GENOME PROJECTS AND MAKING DNA FRAGMENTS

Question 1

Genome

Answer 1

a genome is the entire set of dna including all genes in an organism

Question 2

how does gene sequencing occurs

Answer 2

it can only be done in fragments of dna.

Question 3

proteome

Answer 3

the proteome of an organism is all the protein made by it.
- proteome can be determined by dna sequencing of their genome

Question 4

translating genome in complex organism

Answer 4

-complex organism contains a large section of non coding dna - in addition to that they also contain regulatory genes
- difficult to translate the genome into the proteome as hard to find the bits that codes fro proteins.

Question 5

recombinant dna technology

Answer 5

recombinant dna technology involves transferring a fragment of dna from one organism to another.

Question 6

dna fragments

Answer 6

inorder to transfer gene, we first need to get a dna fragment which consists of the target gene.

Question 7

how can you make dna fragments

Answer 7

1. using reverse transcriptase
2. using restriction endonuclease enzymes
3. using a gene machine

Question 8

sequencing a genome

Answer 8

working out dna base sequence for all dna in a cell

Question 9

reverse transcriptase

Answer 9

• reversing the transcription process ( mrna converted into dna)
• reverse transcriptase makes dna copies from mrna
• first mrna is isolated from the cells that contains a large amount of mrna for protein
• mrna is then mixed with dna nucleotides and reverse transcriptase - in a way that mrna acts as a template to synthesize a new dna strand.
• reverse transcriptase joins dna nucleotides with complentary mrna bases.
• a single stranded dna called cdna is produced.

Question 10

advantage of cdna

Answer 10

• cdna is intron free as it is based on mrna template.

Question 11

restriction endonuclease enzyme

Answer 11

• some sections of dna have palindromic sequences of nucleotides ( anti parallel base pairs that read the same in opposite directions)
• restriction endonuclease are the enzymes that recognise specific palindromic sequence also called recognition sequence and cut dna at that point.
• different restriction endonuclease cut at different recognition sequence because the shape of the recognition sequence is complementary to active site of the enzyme.
• the dna sample is incubated with specific restriction endonuclease which cuts the dna fragment via a hydrolysis reaction.
• sometimes the cut leaves sticky ends

Question 12

sticky ends

Answer 12

sticky ends are the small tails of unpaired dna bases at the end of the fragment.
- sticky ends can be used to bind dna fragment with another piece of dna that has a sticky end with complementary sequences.

Question 13

gene machine

Answer 13

• fragments of dna can be synthesized from scratch
• dna fragments are made in a lab
• first amino acid sequence is identifed for mrna and dna sequence .
• dna sequence is entered into computer for bio safety
• first nucleotide in the sequence is attatched to some sort of support eg beads
• nucleotides are then added step by step in correct prder which also includes adding protecting groups
• short sections of dna arecreated called oligo nucleotides , roughly 20 nucleotides long.
• once complete they are broken off from the support and all protecting groups are removed. oligonucleotides are joined together to create longer dna fragments.

Question 14

why do we add protecting groups while making dna in a gene machine

Answer 14

• to ensure nucleotides are joined at the right place, and to prevent unwanted branching.