Molecular Biology of the Gene Notes

What is the structure of DNA?

DNA is a double helix composed of nucleotides.

What was a mystery in the early 20th century?

The molecular basis for inheritance.

What significant understanding was achieved in the 1950s regarding DNA?

DNA holds the key to understanding inheritance.

What was the Bacterial Transformation Experiment?

An experiment that demonstrated bacteria can transfer genetic information.

Who conducted the Bacterial Transformation Experiment?

Frederick Griffith.

What year did Frederick Griffith conduct his experiment?

1928.

What is Streptococcus pneumoniae?

A bacterium that causes pneumonia in mammals.

What did Rosalind Franklin study when she began working at King's College?

The structure of DNA

Who did Rosalind Franklin meet and work with at King's College in London in 1951?

Maurice Wilkins, who assumed she was his assistant.

What was the name of the photo that Rosalind Franklin made in 1952?

Photo 51

What did James Watson and Francis Crick do with Photo 51?

They got it from Wilkins and took credit for it.

Who were the authors of the two manuscripts that came out in 1953 about DNA structure?

Manuscript #1: Watson and Crick; Manuscript #2: Rosalind Franklin

What happened to Rosalind Franklin in 1958?

She died of cancer.

Who won the Nobel Prize for the structure of DNA in 1962?

Watson, Crick, and Wilkins.

What are DNA and RNA made of?

Polymers of nucleotides

What type of nitrogenous bases are Adenine and Guanine?

Purines (Bigger)

What type of nitrogenous bases are Thymine and Cytosine?

Pyrimidines (Smaller)

How is DNA read?

DNA is read 5 to 3

Who discovered Chargaff's rule?

Erwin Chargaff

What does Chargaff's rule state about the proportions of nucleotides?

The proportion of A and T is always the same, and the proportion of C and G is always the same.

In which decade was Chargaff's rule discovered?

1940s

Who used Chargaff's published information in building their model of DNA?

Watson and Crick

What model does DNA replication follow?

Semi-conservative model

Which enzyme separates the double stranded DNA molecule during replication?

DNA helicase

Which enzyme adds free bases at the 3' end of each single strand during DNA replication?

DNA polymerase

What does the enzyme DNA ligase do?

DNA ligase joins DNA strands together.

What rule does the function of DNA ligase confirm?

Chargaff's Rule.

Who described Chargaff's Rule in their paper on DNA structure?

Watson & Crick.

The Central Dogma

Genes are just information

What is their importance?

DNA is used to make RNA (Transcription)

RNA is used to make proteins (Translation)

What type of sugar base does DNA have?

Deoxyribose

What type of sugar base does RNA have?

Ribose

What are the bases of DNA?

A, T, C, G

What are the bases of RNA?

A, U, C, G (Uracil)

What is the structure of DNA?

Double Helix

What is the structure of RNA?

Single Strand

What is the process of making RNA called?

Transcription

What happens during the initiation phase of transcription?

RNA Polymerase attaches to the promoter to start RNA synthesis

What occurs during the elongation phase of transcription?

Free RNA nucleotides are added complementary to each DNA nucleotide

What happens during the termination phase of transcription?

RNA polymerase reaches the terminator DNA and detaches

What are the three important types of RNA?

Messenger RNA (mRNA), Transfer RNA (tRNA), Ribosomal RNA (rRNA)

What is the function of messenger RNA (mRNA)?

Carries a 3 RNA letter called a codon to the ribosome in the cytoplasm to be used to synthesize an amino acid.

What is the genetic code's nature?

The genetic code is universal and redundant.

What is the role of transfer RNA (tRNA)?

Each tRNA carries an amino acid to the ribosome.

What does the anti-codon on tRNA do?

The anti-codon is a 3 nucleotide sequence complementary to the mRNA codons.

What is the function of ribosomal RNA (rRNA)?

Combines with protein to form a ribosome.

What is the site where proteins are made using amino acid subunits?

The ribosome.

What molecules are involved in the process of translation?

mRNA, tRNA, and rRNA

What marks the beginning of translation?

The start codon on the mRNA

What happens during the elongation phase of translation?

Amino acids are added until the stop codon is reached

What occurs when a stop codon is reached during translation?

Termination of translation occurs

What is a mutation?

A change in the nucleotide sequence of a cell's DNA.

What is a silent mutation?

A mutation that codes for the same amino acid.

What genetic disease is caused by a single nucleotide change?

Sickle-cell anemia.

How many genes are in the complete human genome?

25,000-30,000 genes.

What regulates genes?

Specific proteins.

What can turn genes on and off?

Specific molecules.