Download Cell Membrane

Chapter 3
Cells
Cells- the basic units of living things
• Cells were not discovered until
microscopes were invented in the 1600’s
• Robert Hooke first discovered cells in
1665 when he observed cork cells
• Anton van Leeuwenhoek first observed
living cells from pond water in 1675
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
The Cell Theory
• The cell theory was created based on
observations made by 3 scientists: Mattias
Schleiden, Theodor Schwann, & Rudolph
Virchow
• The Cell Theory Has 3 Parts:
1) All living things are made of one or more cells
2) Cells are the basic units of structure and
function in all living things
3) Cells come from other cells
Cell Size
• There are about 100 trillion cells in the
human body
• It is better to have many tiny cells than
only a few large ones, why?
• Cells need a large surface area in
comparison to their internal size(volume)
Common Features of 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
Membrane Structure
• The cell membrane is a phospholipid bilayer
• Phospholipids: molecules made form
phosphate molecules and lipids
Polar “head”
Non-Polar
“tails”
• Bilayer: the cell membrane is 2 layers
thick, a double layer of phospholipids
Cell Membrane Diagram
Membrane Proteins
•
•
The cell membrane has various proteins
stuck in it that have specific jobs
Types of Membrane Proteins:
1) Cell Surface Marker- identifies cell type
2) Receptor Proteins- recognizes & binds
substances outside the cell
3) Transport Proteins- help substances move
into and out of the cell
4) Enzymes- perform chemical reactions
inside the cell
Membrane Proteins
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
Plant Organelles
• Cell Wall- protective outer membrane
– Supports and maintains cell shape
– Made of a material called cellulose
• Chloroplasts- use light(solar) energy to make
food for plants
– Contain a green pigment called chlorophyll
• 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 3 NOTES!!!