Prokaryotic and Eukaryotic Cell Systems

Question 1

What are the 2 major prokaryotes?

Answer 1

• bacteria (e.g. E. coli)

- archaea (single called organism)

Question 2

What are the 4 main structures share by all prokaryotes, bacteria and archaea

Answer 2

1. The plasma membrane
2. Cytoplasm
3. Ribosomes
4. Genetic material (DNA and RNA)

Question 3

What extra cellular features doe prokaryotes have (that eukaryotes do not)?

Answer 3

• a cell wall
• pili
• flagella

Question 4

What are the functions of a plasma membrane?

Answer 4

• contain the cell (physical limits)
• control of what comes in and out of the cell
• communicate with the surrounding environments

Question 5

Describe the prokaryotic cytoplasm

Answer 5

The cytoplasm in prokaryotic cells is a gel-like fluid (called Jello)

-contains: gDNA, plasmid DNA, ribosomes and proteins

Question 6

Describe a prokaryotic ribosome

Answer 6

They are smaller, slightly different shape and conposition than eukaryotic ribosomes

They have about half the ribosomal RNA (rRNA) and 1/3 fewer proteins than eukaryotic ribosomes

Question 7

Describe prokaryotic genetic material

Answer 7

• contains large quantities of genetic material in the form of RNA and DNA
• the DNA looks like a sting in the middle of the cell
• there is no nucleus
• has minimal genomes(prokaryotic genomes are much smaller that eukaryotic genomes)

Question 8

What is the typical prokaryotic gene structure?

Answer 8

• absence of introns (non-coding sequence

- polycistronic, presence of operons (several genes expressed under the same promotor in the mRNA

Question 9

What does the cell wall (prokaryotes) provide?

Answer 9

Strength and rigidity

Question 10

What is the cell wall (prokaryotes) composed of?

Answer 10

• a peptidoglycan (sugar and peptide molecule
• proteins
• polysaccharides
• lipids

Question 11

Describe a Gram+ cell wall

Answer 11

• relatively thick and featureless under an electron microscope
• peptidoglycan is major component (~50%)
• no lipid and often no protein
• polymers (teichoic acid and/or teichuronic acid) covalently bonded to peptidoglycan

Question 12

Describe a Gram- cell wall

Answer 12

• the cell envelope consists of 2 membranes-the cytoplasmic and the outer membrane with a thin layer of peptidoglycan in between
• the outer membrane contains lipopolysaccharides (LPS), lipids and proteins- LPS is located exclusively in the outer membrane with lipid embedded in the membrane and polysaccharide protruding from it

Question 13

What are the 4 main characteristics of eukaryotic cells?

Answer 13

1. eukaryotes have DNA organised in chromosomes complexed with histones (within a double membrane)
2. its cytoplasm is defined and supported by a complex cytoskeleton system controlling organelle movement
3. have an external glycocalyx (animals) or cell wall (plants, algae, fungi)
4. complex internal membrane system in which membrane is cycled via a cellular packaging and dispatch centre (the Golgi body)

Question 14

What are ‘histones’?

Answer 14

Any of a group of 5 small basic proteins, occurring in the nucleus of eukaryotic cells, that organise DNA into strands into nucleosomes by forming molecular complexes are which the DNA winds

Question 15

What are the 5 main structures shared by all eukaryotes?

Answer 15

1. Plasma membrane
2. Cytoplasm
3. Ribosomes
4. Genetic material (DNA/RNA)
5. Organelles

Question 16

Describe the plasma membrane of a eukaryote

Answer 16

There plasma membrane is similar to that of a prokaryote, but larger

Eukaryotic cells contain internal membranes that delimit the different organelles

Question 17

Describe the membrane of a vacuole

Answer 17

Surrounded by a single membrane, similar to the plasma membrane

Called the tonoplast

Question 18

Describe the membrane of the Golgi apparatus and endoplasmic reticulum

Answer 18

Bound by a single membrane

Question 19

Describe the membrane of the mitochondria

Answer 19

It is surrounded by an outer membrane and an inner membrane to create a matrix (2 membranes)

Question 20

Describe the membrane of the chloroplast

Answer 20

Surrounded by 2 membranes containing a membrane network called thylakoids (envelope)

Question 21

Describe the membrane of the nucleus

Answer 21

2 membranes to create an envelope

Question 22

Describe the eukaryotic cytoplasm

Answer 22

It is more complex than that of prokaryotes as it contains proteins and metabolites

Question 23

What qualities does the eukaryotic cytoplasm give the cell?

