Transcript Ch 9 ppt - Effingham County Schools

TRAITS OF LIVING
THINGS
Chapter 9
Chapter 9 Lesson 1
ESSENTIAL QUESTION:
HOW ARE TRAITS INHERITED?
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
inherited traits
_______________.
Examples:
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.
environment
Some acquired traits come from the ____________
learned
and some are ____________.
Examples:
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
23
gene: short segment of DNA that determines an
organism’s inherited traits
One
chromosome
has hundred
of genes in it.
http://www.youtube.com/watch?v=V9BZ3zx8b8I&feature=player_detailpage
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.
Disorder
Description
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.
Chapter 9 Lesson 2
WHY ARE SOME TRAITS VERY
COMMON?
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
Flower Color
Dominant
Gene
Parent
Gene
Red
Red
Red
Red
Red
Yellow
Other
Parent
Gene
Red
Yellow
Yellow
Gene That
Will Show
Up
Red
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.
Flower 1
Flower 2
RED
YELLOW
RED
RR
RY
YELLOW
YR
YY
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