Chapter 2 Parents & Offspring Lesson 1: Reproduction Lesson 4: Traits and Heredity

I CAN… Explain sexual and asexual reproduction. Compare and contrast sexual and asexual reproduction.

Where do living things come from? Focus Question: Where do living things come from?

Key Vocabulary Sexual reproduction – the production of a new organism from two parents. Fertilization – the joining of an egg cell and a sperm cell to form a new offspring. Asexual reproduction – the production of a new organism from a single parent.

Key Vocabulary Vegetative Propagation – asexual reproduction in plants that produce new plants from leaves, roots, or stems. Runners – plant stems that lie on or under the ground and sprout up as new plants.

Where do living things come from? Living things come from OTHER LIVING THINGS. The survival of a species depends on its ability to produce new members. Every organism comes from a parent organism through the process of reproduction.

Reproduction Reproduction involves the transfer of genetic material from parent to offspring. The genetic material contains information that controls how the new individual will look and function. There are two main types of reproduction: sexual & asexual

Sexual Reproduction A sperm cell from a male and an egg cell from a female join in a process called fertilization. The fertilized egg cell contains genetic material from both parents. The fertilized egg goes on to develop into a new individual who will have some characteristics, or traits from each parent.

Traits A trait is a characteristics of a living thing. What are some traits that we can name?

Asexual Reproduction Produces a new offspring that has the same genetic information as the parent. No female or male sex cells combine during this process. Since there is only one parent, genetic information is not mixed and the offspring is identical to the original parent.

Asexual Reproduction There are organisms that reproduce asexually in all six kingdoms. All members of the bacteria kingdom and most protists replace asexually. Most fungi and many plants can reproduce like this. Animals such as jellyfish, corals, worms, and some echinoderms as well as some kings of lizards, frogs, fish, and insects can form offspring asexually.

Methods of Asexual Reproduction Splitting – the organism makes a copy of its own genetic material and then splits into two cells. Budding – a small part of the parent’s body grows into a tiny and complete version of the parent and then breaks off and continues to grow.

Other Methods of Asexual Reproduction Sometimes female eggs just develop into a new animal without fertilization. Example: Queen honeybee Vegetative Propagation – produces new plants from leaves, roots, or stems. Runners are plant stems that lie on or under the ground and sprout up as new plants. Example: strawberry plants, grasses, aspen trees, ferns

How do sexual and asexual reproduction compare? Asexual reproduction is convenient because the parent does not have to rely on another organism. Sexual reproduction promotes variety in a species that can better adapt to a changing environment.

I CAN… Describe how traits are passed from one generation to the next. Explain dominant and recessive traits.

How are traits passed from one generation to the next? Focus Question How are traits passed from one generation to the next?

Key Vocabulary Heredity – the passing down of traits from parents to offspring. Inherited trait – a trait that an offspring receives from its parents. Instinct – a way of acting or behaving that an animal is born with and does not have to learn.

Key Vocabulary Gene – contains chemical instructions for inherited traits. Dominant trait – one that dominates, or masks, another form of that trait. Recessive trait – one that is hidden, or masked, by another form of the trait.

Key Vocabulary Pedigree – a chart used to trace the history of traits in a family. Carrier - any individual who has inherited the gene for a trait, but does not show that trait physically.

Heredity What causes us to look the way we look? Heredity applies to all organisms. In plants, flower color and plant height are inherited traits. Inherited trait is a trait that an offspring receives from its parents. Some inherited traits in humans include dimples, hair and eye color, facial features, and even the way you laugh.

Can heredity affect behavior? Some behaviors, such as instincts, are inherited. An instinct is a way of acting or behaving that an animal is born with and does not need to learn. A learned behavior is developed during the course of a lifetime. Learning results from practice and experience. The ability to learn helps animals to survive.

How are traits inherited? What controls the traits you inherit? Why do some people look more like one parent than another? Gregor Mendel answered a lot of these questions. He was an Austrian monk who studied and discovered the basic principles of heredity.

Inheridited Traits After years of experimenting, Mendel determined that inherited traits are passed from parents to offspring through reproduction. He believed that each inherited trait is controlled by two factors – the offspring receive one of these factors from each parent. These are called genes. A gene is a chemical instruction for inherited traits. They are stored on cell structures called chromosomes, which are found in the nucleus of the cell.

Who picks the traits we get? Mendel concluded that for every trait there is a dominant form and a recessive trait. Each form of the trait can be represented by a letter. Capital letters = Dominant traits Lowercase letters = Recessive traits.

Dominant vs. Recessive Mendel’s findings are important because they apply to all organisms. In humans, genes that determine the shapes of your earlobes, hairlines, and thumbs all have dominant and recessive forms. Dominant traits tend to be expressed more frequently than recessive traits.

How do we trace inherited traits? Some of the traits controlled genes are easy to see, like hair color. Genes also control many things you cannot see. Some individuals carry a trait without showing evidence of that trait. You can find out who carries what trait by using a pedigree.

Pedigree A pedigree is a chart used to trace the history of traits in a family and are used to study heredity patterns. Parents and offspring are shown in a pedigree. Horizontal lines connect parents and vertical lines connect parents to offspring. Males are represented as boxes and females are shown as circles. Individuals with a dominate trait are shaded and unshaded shapes represent recessive individuals.