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Chapter 5
Inside the Cell
Measuring Cell Size:
• Most cells are too small to see with the
naked eye
• Cells are usually measured in micrometers
because they are so small
– Ex: Red Blood Cells 10 micrometers
Unicellular Organisms
• 1 Cell Organisms, this single cell performs
all functions necessary for life
• These organisms use cellular respiration
to generate energy from food
• Some algae can also use photosynthesis
as a process to make their own food using
sunlight
Ex: Bacteria, Amoeba, Paramecium, Algae
Multicellular Organisms
• Made of many cells
• Most likely evolved from unicellular
organisms
• Cells are specialized to perform specific
tasks
– Ex: not all plant cells can perform
photosynthesis
• Different cells come in different shapes
and sizes
Levels of Organization
Cells  Tissues  Organs  Systems  Organisms
Cells- the basic unit of all living things
Tissues- similar cells working together to perform a
specific function
Ex: muscle tissue, brain tissue, blood, skin
Organs- many tissues combined together that perform a
specific function
Ex: stomach, brain, kidney, leaf
Systems- groups of organs working together
Ex: Digestive System, Nervous System
Organism- a group of organ systems working together
Common Features of All Cells
• Cell Membrane- encloses the cell and
separates it from the outside
environment
• Cytoplasm- the material inside the cell
membrane
• Cytoskeleton- a system of microscopic
fibers that support cell structures
• Ribosomes- make proteins for the cell
Prokaryote Cells
• Prokaryotes are the smallest & simplest
type of single celled organisms
• Prokaryotes are single celled and have
NO NUCLEUS
• Prokaryotes are believed to be the 1st
living things on earth
– Ex: Bacteria
Characteristics of Prokaryotes
• Prokaryotes live in a wide range of conditions
Ex: in the soil, water, animals
• Cytoplasm- everything on the inside of the cell
membrane
• DNA- prokaryotes have a single circular loop of
DNA
• Cell Wall- protective outer layer that provides
structure and support
• Cell Membrane- thin, flexible layer just beneath
the cell wall
• Flagella- long threadlike tails that allow
movement
Prokaryotes
Eukaryote Cells
• Eukaryotes are more complex single and
multicellular organisms
• Eukaryotes have internal cell structures
and have a nucleus
• Eukaryotes are thought to have evolved
from prokaryotes
Characteristics of Eukaryotes
• Eukaryotes contain many specialized structures called
organelles
• Cytoplasm- the fluid & organelles inside the cell
membrane
• Nucleus- contains the DNA in the cell, controls cell
functions
• Cell Membrane- surrounds the cell and controls
movement of things into and out of the cell
• Flagella- tail-like structure used for movement
• Cilia- short hair-like structures used for
movement
Eukaryotes
Cell Structures
• The Cytoskeleton- provides an interior
framework for an animal cell
– Has a similar function to the skeleton in the
human body
– The Cytoskeleton is made of 3 types of fibers:
• Actin Fibers- long slender strands of protein
• Microtubules- hollow tubes made of tubulin, that
transmit information from the nucleus to
different parts of the cell
• Intermediate Filaments- thick ropes of protein
that provide structural support inside the cell
and hold cell parts in place
The Cytoskeleton
The Cell Membrane
• The cell membrane surrounds the cell and
acts as a barrier between the inside
and outside of a cell
• Selectively Permeable- only certain
substances are allowed to enter and
leave the cell through the cell
membrane
Cell Membrane
Cell Parts
• Organelles- structures inside the cell that
perform specific functions
The Nucleus
• Control center of the cell
• Instructs all other cell parts what to do
• Contains chromosomes made of DNA
• Nuclear Envelope- membrane that surrounds
the nucleus
– Contains pores“holes” that allow substances into and
out of the nucleus
• Nucleolus- central core of the nucleus that
makes ribosomes
The Nucleus
Ribosomes
• Ribosomes make proteins for the cell
– Free Ribosomes: are scattered throughout
the cytoplasm
– Attached Ribosomes: are located on the
surface of the rough endoplasmic reticulum
Endoplasmic Reticulum(ER)
• The ER is a system of folded membranes
found near the nucleus
• The ER transports proteins throughout the
cell
• Smooth ER- has no ribosomes on it’s
surface
• Rough ER- has ribosomes on it’s surface
Endoplasmic Reticulum
Golgi Apparatus
• The Golgi is a flattened membrane of sacs
found in the cytoplasm
• The Golgi packages & distributes
materials inside the cell using vesicles
• Vesicles- small sacs that hold and carry
substances in the cell
Golgi Apparatus
Processing Proteins
Lysosomes
• Lysosomes are small, spherical organelles
containing digestive enzymes
• Lysosomes break down food molecules &
toxins inside the cell
Mitochondria
• The mitochondria is a bean shaped
organelle found throughout the cytoplasm
• The mitochondria produces energy(ATP)
• The “Powerhouse” of the cell
* Mitochondria have their own DNA inside
Centrioles
• Animal cells contain 2 pairs of centioles
• Centrioles are responsible for coordinating
cell division(mitosis)
Plant Organelles
• Cell Wall- protective outer membrane
– Supports and maintains cell shape
– Made of a material called cellulose
Plant Organelles
• Chloroplasts- use light(solar) energy to
make food for plants
– Contain a green pigment called chlorophyll
Plant Organelles
• Central Vacuole- a large water, mineral,
and waste storage chamber in plant
cells
– The vacuole takes up a very large area in a
plant cell
Plant Organelles
END OF CHAPTER 5 NOTES!!!