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A Level OCR A Biology > 2.6 Prokaryotic and eukaryotic cells > Flashcards

2.6 Prokaryotic and eukaryotic cells Flashcards

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1
Q

Animals, plants, and fungi are all what?

A

complex multicellular organisms

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2
Q

The cells making up animals, plants, and fungi are what type

A

eukaryotic

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3
Q

There is a lot evidence that suggests that eukaryotic cells are what?

A

eukaryotic cells evolved from less complex prokaryotic cells

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4
Q

Less complex prokaryotic cells are present where?

A

present in great numbers and live in an incredibly diverse range of habitats

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5
Q

Prokaryotic cells, unicellular organisms can be classed into two what?

A

evolutionary domains- Archaea and Bacteria

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6
Q

These unicelllular organisms are classed into what two evolutionary domains?

A

archaea and bacteria

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7
Q

Where have the two evolutionary domain, archaea and bacteria evolved from?

A

an ancient common ancestor

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8
Q

What may have been among the earlliest forms of life on earth?

A

prokaryotic cells

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9
Q

When have prokaryotic cells first appeared?

A

around 3.5 billion years ago when the surface of the Earth was a very hostile environment

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10
Q

Scientists believe that prokaryotic cells were adapted to living in extremes of what??

A

that these early cells were adapted to living in extremes of salinity, pH and temperature

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11
Q

Early cells that were adapted to living in extremes of salinity, pH and temperature
that still exist today are called what?

A

extremophiles

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12
Q

Where can extremophiles be found?

A

in hydrothermal vents and salt lakes- similar environments to those believed to have made up the early Earth

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13
Q

What are extremophiles usually the domain of?

A

Archaea and more recently they have been found in more hospitable environments such as soil and the human digestive system

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14
Q

Prokarytic organisms are always what?

A

unicellular with a relatively simple structure

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15
Q

The DNA in prokaryotic organisms are not contained within what?

A

within a nucleus

: they have few organelles and the organelles they do have or not membrane bound

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16
Q

Describe the DNA in both eukaryotes and prokaryotes

A

the structure of the DNA contained within prokaryotes is fundamentally the same as in eukaryores but packaged differently

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17
Q

Describe the DNA in a prokaryote

A

They generally have only one molecule of DNA, a chromosome, which is supercouiled to make it more compact

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18
Q

What shape is the chromosome in prokayotes and why?

A

supercoiled to make it more compact

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19
Q

The genes on the supercoild chromosome of the prokaryote is often what?

A

often grouped into operons, meaning a number of genes are switched on or off at the same time

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20
Q

Which ribosomes are smaller. Prokaryotic or eukaryotic?

A

prokaryotic

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21
Q

The relative size of ribosomes in prokaryotic cells are determined by what?

A

the rate at which they settle, or form a sediment in solution

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22
Q

The larger eukaryotic ribosomes are desginated what?

A

80s

23
Q

The smaller prokaryotic ribosomes are designated what?

A

70s

24
Q

Both designated ribosomes are necessary for protein synthesis, although the larger 80s ribomes are involved in what?

A

the formation of more complex proteins

25
Q

Prokaryotc cells have a cell wall made from what?

A

peptidoglycan, also known as murein

26
Q

What is peptidoglycan, the thing cell walls are made from in prokaryotic cells/

A

it is a complex polymer formed from amino acids and sugars

27
Q

The flagella of prokaryotes is what compared to the equivallent structure of eukaryotes and does not have the?

A

it is thinner and

does not have the 9+2 arrangement

28
Q

In prokaryotic cells, the energy to rotate the filament that forms the flagellum is supplied from the process of what?

A

chemiosis, not from ATP as in eukaryotic cells

29
Q

In prokaryotic cells, the flagelllum is attached to the cell membrane of a bacterium by and is rotated by what?

A

a basal body and rotated by a molecular motor

30
Q

In prokaryotic cells, the basal-body attaches the filament comprising the flagellum to what?

A

the cell-surface membrane of a bacterium

31
Q

In prokaryotic cells, flagellum wise, what does a molecular motor cause

A

causes the hook to rotate giving the filament a whip like movement, which propels the cell

32
Q

The first eukaryotic cells appeared when?

