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WARM-UPIf the DNA sequence is ---
AAA TAT CCG TAG CAA ATG Write the mRNA sequence, tRNA anticodon
sequence, and the six amino acids.
DNA: AAA TAT CCG TAG CAA ATG
mRNA:tRNA:Amino acids:
ReviewChromosomes v. Genes v. DNA
• Chromosomes contain genetic information
• Genes are sections of chromosomes
• Segments of genes are called DNA
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DNA and RNA are examples of what major
macromolecule?
Nucleic Acids
What are the other 3 macromolecules?
-Lipids-Carbohydrates-Proteins
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What does DNA stand for?
Deoxy-ribo-nucleic acid • DNA DNA is often called the blueprint
of life
• DNA contains the instructions for what traits (eye/hair color, etc.) are inherited from generation to generation
• Where is it found? Nucleus
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DNA StructureDNA Structure• Composed of sub-units called Nucleotides• Nucleotides can be broken down into 3 parts
1. Phosphate Group
2. Deoxyribose Sugar (5 carbon sugar)
3. Nitrogenous Base
•Cytosine (C)•Guanine (G)•Adenine (A)•Thymine (T) 2. Deoxyribose Sugar
1. Phosphate
3. Nitrogenous Base
(A, T, G, C)
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The Shape of DNAThe Shape of DNA• The basic shape is
like a twisted ladder or zipper.– This is called a
double helix, which means it is double stranded
NitrogenousNitrogenousBase (Base (C,G, A or TC,G, A or T))
““Rungs of ladder”Rungs of ladder”
““Legs of ladder”Legs of ladder”
Phosphate &Phosphate &Sugar BackboneSugar Backbone
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One Strand of DNAOne Strand of DNA
• One strand of DNA is a polymer of nucleotides.
• One strand of DNA has many millions of nucleotides.
nucleotide
phosphate
deoxyribose
bases
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NucleotidesNucleotides
C C
C
OPhosphate
O
CC
O -P OO
O
O -P OO
O
O -P OO
O One deoxyribose together with its
phosphate and base make a nucleotide.
Nitrogenous base
Deoxyribose
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DNADNA
P
P
P
O
O
O
1
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4
5
5
3
3
5
P
P
PO
O
O
1
2 3
4
5
5
3
5
3
G C
T A
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Double Stranded DNADouble Stranded DNA
• Remember, DNA has 2 strands that fit together like a zipper.
• The teeth are the nitrogenous bases but why do they stick together?
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Chargaff’s RuleChargaff’s Rule• They stick together because of They stick together because of
hydrogen bonds of the hydrogen bonds of the nitrogenous basesnitrogenous bases
• AdenineAdenine always pairs with ThymineThymine– A T
• Cytosine Cytosine always pairs with GuanineGuanine– C G
G C
T A
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DNA by the NumbersDNA by the Numbers
• Each cell has about 2 m of DNA.
• The average human has 75 trillion cells.
• The average human has enough DNA to go from the earth to the sun more than 400 times.
• DNA has a diameter of only 0.000000002 m.
The earth is 150 billion mor 93 million miles from the sun.
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What about RNA?Stands for: Ribo-nucleic
acid • Structure similar to DNA but different
– Nucleotides divided into 3 parts1. Phosphate Group2. Ribose Sugar3. Nitrogenous Base
– Adenine (A)– Uracil (U) (Replaces Thymine)– Guanine (G)– Cytosine (C)
– Single stranded
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How are DNA and RNA related?
