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Unit 8: DNA, Proteins, and Biotechnology Mr. Nagel
Meade High School
Think…
• What three parts comprise a nucleotide? • What are the four bases of DNA? • How are nucleotides connected to each
other?
IB Syllabus Statements • 3.5.1
– Compare the structure of RNA and DNA. • 3.3.1
– Outline DNA nucleotide structure in terms of sugar (deoxyribose), base and phosphate.
• 3.3.2 – State the names of the four bases in DNA.
• 3.3.3 – Outline how DNA nucleotides are linked together by covalent bonds into a single
strand. • 3.3.4
– Explain how a DNA double helix is formed using complementary base pairing and hydrogen bonds.
• 3.3.5 – Draw and label a simple diagram of the molecular structure of DNA.
• 7.1.1 – Describe the structure of DNA, including the antiparallel strands, 3’–5’ linkages and
hydrogen bonding between purines and pyrimidines.
http://click4biology.info/c4b/3/Chem3.3.htm
Hershey and Chase
Franklin & Watson & Crick
Structure of DNA
• http://www.blc.arizona.edu/Molecular_Graphics/DNA_Structure/DNA_Tutorial.HTML – Modeling time!
– Pay attention to ‘labeling’ of C3, C5: ultimately
where we get 3’ and 5’ from – Antiparallel – 3’ = naked side; 5’ capped with phosphate
Warm Up
• How many hydrogen bonds exist between
Adenine and Thymine? Guanine and Cytosine?
• What carbon of the deoxyribose sugar: – Does the nitrogen base attach? – Determines if the sugar is ribose or deoxyribose? – Has a phosphate group attached?
IB Syllabus Statements • 3.3.4
– Explain how a DNA double helix is formed using complementary base pairing and hydrogen bonds. • 3.3.5
– Draw and label a simple diagram of the molecular structure of DNA. • 7.1.1
– Describe the structure of DNA, including the antiparallel strands, 3’–5’ linkages and hydrogen bonding between purines and pyrimidines.
• 4.1.1 – State that eukaryote chromosomes are made of DNA and proteins.
• 7.1.2 – Outline the structure of nucleosomes.
• 7.1.3 – State that nucleosomes help to supercoil chromosomes and help to regulate transcription.
• 3.4.1 – Explain DNA replication in terms of unwinding the double helix and separation of the strands by helicase, followed by
formation of the new complementary strands by DNA polymerase. • 3.4.2
– Explain the significance of complementary base pairing in the conservation of the base sequence of DNA. • 3.4.3
– State that DNA replication is semi-conservative. • 7.2.1
– State that DNA replication occurs in a 5 --> 3 direction.
• 7.2.2 – Explain the process of DNA replication in prokaryotes, including the role of enzymes (helicase, DNA polymerase, RNA primase
and DNA ligase), Okazaki fragments and deoxynucleoside triphosphates. • 7.2.3
– State that DNA replication is initiated at many points in eukaryotic chromosomes.
http://click4biology.info/c4b/3/Chem3.3.htm
Consider
• The DNA in one of your cells is approximately 2 meters long.
• How would you fit all of that into a cell the size of a pin point?
What is a Chromosome?
• How is DNA packaged in an organism?
• Animation: Packing DNA
Modeling Chromosomes
• String • Molecule Set (Histones) • Paper (Scaffold)
Prokaryote vs. Eukaryote Chromosomes
Chromosome Numbers Common Name
Diploid Chromosome
Number Buffalo 60 Cat 38 Cow 60 Dog 78 Donkey 62 Fruit Fly 8 Goat 60 Horse 64 Human 46 Ophioglossum reticulatum (Fern) 1200+ Pig 38 Sheep 54 Turkey 82 Wolverine 42 Yeast 32
Meselson and Stahl (1958) http://www.nature.com/scitable/topicpage/Semi-Conservative-DNA-Replication-Meselson-and-Stahl-421
DNA Replication • Key Terms
– DNA Helicase: – SSBs: – Replication Fork: – DNA Polymerase III: – DNA Polymerase I: – RNA Primer (Primase): – Leading strand: – Lagging strand: – Okazaki Fragments: – DNA Ligase:
DNA Replication • http://www.johnkyrk.com/DNAreplication.html • http://www.bioteach.ubc.ca/TeachingResources/Molecul
arBiology/DNAReplication.swf • http://www.hhmi.org/biointeractive/dna/animations.html
Warm Up
• Mr. Nagel parked next to a pine tree last
night. He did not have to scrape his windshield this morning. Using your knowledge of plant science, postulate a reason why!
• What enzyme unwinds the hydrogen bonds of DNA for replication?
• What enzyme matches new base pairs to the DNA template, adding nucleotides?
IB Syllabus Statements • 2.5.1
– Outline the stages in the cell cycle, including interphase (G1, S, G2), mitosis and cytokinesis.
• 2.5.2 – State that tumours (cancers) are the result of uncontrolled cell division and that
these can occur in any organ or tissue.
• 2.5.3 – State that interphase is an active period in the life of a cell when many metabolic
reactions occur, including protein synthesis, DNA replication and an increase in the number of mitochondria and/or chloroplasts.
• 2.5.4 – Describe the events that occur in the four phases of mitosis (prophase,
metaphase, anaphase and telophase).
• 2.5.5 – Explain how mitosis produces two genetically identical nuclei.
http://click4biology.info/c4b/2/cell2.5.htm
Cell Cycle • Interphase
– G1, S, and G2 • G = Gap • S = Synthesis
– Mass production! • Cancer cells
– What do you think goes wrong?
• CDKs (cyclin dependent kinases) ex: p57
• Perfect reproduction (two identical nuclei)
• Growth, embryonic development, tissue repair, asexual reproduction
• P.M.A.T.
