Ch. 9 &10Ch. 9 &10

DNA, RNA & Protein DNA, RNA & Protein SynthesisSynthesis

I. DNA-Deoxyribonucleic I. DNA-Deoxyribonucleic AcidAcidA. In 1953 James Watson and Francis Crick A. In 1953 James Watson and Francis Crick

built a model of DNA based on x-rays built a model of DNA based on x-rays taken by Rosalind Franklintaken by Rosalind Franklin

B. DNA Structure

1. Shape- Double Helix (winding staircase)

2. Made of Repeating Nucleotides: 3 parts

a) Phosphate group

b) Deoxyribose Sugar

c) Nitrogen base

C. Nitrogen Bases- 2 types

1. Purines- 2 carbon rings in structure, Adenine & Guanine

2. Pyrimidines- 1 carbon ring in structure, Thymine & Cytosine

D. A Purine is always paired with a pyrimidine, held together by weak H bondsA=T G C2 stars 3 stars

E. Bases are always attached to deoxyribose sugars

PP

SS

PP

SS

PP

SS

DNA drawing

-A

-C

-G

-C

-G

-T

=

=

=

Right-hand rule= nitrogen bases only bond on R side-results in 2 opposite running strands

PPSSPPSSPPSS

http://www.ted.com/talks/james_watson_on_how_he_discovered_dna.html

QUIZQUIZ1.1. Name the people who made the first model of DNA.Name the people who made the first model of DNA.

2.2. What are the 4 nitrogen bases (words not letters)?What are the 4 nitrogen bases (words not letters)?

3.3. What are the three parts that make up a What are the three parts that make up a nucleotide?nucleotide?

4.4. What is DNA’s shape?What is DNA’s shape?

5.5. Which bases are pyrimidines?Which bases are pyrimidines?

6.6. Which are doubled-ringed, purines or pyrimidines?Which are doubled-ringed, purines or pyrimidines?

7.7. What type of bonds hold the nitrogen bases What type of bonds hold the nitrogen bases together in the middle of the DNA strand?together in the middle of the DNA strand?

8.8. How many bonds form between A and T? How many bonds form between A and T?

9.9. How many bonds form between G and C?How many bonds form between G and C?

10.10. Why is a DNA molecule said to be complementary?Why is a DNA molecule said to be complementary?

11.11. What is the complementary strand of DNA for What is the complementary strand of DNA for ACATGG?ACATGG?

Answers-18 pts totalAnswers-18 pts total1.1. 2-Watson and Crick2-Watson and Crick2.2. 4-Adenine, Guanine, Cytosine, Thymine4-Adenine, Guanine, Cytosine, Thymine3.3. 3-Phosphate, Sugar, Base3-Phosphate, Sugar, Base4.4. 1-Double helix/winding staircase1-Double helix/winding staircase5.5. 2-Thymine, cytosine2-Thymine, cytosine6.6. 1-Purines1-Purines7.7. 1- Hydrogen Bonds1- Hydrogen Bonds8.8. 1- 2 hydrogen bonds1- 2 hydrogen bonds9.9. 1- 3 hydrogen bonds1- 3 hydrogen bonds10.10. 1- by knowing the nitrogen bases on one 1- by knowing the nitrogen bases on one

side of the DNA we can determine the side of the DNA we can determine the sequence of bases for the other side of the sequence of bases for the other side of the DNADNA

11.11. 1-TGTACC1-TGTACC

II. DNA ReplicationII. DNA Replication

A.A. Replication- the process of copying Replication- the process of copying DNA to get ready for cell division, DNA to get ready for cell division, occurs in the nucleusoccurs in the nucleus

B.B. StepsSteps1.1. Helix unwinds and an enzyme (DNA Helix unwinds and an enzyme (DNA

helicase) breaks the Hydrogen bonds helicase) breaks the Hydrogen bonds between the basesbetween the bases

2.2. Enzyme (DNA Polymerase) moves along Enzyme (DNA Polymerase) moves along each strand and adds the each strand and adds the complementary base to each ½ strand; complementary base to each ½ strand; Polymerase also proofreads its workPolymerase also proofreads its work

3. Strands Detach and 2 new identical strands are formed

4. Process is considered a semi-conservative process because the strands are ½ original, ½ new DNA

III. Protein SynthesisIII. Protein Synthesis

A. The process of producing proteins A. The process of producing proteins made of amino acids from the made of amino acids from the instructions provided by the DNAinstructions provided by the DNA

B. RNA-(ribonucleic Acid) gets B. RNA-(ribonucleic Acid) gets instructions to ribosome to instructions to ribosome to make proteinsmake proteins

1.1. Single StrandSingle Strand

2.2. Ribose instead Ribose instead of Deoxyribose of Deoxyribose SugarSugar

3.3. No Thymine, No Thymine, Uracil replaces Uracil replaces ThymineThymine

4.4. 3 Types of RNA3 Types of RNA

a) Messenger RNA- (mRNA)- copy a) Messenger RNA- (mRNA)- copy of information from DNAof information from DNA- every 3 nitrogen bases make a - every 3 nitrogen bases make a codon, these code for a specific codon, these code for a specific amino acidamino acid

b)Transfer RNA- (tRNA)- transports amino acids, has a matching anti-codon

-3 nitrogen bases make an anticodon

c) Ribosomal RNA- (rRNA)- makes up ribosomes

C. C. TranscriptionTranscription-unwinds DNA and -unwinds DNA and makes a copy called mRNA, makes a copy called mRNA, occurs occurs in the nucleusin the nucleus

***2 steps for Protein Synthesis

D. D. TranslationTranslation- mRNA and tRNA - mRNA and tRNA build a protein out of amino acids. build a protein out of amino acids.

Occurs in the cytoplasm at a Occurs in the cytoplasm at a ribosomeribosome

AnimationsAnimations

http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf

http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf

http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf

IV. Mutations- a change in the DNA of a gene, occurs

during replication

3 types:1. Substitution- one nucleotide is replaced with a different nucleotide2. Insertion- one or more nucleotides are added3. Deletion- one or more nucleotides are deleted

Humans inherit 3 billion base pairs of DNA from each parent. That means that each cell has 6 billion pairs that can be a target of a mutation. It is estimated that mutations occur in

about 1 in every 50 million nucleotides. That means that each new cell could have some 120 mutationsMutations can:

-have no effect (occur in the “junk DNA”, about 97% of DNA does not encode for anything- that we know of)

-be silent-mutations that code for the same amino acid

-cause disease such as Cystic Fibrosis, Retinoblastoma, Sickle Cell anemia

-occur in gametes (egg & sperm)- can result in Fragile X syndrome and Huntington’s disease