3- DNA and how genes work Flashcards
What are the bases that form DNA?
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
What are the bases that from RNA?
Adenine (A)
Guanine (G)
Cytosine (C)
Uracil (U)
What are the sugars that form DNA?
Deoxyribose
What are the sugars that form RNA?
Ribose
Sketch a DNA double helix showing base pairs and 5’ and 3’ ends
accurate drawing
What direction does the DNA run?
5 prime end to 3 prime end
What end of DNA are new bases added to?
3 prime end
What is meant by the term “Semi-conservative” replication?
Each daughter strand contains one conserved strand and one new strand
Where does the DNA unwind?
Replication origin
Where does DNA synthesis begin?
Replication fork
Where does DNA synthesis begin?
Replication fork
What is the role of DNA polymerase?
Catalyses the addition of nucleotides to the growing end a new DNA molecule
What is the 3’->5’ strand known as?
Leading strand
What is the 5’->3’ strand known as?
Lagging strand
How is the 5- 3 strand synthesised?
Short strands called Okazaki fragments are made in the 5-3 direction
These strands are made in small pieces discontinuously
DNA ligase joins them together via “backstiching”
This process takes longer hence the lagging
What are exons?
The coding region of a gene
What happens when the introns are spliced?
mRNA is produced
What is transcription?
Copying of DNA into messenger RNA
What is the main enzyme involved in transcription?
RNA polymerase
What are the 4 key elements of the gene for transcription and what are the functions?
Transcription start-site-where the copying of the DNA strand into RNA begins
TATA box- signal for the start of transcription
Promoter- where transcription factors bind to regulate transcription
Terminator sequence/stop site- the signal for RNA polymerase to stop copying the DNA template into RNA
What is translation?
RNA to a protein
What happens when the genetic code loses a base?
There is a frame shift mutation
What is the role of tRNA in protein synthesis?
Brings each of the 20 amino acids to the growing protein
Contain an anti-codon sequence that recognise the codon for each amino acid
What happens to the proteins after translations?
Proteins are transferred to the golgi apparatus for final “polishing” and secretion
