T2.7 Replication, Transcription and Translation

Question 1

Who discovered the evidence for semi-conservative replication?

Answer 1

Meselson and Stahl

Question 2

What does semi-conservative mean

Answer 2

• Two strands seperate and they each serve as a template for the creation of the new strand
• The new DNA molecule is composed of an original strand and a newly synthesized strand

Question 3

Structure of helicase

Answer 3

Globular protein composed of 6 polypeptide arranged in a donut shape

Question 4

Function of helicase

Answer 4

Uses ATP to move along DNA and breaks hydrogen bonds between nitrogenous bases

Question 5

Function of polymerase

Answer 5

Adds complimentary bases to the 3’ end of new growing strand

Question 6

Which direction is the newly synthesized strand of DNA created?

Answer 6

5’ to 3’ direction

Question 7

What is Polymerase chain reaction (PCR)

Answer 7

a method to amplify the production of any pieceof DNA by heating

Question 8

What is Taq DNA Polymerase

Answer 8

The DNA Polymerase extracted from Thermua aquaticous, which is found in hot springs and lives at temps of 75 C

Question 9

Why is Taq DNA Polymerase used in PCR

Answer 9

The polymerase, and other proteins, can resist denaturation at the temps needed to seperate DNA helix into single strands (95 C) that can be copied by the Taq DNA polymerase. This makes it so DNA can be made a lot faster than having helicase unwind the strand every time.

Question 10

General concepts of Transcription

Answer 10

RNA Polmerase seperates DNA, adds complimetary nucleotides to form single strand of mRNA

DNA -> mRNA

Question 11

Sense strand

Answer 11

DNA sequence that contains the protein coding sequences, and is not what is copied in transcription. It is opposite to the anti-sense strand.

Question 12

Anti-sense strand

Answer 12

Acts as the template and has complementary base sequence to the mRNA. It is what mRNA binds to. Another name is the template strand

Question 13

Outline of the process of translation

Answer 13

• Synthesis of polypeptide determined by the base seuence of mRNA molecule.
• mRNA code is translate from 5’ to 3’ end
• occurs at ribosome

mRNA -> polypeptide

Question 14

Outline of the process of translation

Answer 14

• Synthesis of polypeptide determined by the base seuence of mRNA molecule.
• mRNA code is translate from 5’ to 3’ end
• occurs at ribosome

mRNA -> polypeptide

Question 15

Structure of a ribosome

Answer 15

• large and small subunits
• composed of mostly rRNA and some proteins/enzymes
• picture

Question 16

Codon

Answer 16

A sequence of 3 bases on the mRNA that codes for an amino acid

Question 17

Degenerate code

Answer 17

Refers to codons that code for the same amino acid, ex serine (6 codons code for it)

Question 18

3 components that work together to synthesize polypeptides by translation

Answer 18

1) mRNA’s sequence of codons that specifies the amino acid sequence
2) tRNA molecules’s anticoon of 3 bases that binds to the complementary codon on mRNA, which carries the corresponding amino acid
3) Ribosomes that act as the binding site for mRNA and tRNA, also catalyzes the assembly of polypeptide

Question 19

Define Universal code

Answer 19

You can put in any gene into a cell, and it will still make the protein, meaning that the proteins always code for the same protein in every cell

Question 20

How is the production of human insulin in bacteria an example of the universality of the genetic code

Answer 20

They put human genetic code into an e. coli bacteria, and the bacteria produced the exact same insulin it produced in the human.

Question 21

What did Meselson and Stahl’s experiment demonstrate?

Answer 21

Figured out which possible outcome of DNA replication was right (semi-conservative)

Question 22

Three possible outcomes based on Watson and Crick’s DNA model

Answer 22

Disperative: chunks itself into segments and each would be copied
Conservative: DNA would be wrapped around histone proteins and would duplicate
Semi-conservative
link to picture of them

Question 23

What was the isotope Meselson and Stahl used

Answer 23

Nitrogen-15 (extra neutron)

Question 24

Why did Meselson and Stahl use N-15

Answer 24

Nitrogen is an important part of the DNA structure, and it can be seperated from the regular DNA on the basis of density

Question 25

Where the strands in the original DNA of the e-coli heavy or not heavy (N-14 or N-15)?

Answer 25

Heavy, N-15

Question 26

After growing the E.coli in normal media for one round of replication what happened to the density of the DNA?

Answer 26

The DNA grew lighter.

Question 27

What is the reason for the DNA to grow lighter after the first round of replication?

Answer 27

The DNA would split itself in the middle and used semi-conservation, so every DNA would have heavy and not heavy

Question 28

What did they observe about the density of the DNA after the 2n round of replication?

Answer 28

The DNA was 50% light and 50% heavy nitrogen