Topic 2.1 - DNA and RNA structure Flashcards
What pentose sugar is found in DNA?
Deoxyribose
What 3 components are nucleotides made of?
A phosphate group, a pentose sugar and an organic base
What organic bases are in DNA?
A (adenine) T (thymine) C (cytosine) G (guanine)
What pentose sugar is found in RNA?
Ribose
What organic bases are found in RNA?
A (adenine) U (uracil) C (cytosine) G (guanine)
Which reaction joins nucleotides together?
What molecule does it remove?
Condensation reactions
Water
What bond is formed between nucleotides?
Phosphodiester bonds
What does an organic base consist of?
Nitrogen, Oxygen, Carbon and Hydrogen
What 3 types of RNA are there?
mRNA (messenger RNA)
rRNA (ribosomal RNA)
tRNA (transfer RNA)
How many strands does DNA have?
2 (double)
double helix
How many strands does RNA have?
1 (single)
What type of bond forms between complimentary organic bases?
Hydrogen bonds
How many bases code for 1 amino acid?
3 (triple code)
What two types of alleles are there?
Dominant and recessive
Who was the man that named the alleles through pea plant experiments?
Gregor Mendel
What does DNA occur in?
Long lengths of chromosomes
What do chromosomes consist of?
Genes
What organic bases are complimentary to one another?
A - T
A - U
G - C
What is the purpose of RNA?
allowing the genetic code to be copied/transferring genetic information for protein synthesis
What is the purpose of DNA?
Holding genetic information
Cell division
How is the double helix formed?
The uprights of the phosphate and deoxyribose wind round one another (sugar-phosphate backbone). Organic bases comprise rungs (bridges).
Within the double helix, they run anti-parallel to each other.
Explain what makes the DNA a stable molecule.
in detail, not just two points
- hydrogen bonds (3 between G and C, 2 between A and T)
- such hydrogen bonds connect the two strands of the double helix together
- if there are more G and C pairs in DNA molecule, it is more stable as the h bonds contribute towards overall stability and strength
- phosphodiester bonded backbone protect reactive organic bases in helix
- interactive forces between base pairs that hold molecule together
Name the man who conducted the experiment on mice with 2 strains of pneumococcus bacteria
Frederick Griffiths
How are nucleotides arranged in the double helix?
Numbering of carbon atoms in deoxyribose sugar (3’ and 5’)
- one strand runs 5’-3’ but the other runs 3’-5’ (anti-parallel)
- 5’ carbon has phosphate group attached
- 3’ carbon has hydroxyl group attached
What is the structure of mRNA (messenger RNA) and how is it made?
It is a long, single stranded molecule that’s formed into a helix.
It is manufactured, in the nucleus, during transcription of a strand of DNA.
What does mRNA do?
It carries the genetic code from the DNA to the ribosomes in the cytoplasm, and leaves the nucleus through a nuclear pore.
What is the structure of rRNA (ribosomal RNA)?
It is found in the cytoplasm and is a large, complex molecule made up of both double and single helices.
What does rRNA do?
Combines with proteins to form ribosomes
What is the structure of tRNA (transfer RNA)
Small single-stranded molecule that forms a clover leaf shape.
- One end of the chain ends in a cytosine-cytosine-adenine sequence at which point the amino acid it is carrying attaches itself.
- The other end of the chain is a sequence of three bases called the anticodon.
What does tRNA do?
transport amino acids to the ribosome so proteins can be synthesised
Where does protein synthesis take place?
The ribosomes
List the order in how proteins are synthesised.
Triplet codes in a gene
- Pre-mRNA
- mRNA
- sequence of amino acids made by ribosomes
(tRNA and rRNA)
- Protein
