What do genes look like?. I. Genes – segments of DNA that carry hereditary instructions and are...
-
Upload
shon-carroll -
Category
Documents
-
view
220 -
download
2
Transcript of What do genes look like?. I. Genes – segments of DNA that carry hereditary instructions and are...
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
Chromosome
Supercoils
Coils
Nucleosome
Histones
DNA
double
helix
Section 12-2
Go to Section:
II. DNA – Hereditary material that controls all the activities of a cell and provides the instructions for making proteinsA. DNA is made of nucleotides
B. Nucleotides have three parts; 5-carbon sugar, phosphate group and a nitrogen base
1. Nucleotides are identical except for the nitrogen base
2. A nucleotide can contain 1 of 4 Nitrogen Bases – • Adenine• Guanine• Cytosine• Thymine
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
Hydrogen bonds
Nucleotide
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Structure of DNASection 12-1
Go to Section:
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
AGTCCGATCGTAACTGGGTCACATCGTAAGTGTACACGTA
TCAGGCTAGCATTGACCCAGTGTAGCATTCACATGTGCAT||||||||||||||||||||||||||||||||||||||||AGTCCGATCGTAACTGGG
TCAGGCTAGCATTGACCC||||||||||||||||||
TAAGTGTACACGTA
AGTGTAGC
TCACATCG
ATTCACATGTGCAT
TCACATCGTCACAT
CGTCA
CATCGTAAGTGTACACGTATAAGTGTACACGTATAAGTGTACACGTA
AGTGTAGCAGTGTAGC
ATTCACATGTGCATATTCACATGTGCAT
||||||||||||||||||||||
ATTCACATGTGCAT
TAAGTGTACACGTA
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 codonC. One codon is the code for one amino
acidD. Long chains of amino acids make
proteinsE. ****Proteins determine an organisms
traits and characteristics
Messenger RNA
Messenger RNA is transcribed in the nucleus.
Transfer RNA
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.
mRNA Start codon
Ribosome
Methionine
Phenylalanine tRNALysine
Nucleus
Making a Protein – Translation Section 12-3
mRNA
Go to Section:
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.
mRNARibosome
Translation direction
Lysine tRNA
tRNA
Ribosome
Growing polypeptide chain
mRNA
Completing the PolypeptideThe process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain.
Making a ProteinSection 12-3
Go to Section:
The Genetic Code
Go to Section:
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: ___________
The Genetic Code
Go to Section:
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
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA: AAU AAA GGG UUA
Amino Acid Chain (Protein):
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA: AAU AAA GGG UUA
Amino Acid Chain (Protein):
Asparagine:
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA: AAU AAA GGG UUA
Amino Acid Chain (Protein):
Asparagine: Lysine
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: TTA GCG CCC AAT
RNA: AAU CGC GGG UUA
Amino Acid Chain (Protein):
Asparagine: Lysine: Glycine:
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: TTA TTT CCC AAT
RNA: AAU CGC GGG UUA
Amino Acid Chain (Protein):
Asparagine: Lysine: Glycine: Leucine
This protein will determine a characteristic or trait
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA: UUU AGA CUG GUA
Amino Acid Chain (Protein):
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA: UUU AGA CUG GUA
Amino Acids Chain (Protein):
Phenylalanine:
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA: UUU AGA CUG GUA
Amino Acids Chain (Protein):
Phenylalanine: Arginine:
The Genetic Code
Go to Section:
Making a Protein:
DNA in Nucleus: AAA TCT GAC CAT
RNA: UUU AGA CUG GUA
Amino Acids Chain (Protein):
Phenylalanine: Arginine: Leucine:
The Genetic Code
Go to Section:
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
Hydrogen bonds
Nucleotide
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Structure of DNASection 12-1
Go to Section:
III. Mutations- changes in the DNA sequence that affect genetic information (not all are harmful)
Can affect all types of cells
A. 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)
IV. 2 types of mutations
A. Gene Mutations (#1) - changes in a single gene. 2 types of gene mutations-
1. 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
B. Chromosomal Mutations (#2) - changes in whole chromosomes. 4 types of chromosomal mutations.
1. Deletion- loss of all or part of chromosome2. Duplication- segment of a chromosome is repeated3. Inversion- chromosome becomes reversed4. Translocation- part of a chromosome breaks off and attaches to a different chromosome
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)
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 types1. 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
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
Concept MapSection 15-3
includes
Evidence of Evolution
Physical remains of organisms
Common ancestral species
Similar genes Similar genes
which is composed of which indicates which implies which implies
The fossil recordGeographic
distribution of living species
Homologous body structures
Similaritiesin early
development