Nucleic acids - DNA & RNA structure Flashcards
What is the genetic material of living organisms?
Deoxyribose nucleic acid (DNA)
DNA carries the genetic code in all living organisms.
Where is DNA mainly found in eukaryotic cells?
In the nucleus, chloroplasts, and mitochondria
DNA forms chromosomes in the nucleus.
What is the role of ribonucleic acid (RNA) in cells?
Main component of ribosomes, plays an important role in protein synthesis
Some RNA is also found in the nucleus and cytoplasm.
What type of genetic material do certain viruses, like SARS-CoV-2, contain?
RNA
These viruses cause diseases such as COVID-19, Ebola, mumps, and influenza.
True or False: Viruses are considered living organisms.
False
They cannot replicate on their own and depend on living cells for replication.
What are the components of a nucleotide?
Pentose sugar, nitrogen-containing organic base, phosphate group
The base and phosphate group are covalently bonded to the sugar.
List the nitrogenous bases found in DNA.
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T)
RNA replaces thymine with uracil (U).
What are purine bases?
- Adenine
- Guanine
Purine bases have 2 rings of atoms.
What are pyrimidine bases?
- Cytosine
- Thymine (in DNA)
- Uracil (in RNA)
Pyrimidine bases have 1 ring of atoms.
Fill in the blank: DNA is ______-stranded.
double
RNA is usually single-stranded.
How do nucleotides form DNA or RNA
Join together in chains to form DNA or RNA strands - the phosphate group of one nucleotide forms a covalent bond to the pentose sugar of the next one, this carries on to form a large polymer
What type of reaction links nucleotides together?
Condensation reactions - a molecule of water is released during the formation of each covalent bond
What is the structure formed by the nucleotide polymer called?
sugar-phosphate backbone
What is the sugar in RNA nucleotides?
Ribose
DNA contains deoxyribose.
What types of RNA are found in cells?
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
Each type has a specific function in protein synthesis.
What type of bond forms between adjacent RNA nucleotides?
Phosphodiester bond
Formed by condensation reactions releasing a molecule of water.
Describe the structure of DNA.
Double helix made of two antiparallel strands linked by hydrogen bonding
Strands run in opposite directions.
What is complementary base pairing in DNA?
Adenine pairs with Thymine, Guanine pairs with Cytosine
A-T forms two hydrogen bonds, G-C forms three hydrogen bonds.
What does the term ‘antiparallel’ refer to in DNA structure?
The two strands run in opposite directions
One strand is 5’ to 3’ and the other is 3’ to 5’.
How are the carbon atoms in nucleotides numbered?
From the right in a clockwise direction
This helps identify the bonds in the sugar-phosphate backbone.
What is the sugar-phosphate backbone?
The chain formed by covalent bonds between the pentose sugar of one nucleotide and the phosphate group of the next nucleotide
It is a key feature of nucleic acids.
What is the three-dimensional shape of DNA called?
Double helix
This refers to the overall structure of DNA.
What is mRNA?
messenger RNA - formed in the nucleus and transported to the ribosomes in the cytoplasm
What is tRNA?
transfer RNA - responsible for transporting amino acids to ribosomes during protein synthesis
