DNA and RNA Flashcards
What are DNA and RNA both types of
Nucleic Acid
Where are DNA and RNA found
In all living cells
What are both DNA and RNA needed for
To build proteins and allow for proper functioning of cells
What types of molecules are DNA and RNA
Information carrying molecules
Do DNA and RNA have the same functions
No
Which can carry more info - DNA or RNA
DNA
What is DNA’s function
Hold or store genetic information. Contains instructions for the growth and development of all organisms
What is RNA’s function
Transfer the genetic code found in DNA out of the nucleus and carry it to the ribosomes in the cytoplasm.
What is each nucleotide in DNA and RNA formed from
A pentose sugar, a nitrogen containing organic base and a phosphate group
What are the components of a DNA nucleotide
Deoxyribose sugar with hydrogen at the 2’ position, a phosphate group and one of four nitrogenous bases - adenine (A), Cytosine (C), guanine (G) and thymine (T)
Which nitrogenous bases bond together
A-T and C-G
What are the components of a RNA nucleotide
A ribose sugar with a hydroxyl (OH) group at the 2’ position, a phosphate group and one of four nitrogenous bases - Adenine (A), cytosine (C), guanine (G) or uracil (U).
How does the presence of 2 hydroxyl groups affect RNA
Makes it more susceptible to hydrolysis
Why is DNA tight storage molecule and RNA the transport molecule
RNA has a shorter lifespan due to it being more susceptible to hydrolysis.
What two structural forms do the nitrogenous bases in RNA and DNA occur in
Purines and Pyrimidines
Which bases are Purines
Adenine and Guanine - they have a double ring structure
Which bases are pyrimidines
Cytosine, Thymine and Uracil - they have a single ring structure
How many strands does DNA have?
DNA is double - stranded (double helix)
How many strands does RNA have?
Single - Stranded
Where do the condensation reactions occur between nucleotides making up DNA and RNA
The phosphate group of one nucleotide and the pentose sugar of the next nucleotide
What does a condensation reaction between two nucleotides form
A phosphodiester bond
Why is it called a phosphodiester bond
Because it consists of a phosphate group and two ester bonds
What is the sugar phosphate backbone
The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds
What are the key differences between DNA and RNA
RNA doesn’t contain Thymine, instead it contains uracil, RNA also contains the pentose sugar ribose - instead of deoxyribose
What is the structure of DNA
DNA molecules are made up of 2 polynucleotide strands lying side by side, running in opposite directions (antiparallel), each strand is made from alternating deoxyribose sugars and phosphate groups bonded (phosphodioester bonds) - forming the sugar phosphate backbone
How are the 2 antiparallel strands in DNA held together
By hydrogen bonds between the nitrogenous bases
What is the structure of RNA
Made up of alternating ribose sugars and phosphate groups linked together, with the nitrogenous bases of each nucleotide projecting out sideways from the single - stranded RNA molecule
What are the three versions of RNA
mRNA, tRNA and rRNA
How do ribosomes make polypeptides
They ‘read’ RNA in a process known as translation
What is RNA that forms proteins
rRNA
What does rRNA do in ribosomes
Has enzymatic properties that catalyse the formation of peptide bonds between amino acids
Where are 80s ribosomes found and what subunits are they composed of
Composed of 60s and 40s subunits - found in eukaryotes
Where are 70s ribosomes found and what subunits are they composed of
Composed of 50s and 30s - found in prokaryotic cells as well as in mitochondria and chloroplasts of eukaryotic cells
What is the large subunit in ribosomes the site of
Translation
Are ribosomes surrounded by a membrane?
No
What was DNA called when it was first discovered
Nuclein
How did many scientific researchers react to the new discovery of this DNA molecule
They doubted it could carry the genetic code because of its relatively simple chemical composition
How does DNA have a simple chemical composition
Only made up of simple repeating nucleotides, which themselves were only composed of 3 parts
What did some scientists hypothesise genetic information is carried by
Proteins as they show much higher levels of chemical complexity (Proteins made from 20 different amino acids, DNA just 4 different nucleotides)
What did later experiments confirm
DNA carried the genetic code
How was there variation despite there being just 4 nucleotides
The use of the triplet code
How is DNA conserved throughout generations of cells
DNA is easily copied and therefore inherited between generations within families
