How do you do the voodoo that you do so well! Replication and RNA How do you do the voodoo that you do so well!

DNA structure

Replication - DNA is copied 1st step - two chains separate at replication fork 2nd step - helicase enzymes break hydrogen bonds between base pairs 3rd step - DNA polymerase binds new nucleotides to existing chains -G-C- -A-T- -C-G- -T-A- -G -A -C -T -C- -T- -G- -A- -G- -A- -C- -T- C- T- G- A-

Nucleic Acids! There are two major kinds of nucleic acids DNA stores all the biological information to produce the organism RNA is able to read the message in DNA and use it to construct proteins

RNA - ribonucleic acid RNA (Ribonucleic Acid) - final product of RNA is protein

Differences between DNA & RNA 1. Double helix 2. Thymine 3. One Kind 4. Deoxyribose RNA 1. Single Stranded 2. Uracil (U) 3. Three Kinds 4. Ribose

Transcription - making RNA from DNA RNA Transcription - DNA provides code to make mRNA -A- -T- -G- -C- U- A- C- G-

How Proteins Are Made GENE EXPRESSION Using DNA information to make proteins

2 Stages of Gene Expression 1. Transcription a RNA copy is made from a DNA pattern this copy is called mRNA (messenger RNA) because it carries the DNA’s message to the ribosome!!!!!! Codons are groups of 3 bases in mRNA that translate into amino acids.

2 Stages of gene expression cont’d. 2. Translation 3 different kinds of RNA work together to assemble amino acids into a protein chain.

The steps of protein synthesis mRNA (messenger) leaves the nucleus and enters the cytoplasm. 2. tRNA (transfer) picks up amino acids in the cytoplasm and brings them to the ribosome. 3. rRNA (ribosomal) reads mRNA and starts making a protein.

PROTEIN SYNTHESIS CONT’D 4. tRNA anticodons match up with the mRNA codons. U A C - codon (mRNA) A U G - anticodon (tRNA) 5. Amino acids detach from the tRNA and attach to a growing protein chain. tRNA picks up another amino acid and begins again.

MUTATIONS Mistakes in the DNA code May be helpful, harmful, or no effect helpful mutations can sometimes be passed to offspring caused by breaks in x-somes or parts of x-somes switching places (crossing over) also caused by mutagens (chemicals, drugs, x-rays, smoke, pollution, viruses)

Types of Mutations 1. Germ Cell Mutations - mutations in sex cells; transmitted to offspring; may not be expressed for several generations. May be harmless or lethal 2. Somatic Mutations - mutations in body cells; not passed to offspring; passed to other body cells or affect cell reproduction ex. cancer

Types of Mutations (con’t.) 3. Lethal mutations – cause death, often before birth

Chromosome Mutations Changes in the structure of a chromosome or loss of an entire chromosome. A. Deletions - chromosome segments break off and are lost. B. Inversions - chromosome segments break off and turn around - usually not harmful

C. Addition or Substitution – a base pair is added or removed from a sequence D. Translocations - chromosome segments break off and reattach to totally different chromosome - causes abnormalities in humans