Read Chapter 3 from the book “Genome”The story of Archibald Garrod

Biochemical pathwaysName 10 different types of diseases found

in humans.

What is the leading cause of these diseases?

Genes Make Proteins (Enzymes), Enzymes Catalyze the Reactions of One Substrate to Another

Substrate 1

Substrate 2

Substrate 4

Substrate 3

Enzyme 1

Enzyme 2

Enzyme 3

Where do proteins come from? Like all proteins, enzymes follow this

central dogma:

DNA RNA Proteins Transcription Translation

Genes Make Proteins (Enzymes), Enzymes Catalyze the Reactions of One Substrate to Another

Substrate 1

Substrate 2

Substrate 4

Substrate 3

Gene 1 Enz 1

Gene 2 Enz 2

Gene 3 Enz 3

Genes Make Proteins (Enzymes), Enzymes Catalyze the Reactions of One Substrate to Another

Substrate 1

Substrate 2

Substrate 4

Substrate 3

Gene 1 Enz 1

Gene 2 Enz 2

Gene 3 Enz 3

Substrate 5

Gene 4

Alleles are alternate forms of a gene

A alleleability to make an enzyme

a alleleinability to make an enzyme

A Allele

a Allele

Regulatory sites

Promoter(RNA polymerase binding site)

Start transcription

DNA strand

Stop transcription

Typical Gene Structure

Human biochemical pathways can be very complicated. Although the Human genome project has mapped out the locations of gene on chromosomes, the next frontier is to map out human biochemical pathways.

(An amino acid)

(An amino acid)

PKU is an autosomal recessive genetic disease. Individuals who have PKU have inherited a p allele from their mother and a p allele from their father. The P allele controls the transcription of the P allelle DNA into and RNA that is used in translation to make a protein. What protein enzyme is being made?

The enzyme

What is Phenylketonuria (PKU)?

1. is a rare condition in which a baby is born without the ability to properly break down an amino acid called phenylalanine.

2. Phenylketonuria (PKU) is inherited (autosomal rescessive trait), which means it is passed down through families.

What does this mean? Both parents must pass on the defective gene in order for a baby to have the condition. 3. Babies with PKU are missing an enzyme called phenylalanine hydroxylASE, which is needed to break down an essential amino acid called phenylalanine. The substance is found in foods that contain protein.4. Without the enzyme, levels of phenylalanine and two closely-related substances build up in the body. These substances are harmful to the central nervous system and cause brain damage.

5. Phenylalanine plays a role in the body's production of melanin, the pigment responsible for skin and hair color. Therefore, infants with the condition often have lighter skin, hair, and eyes than brothers or sisters without the disease.Other symptoms may include:

-Delayed mental and social skills-Head size significantly below normal-Hyperactivity-Jerking movements of the arms or legs-Mental retardation-Seizures-Skin rashes-Tremors-Unusual positioning of hands

If the condition is untreated or foods containing phenylalanine are not avoided, a "mousy" or "musty" odor may be detected on the breath and skin and in urine. The unusual odor is due to a build up of phenylalanine substances in the body.

How do you treat this condition?????

• PKU is a treatable disease.

• Treatment involves a diet that is extremely low in phenylalanine, particularly when the child is growing. The diet must be strictly followed. “Diet for life”

• Phenylalanine occurs in significant amounts in milk, eggs, and other common foods.

Also, why should aspartamine, an artificial sweetener found in many diet soft drinks, be avoided by individuals who have PKU?

http://www.dnalc.org/view/15905-Phenylketonuria-PKU-.html

DNA Interactive PKU

GBBE 2012

Yeast lab “The Perfect Organism”

Yeast –Saccharomyces cerevisiaeUnicellular fungusEukaryoteComplex life cycleExists in the diploid and haploid stagesHas mating types in the haploid stateMates to form a diploid organism32 chromosomesMany biochemical variantsGenome completedEconomically important organism

Yeast ChromosomesEntire genome sequenced (12 Mb; 6,200

genes) Centromeres small (~120 bp), unique;

three regions bind proteins, allowing interaction with a single microtubule for segregation; no transcriptional silencing at centromeres

Telomeres (TG1-3)n [Note that human telomere sequence is (TTAGGG)n]

Replication origins (ARS elements) 100-150 bp

Yeast GenesYeast genes are given three letter

abbreviationsGenes are named after the protein that

they encodeWild type genes (dominant) begin in

upper case lettersMutants or recessive begin in lower case

Yeast Cells – Phase Contrast

Yeast Cell TypesMating types(a and alpha) Attraction via pheromonesMatingShmoo formationBuddingAsexual cell formationSporulationShort life cycleEasily manipulated in laboratoryEasily culturedNon-pathogenic

Yeast Cell Types

Mating

Yeast Gene ExampleMy favorite Yeast Gene

Culture of Yeast

• Complex media

• YED- Yeast extract dextrose – Yeast extract and glucose

• YEAD – Yeast extract dextrose with an excess of adenine

• MV- Minimal media ( no adenine ) – This medium should support wild type

Aseptic TechniqueUse disinfectant on work areaUse fresh sterile media. Yeast media is placed in Petri

Dishes . Remove from refrigerator. Warm to room temperature

Use sterile toothpicks for transfer of yeastWork with care to limit exposure of plate to the airDispose of all toothpicks in cup on desk. Empty cup into

hazardous waste bag.Label all plates with date, your initials, experiment, and

other pertinent facts.Incubate cultures agar side up at room temperature.

Secure with tape on edges to insure Petri Dish does not open.

When plates have grown out. Place in refrigerator.

SuppliesGet all supplies from lab tableReturn all supplies to lab tableClean up lab bench