genetic info variation and relationship between organisms 3.4

Question 1

what is a genome?

Answer 1

complete set of genes in a cell

Question 2

what is a proteome?

Answer 2

complete set of proteins a cell can produce

Question 3

what are the structural differences between mRNA and tRNA

Answer 3

mRNA
- linear single shape
- triplet code (codon)
- less stable
- no amino acid region
tRNA
- clover shaped
- triplet code (anticodon)
- more stable
- amino acid region

Question 4

what is transcription?

Answer 4

production of mRNA from DNA

Question 5

what is translation?

Answer 5

production of polypeptides from the sequence of codons carried by mRNA

Question 6

what happens in transcription?

Answer 6

• DNA helix unwinds to expose bases and on strand acts as a template
• catalysed by DNA helicase
• DNA helicase breaks the hydrogen bonds between bases
• free mRNA nucleotides in the nucleus align with complementary bases on strand
• A/U C/G G/C T/A
• RNA polymerase bonds the nucleotides together to form RNA chain
• once copied mRNA is modified and leaves nucleus through nuclear pores

Question 7

how is pre-mRNA modified?

Answer 7

• introns are spliced out of pre-mRNA by protein splicesome
• leaves behind just coding regions (exons)

Question 8

what happens in translation?

Answer 8

• mRNA attaches to ribosome in the cytoplasm
• ribosome attaches at start codon
• tRNA that has complementary anticodon lines up with mRNA codon and binds
• tRNA brings specific amino acid
• amino acids joint together by peptide bonds using ATP (condensation reaction)
• tRNA released after amino acids joint to polypeptide
• ribosome moves along polypeptide until reaches stop codon
• polypeptide formed and now enters Golgi apparatus