DNA"The Blueprint of Life"

Breaking Down the Definitions• Nucleotide• Deoxyribose• Nitrogenous base• Purine• Pyrimidine• Base-pairing rules• Complementary base

pairs• Base sequence• DNA replication• Helicase• Replication fork• DNA polymerase

• Semi-conservative replication• Mutation• RNA• Transcription• Translation• Protein synthesis• Ribose• mRNA• rRNA• tRNA• RNA polymerase• Promoter• Termination signal• Genetic code• Codon• Anticodon• genome

DNA stands for...      DeoxyriboNucleic Acid

Time for a Song!

DNA FACTS

•established by James Watson and Francis Crick 

     •Shape of a double

helix

•codes for your genes  (traits/allleles)•made of repeating subunits called

nucleotides

What is a nucleotide?Has three parts:   

PHOSPHATEDEOXYRIBOSE (5 Carbon sugar)BASE  (A,T,G,C)

Base-Pair Rule

Adenine <==> Thymine

Guanine <==> Cytosine

The sides of the DNA ladder are phosphate & sugar

held together by  hydrogen bonds

Mnemonic

Come up with a memory device/slogan/phrase to remember the 4 nitrogen bases and how they pair up.

Base Pair RuleOne side:     A   T   A      T   C   A      T   G   C      G   G   G

Other side:

DNA Structure Video Clip

DNA Coloring

DNA Candy Ladders

Let's Review What We Know About DNA1.  DNA stands for:   De _____ ribo ______  acid2.  What is the shape of DNA? _______________3.  Who established the structure of DNA?  ____________4.  Adenine always pairs with _______________5.  The sides of the DNA ladder are deoxyribose and _____6.  Guanine always pairs with _____________7.  What is the complimentary sequence:   A A T  G  C A8.  The two sides of DNA are held together by _______ bonds.9.  DNA is composed of repeating subunits called ______________________10.  What are the 4 bases that make up the rungs of the DNA ladder? _______________________________________

DNA REPLICATION

the process by which DNA makes a copy of itself (cell division)

SEMI-CONSERVATIVE - half of the old strand is saved

Steps of DNA Replication

1• Enzyme Helicase separates the DNA strands

2

• Enzymes called DNA polymerases add the compatible nucleotides (found floating in nucleus) to the original strands

• Hydrogen bonds form between the new nitrogen bases

3• DNA polymerases are released• 2 DNA molecules, identical, are created

Errors in Replication

• DNA replication usually occurs with great accuracy.

• Only about 1 error for every BILLION pairs of nucleotides (for example: retyping your Biology text book 1000 times and only making 1 typo)

• When a mistake occurs, the base sequence is changed; this is called a MUTATION

DNA Replication Video

DNA Replication Lab

Protein SynthesisA gene (a segment on a DNA strand) codes for a specific hereditary item (ie hair color).

The gene is the instruction for the making of the protein that creates that item (ie blond hair).

To get the instructions to the ribosome (where proteins are made) DNA uses RNA to deliver the genetic information to the ribosome where the protein is created.

This entire process= PROTEIN SYNTHESIS

RNA - the messenger *single strand*ribose sugar*contains no thymine, uracil instead

*follows base pair rule

DNA:   A  T  A   G  C  GRNA:  

RNA carries the "message" to the ribosomes, where proteins are made

DNA -->  RNA -->  Protein

Proteins are the building blocks of the organism (traits)

Transcription -  process where RNA is made from DNA

Translation - process where proteins are made from RNA

Steps of Transcription

1• RNA polymerase binds to a promoter• The DNA strands unwind and separate

2

• RNA polymerase adds free RNA nucleotides that are compatible with the DNA strand

• Unlike DNA replication, transcription only codes for a particular gene (not the entire strand)

3

• RNA polymerase reaches a termination signal that marks the end of the gene

• RNA polymerase releases, DNA rewinds and the new RNA strand goes on to perform its job

Transcription and Translation Video Clip

Transcription and Translation Coloring

Types of RNA

mRNA

• Messenger RNA

• A single strand, carries instructions to ribosome

rRNA

• Ribosomal RNA

• Part of the structure of the ribosome

tRNA

• Transfer RNA

• Transfers amino acids to the ribosome to make a protein

How the Code Works

The combination of A,T,G,C determines what traits you might have.....

C A T C A T   =  purple hair

T A C T A C  =  yellow hair

Think of the bases of DNA like letters.

Letters form words....

Words form sentences....               *endless               combinations

The Genetic Code

3 adjacent nucleotides (‘letters’) in mRNA specify a particular amino acid (‘word’). 3 nucleotides also = a codon.

There are 64 codons that encode most organisms.

GCU, GCC, GCA, and GCG are all codons that code for the amino acid, Alanine.

Steps of Translation—the making of Proteins

1• tRNA and mRNA join together• Codons match up with anticodons on the tRNA

2• Polypeptide chain is put together• The amino acids that are coded for begin to make a chain

3• The chain continues to grow as more amino acids are

added as the codons instruct

4• The ribosome reaches a ‘stop’ codon and the polypeptide

chain is complete.

DNA Song

Transcription and Translation in Action

Simulation Protein Synthesis

Turkey Time

Protein Power Game