Exam Homework #4
Chapter 10 and 11– Homework
1. Describe the stages of transcription. Initiation- Initiator tRNA binds to small ribosomal subunit. Small subunit/tRNA complex attaches to mRNA and moves along it to an AUG “start” codon. Large ribosomal subunit joins complex. Initiation must occur in the order listed above.
Elongation- mRNA passes through ribosomal subunits. tRNAs deliver amino acids to the ribosomal binding site in the order specified by the mRNA. Peptide bonds form between the amino acids and the polypeptide chain grows.
Termination- A stop codon in the mRNA moves onto the ribosomal binding site. No tRNA has a corresponding anticodon. Proteins called release factors bind to the ribosome. mRNA and polypeptide are released.
2. Name 3 classes of RNA and their function. Ribosomal RNA (rRNA)
– rRNA combines with proteins to form ribosomes
– Ribosomes – site of protein sysnthesis
Transfer RNA (tRNA)
– Transport correct amino acids to ribosomes and pairs up with an mRNA code for that amino acid
– Proteins are polymers of amino acids joined by peptide bonds
Messenger RNA (mRNA)
– Conveys information from chromosomes to ribosomes
– Genetic “blueprint” for making proteins
3. What is the function of RNA polymerase and the promoter? These two have to bind together in order for transcription to occur
4. List 3 ways RNA is modified. Addition of a 5’cap
Addition of a 3’ poly A tail
Introns have to be removed; exons are spliced together
5. What is the genetic code? What does it mean to state the genetic code is redundant and practically universal? Genetic code is practically universal– Most of the code is the same for all organisms
Genetic code is redundant – More than one codon specifies a specific amino acid. For example, six different codons specify leucine.
6. What is the difference between an anticodon and a codon? A codon is found in DNA and describes different genes. An anticodon is a stop sequence found in RNA only.
7. Describe
1. Describe the stages of transcription. Initiation- Initiator tRNA binds to small ribosomal subunit. Small subunit/tRNA complex attaches to mRNA and moves along it to an AUG “start” codon. Large ribosomal subunit joins complex. Initiation must occur in the order listed above.
Elongation- mRNA passes through ribosomal subunits. tRNAs deliver amino acids to the ribosomal binding site in the order specified by the mRNA. Peptide bonds form between the amino acids and the polypeptide chain grows.
Termination- A stop codon in the mRNA moves onto the ribosomal binding site. No tRNA has a corresponding anticodon. Proteins called release factors bind to the ribosome. mRNA and polypeptide are released.
2. Name 3 classes of RNA and their function. Ribosomal RNA (rRNA)
– rRNA combines with proteins to form ribosomes
– Ribosomes – site of protein sysnthesis
Transfer RNA (tRNA)
– Transport correct amino acids to ribosomes and pairs up with an mRNA code for that amino acid
– Proteins are polymers of amino acids joined by peptide bonds
Messenger RNA (mRNA)
– Conveys information from chromosomes to ribosomes
– Genetic “blueprint” for making proteins
3. What is the function of RNA polymerase and the promoter? These two have to bind together in order for transcription to occur
4. List 3 ways RNA is modified. Addition of a 5’cap
Addition of a 3’ poly A tail
Introns have to be removed; exons are spliced together
5. What is the genetic code? What does it mean to state the genetic code is redundant and practically universal? Genetic code is practically universal– Most of the code is the same for all organisms
Genetic code is redundant – More than one codon specifies a specific amino acid. For example, six different codons specify leucine.
6. What is the difference between an anticodon and a codon? A codon is found in DNA and describes different genes. An anticodon is a stop sequence found in RNA only.
7. Describe