Download Chapter 7 Section 7_3 Cell Transport

Chapter 7: Cell Structure and Function
7.3 – Cell Transport
Mr. M. Varco
Saint Joseph High School
Passive Transport
• Every living cell exists in a liquid environment.
Passive Transport
• One of the most important functions of the cell membrane is to regulate
the movement of molecules from one side of the membrane to the
other.
Passive Transport
Diffusion
• A cell’s cytoplasm consists of many difference substances dissolved in
water, all of which move constantly.
• These particles tend to move from an area of high concentration to one of
lower concentration in a process called diffusion
Passive Transport
Diffusion
• If a substance is in higher concentration on either side of cell membrane, the
particles will diffuse to the other side where they are less concentrated.
• Once the concentration of a substance is equal on both side of the cell
membrane, equilibrium is reached.
Passive Transport
Diffusion
• The movement of materials across the cell membrane without using cellular
energy is called passive transport.
Passive Transport
Diffusion
• Facilitated Diffusion is the process in which molecules that cannot diffuse
directly through cell membrane pass through special protein channels.
• Usually takes place for large molecules, such as glucose molecules.
Passive Transport
Diffusion
• Like passive transport, facilitated diffusion does NOT require energy input.
Passive Transport
Osmosis
• Water molecules have difficulty passing through the cell membrane due to the
lipid bilayer.
• Many cells contain water protein channels, known as aquaporins, that allow
water to pass through the cell membrane.
Passive Transport
Passive Transport
Passive Transport
Osmosis
• The diffusion of water through the cell membrane by facilitated diffusion is
called osmosis.
• In osmosis, molecules of water move from an area of high concentration to a
lower concentration.
Passive Transport
Passive Transport
Osmosis
• Once equilibrium is achieved, the two solutions will be isotonic, meaning
they are “same strength.”
• Hypertonic: means “above strength”
• Hypotonic: means “below strength”
Passive Transport
Osmosis
• The net movement of water into or out of a cell produces a force known as
osmotic pressure.
Passive Transport
Osmosis
• Because the cell is filled with salts, sugars, and proteins, it is usually hypertonic
to fresh water.
• As a result, water tends to move quickly into a cell, causing it to swell.
Active Transport
• The movement of materials against a concentration difference is known as
active transport.
• Active transport requires the input of ATP energy.
Active Transport
Molecular Transport
• The movement of smaller molecules across the cell membrane is carried out by
transport proteins called protein pumps.
Active Transport
Bulk Transport
• Larger molecules or materials can be actively transported across the cell
membrane by processes called endocytosis and exocytosis.
Active Transport
Endocytosis
•
The process of taking material into the cell by means of infolding of the cell
membrane is called endocytosis.
•
There are 2 types of endocytosis:
a. Phagocytosis
b. Pinocytosis
Active Transport
•
Phagocytosis occurs when extensions of cytoplasm surround a particle and
package it within a food vacuole
•
Pinocytosis occurs when tiny pockets form along the cell membrane, fill with
liquid from the cell’s surroundings, and pinch off to form vacuoles
Active Transport
Exocytosis
•
During exocytosis, the membrane of the vacuole surrounding the material uses
with the cell membrane, forcing material out
Chapter 7: Cell Structure and Function
7.4 – Homeostasis and Cells
Mr. M. Varco
Saint Joseph High School
The Cell as an Organism
•
Cells are the basic unit of all organisms, but sometimes a single cell is
the organism
•
In terms of their numbers, unicellular organisms dominate life on Earth
The Cell as an Organism
•
Just like other living things, unicellular organisms maintain a relative
internal physical and chemical condition called homeostasis
•
To maintain homeostasis, unicellular organisms:
- Grow
- Respond to their environment
- Transform energy
- Reproduce
The Cell as an Organism
•
Unicellular organisms include both eukaryotes and prokaryotes
•
Examples of unicellular eukaryotic organisms include algae, yeasts,
and fungi
The Cell as an Organism
•
Unicellular organisms include both eukaryotes and prokaryotes
•
Examples of unicellular eukaryotic organisms include algae, yeasts,
and fungi
Multicellular Life
•
Unlike most unicellular organisms, human cells are interdependent
•
The cells of multicellular organisms become specialized for particular
tasks and communicate with one another to maintain homeostasis
Multicellular Life
Cell Specialization
•
The cells of multicellular organisms are specialized
•
Specialized animal cells: human trachea cells purify air that we breathe
Multicellular Life
Cell Specialization
•
Specialized plant cells: pine pollen grains help trees become fertilized
Multicellular Life
Levels of Organization
•
The specialized cells of multicellular organisms are organized as follows:
- Cells
- Tissues
- Organs
- Organ systems
Multicellular Life
Levels of Organization
•
A tissue is a group of similar cells that perform a particular function
•
Many groups of tissues work together as an organ
•
A group of organs working together is called an organ system
Multicellular Life
Communication
•
Cells in a large organism communicate by means of chemical signals
that are passed from one cell to another
•
To respond to one of these chemical signals, a cell must have a
receptor to which the signaling molecule can bind