Standard Biology Ch. 28 DNA- Life’s Code
28.1 The DNA Molecule
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DNA
DNA is the chemical that makes up your genes.
Genes make up your chromosomes. Genes determine your traits. Chromosomes are located in the nucleus
of cells.
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DNA Structure
DNA- deoxyribonucleic acid
All living things have DNA
Built like a ladder
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DNA Structure
Sides are alternating sugar (deoxyribose) and phosphate
Rungs are nitrogen bases (4 types)
A= adenine T= thymine C= cytosine G= guanine
Base pairing rules: A goes with T and C goes with G
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Seven Features of DNA
1. DNA has 2 sides like the up right part of a ladder
2. Sides are made of sugar and phosphate3. There are parts that connect the sides of
the ladder (like “rungs”)4. The “rungs” are the nitrogen bases5. The four nitrogen bases are A, T, C, and G6. A goes with T and C goes with G7. DNA is a twisted ladder called a double
helix
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DNA and Chromosomes
DNA is in every cell of your body and is the same in every cell
Your DNA is different from every other person’s DNA (except identical twins)
DNA is located in the nucleus and makes up genes and chromosomes
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Proof that DNA Controls Traits
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Proof that DNA Controls Traits
Transformation DNA from the harmful
dead bacteria got into the harmless live bacteria and made the harmless bacteria able to cause pneumonia and kill the mice (Fig. 28-4 p. 590)
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How DNA Works
Works like a computer- reads a signal then transfers to a type of protein
DNA is a base code (3 base code) of nitrogen bases
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How DNA Works
Normal red blood cells:
GAGTGAGGCTTC
CTCACTCCGAAG
Sickle cell disease red blood cells:GAGTGAGGCTAC
CTCACTCCGATG
Slightly different order of base pairs and codes for a different protein giving a different trait
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Making Proteins
DNA directs the making of proteins in a cell
DNA stays in the nucleus and proteins are made in the cytoplasm at ribosomes
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DNA to RNA to Protein
Two step process: transcription and translation
Transcription (rewrite): RNA is made from DNA; occurs in the nucleus
Translation (change language): protein is made from RNA code; occurs in the cytoplasm at the ribosome
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Making Proteins
RNA is the helper molecule for DNA to make protein
RNA acts like a messenger and carries the code from the DNA to the ribosome
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Making Proteins
Each 3 nitrogen bases is a codon (Like a word)
Each codon has meaning as an amino acid
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Making Proteins
There are 20 different amino acids, the order of the amino acids gives us all our different
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How DNA Copies Itself
DNA needs to be copied before cell division can take place (both mitosis and meiosis) Fig. 28-8 p. 594)
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How DNA Copies Itself
1. DNA untwists
2. DNA unzips
3. Loose nitrogen bases with a sugar and phosphate fill in on open middle section following base pairing rules (A=T and C=G)
4. 2 new DNA are formed that are exactly alike
REPLICATION
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How DNA Copies Itself
Standard Biology Ch. 28 DNA- Life’s Code
28.2 How the Genetic Message Changes
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Mutations
Change in copying the DNA message
Wrong T, C, A, or G then get the wrong protein made and a different trait
Sickle cell disease- change of T to A
Hemophilia- mutation in sex cell of mother
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Mutations
Causes of mutations Copying mistakes Radiation- X rays and
sun’s UV Chemicals- tobacco,
benzene, asbestos and others
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Cloning
Have same exact genes and DNA
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Twins
Identical twins:
egg 1 + sperm 1
fertilized egg 1
baby baby
Fraternal twins:egg 1 + sperm 1 egg 2 + sperm 2
fertilized egg 1 fertilized egg 2
baby baby
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Steps Needed to Clone a Frog
1. Light frog A- egg cell with nucleus removed
2. Dark frog B- nucleus from cell of intestine
3. Add together- get genetic clone of the dark frog
(Fig. 28-12 p. 599)
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Plant and Animal Breeding
Getting the traits we want
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Plant and Animal Breeding
Breeding- bringing together 2 living things to produce offspring (plants and animals)
Most crops and livestock today are produced by selective breeding
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Splicing Genes and Gene Therapy
Splice means to insert Splicing genes mean
to add or insert one gene from one organism into another organism
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Splicing Genes and Gene Therapy
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Splicing Genes and Gene Therapy
Gene therapy is the adding of a healthy gene into a person suffering from a genetic disorder Cystic fibrosis Hemophilia
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Splicing Genes and Gene Therapy
Recombinant DNA is formed when DNA from one organism is inserted into another organism
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Splicing Genes and Gene Therapy
Today use recombinant DNA to produce many vitamins, adhesives, and drugs
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Splicing Genes and Gene Therapy
Insulin- human gene for insulin added to bacteria so that the bacteria produce human insulin for people with diabetes
Insulin Production for Persons with Diabetes