Bellwork What are the 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 mRNA strand look like?

DNA Structure Double Helix. made up of millions of tiny subunits called Nucleotides. Phosphate group Pentose sugar (deoxyribose) Nitrogenous base Phosphate 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) Cytosine (C) Guanine (G) Form a base pair. 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. C

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

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

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

Two types of nucleic acids # of strands kind of sugar TRANSCRIPTION DIFFERS FROM REPLICATION IN THAT ONLY 1 STRAND OF THE DNA MOLEUCLE IS TRANSCRIBED AND THAT MEANS THAT THE RESULTING RNA MOLECULE IS SS ALSO MRNA IS SHORT COMPARED TO A LARGE CHROMOSOME bases used

Types of RNA mRNA = 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 mRNA = messenger RNA tRNA = transfer RNA Transfers amino acids to the ribosome for protein synthesis Found in the cytoplasm rRNA = ribosomal RNA

Transcription First the DNA is “unzipped”. Complementary RNA nucleotides are added to the template strand, forming the new RNA molecule. DNA DNA coding strand 5’ G T C A T T C G G 3’ G RNA 5’ U C A 3’ 3’ CALLED TRANSCRIPTION BECAUSE THE NUCLEIC ACID LANGUAGE OF DNA HAS TO BE REWRITTEN AS A SEQUENCE OF BASES ON RNA ACTIVATED GENES DO NOT LEAVE THE NUCLEUS BECAUSE THE CYTOPLASM IS TOO HOSTIL INSTEAD A MESSAGE IS CARRIED ON A STRAND OF MRNA THE PROCESS OF MRNA FORMATION IS CALLED TRANSCRIPTION BECAUSE IN THE NUCLEUS THE MRNA IS TRANSCRIBED FROM THE DNA TEMPLATE C A G T A A G C C 5’ DNA template strand

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

What happens after transcription? The new mRNA 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 INTRONS- they stay IN the nucleus.

What happens after transcription? The new mRNA 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 mRNA and creating the amino acid sequence of a protein. DNA T C A G template strand Transcription mRNA A G U C Messenger RNA Codon Translation THE GENETIC INSTRUCTIONS FOR THE AA SEQUENCE OF A POLYPEPTIDE CHAIN ARE WRITTEN IN DNA AND TRANSCRIBED TO RNA AS A SERIES OF 3 BASE WORDS CALLED CODONS TRIPLETS IN THE DNA ARE TRANSCRIBED INTO COMPLEMENTARY 3 BASE CODONS IN THE MRNA AND THEN THE MRNA CODONS ARE TRANSLATED INTO AA THAT WILL MAKE UP A POPYPEPTIDE Protein Lysine Serine Valine Polypeptide (amino acid sequence)

Transcription Translation CUC IS WHAT IS ON MRNA GAG GLUTAMIC ACID THE TRNA MOLECULE BINDS TO THE MRNA MATCHING UP ITS COMPLEMENTARY ANTICODON TO THE MRNA CODON GO OVER THIS OVERHEAD Transcription Translation

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

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

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

mRNA codons and the Amino Acids for which they code

Gene Mutations Point mutations: a single nucleotide is changed Ex. Of a triplet sequence: 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

Gene Mutations Point mutations: a single nucleotide is changed Ex. Of a triplet sequence: the fat cat sat Point mutations: a single nucleotide is changed Deletion: Ex. F in fat is deleted: the atc ats at 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: the fat cat sat Substitution: Ex. F in “fat” is changed to an “e”: the eat cat sat Deletion: Ex. F in fat is deleted: the atc ats at (frameshift mutation) 26