• DNA codes for RNA, which guides protein synthesis – The reading and expression of
genes is from DNA to RNA to protein
– DNA -> RNA -> Protein = Central Dogma of Biology
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DNA StructureDNA Structure•Rosalind Franklin took
diffraction x-ray photographs of DNA crystals
• In the 1950’s, Watson & Crick built the first model of DNA using Franklin’s x-rays
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DNA NucleotideDNA Nucleotide
O=P-O O
PhosphatePhosphate GroupGroup
NNitrogenous baseNitrogenous base (A, G, C, or T)(A, G, C, or T)
CH2
O
C1C4
C3 C2
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SugarSugar(deoxyribose)(deoxyribose)
O
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Pentose SugarPentose Sugar• Carbons are numbered
clockwise 1’ to 5’CH2
O
C1C4
C3 C2
5
SugarSugar(deoxyribose)(deoxyribose)
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Antiparallel Antiparallel StrandsStrands
• One strand of DNA goes from 5’ to 3’ (sugars)
• The other strand is opposite in direction going 3’ to 5’ (sugars)
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Nitrogenous Nitrogenous BasesBases
• Double ring Double ring PURINESPURINESAdenine (A)Adenine (A)Guanine (G)Guanine (G)
• Single ring Single ring PYRIMIDINESPYRIMIDINES
Thymine (T)Thymine (T)Cytosine (C)Cytosine (C) T or C
A or G
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Base-PairingsBase-Pairings•Purines only pair with
Pyrimidines•Three hydrogen bonds
required to bond Guanine & Cytosine
CG
3 H-bonds
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T A
•Two hydrogen bonds are required to bond Adenine & Thymine
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DNA DNA ReplicatiReplicati
onon
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3 Questions about DNA Replication
1. What is DNA Replication? the process where DNA make a copy of itself
2. Why does DNA need to copy? Simple: Cells divide for an organism to grow or reproduce, every new cell needs a copy of its DNA or instructions to know how to be a cell.
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3. When does DNA 3. When does DNA replication occur? replication occur? – It occurs right before the It occurs right before the
cell dividescell divides– During the During the S Phase S Phase of of
interphase of the cell cycleinterphase of the cell cycle
3 Questions about DNA Replication
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Synthesis Phase (S Synthesis Phase (S phase)phase)
• S Phase during interphase of the cell cycle
Mitosis-prophase-metaphase-anaphase-telophase
G1 G2
Sphase
interphase
DNA replication takesDNA replication takesplace in the place in the S phaseS phase..
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DNA Replication is DNA Replication is Semiconservative Semiconservative
• TheThe two strands of the parental molecule separate, and each acts as a template for a new complementary strand
• In other words: In other words: when DNA makes a copy, one half of when DNA makes a copy, one half of the OLD strand is always kept in the NEW strand. the OLD strand is always kept in the NEW strand. – This helps reduce the number of COPY errors.This helps reduce the number of COPY errors.
• New DNA consists of 1 PARENTAL (original) and 1 NEW strand of DNA
Parental DNA
DNA Template
New DNA
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Semiconservative Replication
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Question:Question:
•What would be the complementary DNA strand for the following DNA sequence?
DNA 5’-CGTATG-3’DNA 5’-CGTATG-3’
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Answer:Answer:
DNA 5’-GCGTATG-3’DNA 5’-GCGTATG-3’
DNA 3’-CGCATAC-5’DNA 3’-CGCATAC-5’
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1. What is the complimentary mRNA sequence to DNA sequence A-T-T-G-C-A?
A. T-A-A-C-G-T C. U-A-A-C-G-T B. U-A-A-C-G-U D. T-A-A-G-C-U
2. What causes the two sides of the double helix of DNA to stay joined together?
A. joining of phosphate molecules C. joining of base pairs
B. joining of sugar molecules D. joining of RNA3. What the three main parts of a nucleotide of DNA? (Choose all that
Apply) A. phosphate group C. deoxyribose sugar B. ribose sugar D. nitrogenous base
4. The process whereby DNA unzips and makes a strand of mRNA is called?
A. replication C. translation B. transcription D. complementation
5. When does DNA replication occur? A. During transcription C. During translation B. During mitosis D. During the S phase of interphase
6. Determine the amino acids sequence from this mRNA sequence: AUG CCC GGA UUA UAG (Use amino acid chart on board)
A. Met Pro Gly Leu Stop C. Met Leu Pro Gly Stop B. Stop Leu Pro Gly Met D. Met Pro Cys Gly Stop
Lesson Closure
3 things you learned in class 3 things you learned in class todaytoday
2 questions you have about the 2 questions you have about the lessonlesson
1 real-life connection1 real-life connection
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MIND MAPSCreate a map using all of the following terms
Be sure to link them together
DNA RNANucleotide ThymineTranscription chromosomeTranslation nucleic acidUracil deoxyribose sugarRibose sugar mRNAAmino acid UnzippingNucleus ProteinDouble Helix
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