Transcript CH11-Summary

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.
Chapter 11
Section 1 Control of Gene Expression
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
Chapter 11
Control of Gene Expression
• Research still being done about the
presence of introns and exons
– Believe to regulate translation of RNA
– Act as a switch
Chapter 11
Control of Gene Expression
Removal of Introns After Transcription
Chapter 11
Control of Gene Expression
• 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
Section 1 Control of Gene Expression
Controlling Transcription in Eukaryotes
CH11 pg 225
Developmental Genes
• 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 and Inheritance
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
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
Section 1 Chromosomes
and Inheritance
Mutations, continued
• Chromosome Mutations
– Chromosome mutations are changes in the
structure of a chromosome or the loss or gain of
an entire chromosome.
Chapter 12
Section 1 Chromosomes
and Inheritance
Chromosomal Mutations
Chapter 12
Section 1 Chromosomes
and Inheritance
Mutations, continued
• Gene Mutations
– Gene mutations are changes in one or more of the
nucleotides in a gene.
Chapter 12
Gene Mutations
Section 1 Chromosomes
and Inheritance
Chapter 12
Section 2 Human Genetics
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
Chapter 12
Section 2 Human Genetics
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.
Chapter 12
Section 2 Human Genetics
Detecting Genetic Disease, continued
• Genetic Counseling
– Genetic counseling informs screened individuals
about problems that might affect their offspring.
Chapter 12
Section 2 Human Genetics
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.
Chapter 12
Section 2 Human Genetics
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.