protein synthesis

Question 1

protiens

Answer 1

• contain enzymes (workhorses) of all living organisms

Question 2

RNA

Answer 2

• messenger RNA (mRNA)
• transfer RNA (tRNA)
• ribosomal RNA (rRNA)

Question 3

what happens in the nucleus

Answer 3

• mRNA is formed
• same way as in replication
• transcription

Question 4

transcription

Answer 4

• small piece of DNA unwinds
• RNA polymerase catalyses the breaking of the hydrogen bonds
• polymerase attaches to a DNA strand and causes complimentary base pairings
• nucleotides join to sugar forming an mRNA strand
• genetic code is transcribed to mRNA
• uracil used
• completed strand of mRNA breaks away
• moves through nucleic pores to ribosomes for protein synthesis

Question 5

what determines which proteins

Answer 5

• a polymer (long chain) of small units (monomers) called amino acids
• twenty involved in protein synthesis
• amino acid linkage makes protein

Question 6

role mRNA

Answer 6

• genetic code is carried as a sequence of ‘codewords’
• each one being made up of any three bases called a codon
• 64 codons that code except for 3 (code 20 amino acids)
• UGA, UAA, UAG are the stop codons
• 3 codons code for protein synthesis
• the order of codons determine the sequence of amino acids and therefore determine the protein made

Question 7

what happens at the ribosomes

Answer 7

• mRNA binds to ribosome at the start of first codon

- codons of mRNA act as template (determine the amino acids linked)

Question 8

role of tRNA

Answer 8

• found in nucleoplasm made of nucleotides
• three bases at one end (called an anticodon picking the specific amino acid)
• transfers to ribosome
• can bind to an amino acid and the mRNA at the other to code for depositing amino acids in specific position to form protein

Question 9

Translation

Answer 9

• start signal codon starts the process of protein synthesis
• stop codons tell the process to stop because the chain of proteins is complete
• anticodon bases link up to their complementary bases of the codon
• code of mRNA is translated into a sequence of amino acids
• tRNA molecule carries more of its specific amino acid to the ribosome
• catalysed by enzymes, amino acids link with peptide bonds to for polypeptide chain
• polypeptide chains link to functional protein

Question 10

role of rRNA

Answer 10

• with proteins makes up ribosomes
• moves from codon to codon reading the code
• controls the process of protein synthesis

Question 11

antibiotics interference

Answer 11

• counteract bacterial infections
• interact with bacterial ribosomes, inhibiting the function of protein synthesis
• antibiotics can target bacteria and not the host
• protein production is inhibited because bacteria can not produce proteins
• tetracyclines prevent attachment of tRNA’s carrying amino acids
• chloramphenicol prevents the formation of peptide bonds

Question 12

genetic aberrations

Answer 12

• caused by mutations
• alteration in the genetic makeup
• more damaged nucleotides (crossing over paternal and maternal chromosomes in meiosis, replication of DNA, transcription of DNA to RNA)
• breakdown of DNA by mutagens (environmental factors eg. sunlight, radiation and smoking, mutagenic chemicals, viruses and micro-organisms)

Question 13

gene mutations

Answer 13

• small localised changes in structure of DNA strands

- point mutations (single nucleotide) - substitution, insertions, deletions