DLA Genetics And Translation

Question 1

How are DNA, RNA & proteins written?

Answer 1

DNA + RNA= 5’—> 3’

Protein = N-terminus to C-terminus

Question 2

Summarize the protein naming convention

Answer 2

Peptides are synthesized and named from the N-terminus. To C-terminus

Nucleotides are named from the 5’ end to the 3’ end

Name this tripeotide: Pro-Arg-Gly

Question 3

Explain the triplet code

Answer 3

The template strand is always the same strand for a given gene

• During translation, the mRNA base triplets, called codons, are read in the 5’ to 3’ direction
• Codons along an mRNA molecule are read by translation machinery in the 5’ to 3’ direction
• Each codon specifies the amino acid (one of 20) to be placed at the corresponding position along a polypeptide

Question 4

The genetic code is…

Answer 4

Non overlapping and comma free

Question 5

What is a reading frame?

Answer 5

A sequence of nucleotides in mRNA is read in sequential sets of three nucleotides which are translated into amino acids

• There are three possible reading frames in protein synthesis
• The same mRNA sequence can specify three completely different amino acid sequences, depending on the ‘reading frame’

Question 6

One mRNA contains how many reading frames?

Answer 6

3

Question 7

What is a frame shift mutation?

Answer 7

Insertion or deletion of one base pair
-causes frameshift in the RNA code

Insertion or deletion of two base pairs
-Causes a frameshift in the RNA code

Insertion or deletion of three base pairs

• Causes a change in amino acid content of protein
• Insertion or deletion of an amino acid
• Usually has no effect, but sometimes it does (a classic example is the 🔼F508 mutation of cystic fibrosis)

Insertion or deletion of any multiple of 3 nucleotides will lead to larger in frame changes

Question 8

WhAt are the 3 stop codons?

Answer 8

UAA
UAG
UGA

Question 9

What is the start codon?

Answer 9

AUG

Question 10

When were all 64 codons deciphered?

Answer 10

By the mid-1960s

Question 11

Explain the genetic code being universal

Answer 11

• shared by the simplest bacteria to the most complex animals
• Genes can be transcribed and translated after being transplanted from one species to another
• Suggests that the genetic code has been conserved from the early stages of evolution
• Minor differences do exist (mitichondria)
  
  • For instance in mitichondria, Trp has two codons
  • Main point: minimize the impact of the change

Question 12

What are the major RNA species in animals?

Answer 12

rRNA, tRNA, mRNA- 99.9%

snRNA- small nuclear (splicing of mRNA)

snoRNA( small nocleolar RNA)

miRNA (microRNA)(gene regulation)

Question 13

What are the components of translation?

Answer 13

mRNA

Ribosomes

Charged tRNA

GTP

Initiation factors

Question 14

What are the 3 binding sites of ribosomes for tRNA

Answer 14

P site- holds the tRNA that carries the growing polypeptide chains

A site- holds the tRNA that carries the next amino acid to be added to the chain

E- exit site

Question 15

Differentiate eukaryotic and prokaryotic ribosomes

Answer 15

Prokaryotic- 50s and 30 subunits , nucleotides 23s RNA nucleotide for 50s subunit

16s RNA and 5s RNA for 30s subunit

Eukaryotic- 60s and 40s subunits, nucleotides= 28s RNA, 5.8s and 5s RNA for 60s subunit

40s subunit had 18s RNA nucleotide

Proteins present in all but the eukaryotic ribosome is bigger and more complex then the prokaryotic

Question 16

Describe ribosomes

Answer 16

1. The ribosomes has two subunits each composed of rRNA and numerous proteins
2. About 2/3 of the mass of the ribosome is RNA
3. In E. Coli the small 30s subunit is involved in the initial binding to mRNA
4. The larger 50s subunit contributes the peptidyltransferase activity
5. Both 30s and 50s contribute to the E-, P-, and A- sites

Question 17

Describe the secondary structure of tRNA

Answer 17

The tRNA may be thought of as an adaptor molecule

The tRNA secondary structure resembles a clover leaf

The 3’-OH attaches amino acids

The 5’ position of the anticodon is the “wobble” position

The anticodon recognizes 3 bases on the mRNA by base pairing

There are many unusual (or modified) bases in the tRNA

Question 18

Describe the tertiary structure of the tRNA

Answer 18

More complex than the secondary structure

Covalent attachment of activated amino acids occurs at this site

Base-pairing with mRNA codons involves these exposed bases (the anticodon)

Question 19

Explain the wobble hypothesis

Answer 19

• Codon -anticodon pairing follows traditional rules for first two bases of codon, but less stringent for the last base
• So, less than 61 tRNAs exist, since some tRNAs May read more than one codon
• Inosine(I) is a nucleotide formed when hypoxanthine (base) is attached to a ribose ring

Question 20

Come back

Answer 20

Come. Back