Chapter 4:Chapter 4:Animal Growth Animal Growth

and Heredityand HeredityLesson 1: How Does Cell Division Affect Lesson 1: How Does Cell Division Affect Growth?Growth?Lesson 2: How are Characteristics Lesson 2: How are Characteristics Inherited?Inherited?Lesson 3: What Other Factors Affect Lesson 3: What Other Factors Affect Characteristics?Characteristics?

Lesson One:Lesson One:

VOCABULARY:VOCABULARY:

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

MitosisMitosis: The process by which most cells : The process by which most cells divide.divide.

ChromosomeChromosome: A threadlike structure in the : A threadlike structure in the nucleus, made up of DNA.nucleus, made up of DNA.

Lesson One: How Does Cell Lesson One: How Does Cell Division Affect Growth?Division Affect Growth?

Growth and DevelopmentGrowth and Development

All living things begin life as a single cell.All living things begin life as a single cell. In plants and animals, the cells start dividing.In plants and animals, the cells start dividing. The fully formed plant or animals is made up The fully formed plant or animals is made up

of trillions of cells.of trillions of cells. Even in adult organisms, cells continue to Even in adult organisms, cells continue to

divide and replace the worn out cells.divide and replace the worn out cells. The new cells have the same function as the The new cells have the same function as the

old cells.old cells.

Lesson One: How Does Cell Lesson One: How Does Cell Division Affect Growth?Division Affect Growth?

Growth and DevelopmentGrowth and Development

As living things grow, they As living things grow, they must pass through several must pass through several stages which make up the stages which make up the life life cyclecycle..

Some animals change a great Some animals change a great deal as they grow into adults.deal as they grow into adults.

Butterflies and other insects Butterflies and other insects have one kind of body while have one kind of body while young and another type of body young and another type of body when they become an adult.when they become an adult.

The stages they go through as The stages they go through as they grow are called they grow are called metamorphosis.metamorphosis.

Other animals do not change Other animals do not change as much during their life cycle as much during their life cycle and look pretty much the same and look pretty much the same when they are young as when when they are young as when they are old except bigger.they are old except bigger.

Lesson One: How Does Cell Lesson One: How Does Cell Division Affect Growth?Division Affect Growth?

CELL DIVISIONCELL DIVISION

The process by which The process by which most cells divide is called most cells divide is called mitosismitosis..

Mitosis is controlled by Mitosis is controlled by the cells nucleus.the cells nucleus.

The nucleus contains The nucleus contains threadlike structures threadlike structures called called chromosomeschromosomes..

Chromosomes are made Chromosomes are made up of chemical DNA.up of chemical DNA.

DNA has the information DNA has the information needed to direct a cells needed to direct a cells function and tell the cell function and tell the cell when to divide.when to divide.

Lesson One: How Does Cell Lesson One: How Does Cell Division Affect Growth?Division Affect Growth?

In mitosis, each new cell In mitosis, each new cell gets a copy of the parent’s gets a copy of the parent’s chromosomes. chromosomes.

This passes along the DNA This passes along the DNA which is why the cells look which is why the cells look and function just like the and function just like the parent cells.parent cells.

New cells replace damaged New cells replace damaged tissue which is called tissue which is called regenerationregeneration..

In humans, regeneration In humans, regeneration happens mostly for healing happens mostly for healing wounds.wounds.

However, some animals However, some animals can regenerate an entire can regenerate an entire body part (like a starfish).body part (like a starfish).

Lesson One: How Does Cell Lesson One: How Does Cell Division Affect Growth?Division Affect Growth?

Sexual and Asexual Sexual and Asexual Reproduction:Reproduction:

Sexual reproduction happens Sexual reproduction happens when two cells from two different when two cells from two different individuals join and form a individuals join and form a zygote. zygote.

Organisms that reproduce Organisms that reproduce sexually have 2 types of cells: sexually have 2 types of cells: Body cells and reproductive cells Body cells and reproductive cells (or (or gametes)gametes)..

Gametes contain only half the Gametes contain only half the number of chromosomes (23 number of chromosomes (23 chromosomes) as body cells. chromosomes) as body cells.

