prokaryotic cells

Question 1

what are bacterial cell walls made of

Answer 1

peptidoglycan (murein)

Question 2

describe the structure and function of flagella

Answer 2

a long hair-like strucutre that rotates enabling the prokaryote to move (like a propeller)
some prokaryotes have more than one
not present in all prokaryotes

Question 3

what is the difference between eukaryotic and prokaryotic cells

Answer 3

prokaryotic cells have a cytoplasm that lacks membrane-bound organelles
their ribosomes are structurally smaller (70 S) in comparison to those found the eukaryotic cells (80 S)
no nucleus (instead they have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins)
a cell wall that contains murein (a glycoprotein)

Question 4

what is the structure of plasmids

Answer 4

small loops of DNA that are separate from the main circular DNA molecule
plasmids contain genes that can be passed between prokaryotes (e.g. genes for antibiotic resistance)
not present in al prokaryotes

Question 5

structure of capsule

Answer 5

not present in all prokaryotes
prevents bacterium from drying out

Question 6

compare the genetic material of eukaryotes and prokaryotes

Answer 6

E DNA contains introns and exons P contains only exons
E DNA is bound around histones P DNA is not bound around histones
P has circular DNA, E has linear DNA
both P and E contain chromosomes
both P and E have genetic information in the form of DNA
P contain extra chromosomal DNA known as a plasmid. E do not contain plasmids

Question 7

what organelle(s) are present in both prokaryotes and eukaryotes + why

Answer 7

ribosomes - they are not membrane bound

Question 8

what structures are only present in prokaryotes and not in eukaryotes

Answer 8

plasmid
slime capsule
mesosome
70s ribosomes
circular DNA
pili (pilus)

Question 9

why can you not state a flagellum is only present in prokaryotes

Answer 9

sperm cells, a eukaryote specialised cell contains a flagellum

Question 10

what is the difference in the components of a cell wall

Answer 10

P membrane: peptidoglycan/murein
E membrane: cellulose (plants). chitin (fungi)

Question 11

what is the role of the pili

Answer 11

cytoplasmic processes extending through cell wall
involved in attachment

Question 12

what is the role of the mesosome

Answer 12

infolding of the cell membrane - site of respiration

Question 13

what is the role of the storage glycogen granule

Answer 13

glycogen can be hydrolysed to glucose to be used in repsiration
releases energy for multiple metabolic processes e.g active transport and cell division

Question 14

what form of A-sexual reproduction do bacteria carry out

Answer 14

binary fission

Question 15

describe the process of Binary fission

Answer 15

DNA replicates, along with plasmids
DNA attaches the mesosome - cell elongates (helps to separate DNA)
septum (cross wall) develops across middle of the cell
septum grows across cell dividing it in two
cytoplasm divided into 2 to produce 2 genetically identical daughter cells

Question 16

what can’t bacteria carry out mitosis

Answer 16

mitosis is nuclear division, but bacteria don’t have a nucleus
E have many linear chromosomes which can only be correctly separated into daughter cells by attachement to a spindle
P only have one circular chromosome, and so do not need to form a spindle
step 4 - two daughter cells separate

Question 17

what are the similarities between binary fission and mitosis

Answer 17

DNA replicates before cells divide
cells divide to form two genetically identical daughter cells

Question 18

what are the differences between binary fission and mitosis

Answer 18

binary fission
chromosome(s) do not condense prior to separation, no spindle
no lining up of chromosomes, separate by cell elongation
chromosome(s) do not separate into chromatids
mitosis
spindle, chromsomes condense prior to separation
lining up of chromosomes, separated by shortening of spindle fibres
chromosomes separated into chromatids