chapter 10 and 13. 1. what physical trait did martin fugate and his wife pass on to their many...
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Analysis Questions for The Blue People of Troublesome Creek
1. What physical TRAIT did Martin Fugate and his wife pass on to their many generations of offspring?
2. What physical VARIATION of this trait did Martin Fugate and his wife pass on to their many generations of offspring?
3. Why did this condition occur?
4. What role did genes play in both the appearance of the trait and the passing on of the trait?
5. Based on this reading and your responses to the above questions, how might you begin to define the term “genetics”?
6. Based on this reading and your responses to the above questions, how might you begin to define the term “trait”?
7. Based on this reading and your responses to the above questions, describe the relationship between enzymes (proteins) and traits.
On the road to discovery of DNA…. Hershey and Chase 1952
› worked with viruses that infect bacteria called bacteriophages and E. Coli bacteria
› Found DNA, not protein, is the hereditary molecule.
Chargaff 1947› For all organisms, adenine = thymine and
cytosine = guanine
Wilkins and Rosalind Franklin, early 1950’s studied the structure of DNA crystals using X-
rays. Found double helix with equal subunits
Watson and Crick, 1953 Used Chargaff's base data and Franklin’s X-ray
diffraction data to construct a model of DNA.
DNA is found packed in the nucleus of eukaryotic organisms; it is found in the cytoplasm of prokaryotic organisms
DNA is packed together and wrapped around special proteins called HISTONES
DNA bound protein is called CHROMATIN
When chromatin condenses (gets thicker) it forms CHROMOSOMES
Gene DNA Chromatin Chromosomes
DNA structure Double Helix - twisted ladder
Made of monomers called nucleotides
Nucleotides are composed of:› Deoxyribose: 5 carbon sugar
(side of helix) › Phosphate group (side of helix)› Purine and Pyrimidine Base
(steps ladder)› Hydrogen bonds hold sides
together
Nitrogenous Bases Two types:
› Purines (two rings) larger bases
› Pyrimidines (one ring) smaller bases
Purines (2 RINGS)› Adenine and
Guanine Pyrimidines (1 RING)
› Thymine and Cytosine
PurinesAdenine Guanine
PyrimidinesCytosine Thymine
Phosphate group Deoxyribose
Chargaff’s rules: Base pairing rule is A-T and G-C Thymine is replaced by Uracil in RNA Bases are bonded to each other by weak
hydrogen bondsDiscovered because of the relative percent of each base; (notice that A-T is similar and C-G are similar) there was complementary base pairing of a purine with a pyrimidineThe paired bases can occur in any order, giving an overwhelming diversity of sequences http://www.dnatube.com/video/1358/Structure-of-DNA-explained-in-detail
DNA REPLICATION Making a complete copy of an
entire length of DNA Occurs in S phase of cell cycle
for both Mitosis and Meiosis Occurs in the nucleus of the
cell Complimentary sides are formed due to nitrogenous
base pairing joined by hydrogen bond
Semi Conservative Model
Explains process of replication
1 original DNA serves as template (guide) for making another DNA side
Replication will work in opposite directions on both sides at same time
an enzyme called helicase “unzips” the DNA to create a replicating bubble.Single stranded binding proteins keep 2 sides apart and stableAnother enzyme, DNA polymerase, moves along the bases on each side and connects complementary nucleotides.
How Does Replication Start?
Anti Parallel Strand DNA runs in opposite directions It is read in a 5 3 direction
› 5’Carbon of Deoxyribose has phosphate attached to it
› 1’ Carbon of sugar has nitrogen base attached to it
› 3’ Carbon of sugar has an open bond (connector site for next nucleotide)
Leading vs. Lagging Strand
in replication forkLeading
Runs in a continuous 5’ 3’ direction as it opens
Lagging Doesn’t run in 5’
3’ direction Slower, works
backward making Okazaki fragment
• http://www.dnatube.com/video/2335/Video-for-DNA-Replication• http://www.dnatube.com/video/335/Animated-DNA-Replication
Differences between DNA & RNA DNA
Structure: › Double stranded
Sugar› Deoxyribose
Bases:› Adenine› Guanine› Cytosine› Thymine
RNA Structure:
› Single stranded Sugar
› Ribose Bases:
› Adenine› Guanine› Cytosine› Uracil
Transcription- how RNA is madeOccurs in Nucleus
Makes a disposable copy of DNA, just in form of RNA RNA polymerase temporarily separates the strands of a small section of the DNA molecule exposing some of the bases of the DNA molecule.Along one strand, the RNA polymerase binds complementary RNA nucleotides to the exposed DNA bases.As the RNA polymerase moves along, it makes a strand of messenger RNA (mRNA). It carries DNA’s message out of the nucleus and into the cytoplasm.
Types of RNA:1) Messenger RNA (mRNA)
o carries information from DNA to ribosome
2) Ribosomal RNA (rRNA)o Combines with proteins that
makes up ribosomes
3) Transfer RNA (tRNA)o Carries amino acids to
ribosome
PROTEIN SYNTHESISTRANSCRIPTION – the synthesis of RNA
under the direction of DNA
TRANSLATION – the actual synthesis of a protein, which occurs under the direction of
mRNA
http://www.dnatube.com/video/3450/DNA-Transcription
http://www.dnatube.com/video/5763/DNA-Transcription-animation
Codons
a sequence of 3 nitrogen bases on mRNA that code for 1 amino acid, it’s a triplet code; Universal with all life.
