Lesson 7.3

The movement of materials against a concentration difference is known as ________________________ transport. Active transport requires ________________________.

Active; energy

_____________________________ use phagocytosis for taking in food

Amoebas

Water channel protein in a cell

Aquaporin

Many cells contain water channel proteins, known as ______________________________, that allow water to pass right through them. Without aquaporins, water would __________________________ in and out of cells very slowly.

Aquaporins; diffuse

Water will tend to move across the _______________________ until ________________ is reached. At that pint, the ______________________________ of water and sugar will be the same on both sides.

Barrier; equilibrium; concentrations

Many cells use such proteins o move _______________, ___________________, and __________________________ ions across cell membranes.

Calcium; potassium; sodium

Cell membranes have proteins that act as ___________________________, or channels, making it easy for certain molecules to cross

Carriers

In plants, the movement of water into the cell causes the central vacuole to swell, pushing cell contents out against the ____________ _____________.

Cell wall

Cells sometimes must move materials against a ________________________________ difference.

Concentration

At that point, the ___________________________________ of the substance on both sides of the cell membrane is the same, and ___________________________________ is reached.

Concentration; equilibrium

Since most cells in large organisms do not come in ____________________ with fresh water, they are not in danger of bursting

Contact

Other cells, including those of plants and bacteria, that come into ______________________ with fresh water are surrounded by tough cell walls that prevent the cells from expanding, even under tremendous _____________________ pressure.

Contact; osmotic

Process by which particles tend to move from an area where they are more concentrated to an area where they are less concentrated

Diffusion

__________________________________ is the driving force behind the movement of many substances across the cell membrane.

Diffusion

The cytoplasm of a cell is a solution of many different substances ___________________________ in water.

Dissolved

The use of energy in these systems __________________ cells to concentrate substances in a particular location, even when the _________________ of diffusion might tend to move these substances in the opposite direction.

Enables; forces

The membrane forms a pocket around a particle. The pocket then breaks loose from the outer portion of the cell membrane and forms a vesicle within the cytoplasm.

Endocytosis

The process of taking material into the cell by means of infoldings, or pockets, of the cell membrane

Endocytosis

The movement of molecules by facilitated diffusion does not require additional use of the cell's _________________

Energy

A considerable portion of ____________________ used by cells in their daily activities is devoted to providing the energy to keep this form of ___________________ transport working.

Energy; active

Engulfing material through endocytosis requires a considerable amount of ___________________ and, therefore, is a form of ______________________ transport.

Energy; active

Endocytosis = ?

Enter

Exocytosis = ?

Exit

Many cells also release large amounts of material from the cell, a process known as _________________________.

Exocytosis

The membrane of a vesicle surrounds the material then fuses with the cell membrane. The contents are forced out of the cell.

Exocytosis

Molecules that cannot directly diffuse across the membrane pass through special protein channels in a process known as _________________________ _________________________________.

Facilitated diffusion

Process of diffusion in which molecules pass across the membrane through cell membrane channels

Facilitated diffusion

Some cells, such as the eggs laid by fish and frogs, must come in contact wi fresh water. These types of cells tend to ________________ water channels.

Lack

Every living cell exists in a ________________ environment

Liquid

In endocytosis, the pockets fill with _____________________ and pinch off to form ___________________________ within the cell.

Liquid; vacuoles

In ________________________________, extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then ________________________ it.

Phagocytosis; engulfs

In __________________________________, cells take up liquid from the surrounding environment by forming tiny pockets along the cell membrane.

Pinocytosis

Small molecules and ions are carried across membranes by _______________________ in the membrane that act like pumps

Proteins

Hundreds of different ________________________________ have been found that allow particular __________________________ to cross cell membranes.

Proteins; substances

Changes in protein shape seem to play an important role in the ____________________________ process.

Pumping

Because the cell is filled with _________________, __________________, _______________, and other ________________________, it is almost always hypertonic to fresh water.

Salts; sugars; proteins; molecules

The transport of these larger materials sometimes involves changes in the __________________ of the cell membrane.

Shape

What is passive transport?

The movement of materials across the cell membrane without using cellular energy is called passive transport

What is active transport?

The movement of materials against a concentration difference is known as active transport. Active transport requires energy.

If there are more sugar molecules on the right side of a barrier than on the left side, then which side has a lower water concentration?

