Plasma Membrane Chapter 7

Functions of the Plasma membrane

1. Protect the cell 2.Control incoming and outgoing substances 3.Maintain ion concentrations of various substances 4.Selectively permeable - allows some molecules in, others are kept out

Isotonic Solution

Both solutions have same concentrations of solute.

Which situation would increase the fluidity of a phospholipid bilayer? A.Decreasing the temperature B. Increasing the number of proteins C.Increasing the number of cholesterol molecules D.Increasing the number unsaturated fatty acids

Increasing the number of cholesterol molecules

proteins move needed substances or waste materials through the plasma membrane.

Transport

Facilitated Diffusion

Use of proteins to carry polar molecules or ions across.

Cholesterol

cholesterol prevents membranes from freezing and maintains membrane fluidity. cholesterol is not present in bacteria. Plant cells also lack cholesterol, but they contain related compounds that fulfill a similar function.

Active Transport

-Cell uses its energy (ATP) to move substances across the membrane -Substances move against the concentration gradient (from LOW TO HIGH concentration) -Carrier proteins help move substances across the membrane.

The Phospholipid Bilayer consists of

-Phosphate heads -2 fatty acids tails -Cholesterol embedded to give support to cell -Some proteins are embedded, while others simply adhere to the surfaces of the bilayer.

Which is a factor that affects the rate of diffusion?

-Pressure -Concentration -Temperature

How would a cell be affected if it lost the ability to be selectively permeable?

A cell would be affected if it lost the ability to be selectively permeable because the cell would die and no longer exist.

Explain what a mosaic is and then explain why the term fluid mosaic model is used to describe the plasma membrane.

A mosaic is a picture or pattern produced by arranging together many small colored pieces.The term fluid mosaic model is used to describe the plasma membrane because the cell membrane is embedded with many different proteins and other substances that gives it the look similiar to a mosaic.

is the basic structure that makes up the plasma membrane.

A phospholipid

Endocytosis

A process in which a substance gains entry into a cell without passing through the cell membrane. This process is subdivided into: Phagocytosis(cell eating) and Pinocytosis (cell drinking)

Which type of transport requires energy input from the cell?

Active transport

Why is active transport an energy-utilizing process?

Active transport is an energy-utilizing process because it utilizes energy called ATP which when the last bond is broken it helps molecules to go against the concentration gradient.

Active transport,facilitated transport

Active transport needs energy to transport molecules against the concentration gradient while Facilitate transport uses proteins to transport the molecules into the plasma membrane. These two terms are related because they are methods of transport across the plasma membrane.

Which is not a factor that affects the rate of diffusion?

Conductivity

Endocytosis, exocytosis

Endocytosis is the process by which a cell surrounds a substance in the outside environment, enclosing the substance in the portion of the plasma membrane (entering the cell). While Exocytosis is the expulsion of waste materials out of the cell and in the secretion of cellular products such as digestive enzymes or hormones (exists the cell).These two terms are related because they help larger particles to move through the plasma membranes that can't be moved with diffusion or transport.

Exocytosis

Exocytosis is important in expulsion of waste materials out of the cell and in the secretion of cellular products such as digestive enzymes or hormones.

Concentration gradient

High to low concentration.

Hypertonic solution, Hypotonic solution

Hypertonic solution is when one solution has a higher concentration of solute than another while Hypotonic solution is when one solution has a lower concentration of solute than another. These two terms are related because of osmosis.

Hypothesize how oxygen crosses the plasma membrane if the concentration of oxygen is lower inside the cell than it is outside the cell.

If the concentration of oxygen is lower inside the cell than it is outside the cell then Oxygen crosses the plasma membrane from the outside to the inside of the cell due to the concentration gradient going from a high concentration to a low concentration.

Solutions

Made of solute and a solvent

Proteins

Many of the proteins act as channels or active transport molecules. Others function as receptors, which bind information-providing molecules, such as hormones, and transmit corresponding signals based on the obtained information to the interior of the cell.

Hypertonic

One solution has a higher concentration of solute than another.

Hypotonic Solution

One solution has a lower concentration of solute than another.

is the property that allows only some substances in and out of the cell.

Selectively permeable

Glycoproteins

Some proteins are embedded, while others simply adhere to the surfaces of the bilayer. Some of these proteins have carbohydrates attached to their outer surfaces.

Solute

Substance that is dissolved or put into the solvent. Salt and sucrose are solutes.

Solvent

The liquid into which the solute is poured and dissolved. We will use water as our solvent today.

Diffusion

The movement of molecules from an area of high concentration to an area of low concentration.

Osmosis

The movement of water from an area of high concentration to an area of low concentration.

How does the orientation of the phospholipids in the bilayer allow a cell to interact with its internal and external environments?

The orientation of the phospholipids in the bilayer allows a cell to interact with its internal and external environment because Polar hydrophilic heads are on the outside the cell and nonpolar hydrophobic heads inside of the cell.

Describe how the plasma membrane controls what goes into and what comes out of the cell.

The plasma membrane is a flexible living boundary which is selectively permeable. This allows the plasma membrane to select what comes into and out of the cell.

Explain how the plasma membrane maintains homeostasis within a cell.

The plasma membrane maintains homeostasis within a cell by by controlling the substances that enter or leave the cell.

List and describe the types of Cellular Transport.

Two types of Cellular Transport is passive and active transport. Passive transport includes osmosis, diffusion, and facilitated diffusion.

Hydrophilic

Water attracting

Hydrophobic

Water repelling

What might happen to a cell if it no longer can produce cholesterol?

What might happen If the cell can no longer produce cholesterol is that it cannot maintain homeostasis.

Sketch a before and after an animal cell is placed in a Hypotonic solution.

When an animal cell is placed in a hypotonic solution because of how much more water there is outside the cell and how little inside the cell the water around the cell would would travel from high concentration to low concentration. Meaning it will go into the animal cell since there is less water there. But since there is too much water going into the animal cell it will explode.

Substances allowed to pass through the plasma membrane

water, CO2, Glucose, O2, Amino Acids.