2.1.2 Structure of Prokaryotic cells and of viruses

Question 1

Which are smaller, prokaryotes or eukaryotes?

Answer 1

prokaryotes

Question 2

Do prokaryotic cells or eukaryotic cells have membrane-bound organisms?

Answer 2

eukaryotic

Question 3

Do prokaryotic cells have larger or smaller ribosomes than eukaryotic cells?

Answer 3

smaller

Question 4

Do prokaryotic cells have a nucleus?

Answer 4

no

Question 5

What do prokaryotic cells have instead of a nucleus?

Answer 5

a single circular chromosome, which is free in the cytoplasm

Question 6

Do prokaryotic cells have mitochondria?

Answer 6

no

Question 7

Do prokaryotic cells have chloroplasts?

Answer 7

no - but can still photosynthesise

Question 8

Do prokaryotic cells have an endoplasmic reticulum?

Answer 8

no

Question 9

Do prokaryotic cells have a Golgi apparatus?

Answer 9

no

Question 10

What is the cell wall made of in prokaryotic cells?

Answer 10

murein

Question 11

Are plasmids present in every prokaryote?

Answer 11

no - only some

Question 12

What are plasmids?

Answer 12

small loops of additional DNA which only carry a few genes

Question 13

Does every prokaryote have a capsule?

Answer 13

no - only some

Question 14

What is a capsule?

Answer 14

a thick slimy layer on the outside of the cell wall (made of protein)

Question 15

What is the purpose of the capsule?

Answer 15

• prevents the bacteria from drying out
• protects the bacteria against the hosts immune system

Question 16

Does every prokaryote have flagella?

Answer 16

no - only some

Question 17

What is the purpose of the flagella?

Answer 17

it rotates to enable the bacteria to move

Question 18

Give 3 features found in all virus particles:

Answer 18

• genetic material
• capsid
• attachment protein

Question 19

What is the purpose of attachment proteins on viruses?

Answer 19

they bind to receptors on cells

Question 20

Viruses are

Answer 20

acellular and non living

Question 21

Why are viruses described as acellular?

Answer 21

they do not have a cell surface membrane

Question 22

Why are viruses described as non-living?

Answer 22

cannot respire/excrete

Question 23

Why are antibiotics ineffective against viruses?

Answer 23

do not have bacterial structures/enzymes

Question 24

Describe the DNA in prokaryotic cells

Answer 24

Nucleoid - single circular piece of DNA with no nuclear membrane
Plasmids - separate circles of DNA carrying only a few genes

Question 25

List 5 parts of a HIV.

Answer 25

RNA Reverse transcriptase (specific to HIV) Capsid Lipid envelope (not all viruses have this) Attachment proteins (specific to HIV)

Question 26

MRNA Euk cells vs prok cells

Answer 26

Euk - pre MRNA only - splicing only - introns removed Prok - introns not present

Question 27

Virus structure not in Bacteria

Answer 27

Capsid Reverse transcriptase RNA genome Envelope

Question 28

Bacteria structure (not in plants)

Answer 28

circular DNA Meurein cell wall Smaller/ 70s ribosomes in cytoplasm

Question 29

Describe ribosomes in prokaryotic cells.

Answer 29

the site of protein synthesis smaller (70S) not attached to any membranes

Question 30

define the term prokaryotic cell

Answer 30

DNa is Free in cytoplasm, no organelles e.g. bacteria and archaea

Question 31

Contrast eukaryotic and prokaryotic cells

Answer 31

Prokaryotic: Small cells and always unicellular No membrane-bound organelles and no nucleus Circular DNA not associated with proteins Small ribosomes (70S) Binary fission, always asexual reproduction Cellulose cell wall (in plants) or chitin (in fungi) Capsule, sometimes plasmids, and cytoskeleton Eukaryotic: Larger cells and often multicellular Always have organelles and a nucleus Linear chromosomes associated with histones Larger ribosomes (80S) Mitosis and meiosis, sexual and/or asexual reproduction Murein cell walls No capsule, no plasmids, always a cytoskeleton

Question 32

Give two ways in which the arrangement of prokaryotic DNA is different from the arrangement of the human DNA in Figure 1.

Answer 32

(Prokaryotic DNA) is 1. Circular (as opposed to linear); 2. Not associated with proteins/histones ; 3. Only one molecule/piece of DNA OR present as plasmids;

Question 33

Answer 33