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CHAPTER 28:  DNA – LIFE’S CODE

___________ (Deoxyribonucleic Acid): A molecule that makes up genes and determines the traits of all living things.

Structure of DNA 

·        Alternating ____________________ & _____________________ (Phosphate group). These make up the “________________” portion of the ladder.

·        ____________________________ make up the _____________ of ladder. Four Nitrogen bases exist:

________________________________ states that ____=____, and ____=____

__________________________ - Sugar + Phosphatic Acid + Nitrogen Base (A,T,C,G)

____________________ & _____________________ built a model to show that DNA was a ______________________________ (structure).

DNA & Chromosomes 

__________________ - Pieces of DNA on a chromosome that code for certain traits. 

_________________________________ performed an experiment that showed:

How DNA Works

The Nitrogen bases ____________________ on the nucleotides in DNA spell out a message that is stored in code form. The ______________ of the ___________ is the __________________.

 The order of bases on this gene codes for ________________ Red Blood Cells

The order of bases on this gene codes for ________________ Red Blood Cells. Changing ONE Nitrogen base will change the ___________________ being made. This may not be the correct protein needed for certain functions in the body.

Consider our Alphabet. The letters are always the same, but we put them in __________________________________ to form ____________________  _________________. Example:

DNA Replication –

Steps:

Making Proteins 

_________________ are chains of amino acids that perform necessary life functions.

 _________ (Ribonucleic Acid) – A chemical that acts as a messenger for DNA.

 DNA vs. RNA

Three Forms of RNA:

·        ____________ (Messenger RNA):  In nucleus. Can leave nucleus to make proteins for DNA

·        ____________ (Transfer RNA): In cytoplasm. Carries Amino Acids to ribosome to be added to growing proteins

·        ____________ (Ribosomal RNA): In cytoplasm. Makes up the ribosome.

2 Steps Involved in Making Proteins:

 _____________________________: A DNA copy of the gene is made (DNA -> RNA) (Occurs in the ____________________)

_____________________________: mRNA, tRNA, & rRNA work together to assemble Amino Acids into a Protein (Occurs in the ___________________)

Central Dogma:

Transcription (Step 1 in making a protein) Refer to diagram 28-7.

 DNA separates            mRNA copy is made                     mRNA leaves nucleus
                                                        of DNA                              to make proteins

The Genetic Code – The code that translates DNA language into proteins from mRNA codons.

___________________ - 3 nucleotides of mRNA that determine which amino acid will be added to a growing protein chain.

Codons may be translated into amino acids using the following chart:

_______: START codon. (Methionine). Initiates the start of protein production.

____________________________: STOP codons. These signal the end of the protein

EXAMPLE: Translate the following sequence of DNA:

 DNA:            TAC             TTA             AGT             CCG           ATC

RNA:             _________________________________________

Amino Acid: __________________________________________

(Protein)

Translation (Step 2 in making proteins) RNA -> Protein

·        ____________ binds to _____________with AUG, ____________ codon to initiate the beginning of the protein

·        ___________ molecules carry the correct ________________________ to the ribosome

·        ____________________, 3-nucletide sequences that are complementary to mRNA codons, assure that the correct amino acid is carried to the ribosome.

·        Amino Acids are added to the growing protein chain until a __________ codon is reached.

·        New ________________ is ___________________ into the cell to perform its function.

Mutation –

In a mutation, Nitrogen bases are joined incorrectly during DNA replication.

Example: ___ = ___ or ___ = ___ (correct pairing would be C = G or T = A)

The message or “code” has now changed. An ____________________________ will be made, and a ________________________________ may appear.

Example: Hemophiliacs have a _______________________ in the gene that codes for a ___________________ that __________________________. Therefore, they cannot _________________________________.

Causes of Mutations

Cloning

 ___________________ - Two organisms that have the same DNA; they are exact copies of each other.

Identical Twins:                                                       Fraternal Twins:

Animals are currently being cloned. Do you think humans should be cloned?

Plant & Animal Breeding

 _____________________________ - Bringing together of 2 living things to produce desirable offspring.

This process is used to produce:

Splicing Genes –

Procedure:

_______________________________________ - DNA that is formed when DNA from one organism is placed into the DNA of another organism.

Splicing Genes works because:

Examples of the Benefits of Gene Splicing