Types of Cells

Question 1

3 main differences between prokaryotic and eukaryotic.

Answer 1

• Eukaryotic cells have a separate membrane-enclosed nucleus, whereas the DNA of prokaryotes is freely floating in the cytoplasm.
• Eukaryotic cells have a complex system of membrane-bound organelles that divides the cell into numerous enclosed regions – known as compartmentalisation. Prokaryotes do not have any membrane-bound organelles.
• Prokaryotes have 70s ribosomes while Eukaryotic 80s ribosomes
• Prokaryotes have naked loops of DNA while Eukaryotic have strands associated with proteins. 4 or more chromosomes present.

Question 2

Cell wall Function (Prokaryotic)

Answer 2

Encloses the cell, protecting it and helping to maintain its shape; prevents the cell from bursting in hypotonic (dilute) media.

Question 3

Plasma membrane Function (Prokaryotic)

Answer 3

Surrounds the cell, controlling the movement of substances in and out of the cell.

Question 4

Cytoplasm (Prokaryotic)

Answer 4

Medium that fills the cell and is the site of all metabolic reactions.

Question 5

Pili (singular: pilus) (Prokaryotic)

Answer 5

Protein filaments on the cell wall that help in cell adhesion and in transferring of DNA between two cells.

Question 6

Flagella (singular: flagellum) (Prokaryotic)

Answer 6

Much longer than pili, these are responsible for the locomotion of the organism. Their whip-like movement propels the cell along.

Question 7

70S ribosomes (Prokaryotic)

Answer 7

Are the sites of protein synthesis.

Question 8

Nucleoid region (which includes naked DNA, that is, DNA not associated with proteins known as histones)
(Prokaryotic)

Answer 8

Controls all the activities of the cell, as well as the reproduction of the organism.

Question 9

Plasmids (Prokaryotic)

Answer 9

Small circles of DNA that carry a few genes; often these genes give the cell antibiotic resistance and are used in creating genetically modified bacteria.

Question 10

Prokaryotes reproduce by …

Answer 10

reproduce by binary fission

Question 11

Binary fission

Answer 11

is a means used by prokaryotes to reproduce asexually.

Question 12

Compartmentalisation

Answer 12

refers to the formation of compartments within the cell by membrane-bound organelles.

Question 13

Pros of Eukaryotic cells being compartmentalised

Answer 13

• Greater efficiency of metabolism as enzymes and substrates are enclosed, and therefore much more concentrated, in the particular organelles responsible for specific functions.
• Internal conditions such as pH can be differentiated in a cell to maintain the optimal conditions for different enzymes.
• Isolation of toxic or damaging substances away from the cytoplasm, such as the storage of hydrolytic enzymes in lysosomes.
• Flexibility of changing the numbers and position of organelles within the cell based on the cell’s requirements.

Question 14

Plasma membrane Function (Eukaryotic)

Answer 14

Controls the movement of substances in and out of the cell.

Question 15

Cytoplasm Function (Eukaryotic)

Answer 15

Fills the cell and holds all organelles. It also contains enzymes that catalyse various reactions (such as glycolysis) occurring within the cytoplasm.

Question 16

Mitochondria (singular: mitochondrion) (Eukaryotic)

Answer 16

A site of cellular respiration in which ATP is generated.

Question 17

80S Ribosomes (Eukaryotic)

Answer 17

The sites of protein synthesis. Free ribosomes produce proteins used inside the cell itself.

Question 18

Nucleus (Eukaryotic)

Answer 18

Controls all the activities of the cell, as well as the reproduction of unicellular organisms.

Question 19

Nucleolus (Eukaryotic)

Answer 19

Part of the nucleus which is involved in the production of ribosomes.

Question 20

Smooth endoplasmic reticulum (Eukaryotic)

Answer 20

Responsible for producing and storing lipids, including steroids.

Question 21

Rough endoplasmic reticulum (Eukaryotic)

Answer 21

Transports the protein produced by the ribosomes on its surface to the Golgi apparatus. These proteins are usually for use outside of the cell.

Question 22

Golgi apparatus (Eukaryotic)

Answer 22

Processes and packages proteins, which are ultimately released in Golgi vesicles.

Question 23

Vesicle (Eukaryotic)

Answer 23

A small sac that transports and releases substances produced by the cell by fusing with the cell membrane.

Question 24

Lysosomes (absent from plant cells) (Eukaryotic)

Answer 24

Contain hydrolytic enzymes and play important roles in the destruction of microbes engulfed by white blood cells, as well as in the destruction of old cellular organelles.

Question 25

Centrioles (absent from plant cells) (Eukaryotic)

Answer 25

Play an important role in the process of nuclear division by helping to establish the microtubules.

Question 26

Vacuole (Eukaryotic)

Answer 26

Helps in the osmotic balance of the cell and in the storage of substances. It may also have hydrolytic functions similar to lysosomes.

Question 27

Cell wall (absent from animal cells) (Eukaryotic)

Answer 27

Protects the cell, maintains its shape and prevents it from bursting in hypotonic media.

Question 28

Chloroplast (absent from animal cells) (Eukaryotic)

Answer 28

These are double-membrane-bound organelles. They contain pigments (in this case mainly chlorophyll) and are responsible for photosynthesis.

Question 29

Microscope resolution

Answer 29

Microscope resolution is the shortest distance between two separate points in a microscope’s field of view that can still be distinguished as distinct objects.