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