Once two gametes join, they have Once two gametes join, they have the same number of chromosomes the same number of chromosomes as a body cell (46 chromosomes) as a body cell (46 chromosomes) has.has.

Lesson One: How Does Cell Lesson One: How Does Cell Division Affect Growth?Division Affect Growth?

Some organisms have only one cell.Some organisms have only one cell. When the cell divides, the whole When the cell divides, the whole

organism reproduces.organism reproduces. In asexual reproduction there is no In asexual reproduction there is no

joining of cells from different joining of cells from different parents.parents.

Lesson Two: How Are Lesson Two: How Are Characteristics Inherited?Characteristics Inherited?VOCABULARYVOCABULARY

Inherited traitInherited trait: A characteristic passed from : A characteristic passed from parents to their offspring.parents to their offspring.

Recessive traitRecessive trait: A trait that appears only if an : A trait that appears only if an organism has two factors, or genes, for that organism has two factors, or genes, for that trait.trait.

Dominant traitDominant trait: A trait that appears even if : A trait that appears even if an organism has only one factor, or gene, for an organism has only one factor, or gene, for that trait.that trait.

GeneGene: Part of the chromosome. It contains the : Part of the chromosome. It contains the DNA code for an inherited trait.DNA code for an inherited trait.

Lesson Two: How Are Lesson Two: How Are Characteristics Inherited?Characteristics Inherited?

How Characteristics are InheritedHow Characteristics are Inherited

Inherited traits are Inherited traits are characteristics passed from characteristics passed from parents to their offspring.parents to their offspring.

The way traits are passed from The way traits are passed from parents to offspring interested parents to offspring interested Gregor Mendel who studied Gregor Mendel who studied this.this.

Mendel found that a trait is Mendel found that a trait is controlled by a pair of factors controlled by a pair of factors (one from each parent).(one from each parent).

Mendel also learned that Mendel also learned that factors can skip a generation.factors can skip a generation.

Inheritance in all organisms Inheritance in all organisms (including people) works this (including people) works this way.way.

Lesson Two: How Are Lesson Two: How Are Characteristics Inherited?Characteristics Inherited?

Dominant and Dominant and Recessive TraitsRecessive Traits

Mendel did hundreds of crosses of Mendel did hundreds of crosses of pea plants and found that first pea plants and found that first generation plants were always tall.generation plants were always tall.

Mendel believed the first Mendel believed the first generation plants had a hidden generation plants had a hidden factor for shortness. factor for shortness.

In pea plants, tallness is a strong In pea plants, tallness is a strong or or dominant trait.dominant trait.

Even if an organism has only one Even if an organism has only one factor for a dominant trait, that factor for a dominant trait, that trait will appear.trait will appear.

Shortness in a plant is a weak or Shortness in a plant is a weak or recessive traitrecessive trait..

A recessive trait appears only if an A recessive trait appears only if an organism has two factors for that organism has two factors for that trait.trait.

If both a dominant factor and If both a dominant factor and recessive factor are present, the recessive factor are present, the dominant trait always appears.dominant trait always appears.

Lesson Two: How Are Lesson Two: How Are Characteristics Inherited?Characteristics Inherited?

AdaptationsAdaptations Arctic foxes live in very Arctic foxes live in very

cold places. An arctic fox cold places. An arctic fox has adaptations that keep has adaptations that keep it warm in the winter.it warm in the winter.

Adaptations helps a living Adaptations helps a living organism meet their organism meet their basic needs in order to basic needs in order to survive, find a mate, find survive, find a mate, find shelter, hunt or hide.shelter, hunt or hide.

Adaptations are passed Adaptations are passed from parent to offspring from parent to offspring and are inherited traits.and are inherited traits.

Lesson Two: How Are Lesson Two: How Are Characteristics Inherited?Characteristics Inherited?AdaptationsAdaptations

There are 3 There are 3 types of types of adaptations:adaptations:

The The first kindfirst kind is is physicalphysical. .

ExampleExample: An arctic fox has : An arctic fox has white fur in winter which white fur in winter which helps it hide and more helps it hide and more easily sneak up on prey.easily sneak up on prey.

The The second kindsecond kind of of adaptation is adaptation is behavioralbehavioral..

