Transcript Unit H – Applied Genetics in Agriculture and Agriscience

Unit H – Applied
Genetics in Agriculture
and Agriscience
Sexual Reproduction Processes
• Fertilization
– Union of haploid cells in both plants and animals
• Occurs in the ovary of plants and the uterus of
animals
• Embyro
– A fertilized egg/ovule that will grow to produce new
offspring
• Ovary
– Organ responsible for the production of
eggs/ovums in plants and animals.
Sexual Reproduction in Animals
• Fertilization
– Occurs internally in most animals – all mammals.
• Some fish and insects are exceptions
• Haploid Cells
– Male cells are spermatozoa (sperm), released in
semen to aid in the process of fertilization
– Female cells are eggs, produced in the ovary,
fertilized and developed within the uterus
• Females release eggs on a cycle (menstrual cycle) that varies
in time length according to species.
Sexual Reproduction in Plants
• Pollination
– The transfer of male pollen to the female
reproductive organs
• Pollination must occur before fertilization
• Removal of the stamen is the first step in
mechanical cross pollination
• Germination
– The initial vegetative growth of a seed
Reproductive Parts of Plants
• Male – THE STAMEN
– Anther – top of the male part of a flower, contains
pollen
– Filament – long slender stock on which the anther
sits
• Female – THE PISTIL
– Stigma – the swollen end of the pistil, sticky to
receive the pollen
– Style – stalk connecting the stigma to the ovary,
pollen on the stigma
– Ovary – produces and stores the ovums (seeds),
and protects seeds during development
– 1 ovum = I seed & 1 ovary = 1 fruit
Reproductive Parts of Plants
Types of Flowers in Plants
• Complete – have all the parts of a flower
(stamen, pistil, sepals, petals)
• Incomplete – missing any part of the flower
• Perfect – have all the reproductive parts of
a flower (stamen and pistil)
• Imperfect – missing any reproductive part of
the flower (stamen, pistil, or any part of
either)
16.03
ASEXUAL REPRODUCTION &
CLONING
Cloning in Agriscience
• Allows rapid production of large numbers of
genetically identical organisms.
– Agriculturalists can quickly disseminate
outstanding traits.
Cloning in Agriscience
• Most often utilized for the culture of plants –
cheaper, easier process, and less political
opposition.
• The ability to differentiate is more in plants
than animals
• Tissue culture
– the production of plants from small amounts of
vegetative material in an invitro environment
– an increasingly popular and effective method of
plant production.
Cloning in Agriscience
• Animals are cloned almost exclusively by
the division of embryos.
• In recent years, diploid cells have been
cloned, but the process is extremely
expensive and results in high losses.
– Dolly the sheep was produced from mammary
gland cells in a sheep
Cloning in Agriscience
• Clones are genetically identical (the exact
same DNA)
– Any genetic differences results from environmental
factors
• Disease, nutrition, physical injuries, etc.
16.04 – Demonstrate proper technique in simple asexual
propagation of plants
ASEXUAL PROPAGATION OF
PLANTS
Stem Cuttings
• Section of the stem or a branch is cut,
treated with rooting hormone, and placed in
soil or water to encourage the development
of roots.
• Should always be taken just above a node
for best rooting
• Most common method
• Used for both woody and herbaceous
plants.
Stem Cuttings
Air Layering
• Section of the stem or branch has the bark
removed or slightly damaged and a rooting
hormone applied.
• Area is then covered with soil wrapped
cellophane until well developed roots can
be seen through the plastic
• Branch or stem is cut below the roots only
after roots have fully developed.
Air Layering
Tissue Culture
• Common method using extremely small
amounts of plant material
– Often uses meristem tips
• The tip of a branch where most active growth is
occurring
• Tissue is removed from the plant, sterilized
and cultured on agar in aseptic conditions
• Meristematic tissue develops shoots, is
transferred to another media to develop
adventitious roots, is hardened off, and
finally transferred to soil.
Division
• Method of plant propagation conducted by
physically separating a plant into several
smaller plantlets
– Often used for grasses and lilies
– A variation is the production of non-tunicate bulbs
from scales
• Each scale must contain a part of the bottom of the
bulb, the basal plate
Division
Grafting
• Process of removing plant material from
one plant for incorporation into another
plant
– Often used with fruit trees to create dwarf varieties
– Two parts
• Scion – top portion of a graft that will form the main
part of the plant
• Rootstock – bottom portion of the graft that usually
controls growth habit (size of the plant) but produces
no vegetation
Grafting
• Budding is related to grafting
– Instead of using a scion, exchange of plant material
is accomplished with a single bud
• Scion and rootstock remain genetically
distinct even after combination
Grafting
Other Methods
• Leaf Cuttings
• Root Cuttings
16.05 – Explain methods of gene insertion used in the creation of
transgenic organisms
TRANSGENIC ORGANISMS
Characteristics
• Can potentially be created using genes
from ANY living organism
– The trick is finding a method for insertion and
successful expression
• Genetically modified organisms (GMOs)
transmit inserted genes at the same rate as
naturally occurring genes
– Once a gene is inserted, it can be passed on
through sexual reproduction
Steps in Creating a GMO
• Develop a Purpose/Goal
– Transmission of genes from one organism to
another is both expensive and potentially
dangerous
– Expectations for work should be laid out carefully
• DNA must be extracted from the target
organism and the specific gene to be
introduced isolated utilizing restriction
enzymes
Steps in Creating a GMO
• Vectors are used from the transmission of
genes
– Viruses make good vectors, as they often insert
DNA into organisms they affect
• Plasmids are the viruses most often used as vectors
• Plasmids can store large strands of DNA or even
one or more chromosomes
– Some vectors can transmit genes simply through
contact with target cells in a liquid solution or by
microinjection.
Steps in Creating a GMO
• Isolated DNA is inserted into the new
organism by:
– Micromanipulation
• Isolated DNA segment is injected into a target cell
utilizing a microscopic syringe under high
magnification
– Most common
– Biolistics
• Uses a gene gun to fire gold plated .22 caliber shells
that have been covered with the target gene into a
mass of plant cells
– Most often used for plants, as cell mortality is
high
Micromanipulation
Biolistics