Life at the Cellular Level

Question 1

What is the structure and function of the Cell membrane

Answer 1

Phospholipid bilayer
Proteins within the membrane act as receptors to detect chemical messengers and signaling molecules in the fluid surrounding cells

Question 2

Types of Cytoskeleton and its function

Answer 2

Microfilaments
Intermediate filaments
Microtubules

-Supports and maintains CELL SHAPE
-Holds organelles in position - INTERNAL CELL ORDER
-Helps move organelles around the cell - INTACELLULASR TRANSPORT
-Drives and guides cellular migration – MOVEMENT
Protein fibres of the cytoskeleton connect with protein fibres in the extracellular space - ASSEMBLY OF CELLS INTO TISSUES

Question 3

Smooth and Rough endoplasmic reticulum (SER & RER)

Answer 3

SER
- no ribosomes attatched
- mainly associated with lipid and steroid hormone production and metabolism of toxins

RER
- modifies proteins
- has ribosomes attacthed giving it the “rough” appearance

Question 4

Lysosomes

Answer 4

• membrane bound vesicles containing enzymes - they seperate enzymes from the rest of the cell
• Degradative (responsible for the digestion of biological materials)

Question 5

Peroxisomes

Answer 5

• membrane bound vesicles containing enzymes - seperate enzymes from the rest of the cell
• degrade long-chain fatty acids and other foreign toxic molecules - this reaction generate hydrogen peroxide
• peroxisomes break the hydrogen peroxide, protecting the cell

Question 6

Apoptosis vs Necrosis

Answer 6

Apoptosis - controlled, programmed cell death - normal process - essential for normal function

Necrosis - untimely death of cells in response to injury or infection - NOT a normal process

Question 7

Proliferation

Answer 7

Loss of balance between apoptosis and proliferation
- divide without any control
- associated with some CANCERS
- Fail to coordinate with normal cells
- Fail to differentiate into specialized cells
- Displace and replace the normal cells if not stopped

Question 8

Chemical reactions of life

Answer 8

1. Redox reactions
2. Making and breaking C-C bonds
3. Internal rearrangements
4. Group transfers
5. Condensation and hydrolysis reactions

Question 9

Redox reactions

Answer 9

OIL = Oxidation Is Loss
RIG = Reductions Is Gain
LATCL1 - slide 33

Question 10

Making/breaking C-C bonds

Answer 10

LATCL1 - 37

Question 11

Internal rearrangements

Answer 11

LATCL1 - 38

Question 12

Group transfers

Answer 12

LATCL - 39

Question 13

Condensation and hydrolysis

Answer 13

LATCL - 40

Question 14

Proteins structure

Answer 14

long chains of amino acids - formed by condensation reactions ( releases water)

Question 15

Lipids structure

Answer 15

Mainly consists of repeating units of FATTY ACIDS (FAs) - long chains of C and H
bonds between C atoms can be single or double
Saturated - All bonds are single
Mono-unsaturated - one double bond
Poly-unsaturated - more than one double bond

more double bonds in chain - more fluid the fatty acid

Question 16

Nucleic acids structure

Question 17

Hydrophilic molecules

Answer 17

• Molecules that dissolve in water (water loving)
  Examples: Sugars, Alcohols, Aldehydes, Ketones, Compounds with N-H groups, Charged particles (ions)

Question 18

Water as a solvent

Answer 18

• Water is a polar molecule
• This gives a slight positive charge to the H atoms
• And a slight negative charge to the O atoms
• Water forms a “screen” around charged particles - keeps the ions in solution once dissolved

Question 19

Hydrophobic molecules

Answer 19

• Do not dissolve in water, but do dissolve in lipid (water hating)
• Arrange themselves in water so as to minimise contact with surrounding water molecules - HYDROPHOBIC EFFECT
  Examples: Fat soluble vitamins, Lipids, Steroid hormones, Oxygen

Question 20

Amphipathic molecules

Answer 20

• Contain both HYDROPHOBIC AND HYDROPHILIC parts
• many proteins are amphipathic

hydrophobic regions of the protein chain - on inside
hydrophilic regions - on outside

• This allows them to be water-soluble

Examples:

Question 21

Micelle vs Liposome

Answer 21

Micelle - single layer of phospholipid - no core

Liposome - lipid bilayer outer shell - hollow core

both used as drug-delivery systems

Question 22

Chylomicron

Answer 22

used for the transport of liquids in the blood

• like a liposome with protein embedded in the shell
• lipid stored in the core

Question 23

What is pH

Answer 23

pH is the way of designating the concentration of H+ in any aqueous solution

Water has a neutral pH because H+ and OH- are equal

Acidic solutions - Greater H+ and Lower OH-

Basic (alkaline) solutions - Lower H+ and Greater OH-

Question 24

Buffers

Answer 24

Buffers are SOLUTIONS THAT RESIST CHANGES IN pH

WEAK ACIDS AND BASES only partially dissociate - gives unique properties, including the ability to act as a buffer

proteins and DNA can be affected by pH as their chape is dictated by the pH of their environment
- and so for optimal activity they must be at an optimal pH
- maintained by using weak acids and their bases

Question 25

Types of cell surface projections and their properties

Answer 25

• Cilia - SHORT, usually MANY present, move with stiff power stroke and flexible recovery stroke
• Flagella - LONGER, usually ONE or TWO present, movement is snakelike

Question 26

Metabolism

Question 28

Catabolism & Anabolism

Answer 28

Catabolism - energetically FAVOURABLE reaction
(catabolic) - Each step is catalysed by an enzyme

LATCL3-25

Anabolism - energetically UNFAVOURABLE reaction