Download What Do Genes Look Like? - Effingham County Schools

What do genes look like?
I. Genes – segments of DNA that carry
hereditary instructions and are passed
from parent to offspring; genes are located
on chromosomes
Chromosome Structure of
Eukaryotes
Section 12-2
Chromosome
Nucleosome
DNA
double
helix
Coils
Supercoils
Histones
Go to
Section:
II.
DNA – Hereditary material that controls
all the activities of a cell and provides
the instructions for making proteins
A.
B.
DNA is made of nucleotides
Nucleotides have three parts; 5-carbon sugar,
phosphate group and a nitrogen base
1.
2.
Nucleotides are identical except for the
nitrogen base
A nucleotide can contain 1 of 4 Nitrogen
Bases –
•
•
•
•
Adenine
Guanine
Cytosine
Thymine
Nucleotide
Phosphate
Group
Nitrogen Base
Sugar
Can Be:
Adenine
Guanine
Cytosine
Thymine
3. The amount of Adenine = Thymine,
Cytosine = Guanine (Chargaff’s Rule)
III. The Double Helix- 1953, 2 American
scientists, Watson and Crick,
discovered the structure of DNA using
the X-rays made by Rosalind Franklin
A.
2 strands wound around each other like
a twisted ladder
B. Strands are held together by hydrogen
bonds between the nitrogen bases
C. Adenine bonds to Thymine and
Cytosine bonds to Guanine
Section 12-1
Structure of DNA
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Go to
Section:
Mealor’s First Love
IV. Replication: Before a cell divides, DNA
on every chromosome is copied so that
each new cell has an identical set of
chromosomes
DNA Replication
IV. Replication: Before a cell divides, DNA on
every chromosome is copied so that each
new cell has an identical set of
chromosomes
TAAGTGTACACGTA
ATTCACATGTGCAT
TAAGTGTACACGTA
TAAGTGTACACGTA
TCACATCGTAAGTGTACACGTA
AGTCCGATCGTAACTGGGTCACATCGTAAGTGTACACGTA
AGTCCGATCGTAACTGGG
||||||||||||||||||||||
||||||||||||||||||||||||||||||||||||||||
||||||||||||||||||
TCAGGCTAGCATTGACCCAGTGTAGCATTCACATGTGCAT
TCAGGCTAGCATTGACCC
AGTGTAGCATTCACATGTGCAT
ATTCACATGTGCAT
TAAGTGTACACGTA
ATTCACATGTGCAT
Make a complimentary strand
ATT CGT ACG TTT ACT
Make a complimentary strand
ATT CGT ACG TTT ACT
Make a complimentary strand
ATT CGT ACG TTT ACT
TAA
Make a complimentary strand
ATT CGT ACG TTT ACT
TAA GCA
Make a complimentary strand
ATT CGT ACG TTT ACT
TAA GCA TGC
Make a complimentary strand
ATT CGT ACG TTT ACT
TAA GCA TGC AAA
Make a complimentary strand
ATT CGT ACG TTT ACT
TAA GCA TGC AAA TGA
Making the Traits!
I. How DNA works to create our traits – DNA
cannot leave the nucleus. A copy of the
DNA code is made in the nucleus into
RNA. RNA travels to the ribosome where
the code is read and the protein is
assembled
A. The nitrogen bases in every gene make
a code
B. Every three bases makes one codon
C. One codon is the code for one amino
acid
D. Long chains of amino acids make
proteins
E. ****Proteins determine an organisms
traits and characteristics
Making a Protein – Translation
Section 12-3
Nucleus
Messenger RNA
Messenger RNA is transcribed in the nucleus.
Phenylalanine
tRNA
The mRNA then enters the cytoplasm and
attaches to a ribosome. Translation begins at
AUG, the start codon. Each transfer RNA has
an anticodon whose bases are complementary
to a codon on the mRNA strand. The ribosome
positions the start codon to attract its
anticodon, which is part of the tRNA that binds
methionine. The ribosome also binds the next
codon and its anticodon.
Ribosome
Go to
Section:
mRNA
Transfer RNA
Methionine
mRNA
Lysine
Start codon
Making a Protein
Section 12-3
The Polypeptide “Assembly Line”
The ribosome joins the two amino acids—
methionine and phenylalanine—and breaks
the bond between methionine and its tRNA.
The tRNA floats away, allowing the ribosome
to bind to another tRNA. The ribosome moves
along the mRNA, binding new tRNA molecules
and amino acids.
Lysine
Growing polypeptide chain
Ribosome
tRNA
tRNA
mRNA
Completing the Polypeptide
mRNA
Ribosome
Go to
Section:
Translation direction
The process continues until the ribosome reaches
one of the three stop codons. The result is a
growing polypeptide chain.
