A. True B. False

1. All of your cells have different functions. If all of your cells have the same DNA, how do they differentiate from each other and become different cells? A. Through mutations during development B. Through skipping checkpoints in the cell cycle C. By expressing certain combinations of genes and repressing others D. Different cells have different DNA

Central Dogma: Gene  _______  ___________

 Gene - a segment of DNA that codes for a protein  Humans have about 25,000 genes  Each of your 46 DNA molecules in every cell contains a few hundred –a few thousand genes

 Protein synthesis is the process of making a protein from a gene  Gene expression – when a gene is being used to make a protein in a cell  In a multicellular organism, different cells express different genes and at different times

 Gene (segment of DNA)  RNA  protein

 In an organism, all cells (except sperm and egg) have the same DNA molecules  Due to DNA replication and mitotic cell division  Cells can look and behave different by using different genes  Some are expressed and some are not  Depends on hormones environmental factors

 In a simplified form, protein synthesis is a 2 step process: 1. Transcription  mRNA is transcribed from a gene 2. Translation  A protein is synthesized from the mRNA codons

 DNA  Monomers= nucleotides  Deoxyribose sugar  Double stranded  Cannot leave the nucleus  A- T  C-G  RNA  Monomers = nucleotides  Ribose sugar  Single Stranded  Can leave the nucleus  A, U (Uracil),G,C

 mRNA  m = messenger  Carries genetic code from the nucleus to a ribosome  rRNA  R = ribosomal  makes up ribosomes  tRNA  t = transfer  Connects amino acids to mRNA codons

 Occurs in the nucleus in eukaryotes and the cytoplasm in prokaryotes 1. An enzyme unzips an area of a DNA molecule exposing a particular gene 2. RNA Polymerase makes a strand of mRNA from the DNA coding strand (A-U, C-G) 3. The newly made strand separates and leaves the nucleus through a nuclear pore 4. DNA is zipped back by another enzyme

Transcription

Protein Synthesis- Part 1 Transcription From HHMI’s Biointeractive: DNA Animations/Transcription (basic) NAi_transcription_vo1.html

A. ACU B. ACT C. UGA D. AGU

 Occurs in a ribosome of both prokaryotic and eukaryotic cells  The mRNA interacts with the rRNA of the ribosome to initiate translation at the start codon  The sequence of nucleotides on the mRNA is read in triplets called codon  Each codon encodes for a specific amino acid, which can be deduced by using the genetic code chart

1. tRNA brings the correct AA to the correct place on the mRNA 2. Peptide bonds form between the amino acids 3. A growing polypeptide chain forms 4. The process continues along the mRNA until a stop codon is reached 5. The process terminates by release of the newly synthesized polypeptide 6. It will then get folded into its specific shape and be packaged and transported throughout the cell

From HHMI’s Biointeractive: DNA Animations/Translation (basic) Ai_translation_vo1.html

A. Amino acids are assembled into protein on the ribosomes B. Messenger RNA is made from DNA C. Ribosomal RNA and transfer RNA form base pairs D. Transfer RNA contains the genetic code copied from DNA

 Two ends:  1. Amino Acid  2. Anti Codon  The anti codons bond to the mRNA codons  mRNA codon = AGU  Anti codon = UCA  Amino acid Anti codon 

 As the mRNA strand moves through the ribosome, tRNA brings a specific amino acid to each of the mRNA codons

 The amino acids bond together (peptide bonds) and break off from the tRNA-mRNA hold  The newly formed sequence of amino acids will then be folded into a protein and go do its cellular function.

SHAPE MATTERS Structure of the Digestive Enzyme Chymotripsin

 The sequences of amino acids make different proteins  There are only 20 amino acids  The same 20 for all life  All species on Earth use the same code to build proteins  How do you get amino acids in your body?

A. Alanine B. Arginine C. Proline