Anatomy And Physiology Test #1

Front 1

What is the driving force for diffusion?

Back 1

The kinetic energy of the molecules themselves.

Front 2

When does net diffusion stop?

Back 2

Net diffusion stops when concentration on both sides equal (if crossing a membrane) or when there is a uniform distribution of particles.

Front 3

What increases the rate of diffusion?

Back 3

High temperatures

Front 4

What decreases the rate of diffusion?

Back 4

Large molecules

Front 5

3 ways in which the physical barrier of a phospholipid bilayer is overcome for diffusion to occur?

Back 5

1. If the molecules are lipid soluble.
2. If the molecules are small enough to pass through the membrane channels.
3. If the molecules are assisted by a carrier molecule.

Front 6

What types of molecules are targeted by Simple Diffusion?

Back 6

Nonpolar and lipid soluble substances (hydrophobic).

Examples: oxygen, carbon dioxide, and fat soluble vitamins.

Front 7

Main difference between Simple and Facilitated Diffusion regarding direction of Diffusion?

Back 7

SImple Diffusion can only move material in the direction of a concentration gradient.
Facilitated Diffusion moves materials with and against a concentration gradient.

Front 8

Main difference between Simple and Facilitated Diffusion regarding energy?

Back 8

Simple Diffusion does not require energy.
Facilitated Diffusion requires a source of ATP.

Front 9

Chemically speaking, what is the difference between the molecules used in Simple and Facilitated Diffusion?

Back 9

Molecules for Simple diffusion are not saturable
Molecules for Facilitated Diffusion rates are limited by the number of functional membrane proteins and can be saturated.

Front 10

What is the rate of Facilitated Diffusion contingent on?

Back 10

If the particles can only pass through protein channels, then the rate of diffusion is determined by the number of channels as well as the number of particles.

Front 11

Types of molecules that need Facilitated Diffusion?

Back 11

Certain Lipophobic molecules:
Glucose, Amino Acids, and Ions.

Front 12

Two conditions necessary for Facilitated Diffusion Carrier Proteins:

Back 12

Exhibit specificity (selectivity).
Are saturable; rate is determined by number of carriers or channels.

Front 13

What do Transmembrane Integral Proteins do? They are involved in which kind of Diffusion?

Back 13

Transmembrane integral proteins transport specific polar molecules across the membrane (e.g., sugars and amino acids).

Facilitated Diffusion.

Front 14

What happens after a substrate binds to a carrier molecule during Facilitated Diffusion?

Back 14

Binding of substrate causes shape change in carrier.

Front 15

How are molecules selected during Facilitated Diffusion?

Back 15

Selection is by size, shape, and charge.

Front 16

There are two ways in which substances can enter or leave a cell:

Back 16

1. Passive Transport
2. Active Transport

Front 17

What are the three types of Passive Transport?

Back 17

1. Simple Diffusion
2. Facilitated Diffusion
3. Osmosis

Front 18

What are the two parts to Facilitated Diffusion?

Back 18

1. Channel-Mediated Facilitated Diffusion.
2. Carrier-Mediated Facilitated Diffusion.

Front 19

What are the two substances that Active Transport carries across a membrane?

Back 19

1. Molecules
2. Particles

Front 20

Name all three situations for which a molecule or particle would require Active Transport.

Back 20

1. Too large to pass through channels.
2. Incapable of dissolving in the lipid bilayer.
3. Unable to move down its concentration gradient.

Front 21

How is Active Transport similar to Facilitated Diffusion?

Back 21

Both require carrier proteins that combine specifically and reversibly with the transported substances.

Front 22

How is Active Transport different from Facilitated Diffusion?

Back 22

1. Facilitated Diffusion always obeys the concentration gradient as it’s driving force for its kinetic energy.
2. Active Transport uses solute pumps to work against the concentration gradient. This utilizes ATP.

Front 23

How is Primary Active Transport distinguishable from Secondary Active Transport?

Back 23

Distinguishable according to the source of energy.

Front 24

In Primary Active Transport, what is the direct source of energy?

Back 24

Energy comes directly from the hydrolysis of ATP.

Front 25

What is the result from the Hydrolysis of ATP in Primary Active Transport?

Back 25

Hydrolysis of ATP results in the phosphorylation of the transport protein, a step that causes the protein to change conformation in a way that pumps the bound solute across the membrane.

Front 26

In Secondary Active Transport, what is the driving force?

Back 26

Driven indirectly by energy stored in ionic gradients created by operation of Primary Active Transport pumps.

