Download Cells - Tuckahoe Common School District

Cells
The Building
Blocks of Life
How did Cells Form?
• Several Theories of How Cells Formed:
– Cells arose in shallow pools containing “soup”
of chemicals. These chemicals become
combined and formed cells.
– Cells formed in beds of clay that allowed
substances (chemicals) to be contained and
produce living things – cells.
– Meteors and asteroids carried water,
containing life (cells) to the Earth.
Which Cell Theory Is True?
• We still do not know for sure how cells
formed.
Spontaneous Generation?
• The Theory of Spontaneous Generation
states that life could arise from non-living
matter.
– This theory was disproved in 1668 by
Francesco Redi who used raw meat for his
experiments.
Francesco Redi
Redi’s Experiment
Characteristics of Living Things
• All living things share characteristics, they:
– Are made of cells
– Are able to move
– Perform complex chemical activities
– Are able to grow and develop
– Are able to respond to their environment
– Are able to reproduce
What is a Cell?
• The cell is the basic building block of
all living things.
– The first cells on Earth are thought to have
evolved ~3.5 billion years ago.
– These cells could not produce their own
food.
All living things are made of cells
Plant Cells
Animal Cells
All living things are able to move
All living things perform
complex chemical activities
“building up and breaking
down”
• Metabolism is the sum total of all the
chemical reactions that occur in a living
thing.
– In humans these chemical reactions are
ingestion, digestion, respiration, and
excretion.
What are the Needs of Living
Things?
• In order to survive all living things need:
– Energy
– Food
– Water
– Oxygen
– Living space
– To maintain a proper temperature
Cell Theory
• The current cell theory
states that:
– All living things are
made of cells.
– Cells are the basic unit
of structure and
function in living things.
– Living cells only come
from other living cells.
What Are Cells Made Of?
• Organelles, or “tiny organs”, are
the structures that make up a cell.
• Organelles were discovered by
Robert Hooke in 1665 while looking
at cork cells.
How Do Cells Function?
• Each of the organelles in a cell has a defined
function.
• There are many organelles that make up a cell.
– These include the cell wall, cell membrane,
nucleus, cytoplasm, endoplasmic reticulum,
ribosomes, lysosomes, mitochondria, vacuoles,
chloroplasts.
• All organelles working together create the cells
structure.
Cell Organelles – Cell Wall
• The cell wall provides support and
protection for the cell.
• The cell wall is rigid.
• Cell walls are only found in plant cells.
Cell Wall – only in plants
Cell Organelles – Cell Membrane
• The cell membrane is the “doorway” of the cell.
• Cell membranes control the movement of
materials into and out of the cell.
– Pores are the openings in the cell membrane.
• Cell membranes provide support and protection.
– In plant cells the cell membrane is found just
inside the cell wall.
– In animal cells the cell membrane is the outermost
organelle.
Cell Membrane
Cell Organelles - Nucleus
• The nucleus is the “control center”, or
“brain” of the cell which controls all
activities in the cell.
• The nucleus has three parts:
– Nuclear membrane
– Chromosomes
– Nucleolus
Cell Organelles - Nucleus
• The nuclear membrane controls the
movement of materials into and out of
the nucleus.
• The chromosomes direct the activities
within the cell and also pass on genetic
traits to the next generation.
• The nucleolus, or “little nucleus” is the
site of ribosome production.
Cell Organelles Cytoplasm
• Cytoplasm
is the clear,
thick jellylike
substance
that
contains all
the
organelles.
Cell Organelles – Endoplasmic
Reticulum
• The
endoplasmic
reticulum, or
ER, is the
tubular
transportation
system
throughout the
cell.
Endoplasmic Reticulum
Smooth and Rough
Cell Organelles - Ribosomes
• Ribosomes are the protein factories of the
cell.
• Most ribosomes are found attached to the
outside of the endoplasmic reticulum.
– This location helps the cell with efficiency of
production and transport.
Ribosomes
Cell Organelles - Lysosomes
• Lysosomes are the “clean up crew” of the
cell.
• Lysosomes are involved in the digestive
process of the cell.
– Enzymes break down large food into smaller
bits for the mitochondria to use.
– Lysosomes are not common in plant cells.
Cell Organelles - Mitochondria
• Mitochondria are the “powerhouse” of the
cell and supply most of the energy for the
cell.
Cell Organelles - Vacuoles
• Vacuoles are the “storage tanks”
of the cell.
• Vacuoles can store food, water, or
waste.
– In plant cells vacuoles are common.
• Usually one large vacuole per cell.
– In animal cells vacuoles are not
common.
• Usually several small vacuoles per cell.
Cell Organelles - Chloroplasts
• Chloroplasts are the “energy producers”
of plant cells.
• Chloroplasts are only found in plant cells.
• Chloroplasts contain green chlorophyll that
captures energy from the sun.
What Is Cell Specialization?
• In multicellular organisms, cells not only
complete its own life activities, but also
performs a function that contributes to the
life of the organism.
• Within multicellular organisms there is
division of labor or specialization.
– The work of keeping the organism alive is
divided up among different parts of the
organism.
Levels of Specialization
Cells combine to form
Tissues combine to form
Organs combine to form
Organ systems combine to form
Organism
More Specialization
Students combine to form
Classes combine to form
Grades combine to form
Schools combine to form
District