Unit 3 - AOS 1 - CH 1.3 - Reviewing cells

Question 1

SA: V

Answer 1

It is more efficient for cells to be smaller because they have a larger surface area to volume ratio -> allows for the movement of nutrients and waste to occur quickly ( low ratio = no survival)

Question 2

Cell theory

Answer 2

1. All organisms are made from 1 or more cells
2. Cells are the basic unit of structure and function in living things
3. All cells come from pre-existing cells

Question 3

Nucleus

Answer 3

Structure: Membrane surrounded by nucleur envelope (continuous with ER)

Function: Houses chromosomes made of chromatin (DNA, proteins). Contains nucleolus -> ribosomal sub-units are synthesised and assembled

Question 4

Ribosomes

Answer 4

Structure: mall and large ribosomal sub-units found in cytosol or bound to ER

Function: protein synthesis
- Small = read mRNA

Question 5

Endoplasmic reticulum

Answer 5

Structure: Part of interconnected flattened network, membrane-enclosed sacs. Membrane is continuous with nucleus.

Function:
Smooth - synthesis of lipids, metabolism of carbs, calcium storage and detoxication of drugs and poison.
Rough - Synthesis of specific proteins from bound ribosomes.

Question 6

Golgi apparatus

Answer 6

Structure: Collection of fused, flattened sacs = 1 membrane.

Function: Modifies, sorts, tags, packages and distributed proteins to be secreted via vesicles

Question 7

Lysosomes

Answer 7

Structure: Membrane-enclosed sacs of hydrolytic enzymes

Function: Breaks down ingested substances, cell macromolecules and damaged organelles for recycling

Question 8

Vacuoles

Answer 8

Structure: large membrane-bound vesicles

Function: Digestion, storage, waste disposal, water balance, cell growth and protection.

Question 9

Peroxisomes

Answer 9

Structure: Metabolic compartment bound by a single membrane

Function: Transfers hydrogen to water, producing hydrogen peroxide (H2O2), as a by-produce, which is converted to water by other enzymes in the peroxisomes.

Question 10

Mitochondria

Answer 10

Structure: Bound by double membrane, inner membrane has series of folds (cistae) containing enzymes for ATP synthesis.

Function: Site of cellular respiration & ATP synthesis

Question 11

Chloroplasts

Answer 11

Structure: Double membrane around fluid Stoma, containing membranous thyrakloid stacks (sacs) in the grana.

Function: Photosynthesis -> inorganic compounds converted to chemical energy = oxygen and energy ruck organic compounds (sugars)

Question 12

Plasma (Cell) Membrane

Answer 12

Structure: Phospholipid bi-layer with transport and receptor proteins, enclosed in a single membrane. = semi-permeable (only some materials may enter/exit)

Function: Controls the passage of material into and out of cell

Question 13

Phospholipid Structure

Answer 13

POLAR HEAD - Hydrophilic
1. Phosphate group (+)
2. Glycerol (-)

NONPOLAR TAILS - Hydrophobic
1. two chains fatty acids

Question 14

Polar molecule definition

Answer 14

“A molecule that has one negative and one positive charged area.”

Question 15

Cholesterol function (plasma membrane)

Answer 15

• Prevents phospholipids from separating too far
• Flexibility

Question 16

Protein channels (plasma membrane)

Answer 16

Function: allows large substances/ ions to pass

Integral: internal channel
Peripheral: exterior

Question 17

Carbohydrates function (plasma membrane)

Answer 17

• Identification/recognition

Glycoprotein: joins trans-membrane proteins
Glycolipid: Joins with lipids

Question 18

Cytoskeleton function (plasma membrane)

Answer 18

• Protein threads that provide internal support and pathways for molecule transport

Question 19

Definition of passive transport

Answer 19

“Movement of molecules down the concentration gradient (high to low)”

• No cellular energy needed
• Aim is to reach equalibrium

Question 19

Definition of active transport

Answer 19

“Movement of molecules from a low to high concentration (against the concentration gradient)”

• ATP cellular energy needed

Question 19

Examples of passive transport

Answer 19

DIFFUSION: Movement from high to low concentration
e.g., oxygen entering blood stream

OSMOSIS: Movement of water, to create equalibrium between 2 solutions
e.g., cells placed in distilled water will increase in size

FAILITATED DIFFUSION: using protein channel
e.g., removing glucose from blood cell

Question 19

Examples of active transport

Answer 19

ENDOCYTOSIS: into cell (piocytosis, phagocytosis)
EXOCYTOSIS: out of cell

SODIUM/POTASSIUM PUMP: sodium (Na) pumped ouy or potassium (K) pumped into neurons
CONTRACTILE VACUOLE: H2O pumped out to prevent bursting. )osmosis is constanly trying to create equalibrium but this prevents the cell from bursting.