61 of 64 codons code for 20 amino acids on earth
Codons match up with anticodons to create a protein
The Genetic CodeThe Genetic CodeThe Messenger RNA Genetic Code
First LetterSecond Letter
UU C A G
Third Letter
UCAGUCAGUCAG
UCAG
C
A
G
Phenylalanine (UUU)
Phenylalanine (UUC)
Leucine (UUA)
Leucine (UUG)
Leucine (CUU)
Leucine (CUC)
Leucine (CUA)
Leucine (CUG)
Isoleucine (AUU)
Isoleucine (AUC)
Isoleucine (AUA)
Methionine;Start (AUG)
Valine (GUU)
Valine (GUC)
Valine (GUA)
Valine (GUG)
Serine (UCU)
Serine (UCC)
Serine (UCA)
Serine (UCG)
Proline (CCU)
Proline (CCC)
Proline (CCA)
Proline (CCG)
Threonine (ACU)
Threonine (ACC)
Threonine (ACA)
Threonine (ACG)
Alanine (GCU)
Alanine (GCC)
Alanine (GCA)
Alanine (GCG)
Tyrosine (UAU)
Tyrosine (UAC)
Stop (UAA)
Stop (UAG)
Histadine (CAU)
Histadine (CAC)
Glutamine (CAA)
Glutamine (CAG)
Asparagine (AAU)
Asparagine (AAC)
Lysine (AAA)
Lysine (AAG)
Aspartate (GAU)
Aspartate (GAC)
Glutamate (GAA)Glutamate (GAG)
Cysteine (UGU)
Cysteine (UGC)
Stop (UGA)
Tryptophan (UGG)
Arginine (CGU)
Arginine (CGC)
Arginine (CGA)
Arginine (CGG)
Serine (AGU)
Serine (AGC)
Arginine (AGA)Arginine (AGG)
Glycine (GGU)
Glycine (GGC)Glycine (GGC)
Glycine (GGA)
Glycine (GGG)
Translation Occurs in cytoplasm mRNA combines with a ribosome
mRNA carries the codon tRNA carries the anticodon which
pairs up with the codon These amino acid links form a
protein
SO:
Say the mRNA strand reads:› mRNA (codon) AUG–GAC–CAG-UGA› tRNA (anticodon) UAC-CUG-GUC-ACU
tRNA would bring the amino acids: Methionine-Aspartic acid-Glutamine-
stop
http://www.dnatube.com/video/4195/Translation http://www.dnatube.com/video/5934/Basic-explanation-of-
mRNA-Translation
TRANSCRIPTION AND TRANSLATION
http://www.dnatube.com/video/28981/What-is-Transcription-and-Translation
MUTATION Change in nucleotide
sequence of DNA or mRNA that code for a protein
Caused by mutagens (physical or chemical interactions that change the nucleotide sequence of DNA)
2 types of mutations Point
mutations› Single nucleotide mutates and affects a single codon
Reading Frameshift› Alter codon
sequence› Insertion: adding
nucleotides to the sequence
› Deletion: taking out nucleotides from the sequence
A new form of manipulation that biologists created where they can engineer a set of genetic changes directly into an organisms DNA
GENETIC ENGINEERING
Computers and other devices used to help in performing science
DNA gene cloning is an example
BIOTECHNOLOGY
POLYMERASE CHAIN REACTION
Requires no organism in the production of new DNA molecules
Turns a single molecule of DNA into a large, identical DNA molecules
Used in forensics
Recombinant DNA Major focus of genetic engineering
The sequence of nucleotides in the gene being manipulated are
read Desired gene is cut from
surrounding genes DNA from 2 different sources is
joined into one molecule (hybrid)http://www.dnatube.com/video/193/Contruction-of-Recombinant-DNA
Plasmids molecules of DNA found in
bacteria separate from the bacterial chromosome.
small (a few thousand base pairs) and circular
usually carry only one or a few genes
TRANSFORMATION Genetic alteration of a cell that is
caused from directly taking in DNA from outside the cell membrane.
It can occur naturally in some species of bacteria, but it can also be effected by artificial means in other cells
http://www.dnatube.com/video/202/Understanding-Bacterial-Transformation
DNA FingerprintingPattern of bands made up of specific fragments from an individuals DNA
Restriction enzymes can cut the DNA at specific sites with “sticky ends”
DNA Ligase can join DNA at specific sites
The DNA created artificially is called recombinant DNA
Creates a DNA fingerprint Different DNA samples are exposed to
the SAME restriction enzyme creating RFLP (fragments of different lengths of DNA)
Those fragments are loaded into agarose gel and electric currents are used
RFLP’s will separate according to length/size of the fragments which create a unique fingerprint
Gel Electrophoresis
Transgenic Organisms
Recombined DNA from 2 different organisms to make 1 organism that has traits from BOTH parents.
These traits will then be carried on to offspring
Human Genome Project
Began 1990 ended in 2003 Mapped out entire DNA
genome nucleotide sequences for all humans as a species
Contains approximately 40,000 different genes
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