Example: Snakes only move Example: Snakes only move around before sunset or after around before sunset or after sundown. During the hottest sundown. During the hottest part of the day they will hide part of the day they will hide under a rock to stay cool.under a rock to stay cool.

The The third kindthird kind of of adaptation is a adaptation is a life life processprocess..

Example: A human’s body Example: A human’s body produces sweat. This helps produces sweat. This helps keep the body from getting keep the body from getting too hot.too hot.

Lesson Two: How Are Lesson Two: How Are Characteristics Inherited?Characteristics Inherited?Survival and ReproductionSurvival and Reproduction::

All animals have adaptations for survival. All animals have adaptations for survival. For example: porcupines have an For example: porcupines have an

adaptation that protects them from adaptation that protects them from predators.predators.

Adaptations help animals survive so that Adaptations help animals survive so that they can reproduce. they can reproduce.

If a species cannot successfully reproduce, If a species cannot successfully reproduce, it may become extinct.it may become extinct.

Extinction is the death of all organisms Extinction is the death of all organisms of a species.of a species.

Lesson Two: How Are Lesson Two: How Are Characteristics Inherited?Characteristics Inherited?

Genes:Genes: Today, Mendel’s “factors” are called Today, Mendel’s “factors” are called

“genes”.“genes”. A A genegene is part of a chromosome. is part of a chromosome. Genes contain the DNA code Genes contain the DNA code

(information) for inherited traits.(information) for inherited traits.

Lesson Three: Other Lesson Three: Other Factors Factors

that Affect Characteristicsthat Affect CharacteristicsVOCABULARYVOCABULARY::

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

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

EnvironmentEnvironment: all of the things in an : all of the things in an organism’s surroundings that affect it.organism’s surroundings that affect it.

Lesson Three: Other Lesson Three: Other Factors Factors

that Affect Characteristicsthat Affect CharacteristicsInstincts:Instincts:

A bird making a nest and a A bird making a nest and a cat grooming itself are cat grooming itself are examples of instincts.examples of instincts.

An An instinctinstinct is a natural is a natural behavior.behavior.

Most instincts help an Most instincts help an animal survive in its animal survive in its surroundings.surroundings.

Since instincts are Since instincts are inherited, they are passed inherited, they are passed from parents to offspring.from parents to offspring.

Instincts are not just Instincts are not just behaviors of one animal.behaviors of one animal.

Instincts are shared by all Instincts are shared by all members of a species.members of a species.

Lesson Three: Other Lesson Three: Other Factors Factors

that Affect Characteristicsthat Affect CharacteristicsLearned Learned Behaviors:Behaviors:

Most cats are born with an Most cats are born with an instinct to hunt.instinct to hunt.

But they need to learn hunting But they need to learn hunting skills from adult cats.skills from adult cats.

Knowing how to hunt is a Knowing how to hunt is a learned behavior.learned behavior.

A learned behavior is a A learned behavior is a behavior that an animal behavior that an animal obtains by doing something.obtains by doing something.

Not all learned behaviors are Not all learned behaviors are for survival. for survival. (tricks)(tricks)

Some animals can learn Some animals can learn behaviors that are helpful to behaviors that are helpful to people.people.

Lesson Three: Other Lesson Three: Other Factors Factors

that Affect Characteristicsthat Affect CharacteristicsEnvironmental Influences:Environmental Influences:

Some behaviors are neither instinctual or learned.Some behaviors are neither instinctual or learned. They are a result of They are a result of environmental influencesenvironmental influences.. An organism’s environment is everything in its An organism’s environment is everything in its

surroundings that affect it.surroundings that affect it. This may include water, food, air, landforms, and other This may include water, food, air, landforms, and other

living things.living things. When an environment changes, all things that live there When an environment changes, all things that live there

are affected.are affected. Often times animals must move in order to survive.Often times animals must move in order to survive. Human activities can sometimes change an Human activities can sometimes change an

environment.environment. Sometimes the environment causes a Sometimes the environment causes a

physical change in living things physical change in living things (pollution or poison can damage the DNA of living things.)(pollution or poison can damage the DNA of living things.)