Download Standard Biology Ch. 28 DNA

Standard Biology
Ch. 28 DNA- Life’s Code
28.1 The DNA Molecule
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.
2.
3.
4.
5.
6.
7.
DNA has 2 sides like the up right part of a
ladder
Sides are made of sugar and phosphate
There are parts that connect the sides of
the ladder (like “rungs”)
The “rungs” are the nitrogen bases
The four nitrogen bases are A, T, C, and G
A goes with T and C goes with G
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.
2.
3.
4.
DNA untwists
DNA unzips
Loose nitrogen bases
with a sugar and
phosphate fill in on
open middle section
following base pairing
rules (A=T and C=G)
2 new DNA are formed
that are exactly alike
REPLICATION
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How DNA Copies Itself
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Standard Biology
Ch. 28 DNA- Life’s Code
28.2 How the Genetic Message Changes
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 diseasechange 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
fertilized egg 1
baby
egg 2 + sperm 2
fertilized egg 2
baby
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Steps Needed to Clone a Frog
1.
2.
3.
Light frog A- egg cell
with nucleus removed
Dark frog B- nucleus
from cell of intestine
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
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