DNA Replication & Protein Synthesis Designed by Mr. Gaccione

BioTech: DNA Review

The Size of DNA... DNA is located in the nucleus in the form of chromosomes. If the DNA of one cell is stretched out, it makes a 7 ft. long string. There are 5 trillion cells in the human body. If you connected all the DNA together, it would be long enough that it would take light over 10 hours to travel its length.

The Size of DNA... Chromosomes contain a single, long piece of DNA A chromosome is about 0.004 mm long The DNA is about 4 cm long This is 10,000x longer than the chromosome Thus DNA must be wrapped tightly to fit into cells Imagine fitting 900 yards (300m) of rope into a backpack.

The Size of DNA... The DNA molecule looks like a ladder that has been twisted. The DNA molecule is made from two strands, twisted together in a double helix. Watson & Crick – created the double helix model for DNA.

The Structure of DNA DNA is a long molecule made up of repeating units called nucleotides. Each nucleotide is made up of three parts: 1. phosphate group 2. carbon sugar (deoxyribose) 3. nitrogen base

Repeating Nucleotides The sides of the DNA ladder(backbone) is formed by phosphate and sugar groups. The nitrogenous bases are the rungs of the DNA ladder. DNA is 250 million nitrogen bases long. RNA is 3000 nitrogen bases long.

Nitrogenous Bases Purines (bigger) – Pyrmidines (smaller) – There are four kinds of nitrogenous bases. They are divided into two classes: purines and pyrmidines Purines (bigger) – Adenine and Guanine Pyrmidines (smaller) – Cytosine and Thymine

Chargaff’s Rules Chargaff discovered how the nitrogenous bases bond together. Adenine always bonds with Thymine Cytosine always bonds with Guanine

DNA

Hydrogen bonding

DNA Sequence The particular order of the nitrogen bases is called the DNA sequence. This sequence makes each individual unique. An elm tree, eel & an elephant has the same DNA, but what makes them different is the order of the bases.

DNA & Genes Each chromosome carries 2,000 genes. 23 chromosomes = 30,000 to 40,000 genes This is known as “The Human Genome” Genes are locations on chromosomes that give us our traits. Many of these are common to all human beings. So, 99.9% of your DNA is identical to everyone else's.

DNA & Genes The remaining 0.01% influences the differences between us. height, hair color and susceptibility to a particular disease Environmental factors, such as lifestyle (smoking and nutrition) also influence the way we look and our susceptibility to disease.

Mutations Mutations are caused by mutatgens. Examples of mutagens: UV rays, smoking & radiation Mutations are mistakes in the nitrogen bases or in the DNA sequence.

Point Mutation C

Thymine mutation Caused by exposure to UV light. 2 adjacent thymine residues become covalently linked.

Mutations RNA polymerase adds ribonucleotides not deoxynucleotides RNA polymerase does not have the ability to proofread what they transcribe RNA will have an error 1 in every 10,000 nucleotides DNA will have an error 1 in ten million nucleotides)

DNA Replication DNA replication makes an exact copy of the strand, complete with 1 old and 1 new strand. Step 1 DNA unwinds & unzips with the help of DNA polymerase Step 2 Each strand of the parent DNA is used as a template to make the new daughter strand. Step 3 Free floating nucleotides are added by DNA polymerase.

DNA Replication C T A C C G G G A T G G C C T A T

DNA to mRNA to Protein ･DNA acts as a “manager” in the process of making proteins. ･DNA is the template or starting sequence that is copied into RNA that is then used to make a protein.

RNA differs from DNA Ribose is the sugar rather than deoxyribose. Uracil instead of Thymine Adenine, Guanine Cytosine stay the same. 3. Single stranded

Three Different RNAs GUA---UUC---GUU---AGU---UGA messenger RNA (mRNA) – takes a message or 3 letter code(codon) from DNA GUA---UUC---GUU---AGU---UGA ribosomal RNA (rRNA) – meeting place for three RNAs 3. transfer RNA (tRNA) – brings anti-codon & amino acid Ribosome

Protein Synthesis -2 Steps Transcription & translation First step in protein synthesis mRNA transcribes a message (code) from DNA Occurs in the nucleus

Protein Synthesis Transcription DNA Cytoplasm Nucleus RNA Transcription Export G AAAAAA

Protein Synthesis -Transcription Step 1 DNA unwinds & unzips with the help of RNA polymerase Step 2 Only one strand of the parent DNA is used as a template to make mRNA. Step 3 Free floating nucleotides are added by RNA polymerase, making mRNA.

Protein Synthesis-Transcription

Protein Synthesis Transcription

Protein Synthesis -Transcription aking mR from D template U A C C G G A U A

Protein Synthesis -Translation Amino acid Translation Goal: to make a protein Second step in protein synthesis All three RNAs meet (mRNA, rRNA & tRNA) Occurs in the cytoplasm UAC --UUC--GUU--AUG-- Amino acid --AUG-- tRNA brings anti-codon & amino acid Anti-codon

Protein Synthesis - Translation Draw and label the boxes, tRNA, mRNA & rRNA

Translation rRNA & mRNA are in the cytoplasm. Where is tRNA??? Amino Acid? Amino Acid? Amino Acid? Met Amino Acid? Amino Acid? Phe Val Ser Stop! Ribosome ANTI- CODON? UAC ANTI- CODON? AAG CAA UCA ANTI- CODON? ACU ANTI- CODON? ANTI- CODON? - AUG--UUC--GUU--AGU--UGA 5’ 3’ rRNA & mRNA are in the cytoplasm. Where is tRNA???

? ? ? ? ? ? ? ? ? ? ? Protein Synthesis -Translation Review tRNA rRNA mRNA mRNA ? ? rRNA Amino acid ? mRNA ? ? ? mRNA tRNA tRNA

Protein Synthesis -Translation Review Translation is the meeting of all three RNAs (mRNA, rRNA & tRNA). It takes place in the cytoplasm. The goal is to string together amino acids to form a protein. Proteins make up our skin, blood, muscles, heart, enzymes, stomach lining & intestinal linings.

Protein Synthesis - Key Words Transcription DNA Double Helix 3’-5’ strand 5’-3’ strand Phosphate Group Deoxyribose Sugars Ribose sugars Hydrogen Bonds RNA polymerase Nucleus Nuclear pore ER Complementary base pairs rRNA mRNA tRNA