7.1

Question 1

How are proteins made

Answer 1

• The # of amino acid and their sequence differentiates proteins to another
• Information stores within DNA in 4 nucleotide bases
• Based on these 4 nucleotide bases, human have 20 000 diff genes (codes for 100 000 diff proteins)
• RNA send messages from gene, travels to the ribosomes, to assemble proteins

Question 2

IMAGE

Answer 2

Ribosomes: in blue

RNA messangers strand: Pink

Polypetide: Green

Question 3

Proteins

Answer 3

• Drives cell. processes (metabolism)
• Determine physical characteristics
• Absence or alternations can manifest genetic disorders

Question 4

One-gene one polypeptide hypothesis

Answer 4

• Garrod studied alkaptonuria (a person’s urine turn black on contact with air)
• Found that they have a mutated gene that cannot break down a.a tyrosine

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Question 5

One-gene one polypeptide hypothesis - Part 2

Answer 5

• Beadle and Tatum worked with orange bread mould
• direct relationship b/w
  genes and enzymes
• Mutated strain had a defect in a gene that
  coded for needed enzymes (e.g., arginine)

Question 6

Conclusion

Answer 6

• Each gene codes for the synthesis of one polypeptide
• Different polypeptides can be combined to form more
  complex proteins
   E.g., hormones, enzymes, and antibodies

Question 7

Central Dogma

Answer 7

• Developed by Francis Crick
• DNA–>RNA—>polypeptide

2 steps:
Transcription and translation

Question 8

Transcription

Answer 8

• DNA —> RNA
• Occurs in nucleus
• DNA cannot leave nucleas
• RNA can exit nucleas and enter cytosol
• RNA can be used to bind to proteins

Question 9

Translation

Answer 9

• RNA —> protein
• RNA codes for specific a.a
• Occurs in ribosome of cytosol
• Folding changes shape of polypeptide chain into functioning protein

Question 10

RNA vs DNA

Answer 10

DNA:
- Double stranded
- G,C,A,T
- Deoxyribose sugar

RNA:
- Single stranded
- G,U,A,C
- Ribose sugar

Question 11

3 Major types of RNA

Question 12

1. Messanger RNA

Answer 12

• mRNA
• Moves info from DNA-> RNA where it can be translated
• Translated by ribosome into protein

-Varies in length

Question 13

2. Transfer RNA

Answer 13

• tRNA
• Transfers a.a to ribosomes to build proteins
• DIctated by mRNA template

Question 14

3. Ribosomal RNA

Answer 14

• rRNA
• Structural component of ribosome
• Allows tRNA and mRNA to bind to ribosome

Question 15

Transcription

Answer 15

• RNA polymerase creates sequence complementary to DNA template
• mRNA created from 3’ to 5’ direction
• DNA strand is called template strand
• mRNA can exit nucleas and enter cytosol

Question 16

Translation

Answer 16

• mRNA is associated with ribosome
• Ribosome moved along mRNA
• a.a are delivered by tRNA

Question 17

The Genetic Code

Answer 17

3-letter code

 Universal with the same codons specifying
the same amino acids in all living organism,
and all viruses

 This demonstrates the fact that DNA
evolved early in our evolution and
remained virtually unchanged through
billions of years of evolutionary history

Question 18

Codons

Answer 18

• 3 BP codes for one amino acid
• 64 codons
  - 61 are sense codons (with 1 start codon)

     - 3 are stop codons (UAA, UAG, UGA)

• Only 2 amino acids, methionine (Met) and tryptophan (Trp) are
  specified by a single codon
• Rest are synonyms in the genetic code

Question 19

Wobble Hypothesis

Answer 19

• 3rd
  base in a codon can change (wobble), while allowing the codon to still
  code for the same amino acid