Diffusion Through Cell Boundaries Life began in the ocean. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries The first unicellular organisms got everything they needed from the seawater around them. Diffusion Through Cell Boundaries Food O2 Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Salt Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Then, things changed. Multicellular organisms evolved. Now, only the cells on the outside of the organism were in contact with seawater. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries And then things really changed. Organisms left the ocean and began living on dry land. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries How do cells inside a multicellular organism get what they need to live? Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries If the first living things got everything they needed from sea water, how can life exist on dry land? Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries Recall that living things consist mostly of water. It makes up 72% of the mass of our cells. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Even organisms that live in the desert are still about 72% water. Even though we left the ocean, we still carry it inside us. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Like the ocean, the liquid of our bodies is not pure water. Instead, it is a solution. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Solute Copyright Pearson Prentice Hall

+ = Solution A mixture of water and dissolved solute. solute PLASTIC SHEET DEMO. The cell membrane is sometimes called the plasma membrane, since it is in constant contact with plasma (fluid) outside of the cell. A mixture of water and dissolved solute.

Ex: ocean water. PLASTIC SHEET DEMO. The cell membrane is sometimes called the plasma membrane, since it is in constant contact with plasma (fluid) outside of the cell.

+ = Solute The substance that is dissolved in a solution. solute PLASTIC SHEET DEMO. The cell membrane is sometimes called the plasma membrane, since it is in constant contact with plasma (fluid) outside of the cell. The substance that is dissolved in a solution.

PLASTIC SHEET DEMO. The cell membrane is sometimes called the plasma membrane, since it is in constant contact with plasma (fluid) outside of the cell. Ex: glucose, O2, salt.

Diffusion Through Cell Boundaries Like the first unicellular organisms, the cells of multicellular organisms are bathed in solution. We call the solution in our bodies plasma. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Plasma Plasma White blood cells Red blood cells Prokaryotes do not contain nuclei. They evolved BEFORE eukaryotes. This is a bacteria, a typical prokaryote. See how it has no nucleus? The DNA floats freely in the cell. Solution found in multicellular organisms; contains dissolved solute that cells need to live.

Diffusion Through Cell Boundaries Plasma is located in the blood. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries Since blood travels everywhere in the body, our cells are constantly bathed in plasma. Diffusion Through Cell Boundaries Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Cells get the solute they need from plasma by transporting it across the cell membrane. Prokaryotes do not contain nuclei. They evolved BEFORE eukaryotes. This is a bacteria, a typical prokaryote. See how it has no nucleus? The DNA floats freely in the cell. Cell

Diffusion Through Cell Boundaries Since the cell membrane is in constant contact with plasma, it is sometimes called the plasma membrane. Diffusion Through Cell Boundaries Plasma membrane Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Plasma is also located inside the cell, where it is known as cytoplasm. Diffusion Through Cell Boundaries Cytoplasm Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

The concentration of plasma inside and outside the cell is not always the same. Prokaryotes do not contain nuclei. They evolved BEFORE eukaryotes. This is a bacteria, a typical prokaryote. See how it has no nucleus? The DNA floats freely in the cell.

Concentration The amount of solute dissolved in a solution. 5 mg / 1 L PLASTIC SHEET DEMO. The cell membrane is sometimes called the plasma membrane, since it is in constant contact with plasma (fluid) outside of the cell. Less concentrated More concentrated The amount of solute dissolved in a solution.

The amount of water in a solution also affects concentration (more water = less concentrated). Cell Membrane Less concentrated More concentrated Like the security guard in this photo, the cell membrane controls what enters and leaves the cell. The cell membrane also protects the cell against threats from outside, and supports the cell’s shape. 5 mg / 1 L 5 mg / 3 L

Copyright Pearson Prentice Hall The concentration of plasma outside the cell changes frequently. Cell Membrane Like the security guard in this photo, the cell membrane controls what enters and leaves the cell. The cell membrane also protects the cell against threats from outside, and supports the cell’s shape. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries However, the concentration of plasma inside the cell must be kept constant. Diffusion Through Cell Boundaries unchanging Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Activity How it affects the concentration of plasma How cell keeps concentration of cytoplasm constant Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries Exercise Diffusion Through Cell Boundaries = glucose Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Activity How it affects the concentration of plasma How cell keeps concentration of cytoplasm constant Decreases concentration CM transports glucose into the cell Exercise Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries Eating Diffusion Through Cell Boundaries = glucose Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Activity How it affects the concentration of plasma How cell keeps concentration of cytoplasm constant Decreases concentration CM transports glucose into the cell Exercise CM prevents glucose from entering the cell Increases concentration Eating Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels.

Diffusion Through Cell Boundaries Starvation The concentration of plasma inside the cell must be kept constant. Diffusion Through Cell Boundaries = glucose Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Copyright Pearson Prentice Hall

Diffusion Through Cell Boundaries Activity How it affects the concentration of plasma How cell keeps concentration of cytoplasm constant Decreases concentration CM transports glucose into the cell Exercise CM prevents glucose from entering the cell Increases concentration Eating Every living cell exists in a liquid environment. Even in a dry place like the desert, the cells of cacti and scorpions are bathed in liquid. This liquid is full of dissolved molecules of oxygen, CO2, salts, and all kinds of other substances. Some of these drifting molecules eventually enter the cell through pores and channels. Decreases concentration Cell opens up a vacuole Starvation