Unit 4 Bio: cell membrane and transport

2 Major functions of the cell membrane

Regulates what enters and exits a cell and protects the cell and gives it shape

Channel protein

Letter j

Phosphate head

Letter d

Cholesterol molecule

Letter I

Phosphate tail

Letter e

Carbohydrate molecule

Letter a

Phospholipid bilayer

Letter f

Hydrophilic

Water loving

Hydrophobic

Water fearing

Phosphate head- hydrophilic or hydrophobic

Hydrophilic

Phosphate tail- hydrophilic or hydrophobic

Hydrophobic

Explain how cell membranes exhibit selective permeability and help cells to maintain homeostasis

The cell membrane only permits certain materials pass through, and the majority of transport in cells occurs to reach equilibrium so the cell can maintain homeostasis

Difference between passive and active transport

Passive: no energy required (moves from high to low), active: energy required (ATP), moves from low to high

Which types of molecules are able to diffuse across the cell membrane

O2 and CO2, nonpolar (Water is an exception)

Tonicity of #1

Hypotonic

Tonicity of #2

Isotonic

Tonicity of #3

Hypertonic

Describe how diffusion happens in a molecular level. Draw a sketch to support your answer.

Diffusion is the passive movement of molecules from high to low concentration. The goal is to reach equilibrium! (Movement of molecules is random)

Why is diffusion an important process for cells?

Cells don’t need to continuously expend energy to obtain/ release materials, supports the cell in maintaining homeostatis

Would diffusion be positive or negative feedback? Why?

Negative feedback; if there is a change in the concentration of a solute, diffusion will occur to help disperse the materials so there is an even distribution (equilibrium). As a result, homeostasis is maintained.

What is a concentration gradient

A concentration gradient refers to the difference in the concentration of a substance between to areas. Particles, whether in air or liquid, tend to naturally flow from high to low concentration.

Define tonicity

The ability of a surrounding solution to cause a cell to gain or lose water. (Connects to hypertonic, isotonic, hypotonic)

Define osmosis

Passive diffusion of water across a selectively permeable membrane from high to low concentration

Would a high solute drink be hydrating or dehydrating to your body cells

Dehydrating, creates a hypertonic environment

Would a low solute drink be hydrating or dehydrating

Hydrating, creating a hypotonic environment

Describe how facilitated diffusion moves materials across a membrane

Facilitated diffusion moves molecules and ions across the cell membrane through the use of transport proteins (carrier and channel)

Is facilitated diffusion passive or active transport?

Occurs passively from high to low concentration

Which type of molecules would use facilitated diffusion to cross the cell membrane?

Polar and large ions (such as glucose, sodium ions (NA+), chloride ions (Cl-), amino acids)

Phospholipid bilayer

Letter b

Osmosis

Letter x

Simple diffusion

Letter y

Facilitated diffusion

Letter z

Channel protein

Letter a

Discuss how transport proteins contribute to a cell’s selective permeability

Transport proteins allow the movement of specific materials. Channel proteins are like pores that allow larger polar molecules and some ions to pass through, but size matters. Carrier proteins are designed to only work with a specific ion, molecule, or group of substances. Both are selecting which materials are able to pass through.

Explain how active transport moves materials across a membrane? Draw a sketch to support your answer.

active transport moves larger molecules cross the cell membrane through a transport proteins allow (usually) from low to high concentration using energy from molecules of ATP.

Which type of active transport is being shown?

Endocytosis- “enter”

Which type of active transport is being shown?

Phagocytosis

Which type of active transport is being shown?

Exocytosis

Which type of active transport is being shown?

Pinocytosis

How are active transport and facilitated diffusion similar?

Involve the use of transport proteins

How are active transport and facilitated diffusion different?

Active transport moves materials against the concentration gradient (low to high) and uses energy (ATP) to do so

How is active transport helpful compared to passive transport?

Allows cells to obtain necessary materials (food, liquids, ions, etc) and to release waste by going against the normal flow of high to low concentration

How is passive transport helpful compared to active transport?

Is helpful because it does not require the cell to use energy

What types of diffusion require energy?

Active transport

What types of diffusion don’t require energy?

Diffusion, osmosis, facilitated diffusion

What types of diffusion makes use of a channel protein?

Facilitated diffusion

What types of diffusion help to maintain equilibrium?

Diffusion, osmosis, facilitated diffusion

What types of diffusion goes from high to low concentration?

Diffusion, osmosis, facilitated diffusion

What types of diffusion goes from low to high concentration?

Active transport

What types of diffusion makes use of carrier proteins?

Facilitated diffusion, active transport

What types of diffusion involve movement of water

Osmosis

What types of diffusion involve movement of ions (NA+, K+ H+)

Active transport

What types of diffusion is used to intake food particles or release of waste?

Active transport

What types of diffusion involve movement of molecules (i.e. salt, sugar, proteins)

Facilitated diffusion