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Heredity and Reproduction

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Title: Heredity and Reproduction


1
Chapter 3
  • Heredity and Reproduction

2
Heredity and Reproduction
  • A plant or animal is only as developed as its
    genetic components.
  • An animal or plant receives its characteristics
    from its parents.
  • Scientists are continously searching for improved
    crop and animal varieties through Selective
    Breeding.

Read pages 43-45
3
Heredity and Reproductionpage 43
  • The first major breakthrough in plant breeding
    occurred in the 1930s with the development of
    hybrid seed.
  • Hybrid seed produce 25 to 50 greater yields
    than traditional corn varities.
  • Why would hybrids produce more seed?
  • What is drawback to hybrids and how do
    researchers control this?

4
Heredity and Reproductionpage 43
  • Plant breeders use knowledge of genetics and
    heredity to design plant breeding programs.
  • A combination of traditional and molecular
    techniques are used.
  • Scientists believe that there are about 50
    controllable traits in plants that can be
    produced through plant breeding.

5
Heredity and Reproductionpage 45
  • Controllable traits include
  • Palatability
  • Heat and drought tolerance
  • Shape and color
  • Oil
  • Starch, sugar, protein
  • Fiber content, height, salt tolerance, flavor
  • Texture, and time to maturity

6
Chapter 3 Objectivespage 45
  • 1. How is inheritance of traits in plants
    regulated?
  • 2. How do dominant and recessive genes affect
    plant characteristics?
  • 3. How does pollination in plants occur?
  • 4. Why are some plants unable to self pollinate?
  • 5. How do scientists use principles of plant
    genetics to guide their plant breeding programs?
  • 6. How is biotechnolgy being used to supplement
    traditional plant breeding programs?

7
Answer these questions
  • 1. What is selective breeding?
  • 2. Identify five controllable traits that
    scientists can control.
  • 3. Which types of combinations are used in
    plant breeding.
  • 4. What percent does hybridization increase
    yield by.
  • 5. When and what was the first major
    breakthrough in plant breeding?

8
Flowering and Pollination
  • Two major plant classifications are the
    Gymnosperms and the Angiosperms.
  • These include flowering plants, grasses, and
    cereals.

9
Flowering and Pollination
  • All angiosperms develop flowers which contain one
    or more ovules that are enclosed in an ovary or
    carpel.
  • The flower is the reproductive structure for the
    angiosperms.

10
Flowering and Pollination
  • A flower is complete if it has all four of the
    the following structures
  • Sepals, Petals, Stamens, and a Carpel (pistil)

11
Flowering and Pollination
  • An incomplete flower lacks one or more of the
    before mentioned structures.

12
Flowering and Pollination
  • A flower that has both stamens (male reproductive
    tissues) and a carpel (female reproductive
    tissues) is a perfect flower.
  • Imperfect flowers have either stamens or a
    carpel, but not both.

13
Answer These Questions
  • 1. Identify the two major classifications of
    plants.
  • 2. The flower is the ____________ of the
    angiosperms.
  • 3. A complete flower has four structures,
    identify them.
  • 4. A flower which has both male and female is
    tissues is which type of flower?
  • 5. If a flower has either stamen or a carpel,
    which type of flower is this?

14
Flowering and Pollination
  • The sepals and petals help to attract insects to
    the plant by producing a sugary solution called
    nectar.

15
Flowering and Pollination
  • An incomplete flower is one which has no sepals
    or petals.
  • Most cereal and grass plants have incomplete
    flowers, which makes the flowers less visible.

16
Flowering and Pollination
  • Flowering is initiated by
  • Length of uninterrupted darkness (photoperiodism)
  • Exposure to low temperatures (vernalization)
  • Morphological maturity (able to produce seed)

17
Flowering and Pollination
  • The majority of food-producing plants induce
    flowering without external stimulation.
  • As long as they are actively growing, they
    initiate flowers at almost any temperature or day
    length.

18
Flowering and Pollination
  • The Stamen, consists of the Anthers and their
    supporting their supporting filament.
  • The development of pollen grains (microspores)
    occurs in the Anthers.

