DNA RNA Protein Synthesis Cracking the Code of

DNA, RNA & Protein Synthesis Cracking the Code of Life clip: Click on “Watch The Program” and view the first 9 minutes http: //www. pbs. org/wgbh/nova/body/cracking-the-code-of-life. html

Genetic code: The way cells translate information in DNA into proteins o Genetics refers to anything that relates to heredity

The Structure of DNA • DNA = Deoxyribo. Nucleic Acid = A polymer formed from units called nucleotides • Each nucleotide is composed of 3 parts: 1. 5 -carbon sugar (deoxyribose) 2. Phosphate group 3. nitrogenous base

The Structure of DNA: Nitrogenous Bases o The purines: double rings 1. Adenine 2. Guanine o The pyrimadines single rings 1. Cytosine 2. Thymine 3. Uracil (RNA)

Do You Notice a Pattern? Relative Proportions of Nitrogenous Bases in DNA (%) Organism A T G C Human 30. 9 29. 4 19. 9 19. 8 Chicken 28. 8 28. 2 20. 5 21. 5 Grasshopper 29. 3 20. 5 20. 7 Sea Urchin 32. 8 32. 1 17. 7 17. 3 Wheat 27. 3 27. 1 22. 7 22. 8 Yeast 31. 3 32. 9 18. 7 17. 1 E. coli 24. 7 23. 6 26. 0 25. 7

Base Pairing: AKA Chargaff ‘s Rule • Adenine hydrogen bonds to Thymine • Cytosine hydrogen bonds to Guanine

Hydrogen Bonds = the force that holds DNA’s two separate strands together.

1953 -Watson&Crick: • Developed a model of DNA’s structure • Double Helix = two strands twisted

DNA structure video: (1: 19) http: //www. youtube. com/watch? v=qy 8 d k 5 i. S 1 f 0

DNA REPLICATION: Before a cell divides, it must duplicate its DNA. • Copying DNA = Replication • Carried out by enzymes

The steps of replication: 1. DNA unzips: hydrogen bonds are broken and the two strands unwind (Helicase). 2. Each strand serves as a template. 3. The complementary bases attach by DNA polymerase. 4. DNA Ligase links pieces into a single strand 5. Each strand is “proof-read”

DNA replication video (0: 48) http: //youtube. com/watch? v=hf. Z 8 o 9 D 1 tus

Original strand Enzymes unzip strand A T G G C T Complimentary A - T T -A bases are G -C attached C -G T -A A-T T-A G-C C-G T-A T A C C G A A-T T- A G -C C -G T- A Two new strands are identical to each other and the original.

DNA wrapping & DNA Replication 3: 06

Q: How is the information contained in DNA used? A: DNA stays in the ____. nucleus RNA The sequence must be copied into ____. The RNA (_______) acts as a ribonucleic acid ribosomes messenger between DNA and ____.

The Structure of RNA: a single-stranded polymer formed from nucleotides 1. 5 -Carbon sugar (_____) ribose 2. _______ Phosphate group 3. Nitrogen base • cytosine • guanine • adenine uracil • _____

Transcription: process by which a portion of DNA is copied into a complementary strand of RNA. http: //www. stolaf. edu/people/giannini/flashanimat/molgenetics/transcription. swf RNA polymerase 1. An enzyme, _______, attaches to “start signal” (promoter). DNA at a __________ The DNA is separated into 2 strands. 2. _______________ synthesized 3. RNA is _____. The RNA strand is _______ to the DNA strand. complementary

4. RNA is released at a________ “stop signal” (terminator). m. RNA is processed 5. __________

m. RNA Splicing Non-coding • ______segments (introns) are removed. Coding • _______ segments (exons) are spliced together.

A AA U G G C U U A U U U GC AAUGGCUUAUUUGCA

• DNA Transcription 1: 52

3 Main Types of RNA 1. m. RNA (messenger RNA): brings the message of DNA out of the nucleus and to the ribosomes

2. t. RNA (transfer RNA) Carries amino acids from the cytoplasm to the ribosomes where polypeptides (proteins) are formed

• anticodon- 3 nucleotides that are complementary to 3 nucleotides of m. RNA

3. r. RNA (ribosomal RNA): makes up the ribosome • consists of a small subunit & a large subunit

COMPARING THE STRUCTURE OF DNA AND RNA: DNA Name Deoxyribo. Nucleic Acid RNA Ribo. Nucleic Acid Strand # Double Strand (ds) Sugar Deoxyribose Bases Cytosine, Guanine, Adenine, Thymine Types One Single Strand (ss) Ribose Cytosine, Guanine, Adenine, Uracil 3 = m. RNA, r. RNA, t. RNA

DNA codes for proteins • Proteins control biochemical pathways in cells

• Proteins are made of amino acids together forming long chains called polypeptides.

• Each combination of 3 nucleotides on m. RNA form a codon. • Each codon is for a specific amino acid. • There are 64 different codons which code for 20 amino acids.

Protein Synthesis Translation: the synthesis of polypeptides (proteins) using information from m. RNA. http: //www. youtube. c om/watch? v=_EK 3 g 6 px 7 Ik (3: 30)

• Before translation can occur, the DNA sequence is transcribed into m. RNA in the nucleus.

