Central Dogma and Plasma Membrane Organisation and Function

Question 1

Name the two (2) cellular processes involved in gene expression in the order they occur.

Answer 1

Transcription

Translation

Question 2

Define each of these Transcription and Translation

Answer 2

Transcription: (means copy) The information in a specific region of DNA is copied to produce a specific molecule of RNA.
Translation: The RNA attaches to a ribosome where the information in the RNA is translated into amino acids to form a new protein.

Question 3

List the three (3) steps in Transcription and Translation..

Answer 3

Initiation
Elongation
Termination

Question 4

What is a codon?

Answer 4

A group of three nucleotides that identifies an amino acid.

Question 5

What are the four types of structures for proteins?

Answer 5

Primary - most basic level of structure of a protein where amino acids create a polypeptide chain
Secondary - way in which a polypeptide chain is folded or coiled
Tertiary - comprehensive three-dimensional shape with a single polypeptide ‘backbone’ with a number of secondary structure ‘side chains’
Quaternary - protein with more than one polypeptide chain

Question 6

The lipid bilayer is a biological membrane composed of two lipid molecules known as __________.

Answer 6

phospholipids

Question 7

List the three main components of the lipid bilayer

Answer 7

phospholipids
cholesterol
Glycolipids

Question 8

The lipid bilayer is composed of ___% Phospholipids, ___% Cholestrol and ___% Glycolipids.

Answer 8

75%
20%
5%

Question 9

List the two membrane Proteins of the lipid bilayer

Answer 9

Integral - Ion channel, transporter and receptor - extends down across the whole membrane
Peripheral - cell identifier, linker, enzyme - attaches at the outer surface of the membrane

Question 10

M________ F_________ ensures free rotation and movement of proteins and lipids and allows the lipid bi-layer to self-seal.

M_________ P_________is selectively semipermeable, which means that it allows small, nonpolar, uncharged molecules and water to go through it, but not ions and charged (polar) molecules

Answer 10

Membrane Fluidity

Membrane Permeability

Question 11

What are the two gradients in cells? Hint one starts with c, the other with e.

Answer 11

concentration gradient

electrical gradient

Question 12

The concentration gradient is…

Answer 12

the difference in the concentration of a molecule between two sides of the plasma membrane.

Question 13

The electrical gradient is…

Answer 13

the difference in the electrical charges across the bilayer.

Question 14

Define the process of facilitated diffusion.

Answer 14

Solutes too polar or large to move across the lipid bilayer by simple diffusion can cross the
plasma membrane by Facilitated diffusion.

Facilitated diffusion is where an integral
membrane protein assists a substance to cross the membrane.

The integral membrane protein
can be either a membrane channel or a carrier.

Question 15

_______ diffusion is a passive process in which solute moves freely through the lipid bilayer of the plasma membrane of the cell without the help of membrane transport proteins

Answer 15

Simple diffusion

Question 16

Explain in detail how glucose moves across the membrane utilising facilitated diffusion.

Answer 16

Glucose binds to a carrier protein called a glucose transporter (Glut) on the outside of the

membrane. The transporter undergoes a change in shape and glucose passes through the
membrane. The transporter releases glucose on the other side of the membrane.

Question 17

Define the process of active transport.

Answer 17

Active transport is the process where energy is required for carrier protein to move solutes across the membrane against their concentration gradient.

There are two sources of cellular energy can be used to drive active transport: Energy from ATP (adenosine Triphosphate) for primary transport and energy stored in an ionic concentration gradient is the source for secondary active transport.

Question 18

Explain in detail how glucose moves across the membrane utilising active transport.

Answer 18

Glucose is absorbed by into cells by Na+ - glucose symporters, sodium ions move down their
concentration gradient while glucose moves uphill against their concentration gradient.

Question 19

_________ is the net movement of a solvent (water) through a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration or from an area of low solute concentration to an area of high solute concentration.

Answer 19

Osmosis

Question 20

Passive transport can be affected by:

1. The steepness of the concentration gradient: Greater steepness = ______ rate of transport.
2. Temperature: _______ the temperature = faster rate of transport.
3. Size or mass of the diffusing substance: Greater the size/mass = ______ rate of transport.
4. Surface area: Greater the surface area = ______ rate of transport.
5. Diffusion distance: Greater the distance = _____ rate of transport.

Answer 20

faster 
Higher
slower 
faster 
slower

Question 21

What are the three (3) types of passive transports?

Answer 21

Simple Diffusion
Facilitated Diffusion
Osmosis

Question 22

What are the three (2) types of active transports?

Answer 22

Primary

Secondary

Question 23

In Primary Active Transport energy is derived from the hydrolysis of A____, and this pumps a substance across the plasma membrane against its concentration gradient through a carrier P_____.

Answer 23

ATP, protein

Question 24

In Secondary active transport uses energy stored in a N_____ or H_____ concentration gradient to drive other substances against their own concentration gradient through carrier proteins (cotransporter).

The gradient is established by/maintained via p______ active transport.

Answer 24

Na+ or H+

primary active transport

Question 25

In Secondary active transport a_______ move two substances in the opposite direction and s_______ in the same direction.

Answer 25

antiporters, symporters

Question 26

Define secondary active transport.

Answer 26

Energy stored in a Na+ or H+ concentration gradient drives other substances against their own concentration gradient through carrier proteins.

Question 27

Describe how glucose is actively transported across the cell membrane.

Answer 27

Na+ travels down its concentration gradient via a symporter, glucose enters the cell against
its concentration gradient via the same symporter.

Question 28

Describe how calcium is actively transported across the cell membrane.

Answer 28

Na+ travels down its concentration gradient via a antiporter, calcium exits the cell against its
concentration gradient via the same antiporter.