19
Flowering and Pollination
  • As the Anther matures, they break open and pollen
    grains are spread by the wind and insects.

20
Flowering and Pollination
  • The Carpel, includes the Stigma, Style, and
    Ovary.
  • The Stigma is the swollen end of the Style, is
    colorful and allows for the pollen to stick.
  • Pollen grain must land on the Stigma in order for
    pollination to occur.

21
Answer these questions
  • 1. What does the Carpel include?
  • 2. Where does the development of the pollen
    grain occur.
  • 3. What is the photoperiodism?
  • 4. What is meant by morphological maturity?
  • 5. A flower which has no sepals or petals is
    which type of flower.

22
Flowering and Pollination
  • Self-pollination occurs when the anther and the
    stigma are from the same flower.
  • From different flowers on the same plant.
  • From different plants of the same cultivar or
    variety.
  • Cross-pollination involves different flowers on
    plants or different cultivars.

23
Flowering and Pollination
  • Some plants are self-fertile and produce fruit
    and seed without the transfer of pollen form
    another cultivar.
  • Most monocot plants.

24
Flowering and Pollination
  • A plant is considered self-sterile if it requires
    pollen from another plant in order to set fruit.
  • Sterility is due to the protien composition of
    the cell of wall of pollen grains.
  • The protein sends a signal to the stigma
    indicating whether the pollen is from its own
    species or the same plant.

25
Flowering and Pollination
  • Each pollen grain contains a tube cell and a
    generative cell.
  • When the pollen lands on the stigma, germination
    occurs.

26
Flowering and Pollination
  • The tube cell forms a pollen tube that grows
    through the stigma and style.
  • The pollen tube enters the nucleus of the ovule
    by passing through the Micropyle

27
Flowering and Pollination
  • The generative cell has produced two male gametes
    through the process of Mitosis.

28
Flowering and Pollination
  • One gamete unites with the egg cell to form the
    Zygote, which form the embryo.
  • The other male gamete unites with the polar
    nucleus in the ovule to form the endosperm.
  • The endosperm the seeds food reserve for
    germination.

29
Flowering and Pollination
  • The time between pollination and fertilization in
    most angiosperms is 24 to 48 hours.
  • Once fertilization has occurred, the ovule
    becomes the seed and the ovary becomes the fruit.

30
Answer These Questions
  • 1. What is the time between pollination and
    fertilization.
  • 2. How many male gametes are produced through
    mitosis?
  • 3. What is the function of the gametes?
  • 4. Pollen enters the nucleus by passing through
    what opening?
  • 5. What causes sterility.

31
Genetics and Heredity page 54
  • The nucleus of a living cell contains
    Chromosomes.
  • Chromosomes contain information about the genetic
    makeup of the plant.
  • They transmit the information to offspring.

32
Genetics and Heredity page 54
  • Each plant species has the same number of
    chromosomes in all vegetative cells.
  • Sex cells have half the number of chromosomes as
    vegetative cells.

33
Genetics and Heredity page 54
  • Chromosomes are long, thread-like structures
    consisting of DNA (deoxyriboneucleic acid), RNA
    (ribonucleic acid), and consisting of proteins.

34
Genetics and Heredity page 54
  • Genes organic bases located along DNA molecules.
  • The gene is the heredity unit of a plant.

35
Answer these questions
  • 1. Why do vegetative and reproductive cells have
    varying numbers of chromosomes?
  • 2. Which type of material do chromosomes
    contain?
  • 3. What does DNA stand for?
  • 4. What does RNA stand for?
  • 5. What is a gene?

36
Genetics and Heredity page 55
  • Chromosomes are usually found in pairs in each
    vegetative cell.
  • These are called Homologous Chromosomes.
  • They have the same genes affecting the same
    traits and are located at the same position along
    the chromosomes.

37
Genetics and Heredity page 55
  • Matching genes on Homologous Chromosomes are
    called Alleles.
  • Gene alleles always occur on the same Locus
    (location) along the pair of chromosomes.
  • Allelic genes can be dominant or recessive.

