Download Linkage

Biology 30: Ch. 26 – Modern Genetics Notes
Linkage
• Genes which are located on the same chromosome are said to be _________________
Eg. The genes for _______________________ are on the same chromosome.
• In fruit flies several genes have been identified on specific chromosomes
• Significance: linkage reduces the chances for ________________________________
among offspring.
Sex-linked Traits
• Traits (genes) located on the ____________________________
• Example:
fruit flies
(red-eyed male) X (white-eyed female)
• Remember: the Y chromosome in males does not carry traits.
RR = red eyed
Rr = red eyed
rr = white eyed
Xy = male
XX = female
Hemophilia and Pedigree Charts
• Hemophilia is an X-linked recessive disorder characterized by the inability to properly
form blood clots.
• Hemophilia affects males much more frequently than females. This occurs because a
critical blood clotting gene is carried on the ____ chromosome. Since males only
carry _______ chromosome, if that is defective, hemophilia will ________________.
Females, on the other hand, carry _______ chromosomes. If only one is defective, the
other normal X chromosome can compensate. The woman will have normal blood
clotting; she will simply be a ______________of the recessive defective gene.
• This fact will be discovered if some of her children are hemophiliacs. Naturally,
women hemophiliacs are rare because it takes ____________________ chromosomes
in order for the condition to be seen.
• Hemophilia has played an important role in Europe’s history, for it suddenly cropped
up in the children of Great Britain’s Queen Victoria. It became known as the “Royal
disease” because it spread to the royal families of Europe through Victoria’s
descendants.
Color Blindness
• It is mainly a sex linked trait, but it can be acquired due to injury, etc.
• There are two major types of color blindness: those who have difficulty distinguishing
between _______________________, and those who have difficulty distinguishing
between _________________________.
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Biology 30: Ch. 26 – Modern Genetics Notes
DNA Replication
Some good websites for review about DNA and the human genome project.
• http://www.wellcome.ac.uk/en/genome/index.html
• http://www.dnai.org/index.htm
• http://www.101science.com/dna.html
• Search Google for DNA tutorials and you will have no problem finding extra help.
DNA
• Discovery of the DNA double helix
A. 1950’s
B. Rosalind Franklin - X-ray photo of DNA.
C. Watson and Crick - described the DNA molecule from Franklin’s X-ray.
Deoxyribonucleic Acid (DNA)
• Made up of _________________(DNA molecule) in a DNA ___________________.
Nucleotide:
1.
____________________
2.
____________________
3.
____________________
Nitrogenous Bases
• PURINES: _______________________________________________
• PYRIMIDINES:___________________________________________
BASE-PAIRINGS
Base
# of
Purines
Pyrimidines
Pairs
H-Bonds
Adenine (A) Thymine (T)
A=T
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Guanine (G) Cytosine (C)
C G
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Chargaff’s Rule
• ________________ must pair with ______________________
• ________________ must pair with ______________________
• Their amounts in a given DNA molecule will be about the same.
Question: When and where does DNA Replication take place?
• _____________________________________________________________
• Nucleus of eukaryotes
DNA Replication
• Origins of Replication
1. _______________________: hundreds of Y-shaped regions of replicating DNA
molecules where new strands are growing.
2. Replication Bubbles:
a. Hundreds of replicating bubbles (Eukaryotes).
b. Single replication fork (bacteria).
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Biology 30: Ch. 26 – Modern Genetics Notes
• Strand Separation:
1. _____________: enzyme which catalyze the _____________________________
(breaking H-Bonds) of the parental double helix.
2. Single-Strand Binding Proteins: proteins which attach and help keep the separated
strands apart.
3. __________________: enzyme which relieves stress on the DNA molecule by
allowing free rotation around a single strand.
• Priming:
1._____ primers: before new DNA strands can form, there must be small pre-existing
primers (RNA) present to start the addition of new nucleotides (DNA Polymerase).
2._________: enzyme that polymerizes (synthesizes) the _________________.
• Synthesis of the new DNA Strands:
1. _______________: with a RNA primer in place, DNA Polymerase (enzyme)
catalyze the synthesis of a new DNA strand in the ________________ direction.
