Bellwork What are three parts of a DNA

Bellwork What are three parts of a DNA nucleotide? What would the complementary strand of DNA look like (nitrogen bases)? A T G C C G T T A A C G What would the complementary m. RNA strand look like?

DNA Structure Double Helix. made up of millions of tiny subunits called Nucleotides. Phosphate group 2. Pentose sugar 1. Phosphate (deoxyribose) Nitrogenous Base 3. Nitrogenous base Pentose Sugar

Nucleotides Phosphate and sugar backbone the nitrogen bases form the “rungs”. There are four types of nitrogenous bases.

Nucleotides Each base will only bond with one other specific base (Chargaff’s Rule, or Base-Pair Rule). Adenine (A) Thymine (T) Form a base pair. Cytosine (C) Guanine (G) Form a base pair.

Complementary base pairing: the order of the bases in one strand determines the order of the bases in the other strand. A T C G T A C G A T G C T A

Agenda 12/19 - Protein Synthesis Bellwork Essential Question: How does DNA code for proteins? How does DNA determine the structure and function of an organism? New information: Protein synthesis (transcription and translation) Activity: Protein Synthesis practice worksheet in pairs

DNA Gene Trait Protein

Protein Synthesis Overview • DNA is the genetic material within the nucleus. DNA • Transcription creates an m. RNA using DNA information. Transcription RNA • Translation creates a protein using RNA information. Translation Nucleus Protein Cytoplasm

Protein Synthesis Overview • Sections of DNA that code for proteins are called GENES. • GENES determine what proteins are made and therefore what traits an organism has. A Gene DNA Transcription RNA • A gene does not build proteins directly. It sends instructions in the form of m. RNA which directs protein synthesis. Nucleus Translation Protein Cytoplasm

Two Types of Nucleic Acids RNA Number of strands Usually single-stranded Usually double-stranded Nitrogen Bases URACIL (instead of T), Pentose Sugar Codes for… DNA A, C, and G THYMINE (instead of U), A, C, and G Ribose Deoxyribose Codes for proteins Codes for RNA

Two types of nucleic acids # of strands kind of sugar bases used

Types of RNA m. RNA = messenger RNA Made during transcription Carries a complementary copy of the DNA code out of the nucleus for protein synthesis on a ribosome

Types of RNA m. RNA = messenger RNA t. RNA = transfer RNA Transfers amino acids to the ribosome for protein synthesis Found in the cytoplasm r. RNA = ribosomal RNA

Transcription First the DNA is “unzipped”. Complementary RNA nucleotides are added to the template strand, forming the new RNA molecule. DNA coding strand 5’ 3’ DNA G T C A T T C G G 3’ G U C A U U C G G 3’ C A G T A A G C C 5’ DNA template strand 5’ RNA

TRANSCRIPTION RNA polymerase attaches m. RNA nucleotides to the DNA template: Guanine to Cytosine to Guanine Adenine to Thymine Uracil to Adenine RNA polymerase cannot attach Thymine 3’ GUCAUUCG G C AG T A AG C C 5 ’

What happens after transcription? The new m. RNA molecule (and DNA) has more information than is required for making the protein. The parts that aren’t directly needed for making the protein are called INTRONSthey stay IN the nucleus.

What happens after transcription? The new m. RNA molecule (and DNA) has more information than is required for making the protein. The parts that are needed for making the protein are called EXONS- they EXit the nucleus after being spliced together.

Translation The process of reading the RNA sequence of an m. RNA and creating the amino acid sequence of a protein. DNA Transcription T T C A G A A G U C DNA template strand Messenger RNA m. RNA Codon Translation Protein Lysine Serine Valine Polypeptide (amino acid sequence)

Transcription Translation

Protein Synthesis Overview • Transcription creates m. RNA from DNA information- happens in nucleus. • Translation creates protein using RNA information; happens at a ribosome (in cytoplasm or on rough ER). DNA Transcription RNA Translation Nucleus Protein Cytoplasm

5 Minute Writing If one DNA strand has the nitrogen base sequence below, what will the complementary strand look like? What will the m. RNA produced during transcription look like? What happens during the process of translation? AAG GCT TAT GCC CAT

Protein Synthesis Overview • DNA is the genetic material within the nucleus. DNA • Transcription creates an m. RNA using DNA information. • Translation creates a protein using RNA information. Transcription RNA Translation Nucleus Protein Cytoplasm

m. RNA codons and the Amino Acids for which they code

Gene Mutations the fat cat sat Point mutations: a single nucleotide is changed Substitution: Ex. F in “fat” is changed to an “e”: the eat cat sat Ex. Of a triplet sequence:

Gene Mutations the fat cat sat Point mutations: a single nucleotide is changed Deletion: Ex. F in fat is deleted: the atc ats at Ex. Of a triplet sequence: Frameshift mutation: caused by insertion or deletion of fewer (or more) than 3 nucleotides; usually results in all codons after that point being altered.

Gene Mutations When the code is changed due to a mutation, the amino acid sequence may be altered, resulting in changes in the protein (or no protein at all). Ex. Of a triplet sequence: Substitution: Ex. F in “fat” is changed to an “e”: the fat cat sat eat cat sat Deletion: Ex. F in fat is deleted: the atc ats at (frameshift mutation)