reads in a 5'-3' direction