Nucleotides And Nucleic Acid Flashcards
State the number of DNA nucleotide bases that code for a single amino acid
3
Explain the uses of the remaining 44 base combination of amino acids
- several are used as triplets
- some are used to start or for termination of the bases
Which nucleotide bases are common to DNA and RNA
Adenine
Cytosine
Guanine
Explain why DNA replication is considered to be semi conservative
One strand from original DNA and one strand newly formed
The original strand act as a template
Describe the structural relationship between deoxyribose and the other components of the DNA (nucleic acid)
Part of nucleotide Joined by a base and phosphate Phosphate is joined to C5 and 3 Based joined to c1 Nucleotide is a monomer and DNA is polynucleotide
Name the pentose sugars in DNA and RNA
DNA- deoxyribose
RNA-ribose
Describe how polynucleotide strands aww formed and broken down
Condensation reaction between nucleotide from strong phosphodiester bonds (sugar-phosphate backbone)
Hydrolysis reaction to break these bonds
Enzymes catalyse these reactions
Define the structure of DNA
Molecule twist to form a double helix of 2 deoxyribose polynucleotide strands
Hydrogen bonds form between complementary base pairs(AT & GC)
Strands that run antiparallel
Name the purine bases and describe their structure
Adenine C5H5N5
Guanine C5H5N5O
Two ring molecules
Name the pyrimidine bases and describe their structure
Thymine c5H6N2O2
Cytosine C4H5N3O
Unracil C4H4N2O2
Name the complementary base pairs in DNA and RNA
DNA 2 H-bonds between adenine(A) +thymine (T)
RNA 2 H bonds between adenine (A) + Uracil (U)
BOTH have 3 h bonds guanine (G)and cytosine (C)
Explain the role of DNA helicase in semi conservative replication
Breaks hydrogen bonds between base pairs to form 2 single strands
Each of which can act as a template
Describe the method of semi-conservative DNA replication
- DNA heli case breaks the hydrogen bonds between the 2 polynucleotide, unzip to form two single strands
- original strand act as a template,DNA nucleotide join exposed bases
- joined together via DNA polymerase
- one original and one new strand
What are the features of the genetic code
Non overlapping
Degenerate
Universal
How does a gene determine the sequence of amino acids in a protein
Base triplet that code for a specific amino acids
What produces mRNA and occurs in nucleus
Transcription
Outline the process of transcription
RNA polymerase binds to promotor region on a gene
Section of DNA uncoils into 2 Strands with exposed bases. Antisense strand act as template
Free nucleotides are attracted to their complementary bases
RNA polymerase joins adjacent nucleotide to form phosphodiester bonds
What happens after a strand of mRNA is transcribed
RNA polymerase detaches at terminator region
H bonds reform and DNA rewinds
Splicing removes introns from pre-mRNA in eukaryotic cells
mRNA moves out of nucleus via nuclear pore and attaches to ribosome
What produces proteins and occurs in the cytoplasm on ribosomes
Translation
Outline the process of translation
1-Ribosome moves along mRNA until “start” codon
2-tRNA anticodon attaches to complementary bases on mRNA
3- condensation reaction between amino acids on tRNA form peptide bonds
4-Process continues to form polypeptide chain until “stop” codon is reached
Describe the structure of ATP and ADP
ATP has 3 inorganic phosphate groups whereas ADP has 2
What is a mutation
An alternation to the DNA base sequence
Arise spontaneously during DNA replication
What bases are purine and define their structure
Adenine
Guanine
Two carbon nitrogen rings
What bases are pyrimidine and define their structure
Cytosine
Thymine
One carbon nitrogen ring
