DNA CoMpEtiTiOn Come up with a team name that’s DNA-related (ish) Team with the most points gets a special prize! (Class with most overall points also gets a prize)
The information stored on DNA from one human cell equals the amount of information in 1000, 500-page books.
GC AT CG T A GC G C • DNA – Deoxyribonucleic Acid • DNA is made up of repeating… • Nucleotides – has 3 components: • Phosphate Group • Sugar – Deoxyribose • 3. Nitrogen Base • Thymine always goes across from Adenine • Guanine always goes across from Cytosine • **The part that carries the code is the base sequence • Covalent bond – connects nucleotides in a strand • Hydrogen bonds – they connect the 2 strands together • Forms shape of DNA – DOUBLE HELIX
Erwin Chargaff • Chargaff’s Rule: [A]=[T] and [C]=[G] • X-Ray diffraction pictures helped solve the structure of DNA’s double helix Rosalind Franklin Watson & Crick • Finalized the structure of DNA and built the first ever DNA model
DNA is shaped like a double helix (a twisted ladder) This shape was discovered by two scientists: James Watson & Francis Crick (Impossible without Rosalind Franklin’s X-Ray diffraction photo of DNA!)
DNA REPLICATION In general, DNA is replicated by 1. Uncoiling of the helix 2. Separating the strands (breaking the hydrogen bonds between base pairs) 3. Synthesizing two new strands by complementary base pairing
DNA REPLICATION Prokaryotes Eukaryotes DNA replication begins at 1 point, called the “origin” and proceeds in 2 directions (bidirectional) Hydrogen bonds break, two strands separate, 2 new strands are added to the old strands
DNA Replication – • DNA makes a copy of itself • Important during meiosis & mitosis – DNA gets passed on to daughter cells • DNA polymerase adds nucleotides to the parent strands and checks the strand for errors • Each double helix now has 1 old strand & 1 new strand • This is called SEMI-CONSERVATIVE • If the original strand of DNA is ATTGCACT, what is the complementary strand…?
The tips of chromosomes are called telomeres • Genes are not found in this region of the chromosome • These areas are difficult to replicate, so an enzyme – telomerase – adds short, repeated sequences to the ends
DNA Replication • Label ONE strand of your DNA with ANY sequence of your choosing • Label the opposite strand, following the base-pair rules (A – T, C – G) • What’s the 1st step in DNA replication - The DNA “unzips” – crease your paper and “unzip” your DNA
DNA Replication 4. What’s the 2nd step in DNA replication? - DNA Polymerase adds nucleotides • Lay your strands about 2” apart on a piece of paper • Next to each original strand, write the NEW complementary DNA sequence • You should now have 2 identical double-stranded molecules of DNA…yes?
DNA holds the directions for protein synthesis Protein synthesis is the making of proteins A gene is a sequence of DNA that carries the code for making one protein
Protein Examples Hemoglobin is a protein in your blood that transports oxygen Collagen is a proteins that makes your cartilage and tendons Keratin is a protein that makes up your hair & fingernails Enzymes are proteins Everything in you is made of or by proteins!
Nitrogen Bases Sugars & Phosphates RNA DNA RNA – Ribonucleic Acid RNA is like DNA except… * It is single stranded * It has uracil instead of thymine * It has ribose instead of deoxyribose
Types of RNA • mRNA – “messenger” RNA - Carries copies of instructions from DNA for making amino acids into proteins • tRNA – “transfer” RNA - Transfers each amino acid to the ribosome as specified by the code on mRNA • rRNA – “ribosomal” RNA - Makes up part of the ribosome, where proteins are made
Both DNA and RNA are involved in protein synthesis 2 parts of protein synthesis: • Transcription – DNA is converted to RNA • Occurs in the nucleus • Translation – RNA is converted to a protein - Occurs in the cytoplasm
Protein Synthesis • Transcription (the 1st part of Protein Synthesis) • Converts DNA to RNA • DNA (in the nucleus) needs to send a code to the ribosome (in the cytoplasm) • Problem: DNA can’t fit through the nuclear pores • A special “messenger” is used to copy and carry the code…
Protein Synthesis • Transcription • messenger RNA (mRNA) goes into the nucleus and copies the DNA • Uses enzyme – RNA Polymerase • The next step is that mRNA moves from the nucleus to the cytoplasm and to the ribosome • RNA has 1 different base pair! • DNA – ATCG • mRNA – UAGC
Translation (the 2nd part of Protein Synthesis) • Translation – a process that converts mRNA into a protein • Occurs on the ribosome in the cytoplasm of a cell • ______________ - building blocks of proteins; join together into long chains called polypeptides • ____________ - a sequence of 3 bases on mRNA that codes for a single amino acid • _____________ – sequence of 3 bases on tRNA that is complementary to one mRNA codon Amino acids Codon Anticodon “UCU” is the codon that makes an amino acid called SERINE
The tRNA lines up with 3 bases in mRNA (codon) • tRNA anticodon GAA • mRNA codon CUU • Another form of RNA called transfer RNA (tRNA) carries amino acids to the ribosome and matches them to the coded mRNA message • tRNA drops off the amino acid in the correct spot mRNA attaches to the ribosome
Mutations Any change in the DNA structure (specifically the order of nitrogen bases) is a mutation. Mutations can be helpful, harmful, or neutral. Helpful – can create diversity in a population Harmful – can cause things like cancer Neutral – can have absolutely no effect at all A mutagen is something that causes mutations in the DNA (for example: smoking, radiation from the sun etc) Slooze Worm
Mutations An insertion mutation is when a nitrogen base is added to the existing DNA A deletion mutation is when a nitrogen base is subtracted from the DNA A substitution mutation is when one nitrogen base is put in place of another. If our DNA was AATTGGCC An insertion would be AATTAGGCC A deletion would be AATGGCC A substitution would be AAATGGCC
Gene Sequencing – Determining the order of nucleotide bases within a gene DNA Fingerprinting – technique used in criminal investigations. DNA Fingerprinting takes the DNA out of a cell and separates it. This will allow investigators to distinguish body cells of different individuals (since they are unlikely to have the same DNA) Cloning – take the DNA out of one of your cells then take the DNA out of a zygote (fertilized egg). Put the DNA from your cell into the zygote.
Animation Genetic engineering is the process of moving genes from the chromosomes of one organism to those of another organism. Recombinant DNA is formed by joining DNA molecules.from two different organisms
What would represent the strand of DNA from which the mRNA strand in the diagram was made? A.CUCAAGUGCUUCB.GAGUUCACGAAG C.GAGTTCACGAAGD.AGACCTGTAGGA What is the amino acid sequence in the portion of the protein molecule coded for by the piece of mRNA shown in the diagram? A. Ser-Tyr-Arg-GlyB.Leu-Lys-Cys-PheC.Val-Asp-Pro-HisD.Pro-Glu-Leu-Val