A

about 1.5 billion years ago

33
Q

Eukaryotic cells are more _____ than prokaryotic cells

A

complex

34
Q

Where is the DNA present in eukaryotic cells and what do they exist as?

A

present within a nucleus and exists as multiple chromosomes

35
Q

Describe the chromosomes in eukaryotic cells

A

DNA exists as multiple chromosomes: supercoiled

i) each one wraps around a number of proteins called histones, forming a complex for efficient packaging.
ii) this complex is called chromatin and chromatin coils and condenses to form chromosomes

36
Q

Eukaryotic genes are generally what?

A

switched on and off individually

37
Q

Eukaryotic cells have membrane bound organelles. What does this include?

A

mitochondria and chloroplasts

38
Q

Organisms from the plant, animal, fungi, and protoctista kingdoms are all composed of what?

A

eukaryotic cells, many are multicellular

39
Q

What is the theory of endosymbiosis

A
  • evolution of eukaryotic cells
  • mitochondria and chloroplasts, and possibly other eukaryotic organelles, were formerly free-living bacteria, that is prokaryotes
  • these prokaryotes were taken inside another cell as an endosymbiont (an organism that lives within the body or cells of another organism)
40
Q

Outline the difference in prokaryotes and eukaryotes with nucleus

A

prokaryoes- not present

eukaryotes- present

41
Q

Outline the difference in prokaryotes and eukaryotes with DNA

A

prokaryotes- dna is naked, circular and usually no introns (not in chromosomes)
eukaryotes- DNA is bound to proteins, linear and usueally has introns

42
Q

Outline the difference in prokaryotes and eukaryotes with DNA organisation

A

prokaryotes- fold and condense dna

eukaryotes- associate with proteins called histones

43
Q

Outline the difference in prokaryotes and eukaryotes with extra chromosomal DNA

A

prokaryotes- circular DNA called plasmids

eukaryotes- only present in certain organelles such as chloroplasts and mitochondria

44
Q

Outline the difference in prokaryotes and eukaryotes with organelles

A

prokaryotes- non-membrane bound

eukaryotes- membrane bound and non-membrane bound

45
Q

Outline the difference in prokaryotes and eukaryotes with cell wall

A

prokaryotes- peptidoglycan

eukaryotes- chitin in fungi, cellulose in plants, not present in animals

46
Q

Outline the difference in prokaryotes and eukaryotes with ribosomes

A

prokaryotes- smaller, 70s

eukaryotes- larger 80s

47
Q

Outline the difference in prokaryotes and eukaryotes with cytoskeleton

A

prokaryotes- present

eukaryotes- present, more complex

48
Q

Outline the difference in prokaryotes and eukaryotes with reproduction

A

prokaryotic- binary fission, does not have nucleus, asexual

eukaryotic- asexual or sexual

49
Q

Outline the difference in prokaryotes and eukaryotes with cell type

A

prokaryotic- unicellular

eukaryotic- unicellular and multicellular

50
Q

Outline the difference in prokaryotes and eukaryotes with cell-surface membrane

A

prokaryote- present

eukaryote- present

51
Q

list three structural differences between prokaryotic cells and eukaryotic cells

A
  1. dna is free floating
  2. no membrane bound organelles
  3. prokaryotic has cell wall from peptidoglycan
  4. prokaryotic has no nucleus
  5. smaller ribosomes
  6. extra chromosomal DNA
52
Q

Suggest why the lack of membrane-bound organelles does not stop prokaryotic cells making proteins

A
  • Prokaryotic cells have ribosomes, which are needed for protein synthesis
  • ribosomes are not membrane bound
53
Q

Some antibiotics kill bacteria by disrupting the formation of peptidoglycan molecules. Explain why these antibiotics kill bacteria and why they do not have any effect on eukaryotic cells

A

Eukaryotic cells do not have cell walls, neither a cell wall formed of peptidolgycan molecules
-antibiotics do not damage any other cell components for example nucleus, ribosomes and mitochondria

A Level OCR A Biology (7 decks)

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