L2: Membrane Transport Flashcards Preview

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Flashcards in L2: Membrane Transport Deck (21):

Define kinetic energy.

The energy that an object possesses due to its motion


Define thermal energy.

Energy that comes from heat


How do kinetic and thermal energy relate to molecular movement?

Heat is generated by the movement of tiny particles in an object.
Faster the particles move the more heat generated
Kinetic energy is measured while molecule moves and thermal energy measures the amount of heat due to the movement


Define diffusion.

The movement of particles from a region of high concentration to a region of low concentration


Define osmosis.

The movement of a solvent from a region of high concentration to a region of low concentration across a semipermeable membrane



How does diffusion and osmosis relate to semipermeable membranes?

Net diffusion occurs across a gradient if the barrier is permeable and osmosis is the movement of water across a semipermeable membrane.


How is osmotic pressure is generated?

When water moves across a cell membrane bc of the concentration differences, water will accumulate on one side of the membrane causing a high pressure on one side.


What is the general structure of the cell membrane?

Phospholipid bilayer :Hydrophilic heads & hydrophobic tails
Proteins : integral proteins inserted in bilayer / peripheral proteins loosely attached


Compare diffusion to facilitated diffusion.

Diffusion is the only method of transport that is not carrier mediated
Facilitated diffusion:
requires uniporter carrier proteins
Occurs down an electrochemical gradient


Define active transport.

Movement of particles against a concentration/electrochemical gradient (uphill)

Requires metabolic energy (other than kinetic) and carrier proteins


Compare primary and secondary active transport.

Primary: energy is derived directly from the breakdown of ATP and utilizes ATPase transporters

Secondary: energy is derived secondarily from concentration differences created by primary transport and utilizes multiporters. At least one of the solutes move down the electrochemical gradient while one or more move up it electrochemical gradient


If sodium moves down its electrochemical gradient. Why is this referred to as secondary active transport?

A sodium gradient is created by primary active transport with sodium more concentrated outside the cell

Sodium and glucose combined with energy gradient will cause them to come in and there is no energy for it to occur, but eventually sodium will need to be pumped out


Sodium/calcium antiporters move three sodium ion per calcium ion. Why does it take three sodium ions to move one calcium ion?

Bc sodium ions are a lot smaller & they are single charged
Calcium is a double charged cation
Therefore it is not a 1 to 1 ratio


What is an uniporter?

has binding sites that are alternatively available on either side of the membrane

work by binding to one molecule of substrate at a time and transporting it with its concentration gradient.


what is a multiporter?

work by binding to one or more ions/molecules of substrate at a time and transporting it with its concentration gradient.


Define excitable cell and give examples.

Are cells in which an action potential can be induced

Skeletal muscle cells
Cardiac muscle cells
Smooth muscle cells


Which part of a neuron is capable of developing an action potential?



Which of the following  would have to be a transmembrane protein?
A receptor protein
A protein binding to the cytoskeleton
A channel protein
A phosphorylase

A channel protein


Which of the following organelles is directly associated with the synthesis of proteins for secretion?

Golgi apparatus
Rough endoplasmic reticulum
Smoothie endoplasmic reticulum

Rough endoplasmic reticulum


Pits coated with which of the following are often associated with endocytosis?




Which of the following processes does not require the presence of mitochondria?

Oxidative phosphorylation
Production of carbon dioxide and water
Breakdown of glucose to pyruvic acid
Electron transfer between cytochromes
Utilization of oxygen as final electron receptor

Breakdown of glucose to pyruvic acid