2. _____________Strand: synthesized as a _____________ in the ______ direction.
3. __________Strand: also synthesized in the ______ direction, but _____________
__________________ overall direction of replication.
4. _____________: series of short segments on the ___________ strand.
5. ________________: a linking enzyme that catalyzes the formation of a covalent
bond from the 3’ to 5’ end of joining stands.
6. ___________________: initial base-pairing errors are usually corrected by _____
____________________________
DNA Animations
DNA Tutorial: http://207.207.4.198/pub/flash/24/menu.swf
Replication Animation I:
http://nobelprize.org/educational_games/medicine/dna/a/replication/replication_ani.html
Replication Animation II: http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf
Question:What would be the complementary DNA strand for the following DNA sequence?
DNA 5’-GCGTATG-3’
Protein Synthesis
• The production (synthesis) of proteins.
• 3 phases: 1.________________2.___________________3._________________
• Remember:
__________________________________
Question:
How does RNA (ribonucleic acid) differ from DNA (deoxyribonucleic acid)?
1. RNA has a sugar _____________________
DNA has a sugar _____________________
2. RNA contains _______________________
DNA has ___________________________
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Biology 30: Ch. 26 – Modern Genetics Notes
3. RNA molecule is _______________________
DNA is _______________________________
1. Transcription
• The transfer of information in the _________________________ molecule to an
________________ molecule.
• Only _______________________ serves as the template
• Starts at ________________________________
• Ends at _______________________________
• When complete, pre-RNA molecule is released.
Question:
• What is the enzyme responsible for the production of the RNA molecule?
Answer: ___________________________
• Separates the DNA molecule by breaking the H-bonds between the bases.
• Then moves along one of the DNA strands and links RNA nucleotides together.
RNA Base Pairing
• ________________ must pair with __________________
• ________________ must pair with __________________
• _____________________ does not exist in a strand of RNA.
Question:
• What would be the complementary RNA strand for the following DNA sequence?
DNA 5’-GCGTATG-3’
2. RNA Processing
• Maturation of pre-RNA molecules.
• Also occurs in the ___________________.
• ____________ spliced out by splicesome-enzyme and __________ come together.
• End product is a mature RNA molecule that _________________________________.
Types of RNA
• Three types of RNA:
A. _________________________
B. _________________________
C. _________________________
Remember: all produced in the ________________!
A. Messenger RNA (mRNA)
• Carries the information for a ______________________.
• Made up of 500 to 1000 nucleotides long.
• Made up of ____________ (sequence of three bases: AUG - methionine).
• Each _______________, is specific for an ______________.
B. Transfer RNA (tRNA)
• Made up of 75 to 80 nucleotides long.
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Biology 30: Ch. 26 – Modern Genetics Notes
• Picks up the appropriate _______________ floating in the cytoplasm (amino acid
activating enzyme)
• Transports _________________________________.
• Have ____________________ that are complementary to mRNA ______________.
• Recognizes the appropriate codons on the mRNA and bonds to them with H-bonds.
C. Ribosomal RNA (rRNA)
• Made up of rRNA is 100 to 3000 nucleotides long.
• Important structural component of a _________________
• Associates with proteins to form ribosomes.
Ribosomes
• Large and small subunits.
• Composed of rRNA (40%) and proteins (60%).
• Both units come together and help bind the mRNA and tRNA.
• Two sites for tRNA
a. ____ site (first and last tRNA will attach)
b. ____ site
3. Translation
• Synthesis of proteins in the __________________
• Involves the following: 1.___________________ 2.___________________
3.___________________4. ___________________5.___________________
• Three parts: 1.____________________ 2.________________ 3._________________
End Product
• The end products of protein synthesis are a primary structure of a protein.
• A sequence of amino acid bonded together by ______________________.
Polyribosome
• Groups of ribosomes reading same mRNA simultaneously producing many proteins
(polypeptides).
Question:
• The anticodon UAC belongs to a tRNA that recognizes and binds to a particular
amino acid.
• What would be the DNA base code for this amino acid?
Answer:
•
•
•
tRNA - _____________________________
mRNA- ____________________________
DNA - _____________________________
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