Cell types & specialisation Flashcards

1
Q

What are the essential features of a cell?

A
  • Exterior plasma membrane (phospholipid bilayer)
  • Nuclear region w DNA
  • Interior cytoplasm (semifluid matrix)
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2
Q

What are the 2 cell types?

A
  • Prokaryotic
  • Eukaryotic
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3
Q

What are prokaryotic cells like?

A

No nucleus, little defined internal structure & unicellular - v small ~5-2.0um diameter

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4
Q

What are eukaryotic cells like?

A

Contain nuclei, more complex w specialised organelles

May be unicellular or multicellular (animals, plants or fungi)

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5
Q

What are the 3 divisions in the tree of life?

A
  • Eukaryotes
  • Bacteria - prokaryotes
  • Archaea - “”
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6
Q

What type of cells are eubacteria?

A

Prokaryotes

They are the most commonly encountered of the prokarya

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7
Q

What features are most commonly found in eubacteria?

A
  • Plasma membrane (PM)
  • Rigid cell wall - composed of peptidoglycan (carb/protein polymer) external to PM

Simple internal organisation & lack of differentiation
Genomic DNA presented in ‘nuclei’ region - not steerage for cytoplasm

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8
Q

What are the types of bacteria?

A
  • Gram-positive
  • Gram-negative
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9
Q

What is Gram+ bacteria like?

A

Has plasma membrane and cell wall

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10
Q

What is Gram- bacteria like?

A

Has extra periplasmic space outside of the plasma membrane & cell wall

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11
Q

Name a type of gram- bacteria

A

E.coli

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12
Q

What are the main ways that bacterial cells are diverse?

A
  1. Cell shape
  2. Cell appendages
  3. Some have infoldings of the plasma membrane
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13
Q

Why do some bacteria have infoldings in the plasma membrane?

(Give an example)

A

To allow photosynthesis

e.g. Cyanobacteria (blue green) with apparent internal membranes

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14
Q

What are the various cell shapes found in bacterial cells?

A

Round, oval, spiral, curved, rods, chains etc

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15
Q

Give some examples of bacterial cell appendages that allow for specialisation

A
  • Some have rotating flagella on surface for motility
  • Many Gram- have short ‘fimbriae’ for attachment to surfaces and ‘pili’ for attachment to bacteria
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16
Q

What are some features of archaea (prokaryote)?

A
  1. Have many similar features to bacterial cell structure
  2. Have some unique cell shapes - beached, flat & square
  3. Have distinct biochemistry - incl cell membranes, DNA molecular differences
  4. Lack peptidoglycan cell wall
  5. Found in hostile environments
17
Q

How are bacterial and archaea cells similar?

A

Similar:
- Size range
- Shape (rods, round)

Have external flagella and pili
DNA present in nucleoid region, not sep. from cytoplasm

18
Q

What do archaea cells have instead of the peptidoglycan wall which they lack?

A

They instead have very diverse outer surface layers

19
Q

Archaea can be found in hostile environments, give some examples

A
  • Hot volcanic springs
  • Airless marine sediments
  • Salt lakes
20
Q

What are eukaryotes like?

A

Wide variety

Structurally more complex than Prokaryotic cells

21
Q

What are the features of eukaryotic cell structure?

A
  1. Plasma membrane (PM)
  2. DNA cont in a nucleus, separated from cytoplasm by membrane - DNA present on chromosomes
  3. Cytoplasm is compartmentalised - features organelles
  4. Complex cytoskeletal system to maintain cell integrity e.g. microtubules & intermediate & acting filaments
22
Q

What is the role of the plasma membrane in eukaryote cells?

A

It delineates the edge of cell cytoplasm

23
Q

Give some examples of eukaryote cell diversity?

A

Animal, plant, protist, fungal cells

24
Q

What are the main constituents in an animal cell?

A
  • Nucleus
  • Organelles: mitochondria, Golgi body, peroxisomes, RER & SER, small vacuoles
  • Ribosomes
  • CENTRIOLES
  • Cytoskeleton
25
What are the main constituents of a plant cell?
- Nucleus - Organelles: mitochondria, Golgi body, peroxisomes. RER & SER & chloroplasts - Ribosomes - Cytoskeleton - SINGLE LARGE VACUOLE - RIGID CELLULOSE CELL WALL
26
What is a model protist cell like?
- Mainly unicellular - Flexible cell surface with supportive 'pellicle' - Some have contractive vacuole
27
What is a model fungal cell like?
- Unicellular yeasts or filamentous hyphae - Can contain multiple nucleus per compartment - Rigid chitin wall
28
How is multicellularity useful to eukaryotes?
It allows specialisation - cells have different functions within whole organism The cell structure & biology varies according to the function of the cell
29
Why do cells differentiate?
As a result of the expression of subsets of genes within the genome
30
Give 4 examples of specialised functions of cells?
- Movement - Signalling - Transport - Reproduction
31
How are some cells specialised to movement?
- Some have external projection from the cell surface which undulate to cause movement e.g. flagella (few & large) or cilia (small & numerous)
32
Where are flagella and cilia generally found?
Found in unicellular protists/fungi for propulsion & vertebrate tissues incl airways & ears
33
How are some cell specialised to signalling? (Neurones)
Nerve cells (neurones): have a central cell body with terminal dendrites & long axon transmitting electrical signals Length may be > 1 metre
34
How are some cells specialised for transport? (RBCs)
RBCs (erythrocytes) specialised for gas transport; lack nucleus & organelles when mature & instead packed full of haemoglobin Are small (8um) for passage through capillaries
35
How are some cells specialised for reproduction?
Sperm cells have a flagellum for swimming Mushroom spores are produced on gills by specialised 'basidia' swollen reproductive cells