1B - DNA and RNA Flashcards
What are nucleic acids?
A group of the most important molecules.
A complex, organic substance present in living cells, especially DNA or RNA, whose molecules consist of many nucleotides linked in a long chain.
What is a nucleotide made from?
A pentose sugar, and nitrogen containing (nitrogenous) base and a phosphate group.
What are nucleotides?
Monomers that make up DNA and RNA.
What does organic mean?
Contains carbon
What is the pentose sugar in DNA called?
Deoxyribose
What are the four possible bases on DNA nucleotides?
A, T, C, G
Adenine
Thymine
Cytosine
Guanine
What is the pentose sugar in RNA called?
Ribose
What are the four possible bases on RNA nucleotides?
A, U, C, G
Adenine
Uracil
Cytosine
Guanine
What is the difference in the possible bases in the nucleotides for DNA and RNA?
In RNA, uracil (U) replaces thymine (the base that is only found in DNA).
In brief, what are DNA and RNA and what do they do?
Types of nucleic acid found in all living cells and they both carry information.
In more detail, what does DNA do?
Stores genetic information - all the instructions an organism needs to grow and develop from a fertilised egg to a fully grown adult.
In more detail, what does RNA do?
Transfers genetic information from the DNA to the ribosomes.
What is a polynucleotide?
A polymer of nucleotides.
Nucleotides join together to form polynucleotides.
Nucleotides join together to form…
Polyneucleotides.
How do 2 nucleotides join?
Via a condensation reaction between the phosphate group of one nucleotide and the sugar of another.
What bond is formed between to joining nucleotides?
Phosphodiester bond (consisting of the phosphate group and two ester bonds).
How is a phosphodiester bond formed and where?
Through a condensation reaction joining two nucleotides. It forms between the phosphate group of one nucleotide and the sugar of another
What is the chain of sugars and phosphates known as?
The sugar-phosphate backbone.
What is the sugar-phosphate backbone?
The chain of sugars and phosphates in a polynucleotide.
What do two nucleotides form when bonded?
A dinucleotide.
What is the structure of DNA?
- 2 DNA polynucleotide strands joined together by hydrogen bonding between the bases.
- Complementary base pairing.
- 2 hydrogen bonds form between A and T.
- 3 hydrogen bonds form between C and G.
- 2 antiparallel polynucleotide strands twist to form a double helix structure.
What is complementary base pairing in DNA?
Each base can only join with one particular partner,
Adenine always pairs with thymine (A-T) and cytosine always pairs with guanine (C-G).
What does complementary base pairing in DNA mean there is?
Equal amounts of adenine and thymine in a DNA molecule and equal amounts of cytosine and guanine.
What does antiparallel mean?
Run in opposite directions.
When was DNA first discovered and by who?
1953 by Watson and Crick.
What is the name of the structure/shape of DNA?
Double helix
What was thought about DNA when it was first observed in the 1800’s?
Lots of scientists at the time doubted that it could carry the genetic code as it has a relatively simple chemical composition. Some argued that genetic information must be carried by proteins - which are more chemically varied.
What had happened by 1953 in the discovery of DNA?
Experiments had shown that DNA was the carrier of the genetic code. Also, the double-helix structure, which helps DNA to carry out its function, was determined by Watson and Crick.
In more detail, what is RNA made from?
A relatively short, single polynucleotide chain.
What is the difference in the structure of DNA and RNA?
DNA has a double strand of polynucleotide chains whereas RNA is a single strand and is much shorter.
DNA contains the base THYMINE whereas RNA contains the base URACIL
Is the sugar-phosphate backbone reactive?
No it is unreactive.
What does DNA stand for?
Deoxyribonucleic acid.
What does RNA stand for?
Ribonucleic acid.
What are the 3 forms of RNA?
Transfer or tRNA.
Messenger or mRNA.
Ribosomal or rRNA.
What does the sugar phosphate backbone help to do for the DNA?
Protects the more reactive bases.
What bonds form between the base pairs?
Hydrogen bonds.
What does the fact that there are hydrogen bonds between complementary base pairs and that the phosphodiester backbone helps protect bases mean for DNA as a whole?
It makes DNA more stable and better suited for long term storage of DNA.
What is the sugar-phosphate backbone also known as?
Phosphodiester backbone.
What is the phosphodiester backbone?
Another name for the sugar-phosphate backbone.
What base does thymine join to?
Adenine
What base does adenine join to?
Thymine
What base does cytosine join to?
Guanine
What base does guanine join to?
Cytosine
What is meant by the 3’ end and the 5’ end?
The carbon number on the pentose sugar. The nucleotide strands run antiparallel to each other so the 3’ end and 5’ ends of each strand will be at opposite ends.
What do the hydrogen bonds holding the 2 strands together allow to happen?
Allows them to be separated easily during copying.
What does DNA being a large molecule allow?
A lot of information to be stored and transferred.
What does the double-helix structure help to do?
Protect the genetic information carried by the bases.
What are the functional adaptations of DNA?
- Highly stable so passes through generations without change and rarely mutates.
- 2 strands held together by hydrogen bonds allowing them to be separated easily during copying.
- Double helix structure partly protects the genetic information carried by the bases.
- Complementary base pairing makes DNA sequences and RNA compatible allowing RNA to transfer information from the DNA.
What does the complementary base pairing allow to happen in DNA?
Makes DNA sequences and RNA compatible allowing the RNA to transfer information from the DNA.
