Module 3.4 Nucleotides Flashcards
What is the structure of a nucleotide
- Nucleic acid
- Phosphate group
- ribose sugar
What is the name for monomers that make up nucleic acids
Nucleotides
What the two purines
Adenine and guanine
What are the two pyramadines
Cytosine
Thymine
What is the difference between purines and pyramidines
Purines have two carbon nitrogen rings
Pyramidines have 1 carbon nitrogen rings
How does DNA replication occur
- Dna helicase unzips and unwinds the double helix
- Hydrogen bonds break
- Free DNA nucleotides bind into complimentary base pairs
- Hydrogen bonds from between base pairs
- DNA polymerase catalysés reaction of the phophodiester bonds
Why is it semi conservative replication
1 old strand and 1 new strand
How do we know it’s semi conservative replication
There is two strands a old and a new strand
Nitrogen 15 was a heavy strand
Nitrogen 14 was a light strand
Placed them in a centrifuge
Separated two strands
???????
What bases pairs up with each other
Adenine and thymine
Cystosine and guanine
How many hydrogen bonds form between each base pairs
3 between cystosine and guanine
2 between adenine and thymine
Describe the structure of a DNA strand
They are two anti parallel strands
That twist to form a double helix
4 base pairs (adenine, guanine, cytosine and thymine)
A phosphodiester bond forms between carbon and phosphate groups
What is the difference between RNA nucleotides and DNA nucleotides
RNA contains adenine, guanine, cytosine and uracil
DNA contains adenine, guanine, cystosine and thymine
What is the difference between an RNA strand and a DNA strand
RNA has a single strand whereas DNA has a double strand
RNA nucleotides contain (adenine, guanine, cytosine and uracil) but DNA contains (adenine, guanine, cytosine thymine)
RNA has a ribose sugar, DNA has a deoxyribose sugar
RNA is not a double helix whereas DNA
How does transcription work
- RNA polymerase unwinds a segment of the gene
- Hydrogen bonds break
- Free RNA nucleotides bind onto complementary base pairs
- RNA polymerase joins the nucleotides together by forming phosphodiester bonds
- this forms mRNA
- which leaves the nucleus through a nucleuar pore
How does translation work
- mRNA attaches to a ribosome
- tRNA with the correct anti codon will bind onto the start codon of mRNA
- another tRNA that has the complementary anti codon to the next codon will bind onto mRNA
- a peptide bond forms between the amino acids (catalysed by ribosome)
- the tRNA will then leave
- same processes happens until it reaches a stop codon
- the polypeptide chain moves away from the ribosome
