Bio Unit 4: Cell Membrane & Transport

Homeostasis

Balancing act that can be thrown out of place by environmental changes

Positive feedback

Moving away from homeostasis; when a change in a system is amplified(snowball effect)

What are examples of positive feedback?

Childbirth, lactation, blood clotting, fruit ripening

Negative feedback

Returning to homeostasis; when a system responds to change y returning to its original state or by decreasing the rate at which the change is occurring

Examples of negative feedback?

Body temperature, blood pressure, blood sugar levels

What types of cells are surrounded by the cell (plasma) membrane?

All cells

What are the characteristics of the cell membrane?

It’s thin and flexible

Why is the cell membrane thin?

To easily allow for movement of materials into and out of the cell

Why is the cell membrane flexible?

To allow for ease of movement and confirming to different spaces

Plasma membrane functions

Regulates what enters and exits the cell and provides protection and support for the cell

How is the cells membranes structure described?

A fluid mosaic model

Why is the cell membrane described as a fluid mosaic model?

There are many diverse protein molecules suspended in a fluid phospholipid bilayer

What does the plasma membrane include?

Primary and secondary

Primary

Protein and phospholipids

Secondary

Carbohydrates and cholesterol

What part of the phospholipid bilayer is hydrophilic?

Outer portion of the cell membrane that comes in contact with external liquid environment and internal cytoplasm

What part of the phospholipid bilayer is hydrophobic?

The inner part of the membrane that doesn’t come in contact with interior or exterior environments

What part of the bilayer play a role in selective permeability?

Hydrophilic tails

Selective permeability

Only certain molecules can cross the membrane

What molecules can pass the membrane with ease?

Oxygen and water

What cant cross the membrane with ease?

Polar molecules and many ions, they need assistance from transport proteins

What polar molecule can pass the membrane no problem?

Water

Why are proteins embedded in the membrane?

Carry out some of the cells chemicals reactions (enzyme), aid in the transport of specific molecules or ions across, send and receive chemical signal, recognize neighboring cells

What is this?

Transport of materials

What is this?

Cell signaling

What is this?

Cell to cell recognition

What is this?

Enzyme activity

What do membranes regulate?

The movement of particles from the liquid on one side of the cell membrane to the liquid on the other side

Concentration gradient

The different in the concentration of a substance between two area

What is the natural flow of concentration gradient?

High concentration to low concentration

Diffusion

Movement of particles down a concentration gradient from an area of high concentration to an area of low concentration

Equilibrium

Occurs when the volute has become evenly distributed throughout the solution(equal)

Does diffusion require energy?

No it is passive transport

Passive transport

Does not require energy

How do particles move in diffusion?

Randomly

What does diffusion allow cells to gain?

Useful substances they require to obtain energy and grow

What does diffusion allow cells to get rid of?

Waste products

What are substances required by the cell?

Glucose, oxygen, amino acids

What are cells waste products?

Carbon dioxide, urea

Wha is urea?

Excess amino acid

Osmosis

Diffusion of water through selectively permeable membrane

What type of gradient does osmosis follow?

Natural concentration

Natural concentration

High concentration to low concentration

Is osmosis passive?

Yes

Whats the difference between osmosis and diffusion?

Diffusion involves the movement of many types of substances and osmosis refers specifically to the movement of water

What is this?

Osmosis

What is this?

Diffusion

Tonicity

Describes the ability of a surrounding solution to cause a cell to gain or lose water

What determines how a cell will be affected by osmosis?

The solution the cells in

What depends on the concentration of solutes on both sides of the membrane?

Tonicity

What are the 3 types of solutions?

Hypertonic, hypotonic, and isotonic

Hypertonic

The solution is more concentrated compared to the cell; higher concentration of solute and lower concentration of water

Hypotonic

The solution is less concentrated compared to the cell; lower concentration of solute and higher concentration of water

Isotonic

The solution has an equal concentration compared to the cell (on both sides of the membrane); equal concentrations of solute and water

What is this?

Isotonic solution

What is this?

Hypotonic solution

What is this?

Hypertonic solution

Where does water move for a hypertonic solution and how does the cell change?

Out; shrivel

Crenation

Shrivel

How does water move in a hypotonic solution and how does the cell react?

In; swells

How does water move in an isotonic solution and how does the cell react?

In and out; normally

What is this?

Isotonic solution

What is this?

Hypertonic solution

What is this?

Hypotonic solution

How does plants take up water through their roots?

Osmosis

Turgor pressure

The force within the cell that pushes the plasma membrane against the cell wall

Whats the difference between Tonicity between plant cells and animal cells?

The cell wall prevents plant cells from bursting when in a hypotonic solution

What is this?

Hypotonic solution; turgid

What is this?

Isotonic;flaccid

What is that?

Hypertonic; plasmolyzed

Facilitated diffusion

Movement of specific particles (polar or charged substances) across the cell membrane though transport proteins

Does facilitated diffusion require?

No its a form of passive transport

Driving force

Concentration gradient

What concentration does facilitated diffusion use?

Concentration gradient- high to low

What are transport proteins?

Helps specific substances move across the membrane

Types of transport proteins

Channel protein and carrier protein

Channel protein

Creates a hydrophilic channel that some molecules or ions use as a tunnel through the membrane

Carrier protein

Binds its passenger, changes shape, and releases its passenger on the other side

What is this?

Carrier protein

What is this?

Protein channel

Why is osmoses slow?

Because water is a polar molecule

Why can water diffuse rapidly in and out of cells?

A protein channel called aquaporin

What type of transport protein is aquaporin?

Protein channel

Where is aquaporin found?

Plant cells, Disney cells, and red blood cells

Active transport

When a cell must expand energy to move solute against its concentration gradient

What type of protein is involved in active transport?

Transport protein

What source of energy is used for active transport?

ATP

What concentration does active transport use?

Low to high concentration

What is this?

Active transport

What does active transport allow?

A cell to maintain internal concentrations of small molecules and ions that are different from concentrations in its surroundings

What does a cell depend on to move a large molecule across the cell membrane?

Exocytosis and endocytosis

Exocytosis

Used by the cell to export bulky material like proteins and polysaccharides

Endocytosis

Used by the cell to take in large

What do both Exocytosis and endocytosis do?

Material to be transported is packaged within a vesicle that fuses with the cell membrane

What does Exocytosis involve?

A vehicle forming around the material to be released

Is Exocytosis what does the vesicle fuse with?

The cell membrane and forces contents out of the cell

What is this?

Exocytosis

What does a cell form in endocytosis?

A pocket of cell membrane around the material being taken in

What does the pocket do it endocytosis?

Breaks loose from the outer portion and forms a vesicle within the cell

What is this?

Endocytosis