DNA & RNA Flashcards
DNA and RNA are polymers of…
Nucleotides
What are nucleotides made up of?
Phosphate group
Pentose sugar
Nitrogenous base
What bond is formed by a condensation reaction between two nucleotides?
Phosphodiester bond
Draw and label a single DNA nucleotide.
Circle at the top (phosphate)
connected with a line to…
Pentagon (pentose sugar)
connected with a line to…
Rectangle (base)
What sugar is present in DNA?
Deoxyribose
It’s a pentose sugar.
What is a pentose sugar?
A sugar with 5 carbon atoms.
What are the types of nitrogenous bases for DNA?
T - Thymine
A - Adenine
G - Guanine
C - Cytosine
What is the iconic abbreviation to remember the complementary base pairings?
Tigers
Are
Great
Cats
T and A
G and C
What is DNA?
A double helix made from 2 polynucleotide chains held together by HYDROGEN bonds between specific complementary base pairings.
What base pairs with adenine?
Thymine
What base pairs with guanine?
Cytosine
How are the complementary bases held together?
Weak hydrogen bonds hold them together.
How are the nucleotides held together?
Strong phosphodiester bonds hold them together.
Which bond holds bases together and which bond holds nucleotides together?
Hydrogen bonds hold bases.
Phosphodiester bonds hold nucleotides.
How many hydrogen bonds are produced between guanine and cytosine?
3 hydrogen bonds
How many hydrogen bonds are produced between adenine and thymine?
2 hydrogen bonds
What is unique about the DNA strands?
The DNA strands are ANTIPARALLEL to each other.
What does antiparallel mean?
The DNA strands face opposite directions to each other.
This means they bond to the same carbon.
What is a purine base?
A base with 2 rings.
What is a pyrimidine base?
A base with 1 ring.
What bases are examples of purines?
Adenine
Guanine
The one’s that end with “nine”
What bases are examples of pyrimidines?
Thymine
Cytosine
T - Top of pyramid
A
G
C - Bottom of pyramid
Relate the structure of a DNA molecule to its function. [6 marks]
Double helix structure w/ many H bonds =
Provides stability to molecule.
Coiling =
Makes DNA compact - stores lots of info in a small space.
Long molecule =
Stores a large amount of info.
Strong covalent sugar-phosphate backbone =
Gives strength - prevents code from being corrupted.
H bonds between bases are weak =
Allows chains to split easily for replication and transcription.
Sequence of bases =
Allows info to be stored.
What sugar is present in RNA?
Ribose
It is a pentose sugar.
What are the types of nitrogenous bases for RNA?
U - Uracil
A - Adenine
G - Guanine
C - Cytosine
U Are Great Cat
What base pairs with uracil?
Adenine
What is RNA?
A single polynucleotide molecule.
What are the similarities between DNA and RNA?
Polymer of nucleotides (polynucleotides)
Nucleotide is formed from phosphate group, pentose & nitrogenous base.
What are the differences between DNA and RNA?
DNA =
long polymer
double stranded
contains T,A,G,C
contains ribose
holds genetic info in nucleus
cannot transfer genetic info from nucleus to ribosomes
RNA =
short polymer
single stranded
contains U,A,G,C
contains deoxyribose
doesn’t hold genetic info in nucleus
can transfer genetic info from nucleus to ribosomes.
Describe how DNA is replicated. [6 marks]
1~ DNA HELICASE attaches onto DNA molecule & breaks HYDROGEN BONDS between complementary bases.
2~ Each DNA strand acts as a TEMPLATE as 2 polynucleotide strands separate.
3~ FREE nucleotides form H bonds with complementary bases on DNA strand.
4~ DNA POLYMERASE catalyses formation of PHOSPHODIESTER bonds between adjacent nucleotides in condensation reaction.
5~ Forms 2 sets of DAUGHTER DNA helixes that have 1 parent (original) & 1 newly synthesised strand.
Which enzyme breaks down the hydrogen bonds between complementary bases?
DNA helicase
Which enzyme catalyses the formation of phosphodiester bonds in DNA?
DNA polymerase
