DNA Features and Functions

Question 1

what are the 3 main functions of DNA?

Answer 1

1. store info
2. replicate faithfully (preserve info)
3. ability to mutate (variability of info)

Question 2

DNA - store information

Answer 2

• info is carried in/by sequence of bases

type of info DNA carries:
- coding = for proteins and diff RNAs (rRNA, tRNA, small regulatory RNAs)
- regulatory signals = binding sites

• only mRNA is translated, other RNAs are only transcripted
• enhancers are NOT part of genes

Question 3

molecular bio def of a gene:

Answer 3

entire DNA seq necessary for production of a functional protein/RNA

Question 4

DNA - replicate faithfully (experiment)

Answer 4

semiconservative (Meselson and Stahl)
- 0th gen: 1 heavy (15N)
- 1st gen: 2 hybrid
- 2nd gen: 2 hybrid, 2 lighter (14N)
conservative (expected result)
- 1st gen: 1 heavy, 1 light
2nd gen: 1 heavy, 3 light

Question 5

DNA - ability to mutate

Answer 5

• mutations in coding seq -> can alter protein product
• concept of COLINEARITY of genes and protein
  – mutations change proportionality of proteins and genes
• mutations can happen in regulatory seq
• importance of mutations (selection -> evol)
  – formation of new alleles: altered product, no product (knockout), altered regulation of product expression (mutation in regulatory seq)

Question 6

colinearity meaning in genes

Answer 6

peptide length is proportional to gene length

Question 7

Indel meaning?

Answer 7

insertion-deletion mutations (causes frameshift)

Question 8

other name for template strand

Answer 8

antisense strand

Question 9

names for strand that isn’t template strand (3)

Answer 9

“RNA like strand”
coding strand
sense strand

Question 10

only ___ strand is template strand for transcription

Answer 10

antisense
- RNA is ss

Question 11

DNA and RNA are ____ charged

Answer 11

negatively

Question 12

DNA structure (helical shape, strands have ___, complementarity, bonds, grooves, 3’/5’, structure)

Answer 12

• double helix
• strands have polarity
• complementary, antiparallel
• A–T
• G—C
• major groove, minor groove
• 3’ = OH group
• 5’ = phosphate group
• phosphodiester bond links 3’ and 5’ groups to make sugar phosphate backbone