Week 2: Building Blocks

Question 1

What happens in autocatalytic reactions?

Answer 1

Simple building blocks come together to give a complex product.

The product then aggregates to give primitive cell-like structures or “protocells” such as micelles or vesicles.

The protocells speed up reactions in time and give rise to more complex behaviour.

Question 2

What is Darwin’s theory of evolution?

Answer 2

Processes by which genetic mutation that enhance reproduction become more common in successive generations of a population.

Question 3

What are the two classes of cells?

Answer 3

Prokaryotic (bacteria)
Eukaryotic

Question 4

What is the difference between the two classes of cells?

Answer 4

Prokaryotic cells lack a nuclear envelope, whereas eukaryotic cells have their nuclear material separated from the cytoplasm.

Question 5

What indicates the evolutionary relationship between the two types of cell?

Answer 5

Prokaryotic cells are smaller and simpler, but they share the same molecular mechanisms governing their lives as eukaryotic cells, indicating their evolutionary relationship.

Question 6

What are the major differences between the structure of prokaryotic and eukaryotic cells?

Answer 6

Prokaryotes don’t have a nucleus and rarely have membrane bound organelles.

Question 7

What are the similarities between the structure of prokaryotic and eukaryotic cells?

Answer 7

Both have DNA as genetic material, have exterior membranes, have ribosomes, accomplish similar functions and are very diverse.

Question 8

Sketch a basic eukaryote.

Answer 8

(11)

Question 9

Sketch a basic prokaryote.

Answer 9

(12)

Question 10

What shape are most bacterial cells?

Answer 10

Spherical, rod-like, or spiral.

Question 11

What is the range of diameters of most bacterial cells?

Answer 11

1-10 um

Question 12

What is the structure of E. coli?

Answer 12

Rod-shaped, about 1um in diameter and 2um long.

It is surrounded by a rigid wall composed of polysaccharides and peptides.

Within the cell wall is the plasma membrane composed of a phospholipid bilayer and associated proteins.

The DNA is a singular circular molecule in the nucleoid and is not surrounded by a membrane separating it from the cytoplasm.

Question 13

What components are eukaryotic cells made up of?

Answer 13

Nucleus
Ribosomes
Mitochondria
Chloroplasts
Lysosomes

Question 14

What happens in the nucleus of a eukaryotic cell?

Answer 14

Where DNA replication and RNA synthesis occurs.

Question 15

What happens in the ribosomes of a eukaryotic cell?

Answer 15

Where the translation of RNA into proteins takes place.

Question 16

What happens in the mitochondria of a eukaryotic cell?

Answer 16

They plat a role in energy metabolism. They are the site for oxidative reaction and are responsible for generating most ATP derived from the breakdown of organic molecules.

Question 17

What happens in the chloroplasts of a eukaryotic cell?

Answer 17

The sites of photosynthesis and are found only in plant cells and green algae.

Question 18

What happens in the lysosomes of a eukaryotic cell?

Answer 18

Provide specialised metabolic compartments for digestion of macromolecules and oxidative reactions.

Question 19

Give examples of eukaryotic cells.

Answer 19

Protist
Plant cell
Budding yeast cell
Red blood cell
Fibroblast cell
Nerve cell
Retinal rod cell

Question 20

What surrounds the nucleus?

Answer 20

The nucleus is membrane bound and is surrounded by a double membrane.

Question 21

How does DNA vary in different parts of the body?

Answer 21

DNA is similar in every cell in the body. However, depending on the specific cell type, some genes may be turned on or off.

Question 22

What is the prominent structure in the nucleus and what is its role?

Answer 22

The nucleolus.

Produces ribosomes, which move out of the nucleus to positions on the rough endoplasmic reticulum where they undertake protein synthesis.

Question 23

What is the role of the mitochondria?

Answer 23

Provides the energy to a cell to move, divide, produce secretory products and contract.

Question 24

How are mitochondria structured?

