What is a gene and what is Gene Expression?  A Gene is the molecular unit of heredity in a living organism!  Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins.

Gene Expression

Operons  Gene expression requires an operons!  A segment of DNA to which a transcription factor can bind!  Also called a lac operon  The operon regulates gene expression!

Control of Gene Expression  Cells differ in which genes are being expressed  It is based on cell function (nerve vs muscle)  Levels of control in eukaryotes  Transcriptional  Post transcriptional  Translational  Post translational  May rely on signals from outside or inside the cell!

Don’t let this happen to you!!

Types of Control  Transcriptional control  Determines the rate of transcription or if transcription even occurs  The organization of chromatin (form that chromosomes take in non-dividing cells)  Regulator proteins are called transcription factors  Signals from inside/outside cell

Types of Control  Post transcriptional  Involves process of mRNA  Translational control  Involves the ability of the mRNA to bind to ribosomes  Post translational  Involves changes needed for the polypeptide to become functional  Polypeptide: long, continuous chain of amino acids

Closing Question #1   Explain how gene expression plays a role in this scenario.   At 21 o C, a bread mold can often be seen growing on bread as a dark-colored mass.   At 15 o C the same bread mold can often be seen growing as a red mass.

Closing Question 2   The chart shows the relationship between inherited genes, environment and the physical appearance of a sweet potato vine. Determine which gene is most influenced by environment and defend your answer.

MUTATIONS Changes in DNA that affect genetic information

Gene Mutations  Point Mutations – changes in one or a few nucleotides  Substitution  THE FAT CAT ATE THE RAT  THE FAT HAT ATE THE RAT  Insertion  THE FAT CAT ATE THE RAT  THE FAT CAT XLW ATE THE RAT  Deletion  THE FAT CAT ATE THE RAT  THE FAT ATE THE RAT

Gene Mutations  Frameshift Mutations – shifts the reading frame of the genetic message so that the protein may not be able to perform its function.  Insertion  THE FAT CAT ATE THE RAT  THE FAT HCA TAT ETH ERA T  Deletion  THE FAT CAT ATE THE RAT  TEF ATC ATA TET GER AT H H

Chromosome Mutations  Changes in number and structure of entire chromosomes  Original Chromosome ABC * DEF  DeletionAC * DEF  DuplicationABBC * DEF  InversionAED * CBF  TranslocationABC * JKL GHI * DEF

Significance of Mutations Most are neutralMost are neutral Eye colorEye color Birth marksBirth marks Some are harmfulSome are harmful Sickle Cell AnemiaSickle Cell Anemia Down SyndromeDown Syndrome Some are beneficialSome are beneficial Sickle Cell Anemia to MalariaSickle Cell Anemia to Malaria Immunity to HIVImmunity to HIV

What Causes Mutations?  There are two ways in which DNA can become mutated:  Mutations can be inherited.  Parent to child  Mutations can be acquired.  Environmental damage  Mistakes when DNA is copied

Chromosome Mutations  Down Syndrome  Chromosome 21 does not separate correctly.  They have 47 chromosomes in stead of 46.  Children with Down Syndrome develop slower, may have heart and stomach illnesses and vary greatly in their degree of inteligence.

Chromosome Mutations  Cri-du-chat  Deletion of material on 5 th chromosome  Characterized by the cat-like cry made by cri-du-chat babies  Varied levels of metal handicaps

Sex Chromosome Abnormalities  Klinefelter’s Syndrome  XXY, XXYY, XXXY  Male  Sterility  Small testicles  Breast enlargement

Sex Chromosome Abnormalities  XYY Syndrome  Normal male traits  Often tall and thin  Associated with antisocial and behavioral problems

Sex Chromosome Mutations  Turner’s Syndrome  X  Female  sex organs don't mature at adolescence  sterility  short stature

Sex Chromosome Mutations  XXX  Trisomy X  Female  Little or no visible differences  tall stature  learning disabilities  limited fertility

Some mutations even make it on SNL!