MBG Part Two: Lecture 7

Question 1

Following RNA Splicing, what happens?

Answer 1

RNA Editing

Question 2

How does RNA editing change the information content of the genes?

Answer 2

• The modification of mRNA by endogenous guide RNAs
• Inserting or deleting uridine monophosphate residues
• Changing the structures of individual bases (i.e, tRNAs, rRNAs)

Question 3

What base does deamination of cytosine produce?

Answer 3

Uracil

Question 4

What is some RNA editing carried out by?

Answer 4

Guide RNAs (gRNAs) that can be made in the cell.

Question 5

What do gRNAS direct?

Answer 5

The insertion of uridine bases into the mRNA by a repair polymerase.

Question 6

What does the insertion of uridine bases do?

Answer 6

Permanently modifies the mRNA by making new codons that specify new amino acids in the protein.

Question 7

What are Apolipoproteins?

Answer 7

Blood proteins that carry lipids (Fat and cholesterol) in the blood stream

Question 8

What does the anticodon of the tRNA base pair with?

Answer 8

Codons of the mRNA.

Question 9

What is the amino acid covalently attached to?

Answer 9

The 3’ end of the tRNA

Question 10

What is the amino acid attachment site?

Answer 10

Always CCA

Question 11

What does the anticodon arm consist of?

Answer 11

Three bases and interacts with a codon in mRNA.

Question 12

What are the several processing events tRNAs undergo?

Answer 12

• Removal of Extra 5’ and 3’ sequences
• Removal of Introns (do not have consensus splice sequences)
• Nucleotides 5’-CCA-3’ are added to the 3’ end of the tRNA for all tRNAs
• Modification of Several Nucleotides

Question 13

What are ribosomes?

Answer 13

Composed of a large and a small subunit that are assembled from many different proteins and rRNAs.

Question 14

What does a ribosome play a key role in?

Answer 14

Protein Synthesis, including the formation of peptide bonds between amino acids.

Question 15

What is the size of a prokaryotic ribosome?

Answer 15

50S - large subunit

30S - small subunit

Makes 70S Ribosomal Unit

Question 16

What is the size of a eukaryotic ribosome?

Answer 16

60S - large subunit

40S - small subunit

Makes 80S Ribosomal Unit

Question 17

In Prokaryotes, what does one gene make?

Answer 17

23S, 16S, 5S rRNAs plus one tRNA

Question 18

In Eukaryotes, what does one Large rRNA gene make?

Answer 18

18S, 28S, 5.8S rRNAs

Question 19

In Eukaryotes, what does one small rRNA gene make?

Answer 19

5S rRNA

Question 20

In Eukaryotes, what is the nucleolus?

Answer 20

The site of rRNA synthesis and ribosome assembly (small nucleolar RNAs, snoRNAs, help cleave and modify rRNAs)

Question 21

In prokaryotes, where does rRNA synthesis occur?

Answer 21

Occurs in the cytoplasm

Question 22

What are snRNAs?

Answer 22

• Act in complexes with proteins
• Play roles in Post-Transcriptional processing of RNA, such as splicing (splice some assembly)

Question 23

What are snoRNAs?

Answer 23

• Act in complexes with proteins
• Guide the enzymatic chemical modifications of ribosomal RNAs, transfer RNAs and small nuclear RNAs

Question 24

What are siRNA and miRNA?

Answer 24

• Act as short, single stranded RNAs that bind to complementary sequences in mRNA.
• Produced by cleavage of mRNAs, RNA transposes, and RNA viruses.
• Regulate and control gene expression

Question 25

What are Crispr RNAs?

Answer 25

Found in Prokaryotes

Encoded by sequences found in prokaryotic genomes

Question 26

What is the function of LncRNA?

Answer 26

Regulate and control gene expression at the level of transcription or translation by binding mRNA or sequestering micro-RNAs that control gene expression

Bind and recruit proteins involved in DNA modification (X-inactivation in mammals)