This document summarizes plant heredity and genetics. It discusses: - Uniparental reproduction results in offspring that are genetically identical to the parent. Biparental reproduction introduces more genetic variation from two parental gene pools. - Traits are influenced by both inherited genes and the environment. A gene may influence many traits, and one trait can be influenced by multiple genes. - Mendel's laws of inheritance including segregation, independent assortment, and linear order describe how genes are transmitted from one generation to the next. - Non-Mendelian inheritance involves transmission of whole chromosome sets or coordinated gene complexes. Transduction and transformation can also transfer genetic material between bacteria. Mutation introduces inheritable

1. PLANT HEREDITY

2. GENES AND TRAITS
• Pattern of inheritance
• Where a plant is produced by a
single parent, e.g., as in
vegetative reproduction, the
genes of the parent are passed
on unchenged to the offspring.

3. Uniparental reproduction
• Therefore, offspring and parent
are genetically identical, and
they usually display the same
visible traits.
• The only source of genetic
variation is mutation

4. Biparental reproduction
• Two sources of genetic
variation exist in cases of
biparental
• Two sets of genes are pooled in
the zygote
• The offspring may become
unlike the parents

5. Heredity and environment
• Inheriting a certain gene is not
automatically equivalent to
developing a certain trait
• Development of traits is
affected by the environment

6. Gene and environment
• Genes supply a ‘reasonable
promise’
• The total environment of the
genes subsequently permits, or
does nor permit, the translation
of promise into reality

7. Variations
• Inherited variation of traits,
produced by basic genetic
differences
• Acquired variation of traits,
produced by environmental or
developmental effects

8. Traits
• One trait may be controlled by
many genes
• One gene may control many
traits

9. Mendelian inheritance
• Transmission of genes
• Genetic dominace

10. The law of segregation
• Genes do not blend but behave as
independent units.
• They pass intact from one
generation to the next, where they
may or may not produce visible
traits, depending on their dominance
characteristics
• Genes segregate at random, thereby
producing predictable rations of
traits in the offspring.

11. The law of independent
assortment
• The inheritance of a gene pair
located on a given chromosome
pair is unaffected by the
simultaneous inheritance of
other gene pairs located on
other chromosome pairs
• Each trait will be expressed
independently

12. The law of linear order
• Linkage : genes located within the same
chromosome are transmitted together in a
block
• Traits controlled by linked genes are
expressed in a block too
• Crossing over : during meiosis, paired
chromosome in some cases might twist
around each other, might break where
twisted, and broken pieces might fuse
again in the ‘wrong’ order

13. Non-Mendelian Inheritance
• Pre-Mendelian: traits, were inherited
• Mendelian Era: genes, were inherited
• Post Mendelian: chromosome sets,
were inherited, coordinated
complexes of genes, subtly
integrated genetic systems
• Genetic systems are transmitted
within whole cells.

14. Transduction and Transformation
• Transduction : the transfer of genetic
material from one bacteria to another,
through the agency of particular viruses.
E.g. bactheriophage.
• Transformation: a laboratory method to
extract genetic DNA from one strain of
bacteria and to expose another strain of
bacteria to the DNA extract. The second
strain may then absorb some of the DNA
molecules, incorporate them into its own
genetic system, and develop new or
altered traits as a result.

15. Mutation
• Mutation : any stable,
inheritable change in the basic
genetic system with which
every cell is equipped
• Chromosome mutation
• Point mutation
• Somatic mutation