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Chapter 6. Genes and Gene Technology. DNA. Deoxyribonucleic acid Hereditary material that controls all the activities of a cell contains the information to make new cells provide instructions for making proteins. Nucleotide. A subunit of DNA
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Chapter 6 Genes and Gene Technology
DNA • Deoxyribonucleic acid • Hereditary material that controls all the activities of a cell • contains the information to make new cells • provide instructions for making proteins
Nucleotide • A subunit of DNA • Consists of a sugar, a phosphate, and one of the four nitrogenous bases • A, C, T or G • Nucleic acid- a biochemical that stores information needed to build proteins
A, T, C, G • Adnenine – pairs with Thymine • Thymine – pairs with Adenine • Cytosine – pairs with Guanine • Guanine – pairs with Cytosine
Ribosome • A small organelle in cells where proteins are made from amino acids
What Do Genes Look Like? • Chromosomes are made of DNA and proteins • Traits (appearance)are determined by genes (codes of DNA) • Genes are passed from generation to generation • Genes are located on the chromosomes
The gene material must • Able to supply instructions for cell processes and for building cell structures • Able to be copied each time a cell divides
Early Studies • Suggested that DNA was a simple molecule and therefore thought protein carried heredity information • 1940’s – scientists discover that genes of bacteria are made of DNA
Chargaff’s Rules • 1950’s – Erwin Chargaff found the amount in adenine in DNA always matches the amount of thymine • Also, the amount of cytosine always matches the amount of guanine • Clue 1 to the structure of DNA
A Picture of DNA • Clue 2 for the shape of DNA • Rosalind Franklin (1920-1958) • Used x-ray diffraction (bombard the DNA molecule with x-rays that bounce off and create a pattern) • Created a picture of DNA molecule
Died at the age of 38 due to cancer Discriminated throughout her career by Wilkins and Watson Franklin’s Picture
Watson and Crick • Discovered that DNA was helical in shape (double helix) • Franklin’s picture • Spiral shape • Chargaff’s rules • Bases in pairs • Double strand
Watson and Crick • Won the Nobel prize in 1962 with Maurice Wilkins • Rosalind Franklin receive no mention because the Nobel Prize is not awarded posthumously • After her death, W and C gave her credit to their success
Because adenine always bonds with thymine, and cytosine always bonds with guanine, one side of a DNA molecule is complementary to the other.
If the DNA segment is • GATTACTTTAACCT • The complementary strand would be: • CTAATGAAATTGGA • The complementary base pairing allows DNA to REPLICATE or copy itself
DNA replicates by splitting down the middle where the nitrogen bases meet. • The bases on each side of the molecule are used as a template, or pattern for a new complementary side. • This creates two identical molecules of DNA.
DNA functions the same way for all organisms DNA makes us the same and makes us unique DNA
The bases on one side of the DNA molecule can be put in any order, allowing an enormous variety of genes. • Each gene consists of a string of bases. • The order of the bases gives the cell information about how to make each trait.
The double helix wraps around a protein known as a histone and coils and condenses until it appears as a chromosome
The Importance of Environment • Remember, genes only influence your development • Other things affect your growth and development • Nutrition, exercise
Mutation? • Is this possible?
Mutation • A change in the order of the bases in an organism’s DNA • Deletion –removing a base • Insertion – adding a base • Substitution – Switching bases
Insertion • Substitution
Mutagen • Anything that can damage or cause changes in DNA