DNA/RNA Flashcards
What is DNA and what does it do ?
‘Deoxyribonucleic acid’.
It stores, replicates and passes on genetic information.
What is the structure of DNA?
It is a double stranded helix.
What components make up a DNA nucleotide?
- Pentose sugar
- Phosphate group
- Nitrogen base
What are the 4 DNA bases?
- Adenine
- Thymine
- Cytosine
- Guanine
What is RNA?
‘Ribonuceic acid’.
What is the structure of RNA?
It is single stranded.
What are the 4 bases of RNA?
- Adenine
- Uracil
- Cytosine
- Guanine
What is the difference between RNA and DNA?
- DNA forms a helix and RNA does not.
- RNA is shorter than DNA.
- RNA has a uracil base while DNA does not.
- DNA has a thymine base while RNA does not.
What does a nucleotide look like?
[Phosphate] [Nitrogenous base]
\ /
[Sugar]
- A phosphate is represented as a circle, containing a P.
_ A sugar and nitrogenous base are represented as pentagons.
What do nucleotides make?
It is the basic building block of a nucleic acid.
What do nucleic acids make?
They are monomers of DNA.
How do you join nucleic acids?
Through a condensation reaction, when a water molecule is lost.
A phosphodiester bond forms between a phosphate group one nucleotide and the hydroxyl group on the next.
Identify this base and its structure.
NH2
|
C
// \
N C --- N
| || \\
| || C --- H
| || /
C C --- N
/ \\ / |
H N H
- Adenine.
- Double ring structure.
Identify this base and its structure.
O
||
H C
\ / \
N C --- N
| || \\
| || C --- H
| || /
C C --- N
/ \\ / |
H2N N H
- Guanine.
- Double ring structure.
Identify this base and its structure.
NH2
|
C
// \
N C --- H
| ||
| ||
| ||
C C --- H
// \ /
O N
|
H
- Cytosine.
- Pyrimidine structure.
Identify this base and its structure.
O
||
C
/ \ H --- N C --- CH2
| ||
| ||
| ||
C C --- H
// \ /
O N
|
H
- Thymine.
- Pyrimidine structure.
Identify this base and its structure.
O
||
C
/ \
H --- N C
| ||
| ||
| ||
C C --- H
// \ /
O N
|
H
- Uracil.
- Pyrimidine structure.
How do complementary bonds and hydrogen bonds form between bases?
- The sugar phosphate backbone forms rings of DNA ladders.
- Base pairs of opposite strands form complementary base pairs.
- Hydrogen bonds then form between the base pairs. Two hydrogen bonds form between thymine and adenine and three form between cytosine and guanine.
What do bases form?
Bases form nucleic acids which form DNA and RNA.
What base does thymine bind with?
Thymine binds with adenine in DNA.
What bases does adenine bind with?
- Adenine binds with thymine in DNA.
- Adenine binds with Uracil in RNA.
What base does Guanine bind with?
Guanine binds with cytosine.
What are the base pairs?
T - A
G - C
U - A
A - T
C - G
A - U
What is DNA transcription?
Converting DNA to RNA so the ribosomes can translate the RNA code into a protein.
Explain the process of DNA transcription?
- The DNA in the nucleus is unwound, breaking the weak hydrogen bonds, causing the two DNA strands to separate. The helix is now open.
- The free RNA nucleotides in the nucleoplasm find their complimentary base pairs on the DNA.
- RNA polymerase then catalyses the formation of strong chemical bonds between the ribose sugar and phosphate group of the adjoining RNA nucleotides.
- A MRNA molecule is then formed. This leaves the nucleus through the nuclear pores, to the ribosomes.
- Hydrogen bonds between the complimentary bases of DNA reform and the DNA wounds back into a helix form.
What is DNA translation?
The ribosomes make proteins as they read the RNA code. They read it 3 at a time and the TRNA carries specific amino acids to the ribosomes.
What is TRNA?
Transfer RNA.
What is MRNA?
Messenger RNA.
Explain the process of DNA translation.
- The MRNA from the nuclear pores goes to the ribosomes.
- The MRNA and ribosomes then bind.
- They then build a protein by adding one amino acid at a time.
- The TRNA carries amino acids for the codon in ribosomes by bonding to the amino end of TRNA.
- The ribosomes nuild an amino acid chain.
- The first molecule then detaches and repeats this process.
- Now a complete chain of amino acids has been formed.
- The chain then folds up on itself to form a protein.
Does DNA transcription or translation come first?
Transcription takes place before translation.
What is a gene?
A sequence of DNA bases which codes for the amino acid sequence of a polypeptide.