Front 27

How does Secondary Active Transport function?

Back 27

A single ATP pump can indirectly drive the Secondary Active Transport of several other solutes.

Front 28

What type of Transport exhibits a coupled systems capability?

Back 28

Secondary Active Transport.
All coupled systems: they move more than one substance at a time.

Front 29

What kind of Transport is Osmosis most similar to?

Back 29

Simple diffusion of water is known as osmosis.

Front 30

Substances that commonly undergo simple diffusion include:

Back 30

oxygen, carbon dioxide, fats, and alcohol.

Front 31

What condition does Osmosis rely entirely on to occur?

Back 31

(A very non-selective process) Relies only on particle size.

Front 32

During Facilitated Diffusion, describe the phenomena that occurs during the transport.

Back 32

It is believed that the carrier molecules engulf the substance and then change their shape to release the molecule into the cytosol.

Front 33

Explain the concept of Filtration

Back 33

Filtration is the process by which water and solutes are forced through a membrane or capillary wall by fluid or hydrostatic pressure.

Front 34

What is the difference between Filtration and all over Passive Transport Processes?

Back 34

In Filtration, the gradient is a pressure gradient rather than a concentration gradient.

Front 35

What types of molecules are used in Filtration?

Back 35

Filtration is not selective: only blood cells and protein molecules too large to pass through the membrane are held back.

Front 36

What are the two systems utilized in coupled systems when they move more than one substance across the membrane?

Back 36

Symport and Antiport Systems

Front 37

Aside from Osmosis traveling through the membranous pores, how else is water transported?

Back 37

Water also moves freely and reversibly through water specific channels constructed by transmembrane proteins called Aquaporins (AQP).

Front 38

What is an Aquaporin (AQP)?

Back 38

AQP’s are transmembrane proteins common in red blood cells and in cells involved in osmosis. For example, water balance in kidney tubule cells.

Front 39

What does the extent of Osmosis depend on?

Back 39

Depends on the NUMBER of solute molecules, since one molecule or one ion of the solute displaces one water molecule.

Front 40

How does Osmosis stop?

Back 40

As water diffuses into a cell, the point is finally reached where the hydrostatic pressure (the back pressure exerted by water against the membrane) within the cell is equal to its osmotic pressure (the cells tendency to resist further net water entry).

Front 41

Define: Hypertonic

Back 41

When a solution contains a high concentration of nonpenetrating solutes.
Cells immersed in hypertonic solutions lose water and shrink, or crenate.

Front 42

Define: Hypotonic

Back 42

When a solution contains a more dilute concentration of nonpenetrating solutes.
Cells immersed in a hypotonic solution plump up rapidly as water rushes into them.

Front 43

Protein Synthesis involves two steps, name and identify.

Back 43

Transcription: DNA’s information is encoded in mRNA

Translation: Information carried by mRNA is decoded and used to assemble polypeptides.

Front 44

What allows Transcription to begin?

Back 44

Transcription cannot begin until a gene-activating chemical called a transcription factor (TF) stimulates loosening of the histones at the site-to-be of gene transcription and then binds to the promoter.

Front 45

What is a Promoter and when is it utilized?

Back 45

Utilized in Transcription

The Promoter is a special DNA sequence adjacent to the start point of the structural gene that specifies where mRNA synthesis starts and which DNA strand is going to serve as the template strand.

Front 46

What does the Transcription Factor do once Transcription has commenced?

Back 46

The transcription factor (TF) stimulates the binding of RNA polymerase, the enzyme that oversees the synthesis of mRNA.

Once bound, it unwinds 16-18 base pairs of the DNA helix at a time.

Front 47

When does Transcription end?

Back 47

Transcription ends when the polymerase codes a termination signal.

Front 48

Overview of Transcription:
Briefly explain the 4 steps involved.

Back 48

1. Binding of RNA Polymerase to a DNA Promoter.
2. Initiation of transcription on the template DNA strand.
3. Elongation of the mRNA chain.
4. Termination of Transcription accompanied by the release of RNA Polymerase and completed mRNA from the DNA template.

Front 49

What is the role of RNA Polymerase in Transcription?

Back 49

The copying is catalyzed by this enzyme.

Front 50

The initial product of Transcription is..?

Back 50

the Primary Transcript.

Front 51

Functions of pre-messenger RNA in Transcription.

Back 51

Some of the primary transcript codes for proteins.

It is further processed in the nucleus of eukaryotes and then moves to the cytoplasm to serve as messenger RNA.