Unit 3.4 Studying Human Genetics and Biotechnology

Page 67

Unit 3.4 Studying Human Genetics and Biotechnology

Entry 44 Honors4/23

Describe the difference between an GENEtic Disorder and a Chromosomal Disorder.

Describe the difference between an Autosomal Chromosomal Disorder and a Sex Chromosomal Disorder.

Entry 40 11/2

PedigreeA chart of an

individual's ancestors used in human genetics to analyze inheritance of certain traits

Twins Studyhttp://player.discoveryeducation.com/index.cfm?guidAssetId=B8EBDD99-B341-44E3-9834-F7C198E0786C

Draw the PICTURE

A. Problems Studying Human Genetics1. Ethically irresponsible

to conduct testcrosses on humans.Testcross: method to

determine the genotype for a dominant phenotype (AA or Aa?), always use homozygous recessive to compare unknown to.

2. Humans have long life spans and it requires decades to produce several generations to study.Small number of offspring

(and long gestational periods)

Techniques Used to Study Human Genetics

1. Population Sampling- determine how often a trait appears in a small randomly selected group, then apply to the entire population.

2. Pedigrees: graphical record of the inheritance of a single trait over several generations. Determined based on

family/historical documents, interviews, photographs, and medical records.

C. PedigreesShapes represent individuals in

pedigrees, connecting lines represent relationships.

Helpful Hints for figuring out pedigreesIf the pedigree is showing a SEX-LINKED

trait:No male carriersTrait cannot be passed from father to sonMore males will express the trait

If the pedigree is showing an AUTOSOMAL recessive trait Trait can skip a generationTrait CAN be passed from father to son

Pedigree Activity Reminders:

You may ask ONE question about directions; you can ask as many as you want about content

We are using BEADS instead of Pom Poms

You are to remain at your lab station DO NOT WANDER or you will sit in your seat.

There are 12 beads total I better receive 12 beads upon completion or there will be a point deduction.

The beads should never leave the table (ie. Throwing, rolling, tossing etc)

Ticket out the door

1.How many males possess the trait?

2. How many females

possess the trait?

3.What is the genotype

of the second male

in generation III?

D. Human Genome ProjectThe Human Genome Project:

is a collaborative effort among scientists worldwide to map the genes of humans. Allowing them to detect gene variations on the chromosomes which may indicate a disorder.

Hopes are to develop gene therapy or genetically based medicines.http://app.discoveryeducation.co

m/player/view/assetGuid/EF68C74E-129F-4FF1-82D1-EA428498E9AC

E. Detection of Genetic DisordersGenetic

Counseling: can help parents determine the chances of passing a harmful genetic trait to their child

Sonograms: use of sound waves to produce a picture of a fetusUsed to evaluate

baby’s growth and development

Detection of Genetic Disorders

Blood tests: used to screen for proteins Alpha-Feto protein test (AFP)- Levels determine if baby is at risk for Down’s syndrome, Turner’s , or spina bifida.

Amniocentesis: Removes amniotic fluid with fetal cells which can be cultured and produce a karyotype. Karyotype: a picture of the

chromosomesCan identify Down’s,

Klinefelters, and Turners.  Chorionic Villi Sampling:

removes tissue from the placenta for karyotyping.This can be done earlier in

pregnancy and is more risky.

Karyotypes (not in the notes)

F. Prevention/TreatmentGenetic diseases cannot be cured but

treated:Pain medication: to relieve symptoms.Occupational Therapy: help people who have

conditions improve their ability to perform everyday tasks

Blood Transfusions: Sickle-cell/ Hemophiliacs may require this.

Gene Therapy: use vectors (viruses) to replace defective genes with normal onesEx. Treating cystic fibrosis and hemophilia

Ticket out the Door

Pedigree

Identify the following disorder in the Karyotype.

a. Klinefleter’s Syndrome

b. Sickle Cellc. Nondisjuctiond. Hemophilia

Entry 43 4/20 Draw a pedigree and decided if this is an example of

Autosomal or X-linked and if it is dominant or recessive. Include genotypes

Chad and Veronica got married and had Brittany,Kirsten, and Harry. It was discovered that Chad was acarrier and Harry had muscular dystrophy. Brittany married Larry and had Stephan and Stephanie. Stephan also had muscular dystrophy. Larry’s brother Barry also had muscular dystrophy but neither of their parents had

the disorder.

G. DNA FingerprintDNA fingerprint- A unique band

pattern made of DNA fragments. Unique to every individual, unless

you have an identical twinUses for DNA Fingerprinting:

Violent Crimes – determines source of DNA left at a crime scene.

Paternity - used to determine the father of a child

Gel Electrophoresis- tool used to create a DNA fingerprint, it separates pieces of DNA based on size (# of base pairs).

Steps in DNA FingerprintingStep 1: Restriction enzyme cleaves the DNA

sample at a specific sequence.Restriction enzyme: the enzymes that “cuts” the

DNA between the nitrogen basesCleave: to Cut (between nitrogen bases)

Step 2: DNA fragments are loaded into wells on a gel.Step 3: Bands are created as electricity forces DNA

fragments through the gel. Small pieces move further than larger pieces.

Step 4: Compare to other DNA samples.

H. Genetic EngineeringGenetic Engineering: Modifying

DNA or creating recombinant DNA.

Transgenic Organism: an organism which contains foreign DNA from another species.

Recombinant DNA: form of artificial DNA that is created by combining two different sources of DNA.

Process in creating Transgenic organism: Step 1: Restriction enzyme is used to cleave

the desired gene from a DNA sequence (ex. Insulin).

Step 2: The same restriction enzyme is used to cleave the vector. Vector: The structure used to carry the foreign DNA,

bacterial plasmids are commonly used.Plasmid: Circular DNA found in bacteria

Step 3: Foreign DNA and Vector spliced togetherSplice: Combine

Step 4: The recombinant DNA is inserted into the host (bacteria cell). Then the host cell will copy and produce the protein.Insulin can be produced in large quantities by

using genetic engineering and bacteria.

I. Bioethical Concerns for Genetic Engineering

Should we produce artificial proteins?Allergic reactions (adding a peanut gene

to a corn plant)Stem cell researchEnvironmental problems from creating

transgenic organisms:Super weedsAntibiotic resistant bacteriaDestruction of beneficial insects like bees by

pesticides