AOS1: Cellular Structure and function

Question 1

* cells as the basic structural feature of life on Earth,

Cell theory

3 points

Answer 1

All living organisms are composed of one or more cells.

A cell is the basic structural and functional unit of living organisms.

All cells arise from pre-existing cells.

Question 2

including the distinction between prokaryotic and eukaryotic cells

Prokaryotic Cells VS Eukaryotic Cells

Answer 2

Size
Unicellular/Multicellular
Membrane-bound organelles
Division (binary fission vs mitosis and meiosis)
Type of DNA (circular, plasmids vs linear dna in nucleus)

Capsules, cell wall, flagella and pili
Kingdoms (bacteria and archeae vs others)

Question 3

* SA:V ratio as an important factor in the limitations of cell size

What is the importance of SA:V ratio?

Answer 3

Improves the efficiency of nutrients, and waste disposal because of less distance/closer to the extracellular environment.
1. Efficient material exchange with the extracellular environment (nutrient, oxygen, waste/toxin disposal)
2. Intracellular transport is quicker due to smaller travel distance

Long, short and thin/flat = increased SA:V ratio
Big, wide= decreased SA:V ratio
Cell size: Cells require a larger SA:V to perform functions (cellular functions)

Question 4

need for internal compartments (organelles) w/ cellular functions

Why do we need SA:V ratio for organelles?

Answer 4

Increase efficiency of production, quick access to the environment, certain organelles with features (chloroplasts and mitochondria).
Examples:
Chloroplasts have many granum (stacks of multiple thin, flat plates), increasing SA:V ratio, light absorption, and photosynthesis.
Mitochondria have cristae which are heavily folded to increase surface redox reactions and cellular respiration.
Small intestine has villi and microvilli to increase nutrient absorption.

Question 5

* the structure and specialisation of plant…organelles (chloroplasts)

Types of plant organelles

Answer 5

-chloroplasts (photosynthesis)
-cell wall (maintain rigid, turgid structure)
-one large vacuole

Question 6

* the structure and specialisation of animal cell organelles (e.g mitoch

Types of animal organelles

Answer 6

-multiple small vacuoles
-no cell wall
-no chloroplasts

Question 7

Mitochondria Importance

Answer 7

-site of aerobic respiration to produce energy
-energy=ATP

Question 8

Chloroplast importance

Answer 8

-site of photosynthesis
-produces sugars (glucose) for plants

Question 9

* the structure and function of the plasma membrane

Purpose and structure of plasma membrane

Fluid mosaic model, types of proteins

Answer 9

Made of a phospholipid bilayer
Phospholipids= 1 x hydrophilic/polar head (alcohol and phosphate group) + 2 x hydrophobic tails (fatty acid chains).
Fluid: phospholipids which move side to side/laterally
Mosaic: proteins and carbohydrates embedded

Fluid “

Question 10

Function and Types of Proteins in the plasma membrane

Answer 10

Function: transport, catalysis (speeds up reactions, enzymes), communication (signal other cells), adhesion (stick to other cells)
Types:
-Integral-permanent
-Transmembrane- integral that spans the entire membrane
-Peripheral- temporarily attached

Question 11

….passage of water, hydrophilic and hydrophobic substances via osmosis

Osmosis
What substances?
Through where?

Answer 11

Water, hydrophillic substances
Aquaporins, through plasma membrane

-Movement of water from high to low concentration via aquaporins/through plasma membrane
-Water and small hydrophilic substances dissolved in water

Question 12

Function of Chlosterol and Carbohydrates

Answer 12

Cholesterol: lipid steroid regulates membrane fluidity and adds flexibility
Carbohydrates: (glycolipids or proteins) communication, signalling, recognition of foreign cells and adhesion

Question 13

water, hydrophilic, hydrophobic substances via facilitated diffusion

Facilitated diffusion:
What substances?
Through where?

Answer 13

Large, polar, hydrophobic substances
Protein channels

Question 14

water, hydrophilic and hydrophobic substances via active transport

Active transport:
What substances?
Through where?

Answer 14

-Movement of molecules with energy via protein pumps (binding, conformational change and release).
-Two types: protein-mediated and bulk transport.

Question 15

Simple Diffusion:
What substances?
Through where?

Answer 15

-passive movement of molecules from areas of
high concentration to areas of low concentration (down the concentration gradient) through the plasma membrane
-Small, non-polar (uncharged) hydrophobic

Question 16

hydrophilic and hydrophobic substances

Hydrophilic VS hydrophobic substances
Give examples of each.

Answer 16

Hydrophilic: attracted to and dissolve in water
-Usually polar (a molecule with both positive and negative end).

Hydrophobic: repel and be insoluble in water
-Usually non-polar (without a clearly positive or negative end)

Question 17

What parts of the plasma membrane should be included when drawing?

Answer 17

Must include:
proteins, glycolipids, glycoproteins, nonpolar/polar, phospholipid bilayer, polar/non-polar, channels, extracellular/intracellular fluid/cytoplasm

Question 18

Bulk transport
What are the two types? Describe steps.

Answer 18

-(aka cytosis) type of active transport via vesicles to move large molecules in and out of the cell.
-exocytosis “exit” (1. vesicular transport 2. fusion 3. release)
-endocytosis “enter” (1. fold 2. trap 3. bud)