CH11 pg217

Role of Gene Expression

• DNA on several chromosomes– Only some of these genes are expressed at any

given time

• Activation of a gene that results in transcription and the production of mRNA.

Section 1 Control of Gene ExpressionChapter 11

Gene Expression in Eukaryotes

• Structure of a Eukaryotic Gene– Eukaryotic genes are organized into;– noncoding sections, introns, – coding sections, exons

• Mitosis and Meiosis (Interphase)– Promotor (introns and exons)

• Introns are areas that at transcribed only• Exons are transcribed and translated

Control of Gene ExpressionChapter 11

• Research still being done about the presence of introns and exons– Believe to regulate translation of RNA– Act as a switch

Chapter 11

Removal of Introns After Transcription

Control of Gene Expression

Control of Gene ExpressionChapter 11

• Control at the Onset of Transcription– Gene expression can be controlled through

regulatory proteins known as transcription factors.

• Dictate placement of RNA polymerase• Enhancers

Chapter 11

Controlling Transcription in Eukaryotes

Section 1 Control of Gene Expression

Developmental GenesCH11 pg 225

• Homeotic Genes– Genes that determine where anatomical structures

will be placed during development.– For example, appendages

– A specific DNA sequence known as the homeobox regulates patterns of development.

– The homeoboxes of many eukaryotic organisms appear to be very similar.

CH12 pg 235

Chromosomes• Genes reside on chromosomes.

• Sex Chromosomes and Autosomes– Sex chromosomes determine an organism’s sex

(gender). – Chromosomes that do not determine the sex of an

individual are called autosomes.

• Pg 235 – 238 Discusses other influences on traits that we have covered, please review

Chromosomes and Inheritance

Chapter 12

Mutations

• Germ-cell mutations occur in gametes and can be

passed on to offspring.

• Somatic-cell mutations occur in body

cells and affect only the individual organism.

Chapter 12

Mutations, continued

• Chromosome Mutations– Chromosome mutations are changes in the

structure of a chromosome or the loss or gain of an entire chromosome.

Section 1 Chromosomes and Inheritance

Chapter 12

Chromosomal Mutations

Section 1 Chromosomes and Inheritance

Chapter 12

Mutations, continued

• Gene Mutations– Gene mutations are changes in one or more of the

nucleotides in a gene.

Section 1 Chromosomes and Inheritance

Chapter 12

Gene Mutations

Section 1 Chromosomes and Inheritance

Section 2 Human GeneticsChapter 12

Inheritance of Traits

• Pedigrees – Geneticists use pedigrees to trace diseases or

traits through families. – Pedigrees are diagrams that reveal inheritance

patterns of genes.

Chapter 12 Pedigree for Cystic Fibrosis

Chapter 12

Some Important Genetic Disorders

Human Genetics

Section 2 Human GeneticsChapter 12

Detecting Genetic Disease

• Genetic screening examines a person’s genetic makeup and potential risks of passing disorders to offspring.

• Amniocentesis and chorionic villi sampling help physicians test a fetus for the presence of genetic disorders.

Section 2 Human GeneticsChapter 12

Detecting Genetic Disease, continued

• Genetic Counseling– Genetic counseling informs screened individuals

about problems that might affect their offspring.

Section 2 Human GeneticsChapter 12

Treating Genetic Disease

• Genetic disorders are treated in various ways.

• Among the treatments are symptom-relieving treatments and symptom-prevention measures, such as insulin injections for diabetes.

Section 2 Human GeneticsChapter 12

Treating Genetic Disease, continued

• Gene Therapy– In gene therapy, a defective gene is replaced with

a copy of a healthy gene.– Somatic cell gene therapy alters only body cells. – Germ cell gene therapy attempts to alter eggs or

sperm.