Genetic information, variation and relationships between organisms-DNA and protein synthesis

Question 1

How is a protein assembled?

Answer 1

 by transcription and translation
 transcription = production of a single stranded complementary copy of a gene (called mRNA)
 translation = use sequence of codons on mRNA to assemble protein (tRNA brings in AAs)

Question 2

DNA vs RNA?

Answer 2

 deoxyribose sugar vs ribose sugar
 thymine vs uracil
 double stranded vs single stranded
 one type vs two types (mRNA and tRNA)

Question 3

What is mRNA?

Answer 3

 messenger RNA
 single stranded complementary copy of a gene
 carries the code for assembling protein (on DNA called triplet code, on mRNA called codon)

Question 4

What is tRNA?

Answer 4

 transfer RNA
 single stranded RNA folded over into a ‘clover leaf’ shape (held by hydrogen bonds
between the bases)
 has an AA attachment site on the top
 has 3 specific bases on the bottom (anticodon)
 anticodon binds to complementary codons on mRNA

Question 5

What is Transciption?

Answer 5

 occurs in nucleolus of nucleus
 producing a single stranded complementary copy of a gene (called mRNA)
 DNA is double stranded, 1 strand called coding strand & 1 strand called template strand, the template strand will be used to build mRNA

Process
 DNA Helicase breaks the hydrogen bonds between complementary bases in the gene
 the double strand of the gene unwinds
 leaves 2 separate strands (1 coding strand and 1 template strand)
 complementary RNA nucleotides bind to exposed bases on the template strand
 RNA Polymerase joins the sugar-phosphate backbone of the RNA strand
 leaves pre-mRNA (contains introns and exons)
 the copies of the introns are removed by splicing
 leaves mRNA

Question 6

What is Translation?

Answer 6

 takes place on ribosomes of Rough Endoplasmic Reticulum
 uses the sequence of codons on the mRNA to assemble the protein (tRNA brings in AAs)
 process,
 mRNA leaves nucleus via nuclear pore
 mRNA attaches to a ribosome
 complementary tRNA carrying specific AAs bind to the codons on mRNA via their anticodon
 the AAs on the tRNA are joined by peptide bond