Chapter 7.1 - DNA Structure

Question 0

7.1.2 • Outline the structure of nucleosomes

Answer 0

A nucleosome is a section of a reduced DNA strand. The DNA twists itself twice around 8 Histone Molecules and then get fixated by H1 Histone. Through that the length of the DNA gets reduced by 2000 to 6000 times.

Question 1

7.1.1 • Describe the structure of DNA, including the anti parallel strands, 3’ - 5’ linkages and hydrogen bonding between purines and pyrimidines

Answer 1

The DNA double helix is made of two antiparallel strands, kept together by hydrogen bonds between the organic bases. The 3’ linkages is the first one when looking at the DNA and the 5’ is on the opposite side.

Question 2

7.1.3 • State that nucleosomes help to supercoil chromosomes and help to regulate transcription

Answer 2

Nucleosomes help the DNA to fit into the nucleus (supercoiling) and prevent transcription. If the DNA is coiled around the Histone Molecules the RNA cannot read its information => prevents transcription.

Question 3

7.1.4 • Distinguish between unique or single-copy genes and highly repetitive sequences in nuclear DNA

Answer 3

Unique and single-copy genes are gene sequences that are unique. After that (usually 1.5% of our DNA) it repeats itself. The remainder is called the repetitive sequences.

Question 4

7.1.5 • State that eukaryotic genes can contain exons and introns

Answer 4

When the DNA is translated into the mRNA some sections (introns) will be cut out during the caping process. After the copy of the DNA is formed, the 5’ end gets a cap for protection and the 3’ end gets a tail for stability. Also the introns of the DNA will be removed and only the ex robs will remain.