Lecture 14 Notes

Question 1

goals of interpreting genome sequence

Answer 1

1. to have a catalog of the genes
2. to learn about chromosome structure, function, organization:
   - genome organizaion
   - telomeres
   - centromeres
   - other structural features

Question 2

computational approach to find and characterize genes

Answer 2

what features in the DNA sequence indicate the presence of genes?

• ORFs
• protein domains
• regulatory sequences
• evolutionary conservation

-computer algorithms search for ORFs in reading frames

Question 3

what does a long ORF indicate?

Answer 3

part of a gene that codes for a protein

Question 4

experimental approaches to find and characterize genes

Answer 4

-cDNAs- complementary DNAs, made from mRNAs
-RNA seq
-primary transcripts can be placed in different ways in different cells
cDNAs confirm gene assignments and also help identify all gene products

Question 5

cDNA libraries

Answer 5

• a library of clones containing DNA copies of all of the mRNAs from a cell type/tissue/sample
• cDNA = complementary DNA
• double-stranded DNA copies of mRNAs
• eukaryotic mRNAs have poly(A)tails at their 3’ ends

-exons only

Question 6

How to Make a cDNA library

Answer 6

1. purify mRNAs (use poly(A) tails)
2. make DNA copies of mRNAs
3. ligate cDNAs into plasmid or other vector

Question 7

gene families

Answer 7

• encode similar “homologous”proteins
• “homologous” genes and proteins within a family have a single common ancestor
• generated by duplication and divergence of an ancestral gene
• proteins have functional domains whose amino acid sequences are similar in different proteins