Chapter 4: Animal Growth and Heredity

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					          Chapter 4:
        Animal Growth
         and Heredity
Lesson 1: How Does Cell Division Affect Growth?
Lesson 2: How are Characteristics Inherited?
Lesson 3: What Other Factors Affect Characteristics?
                    Lesson One:
    VOCABULARY:

   Life Cycle: The stages that a living thing passes through
    as it grows and changes.

   Mitosis: The process by which most cells divide.

   Chromosome: A threadlike structure in the nucleus,
    made up of DNA.
        Lesson One: How Does Cell
          Division Affect Growth?

Growth and Development

   All living things begin life as a single cell.
   In plants and animals, the cells start dividing.
   The fully formed plant or animals is made up of
    trillions of cells.
   Even in adult organisms, cells continue to divide and
    replace the worn out cells.
   The new cells have the same function as the old cells.
          Lesson One: How Does Cell
            Division Affect Growth?
        Growth and Development

   As living things grow, they must pass
    through several stages which make
    up the life cycle.
   Some animals change a great deal as
    they grow into adults.
   Butterflies and other insects have one
    kind of body while young and
    another type of body when they
    become an adult.
   The stages they go through as they
    grow are called metamorphosis.
   Other animals do not change as
    much during their life cycle and look
    pretty much the same when they are
    young as when they are old except
    bigger.
          Lesson One: How Does Cell
            Division Affect Growth?
          CELL DIVISION

   The process by which most cells
    divide is called mitosis.
   Mitosis is controlled by the cells
    nucleus.
   The nucleus contains threadlike
    structures called
    chromosomes.
   Chromosomes are made up of
    chemical DNA.
   DNA has the information
    needed to direct a cells function
    and tell the cell when to divide.
Lesson One: How Does Cell
  Division Affect Growth?
                In mitosis, each new cell gets a
                 copy of the parent’s
                 chromosomes.
                This passes along the DNA
                 which is why the cells look and
                 function just like the parent
                 cells.
                New cells replace damaged
                 tissue which is called regeneration.
                In humans, regeneration
                 happens mostly for healing
                 wounds.
                However, some animals can
                 regenerate an entire body part
                 (like a starfish).
          Lesson One: How Does Cell
            Division Affect Growth?
       Sexual and Asexual
         Reproduction:
   Sexual reproduction happens when
    two cells from two different
    individuals join and form a zygote.
   Organisms that reproduce sexually
    have 2 types of cells: Body cells
    and reproductive cells (or gametes).
   Gametes contain only half the
    number of chromosomes (23
    chromosomes) as body cells.
   Once two gametes join, they have
    the same number of chromosomes
    as a body cell (46 chromosomes)
    has.
        Lesson One: How Does Cell
          Division Affect Growth?
   Some organisms have only one cell.
   When the cell divides, the whole organism
    reproduces.
   In asexual reproduction there is no joining of
    cells from different parents.
           Lesson Two: How Are
          Characteristics Inherited?
    VOCABULARY
   Inherited trait: A characteristic passed from parents to
    their offspring.
   Recessive trait: A trait that appears only if an organism
    has two factors, or genes, for that trait.
   Dominant trait: A trait that appears even if an organism
    has only one factor, or gene, for that trait.
   Gene: Part of the chromosome. It contains the DNA
    code for an inherited trait.
              Lesson Two: How Are
             Characteristics Inherited?
    How Characteristics are Inherited

   Inherited traits are characteristics
    passed from parents to their
    offspring.
   The way traits are passed from
    parents to offspring interested
    Gregor Mendel who studied this.
   Mendel found that a trait is
    controlled by a pair of factors (one
    from each parent).
   Mendel also learned that factors
    can skip a generation.
   Inheritance in all organisms
    (including people) works this way.
                Lesson Two: How Are
               Characteristics Inherited?
               Dominant and
              Recessive Traits
   Mendel did hundreds of crosses of pea
    plants and found that first generation
    plants were always tall.
   Mendel believed the first generation
    plants had a hidden factor for shortness.
   In pea plants, tallness is a strong or
    dominant trait.
   Even if an organism has only one factor
    for a dominant trait, that trait will appear.
   Shortness in a plant is a weak or
    recessive trait.
   A recessive trait appears only if an
    organism has two factors for that trait.
   If both a dominant factor and recessive
    factor are present, the dominant trait
    always appears.
             Lesson Two: How Are
            Characteristics Inherited?
         Adaptations
   Arctic foxes live in very cold
    places. An arctic fox has
    adaptations that keep it warm
    in the winter.
   Adaptations helps a living
    organism meet their basic
    needs in order to survive,
    find a mate, find shelter, hunt
    or hide.
   Adaptations are passed from
    parent to offspring and are
    inherited traits.
              Lesson Two: How Are
             Characteristics Inherited?
    Adaptations                            The second kind of
                                            adaptation is behavioral.
 There are 3 types                        Example: Snakes only move
                                            around before sunset or after
  of adaptations:                           sundown. During the hottest part
                                            of the day they will hide under a
   The first kind is physical.             rock to stay cool.
   Example: An arctic fox has white
    fur in winter which helps it hide
    and more easily sneak up on prey.      The third kind of adaptation
                                            is a life process.
                                           Example: A human’s body
                                            produces sweat. This helps keep
                                            the body from getting too hot.
           Lesson Two: How Are
          Characteristics Inherited?
    Survival and Reproduction:
   All animals have adaptations for survival.
   For example: porcupines have an adaptation that
    protects them from predators.
   Adaptations help animals survive so that they can
    reproduce.
   If a species cannot successfully reproduce, it may
    become extinct.
   Extinction is the death of all organisms
    of a species.
          Lesson Two: How Are
         Characteristics Inherited?
    Genes:
   Today, Mendel’s “factors” are called “genes”.
   A gene is part of a chromosome.
   Genes contain the DNA code (information) for
    inherited traits.
       Lesson Three: Other Factors
        that Affect Characteristics
    VOCABULARY:

   Instinct: is a behavior (way of acting) that an organism
    inherits.

   Learned behavior: a behavior that an animal acquires
    through experience.

   Environment: all of the things in an organism’s
    surroundings that affect it.
         Lesson Three: Other Factors
          that Affect Characteristics
    Instincts:
   A bird making a nest and a cat
    grooming itself are examples of
    instincts.
   An instinct is a natural behavior.
   Most instincts help an animal
    survive in its surroundings.
   Since instincts are inherited, they
    are passed from parents to
    offspring.
   Instincts are not just behaviors of
    one animal.
   Instincts are shared by all members
    of a species.
Lesson Three: Other Factors
 that Affect Characteristics
                  Learned Behaviors:
                 Most cats are born with an instinct
                  to hunt.
                 But they need to learn hunting
                  skills from adult cats.
                 Knowing how to hunt is a learned
                  behavior.
                 A learned behavior is a behavior
                  that an animal obtains by doing
                  something.
                 Not all learned behaviors are for
                  survival. (tricks)
                 Some animals can learn behaviors
                  that are helpful to people.
         Lesson Three: Other Factors
          that Affect Characteristics
    Environmental Influences:
   Some behaviors are neither instinctual or learned.
   They are a result of environmental influences.
   An organism’s environment is everything in its surroundings that
    affect it.
   This may include water, food, air, landforms, and other living
    things.
   When an environment changes, all things that live there are
    affected.
   Often times animals must move in order to survive.
   Human activities can sometimes change an environment.
   Sometimes the environment causes a
    physical change in living things
    (pollution or poison can damage the DNA of living things.)

				
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posted:9/29/2012
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