DNA chapter 12- part 1

What did early scientists think was the genetic material?

Protein (not DNA)- because proteins were MUCH more complex than DNA.

Frederick Griffith

Discovered transforming principal with two strains of bacteria and mice. Live R strain bacteria was transformed into live S strain (virulent) by the heat killed S strain.

Avery and McCloud

Discovered DNA was transforming factor

Chargaff

Showed that in DNA the amount of A is equal to the amount of T and the amount of C is equal to the amount of G

What is the purpose of DNA?

It is the genetic material responsible for carrying out all of the functions in the body- the blueprints for life

Nucleotide

A Monomer of DNA- made of three parts phosphate, sugar and a nitrogenous base

Where is DNA found?

The nucleus.

Hershey/Chase

bacterial viruses- called phages- were used to demonstrate that DNA is the genetic material. DNA contains phosphorous, Protein coat contains sulfur- using radioactive labeling and tracing they found the infected bacteria contained phosphorous and not sulfur. Making DNA the genetic material.

Watson/Crick

Discovered/Proved that DNA took the shape of a double helix

Rosalind Franklin

Took x-rays of DNA to reveal that it was helical in structure with even spacing within the molecule. Did NOT receive the nobel prize due to death.

What is the difference between a nucleotide and a nitrogenous base?

A nucleotide is made up of three parts; a sugar, a phosphate and a nitrogenous base. So the nitrogenous base is a part of the nucleotide.

What does DNA stand for?

Deoxyribonucleic Acid

What does RNA stand for?

Ribonucleic Acid

What makes DNA different than RNA?

The sugar, its the location it functions, T vs U, and the number of strands that make it up.

Purines

Adenine and Guanine- double ring structure

Pyrimidines

Thymine, Cytosine and Uracil - Single ring structure

In RNA what nitrogenous base pairs with Adenine?

Uracil

In what direction MUST DNA be assembled?

5' to 3'

What enzyme is responsible for unwinding the DNA?

DNA helicase

What enzyme is responsible for adding nitrogenous bases to the newly synthesized DNA strand?

DNA Polymerase

How many molecules of DNA are present in one double strand?

two

What are the three parts to a nucleotide?

Sugar, Phosphate and a Nitrogenous Base

What does tRNA stand for?

transfer RNA

What does rRNA stand for?

ribosomal RNA

What does rRNA do?

forms ribosomes

What occurs in transcription?

a mRNA strand is formed from the DNA strand in the nucleus

Codon

a nucleotide triplet in mRNA that codes for a specific amino acid

tRNA

uses the anti-codon to bring an amino acid to its codon in translation

translation

the mRNA code is made into protein with the help of the anticodon and tRNA

hydrogen bonds

holds the two strands of the double helix together by bonding between the complementary nitrogenous bases

covalent bonds

holds the sugar-phosphate backbone together in DNA

gene

section of DNA that has the information coded for one particular protein

anti-codon

only found in tRNA- used to bring amino acid to ribosome for protein synthesis

RNA Polymerase

enzyme responsible for adding nucleotides during transcription

Okazaki Fragments

short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication.

Leading Strand

strand in DNA replication where nucleotides are added continuously in the 5' to 3' direction

Lagging Strand

strand in DNA replication where nucleotides are added in small fragments that are later connected together

5' to 3'

The direction DNA is synthesized

Transcription

Using the DNA template a complimentary mRNA strand is synthesized

What are the three parts to a DNA nucleotide?

Deoxyribose, A Phosphate and a nitrogen base (A, T, C or G)

What are the three parts to an RNA nucleotide?

Ribose, a phosphate, and a nitrogen base (A, U, C or G)

mRNA

Messenger RNA

Nobel Prize Winners for discovering DNA

Watson, Crick, Wilkins

DNA Backbone

the sides of the ladder- comprised of alternating Deoxyribose sugars and phosphates held together by covalent bonds

Number of codons used in protein synthesis

64

Number of available amino acids

20

How do nitrogenous bases fit together according to Chargaff's rules and Watson and Crick's Model?

Purine-Pyrimidine

Start Codon

AUG- Methionine

Stop Codons

Signals protein synthesis to end- three codons- UAA, UAG, UGA

Amino Acid

Every 3 mRNA bases= one amino acid, a monomer of a protein

Central Dogma of Biology

DNA--> RNA --> Protein

DNA Proofreading Enzymes

Enzymes that repair errors in DNA replication

Steps of Protein Synthesis

1. DNA is copied in the nucleus into a single strand of mRNA

2. mRNA leaves the nucleus headed to a ribosome

3. mRNA binds to the ribosome

4. tRNA picks up amino acids and transports them to the ribosome

5. The individual amino acids form peptide bonds as the mRNA moves through the ribosome, releasing the tRNA and forming a protein

Semi Conservative Replication

One parent strand is conserved during DNA synthesis, meaning the two daughter strands are each made up of one parent strand (original) and one daughter strand (copy)