38
Genetics and Heredity page 55
  • A dominant gene causes a certain characteristic
    to be expressed.
  • A recessive gene causes the character to be
    expressed only if the alleles from both parents
    are recessive.
  • Dominant genes are represented by capital
    letters.
  • Recessive genes are represented by small letters.

39
Genetics and Heredity page 56
  • Meiosis controls the formation of egg and sperm
    cells.
  • As gametes are formed, the two alleles for a
    particular trait separate (segregate).
  • They segregate randomly so that each gamete
    receives one allele or the other.

40
Genetics and Heredity page 56
  • The allele composition of a plant is the
    Genotype.

41
Genetics and Heredity page 56
  • A common method of predicting the genotypes and
    phenotypes of offspring is the Punnett Square.

42
Answer these questions
  • 1. A common method for determining phenotypes
    and genotypes is the?
  • 2. The allele composition of a plant is known as
    the?
  • 3. What is a homologous chromosome?
  • 4. Meiosis controls formation of which two sex
    cells?
  • 5. Allelic chromosomes can be of two types,
    identify them.

43
Plant Breeding page 57
  • Read pages 57-60
  • Plant Breeding the process of selectively
    mating plants.
  • A basic type of plant breeding is Selection.
  • Selection is when two plants with desirable
    traits are chosen from a population and then
    reproduced.

44
Plant Breeding page 58
  • Hybridization the crossing of two plants that
    have different genotypes.
  • Crossbreeding usually produces a plant that is
    more vigorous in growth that either of its two
    parents.
  • Hybrids do not pass many of their traits to their
    offspring, so parent stocks must be crossed each
    year to produce new seed.

45
Plant Breeding page 58
  • The production of hybrid seed is managed by
    production organizations.
  • Growers are under contract to grow the parent
    lines and make the hybrids.
  • Seed production fields must be isolated from
    other fields to prevent unwanted
    cross-pollination.

46
Plant Breeding page 58
  • When tassels begin to emerge, the female plants
    are detassled to prevent selt-pollination.
  • The wind then cross-pollinates the male parent
    with the female to produce hybrid seed.

47
Plant Breeding page 59
  • Inbreeding the process of crossing two similar
    parents.
  • After inbreeding five to seven generations,
    certain phenotypes will be expressed.

Single Cross Inbred parent A x Inbred Parent
B Single cross AxB
Three Way Cross Inbred parent A x Inbred Parent
B Single Cross AxB x Unrelated Inbred C Three-way
cross (AxB) x C
48
Plant Breeding page 59
  • Backcrossing offspring are continously crossed
    with one of the parents.

49
Biotechnology Techniques
  • Biotechnology the management of biological
    systems for the benefit of humanity.
  • Biotech uses molecular biology and molecular
    genetics for developing plant breeding methods.
  • These include tissue culture, protoplast fusion,
    embryo manipulation, recombinant DNA.

50
Biotechnology Techniques
  • Micropropagation the propagation (asexual) of
    plant cells or tissues in a closed container.
  • Cell culture modifying the genetic makeup of the
    cell and then regenerating plants with desired
    traits.

51
Biotechnology Techniques
  • Microinjection the mechanical insertion of
    genetic material into a single, living cell.
  • Cell walls can be dissolved using enzymes.
  • This exposes the cells protoplast.
  • This allows the genetic makeup of different
    plants to be fused together.

52
Biotechnology Techniques
  • Recombinant DNA or genetic engineering involve
  • 1. Gene splicing
  • 2. Replication
  • 3. Transfer of genes to other organisms
  • Transgenic organisms would carry in their cells a
    foreign gene.

53
Biotechnology Techniques
  • 1. Starts with cutting gene with an enzyme.
  • 2. The sliced gene is then removed and inserted
    into a circular DNA molecules called plasmids
    found in bacteria.

54
Biotechnology Techniques
  • 3. An enzyme is used to seal the spliced ends.
  • 4. The DNA plasmid is inserted into a cell
    selected for alteration.
  • 5. The result is a new sequence of DNA.

55
Answer these Questions
  • 1. What three items does genetic engineering
    include?
  • 2. What is micro-injection?
  • 3. What is cell culture?
  • 4. What is biotechnology?
  • 5. Describe the process of gene splicing?
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