TRAITS OF LIVING THINGS Chapter 9

ESSENTIAL QUESTION: HOW ARE TRAITS INHERITED? Chapter 9 Lesson 1

Main Idea: Living things inherit traits from their parents. Examples: eye color, freckles, face shape They acquire other traits from their environment. Examples: riding a bicycle, reading, swimming

Heredity: process through which traits are passed from parents to offspring. Human traits that are passed by heredity are called _______________. Examples: inherited traits eye color, hair color, face shape, blood type An inherited trait can also be a behavior, such as the way a spider spins a web.

Not all traits are passed through heredity; some are picked up along the way, or acquired. Acquired Trait: Traits that an organism develops after it’s born. Some acquired traits come from the ____________ and some are ____________. Examples: environment learned reading, riding a bicycle, playing baseball

How does an organism inherit certain traits? DNA: molecule found in the nucleus of a cell shaped like a double-helix associated with the transfer of genetic information looks like a “twisted ladder” Your DNA contains your genetic information which determines your inherited traits.

How do I get my parent’s DNA? Molecules of DNA are passed from parent to child during reproduction. A copy of the DNA molecules must be made. This is called DNA replication. New DNA molecules are identical to the original. As a cell gets ready to divide, the strand of DNA wind up tightly and form shorter, thicker strands of DNA called chromosomes.

chromosome: short thick coils of DNA Human cells have 46 chromosomes. Where do these come from? _________ from male and ______ from female 23 gene: short segment of DNA that determines an organism’s inherited traits One chromosome has hundred of genes in it.

Uh oh! Something goes wrong! Mutation

If an error occurs during DNA replication, the change is called a mutation. Error (Mutation)

Mutations can be harmful because it change the organism’s chances for survival Some mutations are neither harmful or helpful. Many mutations are caused by chance. Others are caused by environmental factors called mutagens. For example: UV radiation from the Sun or certain chemical such as pesticides

Some human disease are inherited because they result from mutations. DisorderDescription Cystic Fibrosis makes mucus extra thick and sticky; clogs lungs and digestive track Hemophilia prevents blood from clotting, resulting in uncontrolled bleeding Muscular Dystrophy prevents body from making protein for muscle cells, resulting in muscle weakness Sickle Cell Anemia creates red blood cells shaped like sickles. These sickle cells block other cells and do not carry as much oxygen.

WHY ARE SOME TRAITS VERY COMMON? Chapter 9 Lesson 2

Main Idea Over many generations, species develop traits that help them to survive

How Traits Are Passed Asexual Reproduction Offspring is produced by one parent. exact copy of DNA is passed from parent to offspring Examples: bacteria, many fungi & plants Regeneration is a form of asexual reproduction.

Sexual Reproduction Offspring is produced when a female gamete joins with a male gamete. Half of the offspring’s chromosomes comes from the female and the other half from the male Examples: animals, flowering plants

Which trait will be seen? An offspring inherits traits from both parents through chromosomes. Chromosomes are in pairs – one from mom and one from dad. What shows up? That depends on dominant or recessive genes.

Dominant – stronger form of a trait; shows up in the offspring Recessive – weaker form of a trait; does not show up in the offspring Example: Red color is the dominant color of a flower. A bee carries pollen from a red to a yellow flower. If the offspring, gets a red gene and a yellow gene for flower color, what color will the flower be? RED

Dominant Gene Parent Gene Other Parent Gene Gene That Will Show Up Red Yellow RedYellow Flower Color Red Yellow

Purebred – organism that has two of the same genes for a trait. They may be two dominant genes or two recessive genes. Hybrid – organism that has two different genes for the same trait. Offspring of hybrids may show traits that neither of its parents has. Why might the traits of offspring of hybrids be difficult to predict?

Selective breeding – breeding plants and animals for useful traits; genes in offspring are planned. Example: Cross a rose plant with large, sweet-smelling flowers with a rose plant that does not have sharp thorns. Result? A rose plant with large, sweet-smelling flowers with no thorns

Dairy cows are bred to produce milk. Beef cows are bred to produce beef. Farmers and ranchers also use chemicals to make plants and animals better. Hens can lay more eggs. Cows can produce more milk.

In nature, useful traits are not always traits the people would prefer. They are usually the traits that help an organism survive. Adaptations Adaptation: a trait or characteristic that helps an organism survive in its environment Examples: beak shape spines, stingers, & thorns camouflage mimicry warning colors

Beak Shape pelican – long deep beak that helps a pelican scoop up fish hummingbird – long thin beak that reaches nectar deep inside flowers parrot - short and thick beak, which helps it crack and open seeds.

Camouflage Allows organism to hide in the environment Example: Bees collect honey in areas with shadows. Their black strip looks like shadows.

Mimicry When a organism looks like another organism A king snake is not poisonous but looks like a poisonous coral snake so predators will stay away.

Warning colors Bright colors means an organism is poisonous.

Main Ideas How can two red flowers produce an offspring that is yellow? The flower is a hybrid. Each flower carries the recessive gene of yellow. REDYELLOW RED RRRY YELLOWYRYY Flower 1 Flower 2

What adaptation is his animal demonstrating? Camouflage

Reproductive cells contain only 46 chromosomes. Where do these chromosomes come from? 23 = mom 23 = dad Put these in order smallest to largest: chromosome gene nucleus cell