Answer 23

• structure
• cellular movements
• cell signalling

Question 24

Describe a eukaryotic ribosome

Answer 24

Eukaryotic ribosomes are larger with a different shape and composition- also have more RNA and proteins than prokaryotes

Question 25

Describe eukaryotic genetic material

Answer 25

The DNA is organised in chromosomes with complex histones

Contained in a double membrane bound nucleus

Eukaryotes have more DNA than prokaryotes, also have a higher genetic complexity

Question 26

Describe the eukaryotic gene structure

Answer 26

• presence of introns in genes (one gene encodes on protein)
• genes are monocistronic = they function as single units and are expressed individually under the control of individual promoters

Question 27

Name the organelles that all eukaryotic cells have

Answer 27

• a nucleus
• mitochondria
• Golgi and ER

Question 28

Name the additional organelles that plants and algae have

Answer 28

• large vacuoles
• plastids (chloroplasts and amyloplasts-responsible for the synthesis and storage of starch granules through the polymerisation of glucose

Question 29

Describe the eukaryotic cell wall

Answer 29

Eukaryotes either have an external glycocalyx or a cell wall

Plants, algae and fungi have a cell wall made out of cellulose

Animal cells have a glycocalyx, a fuzz-like coat made of glycoproteins and polysaccharides

Question 30

What is the size of the cell in prokaryotes and eukaryotes?

Answer 30

Prokaryotes:
Typically 0.2-2.0μm (diameter)

Eukaryotes:
Typically 10-100μm (diameter)

Question 31

Are there membrane-enclosed organelles in prokaryotes and eukaryotes?

Answer 31

Prokaryotes:
Absent

Eukaryotes:
Present (lysosomes, Golgi, ER, mitochondria, chloroplasts, nucleus etc)

Question 32

What is the flagella like in prokaryotes and eukaryotes?

Answer 32

Prokaryotes:
Consists of 2 protein building blocks

Eukaryotes:
Complex-consists if multiple microtubules

Question 33

Describe the glycocalyx in prokaryotes and eukaryotes

Answer 33

Prokaryotes:
Present as a capsule or slime layer

Eukaryotes:
Present in some cells that lack cell wall

Question 34

Describe the cell wall in prokaryotes and eukaryotes

Answer 34

Prokaryotes:
Usually present, chemically complex

Eukaryotes:
When present chemically simple

Question 35

Describe the plasma membrane in prokaryotes and eukaryotes

Answer 35

Prokaryotes:
No carbohydrates and generally lack sterols

Eukaryotes:
Sterols and carbohydrates that serve as receptors present

Question 36

Describe the cytoplasm in prokaryotes and eukaryotes

Answer 36

Prokaryotes:
No cytoskeleton or cytoplasmic streaming

Eukaryotes:
Cytoplasmic streaming and cytoskeleton

Question 37

Describe the ribosomes in prokaryotes and eukaryotes

Answer 37

Prokaryotes:
Smaller (70S)

Eukaryotes:
Larger (80S)

Question 38

Describe the chromosomal arrangement in prokaryotes and eukaryotes

Answer 38

Prokaryotes:
Single circular chromosomes - lack histones

Eukaryotes:
Multiple linear chromosomes with histones

Question 39

How do prokaryotes and eukaryotes divide?

Answer 39

Prokaryotes:
Binary fission, conjugation, budding, fragmentation

Eukaryotes:
Mitosis, meiosis

Question 40

Describe sexual reproduction in prokaryotes and eukaryotes

Answer 40

Prokaryotes:
No meiosis -transfer of DNA fragments only (conjugation)

Eukaryotes:
Involves meiosis