Nucleic acids and protein synthesis

Question 1

What is the structure of a DNA molecule?

Answer 1

DNA is a double helix consisting of two antiparallel strands of nucleotides. Each nucleotide is made up of a phosphate group, a deoxyribose sugar, and a nitrogenous base

Question 2

Components of nucleotides

Answer 2

• phosphate group
• deoxyribose sugar
• nitrogenous base

Question 3

Nitrogenous bases

Answer 3

• Adenine
• Thymine
• Cytosine
• Guanine
• Uracil

Question 4

What is meant by semiconservative replication?

Answer 4

Semiconservative replication means that each new DNA molecule consists of one original strand and one newly synthesized strand

Question 5

What is the role of DNA polymerase in DNA replication?

Answer 5

DNA polymerase synthesizes new DNA strands by adding nucleotides complementary to the template strand in the 5’ to 3’ direction

Question 6

What is the leading strand in DNA replication?

Answer 6

The leading strand is synthesized continuously in the direction of the replication fork

Question 7

What is the lagging strand in DNA replication?

Answer 7

The lagging strand is synthesized discontinuously in short segments called Okazaki fragments, away from the replication fork

Question 8

What is the function of primase in DNA replication?

Answer 8

Primase synthesizes short RNA primers that provide a starting point for DNA polymerase to begin synthesis of the new DNA strand

Question 9

What is the role of helicase in DNA replication?

Answer 9

Helicase unwinds the double-stranded DNA, creating two single strands that can be used as templates for replication

Question 10

What is the role of DNA ligase in DNA replication?

Answer 10

DNA ligase joins the Okazaki fragments on the lagging strand, sealing nicks in the sugar-phosphate backbone to create a continuous DNA strand.

Question 11

What are the two main stages of protein synthesis?

Answer 11

• Transcription (DNA to mRNA)
• Translation (mRNA to protein)

Question 12

What occurs during transcription?

Answer 12

During transcription, RNA polymerase binds to the promoter region of DNA, separates the DNA strands, and synthesizes a complementary mRNA strand from the DNA template.

Question 13

What occurs during translation?

Answer 13

During translation, the mRNA attaches to a ribosome. tRNA molecules, each carrying a specific amino acid, pair their anticodon with the corresponding codon on the mRNA.

The ribosome moves along the mRNA, facilitating the formation of peptide bonds between amino acids, creating a polypeptide chain until a stop codon is reached.

Question 14

What is the role of tRNA in translation?

Answer 14

tRNA molecules carry specific amino acids to the ribosome and match their anticodon with the mRNA codon, ensuring the correct amino acid sequence in the growing polypeptide chain

Question 15

What is the role of mRNA in protein synthesis?

Answer 15

mRNA (messenger RNA) carries the genetic information from DNA to the ribosome, where it serves as a template for assembling amino acids into a protein.

Question 16

What are post-translational modifications?

Answer 16

Post-translational modifications are chemical changes to the polypeptide chain that occur after translation and are essential for the final functional form of the protein

Question 17

What is a replication fork?

Answer 17

A replication fork is a Y-shaped region where the DNA double helix is separated into two single strands and replication occurs.

Question 18

How does DNA polymerase ensure accuracy during replication?

Answer 18

DNA polymerase has a proofreading function that checks and corrects errors by removing incorrectly paired nucleotides and replacing them with the correct ones.

Question 19

Where and when does Transcription occur ?

Answer 19

• Nucleus
• Interphase ( S phase )

Question 20

Where does Translation occur ?

Answer 20

-> in the cytoplasm at the ribosome

Question 21

Translation process

Answer 21

mRNA is read by ribosomes, and tRNA molecules bring the corresponding amino acids to form a polypeptide chain

Question 22

Codons

Answer 22

Codons are triplets of bases in mRNA that specify an amino acid.

Question 23

Anticodons

Answer 23

Anticodons are complementary triplets of bases in tRNA that pair with codons during translation to ensure the correct amino acid sequence in the protein.

Question 24

Transcription process

Answer 24

RNA polymerase binds to DNA and synthesizes mRNA based on the DNA template

Question 25

What is the genetic code?

Answer 25

The genetic code consists of codons, which are sequences of three nucleotide bases in mRNA. Each codon specifies a particular amino acid or a stop signal during translation.

Question 26

What is the role of ribosomes in protein synthesis?

Answer 26

Ribosomes facilitate the binding of tRNA to mRNA and catalyze the formation of peptide bonds between amino acids, playing a crucial role in the translation phase of protein synthesis.