• Then m. RNA leaves the nucleus and travels to r. RNA – the ribosome.

The Steps of Translation 1. An initiation code (AUG) signals the beginning. 2. t. RNA brings amino acids from the cytoplasm to the ribosome.

i. t. RNA adds the amino acid to the polypeptide chain as the m. RNA moves through the ribosome one codon at a time. ii. The t. RNA anticodon is complementary to the m. RNA codon.

3. At a stop codon, the polypeptide is released. Protein Synthesis 0: 21

Given the following DNA strand, transcribe and translate it into a polypeptide. Use the table at the bottom of the page to determine the corresponding amino acids. DNA: T–A–C–T–T–C–C–C–G–A–A–A–G–G–T–A–T–T m. RNA: t. RNA: (Anticodons) Amino Acids: (m. RNA chart)

Given the following DNA strand, transcribe and translate it into a polypeptide. Use the table at the bottom of the page to determine the corresponding amino acids. DNA: T–A–C–T–T–C–C–C–G–A–A–A–G–G–T–A–T–T m. RNA: A–U–G–A–A-G–G–G–C–U–U–U–C–C–A–U–A–A t. RNA: (Anticodons) U – A – C U – C C–C–G A–A–A Amino Acids: (m. RNA chart) Met – Lys – Gly – Phe – Pro – Stop G–G–U A–U–U

DNA & RNA Animations • Translation 2: 16 • Translation & Protein Assembly 3: 02 • Crash Course DNA Replication (12: 58) • Crash Course DNA Transcription & Translation (14: 07) • DNA Translation 3: 03 • DNA Stated Clearly 5: 24

What happens when there is an error in the human genome? mutation How do gene mutations affect a person? A gene mutation can prevent the normal protein from being made Mutation 1: 07

Gene Mutations: chemical changes in DNA affecting one gene; may be beneficial, neutral or harmful. Point mutations: affects a single nucleotide 1. Base substitution replacement of one nucleotide with another; may result in coding for a different amino acid.

Gene Mutations: chemical changes in DNA affecting one gene; may be beneficial, neutral or harmful. Point mutations: affects a single nucleotide 2. Frameshift mutation– nucleotide reading frame is altered; codes for different amino acid sequence after the point of the mutation. • Base insertion – a nucleotide is inserted • Base deletion – a nucleotide is deleted

If the mutation changes the amino acid sequence of the protein, the protein is likely to be nonfunctional and a new phenotype will result. Ex: various forms of albinism TYR gene mutation causes type 1 OCA 2 gene TYRP 1 gene SLC 45 A 2 gene mutation causes type 2 type 3 type 4

Chromosomal mutations: involve _______ segments of chromosomes, _____ chromosomes, whole entire sets and even _____ of chromosomes.

1. Chromosomal Mutations deletion loss of part of chromosomes duplication segment of chromosome is repeated inversion Part of chromosome becomes oriented in reverse of usual direction translocation Part of 1 chromosome breaks off & attaches to another non-homologous chromosome

Mutagenesis: creation of a mutation Mutagens (physical or chemical agents causing mutations) include radiation, high temperatures, chemical pollutants, & viruses.

Epigenetics video 13: 25

DNA TECHNOLOGIES Gel electrophoresis: Separation of pieces of DNA which have been cut by restriction enzymes according to fragment size.

Steps of gel electrophoresis: 1. Restriction enzymes cut DNA sample

2. The cut segments of DNA are loaded into the wells.

3. Negatively charged DNA fragments move toward “+” end of gel 4. Smaller pieces move faster and a further distance down the gel

Uses of Gel Electrophoresis • To compare different samples of DNA for identification or paternity • To locate a particular gene out of the thousands that an individual has • To determine an organism’s DNA sequence

Technologies using gel electrophoresis: 1. DNA fingerprinting • Identifying individuals: Which suspect was at the crime scene? Suspect #2

Technologies using gel electrophoresis: 1. DNA fingerprinting • Paternity Testing: Whose the father?

Technologies using gel electrophoresis: 1. DNA fingerprinting • Paternity Testing: Whose the father?

What is going on here?

Daughter 2 has a different father & Son 2 is adopted.

Technologies using gel electrophoresis: 1. DNA fingerprinting • Comparison of different organisms: How closely related are these species to the common ancestor?

DNA Fingerprinting Pod. Cast: 6 min Want to know more? Click here to run through a demo of DNA Fringerprinting

Technologies using gel electrophoresis: 2. Determine DNA sequence DNA screening: Using 4 samples of a single stranded DNA sequence and adding modified nitrogen bases, then running a gel electrophoresis

Lets determine the order of sequence of DNA! And the sequence is…… CCGAGGTCAG

Sequencing anyone? GCCATGTCCATGGCA ATCCGTCAGCA

Advantages to knowing a DNA sequence • Study specific genes • Compare genes from different organisms • Discover functions of different genes

NOVA - Cracking the Code of Life 1: 53: 00 Nova - Cracking Your Genetic Code - 53: 27

Gel Electrophoresis Animation Electrophoresis demo