Mitosis
Name That Phase…
Cell Cycle Project
• How long does a typical cell spend in each phase of Mitosis/Cell Cycle?
• Let’s consider an onion root tip cell… – http://www.biology.arizona.edu/cell_bio/activiti
es/cell_cycle/cell_cycle.html
Cell Cycle Project
• How long does a typical cell spend in each phase of Mitosis/Cell Cycle?
• Let’s consider an onion root tip cell… – The average cycle duration is 24 hours.
Interphase Prophase Metaphase Anaphase Telophase TOTAL
Quantity 36
Percent 100%
Time 24 hrs
Interesting Thoughts…
• In the human body, the rate of mitosis is believed to be 25 million cells produced every second!
• That comes out to 2 trillion cells per day!
• Cells that divide rapidly – Skin, Epithelial,
Bone Marrow • Cells that must be
stimulated to divide – Liver
• Cells that do not divide – Nerve, Muscle
Vocabulary is Key! • Somatic Cell • Gamete • Zygote • Haploid • Diploid • Tetraploid • Homologous • Sister Chromatids • Autosomal Chromosome • Crossing Over
Meiosis
• Sex cells – How are they made?
• Like Mitosis, but… – Similarities? – Differences?
Mitosis vs. Meiosis
• Compare Mitosis – http://www.johnkyrk.com/mitosis.html
• To Meiosis – http://www.johnkyrk.com/meiosis.html
• NOVA side by side animation – http://www.pbs.org/wgbh/nova/baby/divi_flash.html
Warm Up
• What is amniocentesis? Why is this
procedure conducted in modern medicine? • How many chromosomes are in each of your
autosomal (non-sex) cells? • How many divisions occur during the process
of mitosis? How many daughter cells are made? For meiosis?
IB Syllabus Statements • 4.2.1
– State that meiosis is a reduction division of a diploid nucleus to form haploid nuclei. • 4.2.2
– Define homologous chromosomes. • 10.2.2
– Distinguish between autosomes and sex chromosomes. • 4.2.3
– Outline the process of meiosis, including pairing of homologous chromosomes and crossing over, followed by two divisions, which results in four haploid cells.
• 10.1.1 – Describe the behaviour of the chromosomes in the phases of meiosis.
• 10.1.2 – Outline the formation of chiasmata in the process of crossing over.
• 10.1.3 – Explain how meiosis results in an effectively infinite genetic variety in gametes through crossing over in prophase I
and random orientation in metaphase I. • 4.2.4
– Explain that non-disjunction can lead to changes in chromosome number, illustrated by reference to Down syndrome (trisomy 21).
• 4.2.5 – State that, in karyotyping, chromosomes are arranged in pairs according to their size and structure.
• 4.2.6 – State that karyotyping is performed using cells collected by chorionic villus sampling or amniocentesis, for pre-natal
diagnosis of chromosome abnormalities. • 4.2.7
– Analyse a human karyotype to determine gender and whether non-disjunction has occurred.
http://click4biology.info/c4b/4/gene4.2.htm
Chromosome Numbers Common Name
Diploid Chromosome
Number Buffalo 60 Cat 38 Cow 60 Dog 78 Donkey 62 Fruit Fly 8 Goat 60 Horse 64 Human 46 Ophioglossum reticulatum (Fern) 1200+ Pig 38 Sheep 54 Turkey 82 Wolverine 42 Yeast 32
Mitosis vs. Meiosis
• Compare Mitosis – http://www.johnkyrk.com/mitosis.html
• To Meiosis – http://www.johnkyrk.com/meiosis.html
• NOVA side by side animation – http://www.pbs.org/wgbh/nova/baby/divi_flash.html
Anatomy of a Chromosome
• Homologous Chromosomes
• Sister Chromatids • Autosomal
Chromosomes
Have you ever…
• Had someone take what you have said out of context? What were the consequences?
• Seen a news clip in which large portions of a speech were removed? Was the meaning of the speech affected?
Types of Genetic Mutations/Disorders
• Nondisjunction • Inversion • Deletion • Translocation • Duplication
• What are they? • Can you illustrate each?
Karyotyping • Chromosomes are
isolated from a DNA sample (amniotic fluid, blood, etc.)
• Stained to create dark bands (rich AT areas)
• Chromosomes matched by size, location of centromere, and banding
Normal Male (XY)
Karyotyping
• http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping.html
• Match each chromosome based on bands and size.
• Identify the condition and sex of each individual – EX: 47, XY, +18 (Trisomy 18, Male)
More Karyotyping
• www.explorelearning.com • Match each chromosome based on bands
and size. • Identify the condition and sex of each
individual – EX: 47, XY, +18 (Trisomy 18, Male)
Karyotyping Answers
• 46, XY (Male) • 46, XX (Female) • 47, XXY, +23 (Klinefelter’s Syndrome, M) • 45, XO, -23 (Turner’s Syndrome, F) • 47, XY, 21 (Down’s Syndrome, M)
Assessment
• What is karyotyping? • How can it be used to learn about an
individual’s genetic makeup? • What benefits and/or detriments could this
technology pose in medicine?
Interesting Info From NIH
• http://www.genetics.com.au/pdf/factsheets/fs06.pdf
Warm Up DNA Replication Review
• What enzyme is responsible for:
– Unwinding the double helix by breaking hydrogen bonds between the base pairs?
– Matching RNA nucleotides to the DNA template? – Extending the DNA molecule from 5’ 3’? – Replacing the RNA primer with DNA? – Fusing the breaks in the sugar-phosphate
backbone between Okazaki Fragments?
