Protein synthesis

Question 1

What are the differences between DNA and RNA

Answer 1

DNA RNA
• Double-stranded • Single-stranded
• Pentose sugar is deoxyribose • Pentose sugar is ribose
• Helical shape • No helical shape
• Nitrogen bases: A-T-G-C • Nitrogen bases: A-U-G-C
• Chains are very long • Chains are shorter
• Bases are paired • No pairing of bases

Question 2

Explain the process of transcription of mRNA from DNA and where it takes place in the cell

Answer 2

occurs in the nucleus of cell
1- DNA molecule unwinds and splits into two
2- one DNA strand serves as a template
3-Enzyme: RNA polymerse binds to the DNA just before the starts
4-the Polymere reads the bases one by one
5- Free RNA nucleotides from the nucleoplasm become attached to the DNA template
6-mRNA noe coded message
7-mRNA now breaks away from DNA and moves into cytosol

Question 3

Explain the translation of mRNA into specific protein

Answer 3

4. Translation of mRNA at the ribosomes
   - The mRNA strand attaches to the ribosome
   - On the mRNA strand, every three nitrogenous bases form a codon
   - tRNA molecules found in the cytoplasm have three nitrogenous bases (called the anti-codon) which bring along a specific amino acid
   - The anti-codon bonds to its corresponding codon
   - Each anti-codon triplet attaches to a specific amino acid on the other end to where the anti-codon is found
   - Amino acid sequence is thus determined by codon sequence on mRNA strand 3.

Question 4

Define the term mutation

Answer 4

A mutation is a change of the structure of a gene that occurs in our DNA sequence. This results in a variant form which is caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes.

Question 5

Explain the assembly of Amino acids into protein

Answer 5

• Amino acids next to one another bond by peptide bond to form chains of polypeptide chains.
• A chain of 20 or more amino acids is called a protein.

Question 6

What are the different types of mutations we find

Answer 6

• Deletion
• Insertion

Question 7

What are the main causes of mutations

Answer 7

• Errors in DNA Replication
On rare occasions DNA polymerase will incorporate a noncomplementary base into the daughter strand. During the next round of replication the miss incorporated base would lead to a mutation.
• Errors in DNA Recombination
Occasionally DNA is lost during replication leading to a mutation.
• Chemical Damage to DNA
Many chemical mutagens, some exogenous, some man-made, some environmental, are capable of damaging DNA.
• Radiation
Gamma rays, X-rays, even UV light can interact with compounds in the cell generating free radicals which cause chemical damage to DNA.