Chapter 9 and 10

DNA: Genetic MaterialHow Proteins are made

James Watson and Francis Crick

• 1950’s• Used past

experiments done by other scientists

• Discovered the structure of DNA

Characteristics of DNA

• Double Helix (twisted staircase)

Nucleotides – make up DNA

• Subunits• Contain 3 parts:

– A phosphate– A sugar-

Deoxyribose– Nitrogen base

• Adenine (A)• Guanine (G)• Thiamine (T)• Cytosine (C)

Nucleotide Pairing

• http://www.phsuccessnet.com/iText/products/0-13-115075-8/index.html

• Adenine pairs with thymine• Guanine pairs with cytosine

9-3 Replication of DNA

• Occurs during what phase of cell cycle?

• Steps:– 2 original DNA stands unzip – Free nucleotides in nucleus are added

to each strand– Two identical molecules of DNA are

formed.

1. DNA unzips

Animation of DNA replication

Chapter 10: Making Proteins

• What is RNA?– It is a copy of DNA– RNA is used to

build proteins– Single stranded– No tymine

RNA nucleotides

• Ribonucleic Acid• 3 parts:

– Sugar: ribose– Single stranded– Nitrogen bases:

• Adenine• URACIL• Cytosine• guanine

RNA pairings

• Adenine pairs with Uracil• Cytosine pairs with Guanine

Types of RNA

• mRNA – messenger RNA• Made in nucleus, strand shape

tRNA – transfer RNA

•Found outside nucleus

•Carries an amino acid

The cell’s alive, it will surviveTranscription and translation are how

proteins are synthesized

Step 1 of Protein synthesis

• Transcription – construction of mRNA– DNA strands separate a site of

needed protein code.– RNA nucleotides are added to DNA.

DNA acts as a template.– mRNA moves out of the nucleus into

the cytoplasm to the ribosome

Illustration of Transcription Biology: Exploring Life

Step 2: Translation

• At the ribosome: mRNA is read in groups of 3.

• Codon – Group of 3 bases

Translation continued• mRNA is read and

interpreted• tRNA receives a

message to come to the mRNA at ribosome

• tRNA carries an amino acid

• (anticodon)

Translation

• This continues until the mRNA is read completely

• tRNA attaches to mRNA to attach the amino acid to the protein chain

• tRNA them detaches leaving behind its amino acid.

• Amino acid will form a protein.

Animation of translation

Mutations

• Changes in the DNA sequence that affect genetic information

• Result from changes in a SINGLE gene (not chromosome abnormality)

Types of Gene mutations

• 1. point mutation– One nucleotide

affected– Examples:

• Substitution• Original - The fat cat ate the

wee rat.• Point Mutation - The fat hat

ate the wee rat.

Insert example diseases

Types of Mutations

• 2. Frameshift mutations – one or more bases are inserted or deleted

• More severe type of mutation

Insertion: • Original- The fat cat ate

the wee rat.• Insertion - The fat cat

xlw ate the wee rat.

Deletion: • The fat cat ate the wee

rat.• Deletion - The fat ate the

wee rat.

Human Genome Project (Collins)• A list of the three

billion pairs of human genome (DNA)

• An international effort• Completed by the July

of 2000 – “working draft”

• Great implications in the field of medicine. (Cancer, Immune Disorders, Hemophilia, rheumatoid arthritis)

DNA Technology (Science)

• Recombinant DNA technology – combining genes from two different organisms to make copies of “good” gene.

Steps of Recombinant DNA

1. Cutting DNA using a RESTRICTION ENZYME

2. Inserting the desired gene into a vector

• Vector – a bacteria (plasmid) or yeast

3. Cloning of “new DNA”

Applications of Recombinant DNA

• Agriculture – frost resistant strawberries

• Industry – clean up oil spills• Medicine • Food industry – nutrasweet

DNA fingerprinting

• Useful in forensic science

• Useful in medicine

Future of medicine

• predictive genetic tests for common conditions i.e. cancer

• 2020, every tumor will undergo “fingerprinting”, develop drugs to attack the particular gene.

Cloning process ex. Dolly

The process of making Dolly