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The Genetics of Organelle-Encoded

Traits

Uniparental inheritance

mtDNA is maternally inherited in animals.

Paternal inheritance of organelles is commonin gymnosperms.

Heteroplasmy

Distinctive DNA within the cytoplasm of a

single cell

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The Genetics of Organelle-Encoded

Traits

Homoplasmy

All wild-type or all mutant-type DNA are in the

cytoplasm of a single cell.

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The Endosymbiotic Theory

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The Gene Structure and Organization of

mtDNA

Ancestral and derived mitochondrial

genomes

Ancestral: retain many characteristics of their

eubacterial ancestors

Derived: differ from eubacterial ancestors

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The Gene Structure and Organization of

mtDNA

Human mtDNA

H strand is template for most genes

L strand is template for a small number of genes

Nonuniversal codons in mtDNA

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Concept Check 1

Which is characteristic of ancestral mitochondrial

genomes?

a. They have genes with many introns.b. They contain more genes than derived genomes

do.

c. They possess much noncoding DNA between

genes.

d. They have nonuniversal codons.

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Concept Check 1

Which is characteristic of ancestral mitochondrial

genomes?

a. They have genes with many introns.b. They contain more genes than derived genomes

do.

c. They possess much noncoding DNA between

genes.

d. They have nonuniversal codons.

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The Replication, Transcription, and

Translation of mtDNA

Random replicating and extensive variation

among different organisms in transcription and

translation

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The Evolution of mtDNA

Common eubacterial origin of all mtDNA

Mitochondrial DNA variation and human history

Model genetic organism

The yeast Saccharomyces cerevisiae

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21.3 Chloroplast DNA Exhibits Many

Properties of Eubacterial DNA

The gene structure and organization of cpDNA issimilar to that of eubacterial DNA.

Replication, transcription, and translation: Little is known about cpDNA replication.

Transcription and translation are similar tothose of eubacteria.

The evolution of cpDNA

Cyanobacteria origin

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21.4 Through Evolutionary Time, Genetic

Information Has Moved Between Nuclear,

Mitochondrial, and Chloroplast Genomes

Much of the original genetic material in the

endosymbiont has probably been transferred to

the nucleus and from chloroplasts to

mitochondria.

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21.5 Damage to Mitochondrial DNA Is

Associated with Aging

Elevated levels of mtDNA defects have been

observed in some patients with late-onset

degenerative disease.

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22.1 Developmental Takes Place Through

Cell Determination

Totipotent cell: the cell that has the potential to

develop into any cell types

Cloning experiments with plants

Cloning experiments with animals

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22.2 Pattern Formation in Drosophila

Serves as a Model for the Genetic

Control of Development

The Development of the Fruit Fly

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Egg-polarity genes:

Maternal origin: determination of anterior-

posterior and dorsal-ventral axes of the

embryo

Morphogen: protein; its concentration gradientaffects the developmental fate of the

surrounding region.

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Determination of the dorsal-ventral axis

Dorsal gene

Dorsal gene in nucleus promotes ventral

development

Dorsal gene in cytoplasm promotes dorsal

development

Determination of the anterior-posterior axis

Bicoid gene (ant), nanos gene (pos),

hunchback gene

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Concept Check 1

High concentration of which protein stimulates

the development of anterior structure?

a. dorsalb. toll

c. bicoid

d. nanos

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Concept Check 1

High concentration of which protein stimulates

the development of anterior structure?

a. dorsalb. toll

c. bicoid

d. nanos

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Segmentation genes:control the differentiationof the embryo into individual segments

Gap genes: broad region gap differentiation Hunchback

Pair-rule genes:affect alternate segments

Segment-polarity genes:development ofindividual segments

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Homeotic Genes: identity of segments

Homeobox: genes encoding DNA binding

proteins; these proteins usually play a

regulatory rule.

Hox genes: encode transcription factors thathelp determine the identity of body regions

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Concept Check 2

Mutations in homeotic genes often cause:

a. the deletion of segments

b. the absence of structuresc. too many segments

d. structures to appear in the wrong places

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Concept Check 2

Mutations in homeotic genes often cause:

a. the deletion of segments

b. the absence of structuresc. too many segments

d. structures to appear in the wrong places

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22.4 Programmed Cell Death Is an

Integral Part of Development

Apoptosis

Controlled, programmed cell death with no

leakage of the cellular content to its

neighboring cells

Necrosis

Injured cells dying in an uncontrolled manner

and spilling their contents over neighboringcells

Key enzyme in apoptosis: capases

Cleaver proteins

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22.5 The Study of Development Reveals

Patterns and Processes of Evolution

Evo-Devo

The study of evolution through the analysis of

development

Some genes in distantly related organisms

can shape similar developmental pathways,

but they may exert quite different effects.

Many major evolutionary adaptations arethrough changes in the expression of genes

that encode proteins that regulate

development.

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22.6 The Development of Immunity Is

Through Genetic Rearrangement

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The Organization of the Immune System

Antigen: molecules that elicit an immune

reaction

Antibody:proteins that binds to antigens and

mark them for destruction by phagocytic cells

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Humoral immunity:the production of

antibodies by B cells

Cellular immunity:depends on T cells

Major Histocompatibility Complex antigen

(MHC antigen)

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Theory of clonal selection

Immunoglobulin Structure

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The Generation of Antibody Diversity

Somatic recombination

Recombination among gene segments

within a single chromosome

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Documents

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