Download Section 2 The Necessities of Life

Study of Life
It’s Alive!! Or Is It?
Table of Contents
Section 1 Characteristics of Living Things
Section 2 The Necessities of Life
Section 1 Characteristics of Living Things
Objectives
• Describe the seven characteristics of of living things.
• Describe how organisms maintain stable internal
conditions.
• Explain how asexual reproduction differs from sexual
reproduction.
Section 1 Characteristics of Living Things
1.) Living Things Have Cells
• All living things are composed of one or
more cells.
• A cell is a membrane-covered structure
that contains all of the materials
necessary for life.
• Some organisms are made up of only
one cell and some are made up of trillions
of cells. In an organism with many cells,
different kinds of cells perform specialized
functions.
Section 1 Characteristics of Living Things
2.) Living Things Sense and Respond to Change
• A stimulus is anything that causes a reaction
or change in an organism or any part of an
organism.
• Homeostasis is the maintenance of a stable
internal environment.
• Responding to External Change
Organisms must respond to change in the
external environment in order to maintain their
homeostasis.
Section 1 Characteristics of Living Things
How do animals maintain Homeostasis?
• By moving from one environment
to another
• If they get too warm they move to the shade
or enter the water, if too hot, they move to
the sun
• Regulating internal conditions
• If we are too hot, we sweat. If we are too
cold we shiver
Section 1 Characteristics of Living Things
3.) Living Things Reproduce
• Organisms make other organisms
similar to themselves.
• In sexual reproduction, two parents
produce offspring that will share
characteristics of both parents.
• In asexual reproduction, a single
parent produces offspring that are
identical to the parent.
Section 1 Characteristics of Living Things
4.) Living Things Have DNA
• The cells of all living things contain the
molecule deoxyribonucleic acid, or DNA.
•DNA controls the structure and function of
cells.
•The passing of traits through DNA is called
heredity.
Section 1 Characteristics of Living Things
5.) Living Things Use Energy
• Organisms use energy to
carry out the activities of
life.
• An organism’s
metabolism is the total of
all of the chemical activities
that the organism performs.
Section 1 Characteristics of Living Things
6.) Living Things Grow and Develop
• All living things, whether they are made of one cell or
many cells, grow during periods of their lives.
• Living things may develop and change as they grow.
Section 1 Characteristics of Living Things
7.) Living Things Adapt
Adaptation - an inherited behavior or
characteristic that enables an organism to
survive & reproduce.
Leads to evolution: change in a population
over time
Section 2 The Necessities of Life
Objectives
• Explain why organisms need food, water, air, and
living space.
• Describe the chemical building blocks of cells.
Section 2 The Necessities of Life
Water
• Your cells and the cells of almost all
living organisms are approximately
70% water. Most of the chemical
reactions involved in metabolism
require water.
Air
• Air is a mixture of several different
gases, including oxygen and carbon
dioxide. Most living things use oxygen in
the chemical process that releases
energy from food.
Section 2 The Necessities of Life
A Place to Live
• All organisms need a place to live
that contains all of the things they
need to survive. Space on Earth is
limited, so organisms are often in
competition with each other.
Food
• All living things need food. Food
gives organism energy and the raw
material needed to carry on life
processes.
Section 2 The Necessities of Life
Food, continued
• Making Food Some organisms, such as
plants, are called producers. Producers can
make their own food by using energy from
their surroundings.
• Taking Food Other organisms are called
consumers because they must eat (consume)
other organisms to get food. Decomposers
are consumers that get their food by breaking
down the nutrients in dead organisms or
animal wastes.
Section 2 The Necessities of Life
Putting It All Together
• All organisms need to break down that food in order
to use the nutrients in it.
• Nutrients are made up of molecules.
• Molecules found in living things are usually made up
of six elements: carbon, hydrogen, nitrogen, oxygen,
phosphorus, and sulfur. CHONPS!
Elements in your body!
Macromolecules of Life
• Smaller organic molecules join together to form
larger molecules
– Macromolecules
– Biomolecules, Macromolecules, Organic molecules,
Organic compounds, Organic molecules, and
Molecules of life…They all mean the same thing!
• 4 major classes of macromolecules:
–
–
–
–
carbohydrates
lipids
proteins
nucleic acids
Macromolecules as Polymers
• Polymers: Long molecules built by linking
repeating building blocks in a chain
– monomers
• building blocks
• repeated small units
H2O
HO
H
HO
H
Dehydration synthesis
HO
H
Section 2 The Necessities of Life
Proteins
• Proteins are large molecules made up of
amino acids.
•Making Proteins Organisms break down the
proteins in food to supply their cells with amino
acids that are then linked together to form new
proteins.
• Proteins in Action Some proteins form
structures that are easy to see. Other proteins
help cells do their jobs. Proteins called
enzymes start or speed up chemical reactions
in cells.
Section 2 The Necessities of Life
Carbohydrates
• Molecules made of sugars are called
carbohydrates.
•Simple Carbohydrates Simple
carbohydrates are made up of one sugar
molecule or a few sugar molecules
linked together.
• Complex Carbohydrates Complex
carbohydrates are made of hundreds of
sugar molecules linked together.
Organisms store extra sugar as complex
carbohydrates.
Section 2 The Necessities of Life
Lipids
• Lipids are compounds that cannot
mix with water.
•Phospholipids are the molecules
that form much of the cell membrane.
• Fats and Oils Fats and oils are
lipids that store energy. When an
organism has used up most of its
carbohydrates, it can get energy from
these lipids.
Section 2 The Necessities of Life
Section 2 The Necessities of Life
ATP
• Adenosine triphosphate, or
ATP, is the major energycarrying molecule in cells.
• The energy in carbohydrates
and lipids must first be
transferred to ATP, which then
provides fuel for cellular
activities.
Section 2 The Necessities of Life
Nucleic Acids
• Nucleic acids are large molecules
made up of subunits called nucleotides.
• Nucleic acids are sometimes called
the blueprints of life because they have
all the information needed for a cell to
make proteins.
• DNA is a nucleic acid.