2.1 Nucleic acids Flashcards
What monomer units make up nucleic acids?
Nucleotides
Which nucleotides are pyrimidines?
Cytosine, Uracil and Thymine
Which nucleotides are purines?
Guanine and Adenine
How do you remember which nucleotides are pyrimidines?
“PYRamids have sharp edges that CUT your finger”
Are pyrimidines single ring or double ring?
Single ring
Are purines single ring or double ring?
Double ring
Describe the process of RNA polymerisation
In a 5’ to 3’ direction, nucleotides are added to the 3’ end as it passes through an enzyme called RNA polymerase
At which end are nucleotides added when lengthening the strand?
The 3’ end everytime, whether it be DNA or RNA
Give a brief description of mRNA
Carries a copy the genetic code from DNA in the nucleus to the ribosome
What does the m in mRNA stand for?
Messenger
Give a brief description of tRNA
Carries amino acids from the cytoplasm to ribosomes and pairs with the complementary codon carried by mRNA
What does the t of tRNA stand for?
Transfer
Give a brief description of rRNA
Combines with proteins to make the organelle ribosome
What does the r of rRNA stand for?
Ribosomal
What are the main differences between DNA and RNA?
- DNA is double stranded, RNA is single
- DNA contains deoxyribose, RNA ribose
- DNA includes thymine, RNA uracil
- DNA is contained within membrane-bound organelles, unlike RNA
Explain anti parallel using 3’ and 5’
Strands run opposite directions to one another, yet are still parallel. 2 strands of DNA run anti parallel to one another. One strand is upside down, compared to the other.
What are the pairing rules for nucleotides in DNA?
A and T pair together, C and G pair together
How many hydrogen bonds do adenine and thymine share?
2
How many hydrogen bonds do cytosine and guanine share?
3
Briefly describe the process of DNA polymerisation
In 5’ to 3’ direction, nucleotides are added to the 3’ end, as it passes through an enzyme called DNA polymerase. Nucleotides will pair to their complementary base.
What is a nucleic acid?
A biomacromolecule, made up of smaller monomers called nucleotides. Examples of a nucleic acid is NDA and RNA
What is a nucleotide made up of?
A phosphate, pentose sugar and a nitrogenous base
What is a condensation polymerisation reaction?
The synthesis of a polymer and releases water as a by product
Why do the two DNA strands run antiparallel?
Because if the negatively charged phosphates were opposite each other, they would repel one another
What type of bond holds nucleotides together.
A phosphodiester bond
How is DNA wrapped more compactly?
Winds around histones, then 8 histones cil to make nucleosomes, then nucleosomes fold to form chromatin fibre which makes loops. Lastly, the loops are compressed and create the chromatid of a chromosome
What is RNA?
A single strand of nucleotide monomers, bonded by phosphodiester bonds. Includes messenger RNA, transfer RNA and ribosomal RNA