The right side, because more of the solution is made of sugar than water

Instead, the cells are bathed in _________________, such as blood, that are ____________________ and have concentrations of dissolved materials roughly equal to those in the cells.

Fluids; isotonic

Large molecules, clumps of __________________, and even whole cells can be taken up by _____________________________.

Food; endocytosis

The inside of a cell's lipid bilayer is hydrophobic - or "water- ______________________________." Because of this, water molecules have a tough time passing through the cell membrane.

Hating

The process by which particles move from an area of ___________________ concentration to an area of ______________________ concentration is known as _________________________________.

High; lower; diffusion

Osmosis involves the movement of water molecules from an area of __________________ concentration to an area of __________________ concentration.

Higher; lower

The more concentrated sugar solution at the start of the experiment was _____________________________, or "above strength," compared to the dilute sugar solution

Hypertonic

When comparing two solutions, the solution with the greater concentration of solutes

Hypertonic

In a ________________________ solution, water rushes out of the cell, causing animal cells to shrink and plant cell ______________________ to collapse.

Hypertonic; vacuoles

Notice how the plant cell holds its shape in _________________________ solution, while the animal red blood cell does not.

Hypotonic

The dilute sugar solution was _____________________, or "below strength"

Hypotonic

When comparing two solutions, the solution with the lesser concentration of solutes

Hypotonic

For organisms to survive, they must have a way to balance the ______________________ and loss of water

Intake

One of the most important functions of the cell membrane is to keep the cell's ______________________ conditions relatively constant. It does this by regulating the movement of _________________________________ from one side of the membrane to the other side.

Internal; molecules

Cells placed in an ____________________ solution neither gain nor lose water.

Isotonic

When the concentration is the same on both sides of the membrane, the two solutions will be ___________________, which means "same strength"

Isotonic

When the concentration of two solutions is the same

Isotonic

Larger molecules and clumps of ________________________ can also be actively transported across the cell __________________________ by process known as ____________________________________ and exocytosis.

Material; membrane; endocytosis

The movement of ___________________________ across the cell membrane without using ________________________ energy is called passive transport.

Materials; cellular

The movement of water through cell ________________________ by facilitated diffusion is an extremely important biological process - the process of __________________.

Membrane; osmosis

During exocytosis, the _________________________ of the vacuole surrounding the material fuses with the cell membrane, forcing the contents ________________ of the cell.

Membrane; out

Diffusion of water through a selectively permeable membrane

Osmosis

The diffusion of water through a selectively permeable membrane

Osmosis

As a result, water moves into them so slowly that ___________ pressure does not become a problem.

Osmotic

Pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

Osmotic Pressure

The net movement of water out of or into a cell exerts a force known as _________________________________ _________________________.

Osmotic pressure

Diffusion depends upon random ________________________________ movements. Substances _____________________ across membranes without requiring the cell to use additional energy.

Particle; diffuse

Even when equilibrium is reached, _________________________ of a solution will continue to move across the membrane in both directions.

Particles

Because almost equal numbers of ______________________________ move in each direction, there is no net change in the ____________________________________________ on either side.

Particles; concentration

If the substance can cross the cell membrane, its ________________________________ will tend to move toward the area where it is less concentrated until it is evenly ____________________________.

Particles; distributed

What are two examples of endocytosis?

Phagocytosis and pinocytosis

Bulk transport can take several forms, depending on the ________________ and ___________________ of the material moved into or out of the cell

Size; shape

The active transport of _________________________ molecules or ions across the cell membrane is generally carried out by transport _____________________________, or protein "___________________," that are found in the membrane itself.

Small; proteins; pumps

In any solution, ______________________ particles tend to move from an area where they are more concentrated to an area where they are less concentrated.

Solute

As a result, water tends to move quickly into a cell surrounded by fresh water, causing it to _______________. Eventually, the cell may _________________.

Swell; burst

Large molecules and even solid clumps of material may be ____________________________ by movements of the cell membrane known as _________________ ____________________________________

Transported; bulk transport

Suppose a substance is present in _________________________ concentrations on either side of a cell membrane.

Unequal

The pocket that results breaks loose from the outer portion of the cell membrane and forms a ______________________ or ________________________ within the cytoplasm

Vesicle; vacuole

However, the increased osmotic pressure makes such cells extremely __________________________________ to injuries to their cell walls.

Vulnerable