The Genetic Code
Making a Protein: Translation
DNA in the Nucleus: ATA GCT CCG TTA
Code is made into RNA: UAU CGA GGC AAU
***In RNA Thymine is replaced by Uracil
Amino Acid Chain is made at the ribosome:
Tyrosine: Arginine: Glycine: ___________
Go to
Section:
The Genetic Code
Making a Protein:
DNA in the Nucleus: ATA GCT CCG TTA
Code is made into RNA: UAU CGA GGC AAU
***In RNA Thymine is replaced by Uracil
Amino Acid Chain is made at the ribosome:
Tyrosine: Arginine: Glycine: Asparagine
http://www.learnerstv.com/animation/biology/Proteinsynthesis.swf
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
Go to
Section:
AAU
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
Go to
Section:
AAU AAA
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
Go to
Section:
AAU AAA GGG
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
AAU AAA GGG UUA
Amino Acid Chain (Protein):
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
AAU AAA GGG UUA
Amino Acid Chain (Protein):
Asparagine:
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
AAU AAA GGG UUA
Amino Acid Chain (Protein):
Asparagine: Lysine
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
AAU CGC GGG UUA
Amino Acid Chain (Protein):
Asparagine: Lysine: Glycine:
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA:
AAU AAA GGG UUA
Amino Acid Chain (Protein):
Asparagine: Lysine: Glycine: Leucine
This protein will determine a
characteristic or trait
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
Go to
Section:
UUU
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
Go to
Section:
UUU AGA
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
Go to
Section:
UUU AGA CUG
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
UUU AGA CUG GUA
Amino Acid Chain (Protein):
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
UUU AGA CUG GUA
Amino Acids Chain (Protein):
Phenylalanine:
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
UUU AGA CUG GUA
Amino Acids Chain (Protein):
Phenylalanine: Arginine:
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
UUU AGA CUG GUA
Amino Acids Chain (Protein):
Phenylalanine: Arginine: Leucine:
Go to
Section:
The Genetic Code
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA:
UUU AGA CUG GUA
Amino Acids Chain (Protein):
Phenylalanine: Arginine: Leucine: Valine
This protein will now determine a trait or a
characteristic
Go to
Section:
Section 12-1
Structure of DNA
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Go to
Section:
III. Mutations- changes in the DNA
sequence that affect genetic information
(not all are harmful)
Can affect all types of cells
Germ Mutations- affect sex cells –
inherited by offspring (ex- Down
Syndrome)
B. Somatic Mutations – affect other
cells- not inherited (many cancers
caused by somatic mutations)
A.
IV. 2 types of mutations
A. Gene Mutations (#1) - changes in a single
gene. 2 types of gene mutations1. Point mutations- affect only one nucleotide
*Can be caused by substitutions
2. Frameshift mutations - type of point
mutation where nucleotide is inserted or
deleted;affects every amino acid after that
point.
*Can be caused by deletion or insertion
Effect of Mutations
• Sickle cell disease
– single nucleotide change AT
Point Mutation
Gene Mutations:
Substitution, Insertion, and Deletion
Deletion
Substitution
Go to
Section:
Insertion
B. Chromosomal Mutations (#2) - changes in
whole chromosomes. 4 types of chromosomal
mutations.
1. Deletion- loss of all or part of chromosome
2. Duplication- segment of a chromosome is
repeated
3. Inversion- chromosome becomes reversed
4. Translocation- part of a chromosome
breaks off and attaches to a different
chromosome
Section 12-4
Chromosomal Mutations
Deletion
Duplication
Inversion
Translocation
Go to
Section:
V. What are the effects of mutations?
A. Proteins are altered.
B. Proteins are unable to perform
“normal” functions.
Sometimes mutations are harmful,
sometimes there is no affect, and
sometimes mutations can be helpful.
(Helpful when mutation produces a trait
that aids in survival)
Populations Can Change!
VI. Genetic Manipulation- when humans change
the genes of an organism to achieve a desired
result.
A. Selective breeding- allowing only the individuals with
desired traits to reproduce. 2 types
1. Hybridization-crossbreeding dissimilar individuals:
offspring will have the best of both
– Ex: donkey x horse = mule
2. Inbreeding-breeding individuals with similar
characteristics: maintain certain characteristics in
offspring
– Ex: German Shepard x German Shepard = German
Shepard
VII. Genetic Engineering – Desired genes are
removed from one organism and added or
recombined into another organism. This forms a
transgenic organism with recombinant DNA
A. This is used to make proteins not normally
made by the cell. Can be used to produce:
Drugs like insulin, Vaccines, Plants resistant to
Insects, Reduce pollution, Better crops/meat
1. The flounder’s
antifreeze gene is
copied and
inserted into a
small ring of DNA
taken from a
bacteria cell.
This diagram shows how one
type of GM food, a strawberry
that resists frost damage is
made.
The flounder is a fish that live in
icy seas. It has a gene that stops
it from freezing to
death.Strawberries are soft fruits
that can easily be damaged by
frost.
2. The DNA ring
containing the
flounder gene is put
into a second
bacterium.
3. This second bacterium is
used to infect the strawberry
cell. The flounder’s antifreeze
gene enters the strawberry’s
DNA.
4. The new GM
strawberry cell is
grown into a GM
strawberry plant
which can be bred
many times.
Strawberry cell
with Antifreeze
gene
Wonder
what they
used to
make this
one
green!
Thanks to the new gene, GM strawberries make
a protein which helps them resist frost. They
don’t contain any other fish genes and, and do
not taste or smell of fish.
What’s Been Done So Far?
• Genetically engineering
chickens so they have no
feathers – why?
• Genetically engineering
mice so they have no fur –
why?
• Genetically engineering
salmon (fish) so they grow
much faster than normal
salmon – why?
http://www.exn.ca/Stories/2
000/04/11/61.asp
• Glowing mice
VIII. Evolution –natural process through
which species change over time
A. The environment “selects” the best traits
– only those best suited will survive and
pass on their traits to offspring.
B. Evolution– occurs because of genetic
differences caused by mutations in DNA
Section 15-3
Concept Map
Evidence of
Evolution
includes
The fossil record
Geographic
distribution of
living species
Homologous
body structures
Similarities
in early
development
which is composed of
which indicates
which implies
which implies
Physical
remains of
organisms
Common
ancestral
species
Similar genes
Similar genes