Answer 24

Are membrane-bound with a double membrane.

The outer membrane is fairly smooth but the inner membrane is highly convoluted forming folds called cristae.

Question 25

What happens on the cristae of the mitochondria?

Answer 25

Sugar is combined with oxygen to produce ATP, the primary energy source for the cell.

Question 26

What does endoplasmic reticulum do?

Answer 26

Functions in both the processing and transport of proteins and the synthesis of lipids.

Question 27

What happens at the Golgi apparatus?

Answer 27

The proteins are further processed and sorted for transport to their final destinations. Carbohydrates are synthesised here and it is also the site of lipid synthesis.

Question 28

What is the cytoskeleton?

Answer 28

Is a network of protein filaments extending throughout the cytoplasm. It determines the structural framework, the cell shape and is responsible for movement of entire cells.

Question 29

What are the five main types of tissues?

Answer 29

Epithelial cells Connective tissues Blood Nervous tissue Muscle cells

Question 30

What do epithelial cells do?

Answer 30

Form sheets covering body surface and line the internal organs.

Question 31

What are the connective tissues?

Answer 31

Bones and cartilage.

Question 32

What are the blood tissues?

Answer 32

Contains red blood cells for oxygen transport, inflammatory reactions and immune response.

Question 33

What do nervous tissues consist of?

Answer 33

Nerve cells (neurons) and sensory cells (ear, eye).

Question 34

What are muscle cells responsible for?

Answer 34

Production of force and movement.

Question 35

What processes can be studied by looking at prokaryotic cells?

Answer 35

Molecular genetics DNA replication Genetic code Gene expression Protein synthesis

Question 36

Why are prokaryotic cells suitable to look at fundamental processes?

Answer 36

Small genome size Rapid growth (20-40 min cycle) Simple nutritional requirements

Question 37

What are the three essential components in a living cell?

Answer 37

Nucleus Ribosomes Mitochondria

Question 38

What is the biological function of the nucleus?

Answer 38

Where DNA replication and RNA synthesis occur.

Question 39

What is the biological function of ribosomes?

Answer 39

Where the translation of RNA into proteins take place.

Question 40

What is the biological function of the mitochondria?

Answer 40

Is the site to undertake energy metabolism and provide with the energy. They are also the site for oxidative reactions and are responsible for generating most ATPs derived from the breakdown of organic molecules.

Question 41

How do cells construct their subcellular compartments?

Answer 41

In eukaryotic cells, each subcellular compartment is surrounded by membrane lipids. Within each compartment, molecules of different sizes and nature are uniquely organised; packed in unique morphological structures from micron to nano scale. These hierarchical organisations are often termed self-assembly or co-assembly, driven by inter and intra-molecular interactions such as van der Waals, electrostatic and H-bonding.

Question 42

Briefly describe the key structural features of a membrane lipid.

Answer 42

Carry 2 hydrophobic acyl chains and one zwitterionic, polar or charged heads. Hydrophobic >> hydrophilic so are spreadable on the surface of water but not soluble. Packed into a membrane bilayer quickly through self assembly so that the hydrophobic chains are packed away from direct water exposure.

Question 43

Explain the difference between prokaryotic and eukaryotic cells.

Answer 43

Prokaryotic cells are much simpler in terms of subcellular compartments and more importantly, their nucleus is not covered by a membrane.

Question 44

Describe the structural differences between cell types.

Answer 44

Bacterial cells, such as E. coli, have a very rigid cell wall and they look mostly rod-like, thus with a distinct size and shape. Mammalian cells do not have a rigid membrane or cell wall, they are very soft, looking similar to a cracked egg.

Question 45

Describe the difference in growth conditions between cell types.

Answer 45

Growth conditions are very different, requiring different growth media, nutrition or energy. For example, plant cells can grow on sugar and lights, whilst mammalian cells rely on sugar, protein and inorganic nutrients.