Chromosomes, Genes and DNA

Question 1

What is a gene

Answer 1

This is a section of DNA that codes for a particular protein that is located in chromosomes, which are in the nucleus of cells.

Question 2

Describe the structure of DNA

Answer 2

• DNA has a double helix structure.
• It is formed by the phosphodiester bonds between each adjacent nucleotide with the phosphate and sugar group as well as hydrogen bonds created between the nitrogenous bases.
• Each nitrogenous base follows the base paring rule and is therefore bonded to each other’s complementary base.
• Each Nucleotide has a sugar group, Phosphate group, and nitrogenous base.

Question 3

What is the relationship between the number of adenine and thymine bases in a strand of DNA

Answer 3

They are in equal numbers

Question 4

What is the relationship between the number of guanine and cytosine molecules

Answer 4

They are in equal numbers.

Question 5

What are the steps in DNA replication

Answer 5

1. The DNA unwinds itself using DNA helicase, which breaks down the hydrogen bonds between the nitrogenous bases to form two template strands
2. Then free DNA nucleotides come towards each template strand and form hydrogen bonds.
3. Then DNA polymerase forms the phosphodiester bonds between the sugar and phosphate group.
4. DNA ligase then seals the gap to form two strands of DNA.

Question 6

What is the name given to 3 nitrogenous bases

Answer 6

Codon

Question 7

What is the difference between DNA and RNA

Answer 7

• DNA has the sugar group, Deoxyribose, and RNA has the sugar group, Ribose.
• DNA has a double helix structure and RNA is single-stranded.
• RNA has uracil and DNA has Thymine.

Question 8

What are the types of RNA

Answer 8

• mRNA (Messenger RNA)
• tRNA ( Transfer RNA)
• rRNA ( Ribosome RNA)

Question 9

What are the steps for Transcription

Answer 9

1. DNA Helicase breaks the hydrogen bonds between the nitrogenous bases.
2. Free RNA nucleotides come and attach to the template strand of DNA by forming hydrogen bonds between complementary bases using the base-pairing rule.
3. RNA Polymerase comes and forms the phosphodiester bonds between the sugar and phosphate group.
4. The RNA strand detaches and moves out for the nucleus through the nuclear pores and into the cytoplasm.

Question 10

What is translation

Answer 10

This is the process of converting the code of the mRNA into a protein

Question 11

Where does translation take place

Answer 11

In the ribosomes.

Question 12

What are the steps in translation

Answer 12

1. The mRNA molecule goes out of the nucleus and attaches to a ribosome in the cytoplasm.
2. The ribosome then reads the mRNA molecule and comes towards the start codon.
3. Then the tRNA molecule comes. tRNA molecules have a specific anti-codon that is complementary to the codon in the mRNA molecule.
4. On the other end of the tRNA molecule is a site where a specific amino acid specific to the anti-codon on the tRNA can attach.
5. Then the tRNA molecule comes with the specific amino acid and attaches with the anti-codon of the mRNA.
6. Then, peptide bonds are formed between the amino acids.
7. The tRNA molecule then goes away to bring another amino acid for the other anti-codon on the mRNA.
8. This process continues until a long strand of protein is created.

Question 13

How do you calculate the possible number of codons that can be made from a certain number of different nitrogenous bases

Answer 13

= Number of nitrogenous bases^3