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Topic 2: Cells, viruses and reproduction of living things > Eukaryotic and prokaryotic cell structure and function > Flashcards

Eukaryotic and prokaryotic cell structure and function Flashcards

1
Q

What is the cell theory ?

A

cells are the fundamental unit of structure, function and organisation in all living organisms

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2
Q

what is differentiation ?

A

the development process by which the structure of the cells of a multicellular organism specialise for a specific function

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3
Q

what is a tissue ?

A

a group of cells that have a common origin and a similar structure that work together to form a single function

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4
Q

what is an organ ?

A

a structure that has a specific function

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5
Q

what is a system ?

A

a group of organs and tissues that perform a particular function

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6
Q

nucleoid

A

the circular DNA molecule found in prokaryotic cells

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7
Q

plasmid

A

circular DNA molecules in their cytoplasm
- usually contain a few genes including : genes conferring resistance to specific antibiotics

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8
Q

What are 70s Ribosomes ?

A

these ribosomes are involved in protein synthesis but they are smaller than 80s ribosomes found in eukaryotic cells

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9
Q

Cell wall

A

prevents cells bursting when in dilute solutions - made of peptidoglycan

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10
Q

Pili and flagella

A

pili - help prokaryotic cells to attach to surfaces or each other
flagella - help the cells to move about

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11
Q

what do bacterial cell walls contain ?

A

polymers of amino acids and sugars called peptidoglycan

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12
Q

Gram positive bacteria have ..

A

thick walls made almost entirely of peptidoglycan

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13
Q

what colour does the gram positive bacteria wall become ?

A

purple when stained by crystal violet

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14
Q

Gram negative bacteria have ..

A

thin walls of peptidoglycan with an additional outer membrane

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15
Q

why does the gram negative bacteria wall not become purple ?

A

the high lipid content of this outer membrane prevents the crystal violet stain getting to the cell wall

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16
Q

The effects of antibiotics on these two types of bacteria ?

A

Gram negative bacteria - the outer membrane is relatively impermeable to antibiotics SO is resistant to many types of antibiotic, including penicillin
Gram positive bacteria - susceptible to penicillin

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17
Q

Structure and function of nucleus

A
  • surrounded by a double nuclear membrane that contains many pores
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18
Q

what is the function of nuclear pores ?

A

Function: allow movement of molecules between the cytoplasm and the nucleus

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19
Q

what is the function of the nuclear envelope ?

A

Function: controls what enters and exists nucleus

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20
Q

what is the function of the nucleolus ?

A

Function: site in the nucleus where the rRNA is created according to instructions in DNA

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21
Q

what is the structure and function of chromatin ?

A

Structure: Chromatin( between nucleolus and nuclear envelope )
Function: makes up eukaryotic chromosomes

22
Q

Structure and function of 80s ribosomes

A

Structure: larger than 70s ribosomes
Function: synthesis protein

23
Q

Structure and function of rough endoplasmic reticulum

A

Structure: ribosomes attached to its outer surface
Function:
- develops the tertiary and quaternary shapes of proteins
- packages to vesicles, transports to the Golgi apparatus

24
Q

Structure and function of smooth endoplasmic reticulum

A

Structure: no ribosomes are attached to it
Function: synthesis lipids, phospholipids and steroids

25
Q

what is the function of the smooth endoplasmic reticulum in the cytoplasm of voluntary muscle fibres ?

A

site of storage of calcium ions - contraction of muscle fibres

26
Q

Structure and function of cell membrane

A
  • double membrane surrounding organelle
  • controls entry and exit of material

Structure: Cristae
Function: extensions of inner membrane - providing a large surface area for the attachment of enzymes and other proteins during respiration

Structure: Matrix
Function: interior of the mitochondria
- contains an aqueous solution of metabolites and enzymes

  • site of aerobic respiration producing ATP for energy
27
Q

Structure and function of centrioles

A

Structure: microtubules
Function: forms a network of unbranched, hollow cylinders
- involved in moving organelles around in the cytoplasm - form centrioles

28
Q

Structure and function of lysosomes

A

Structure: small spherical vesicles bound by single membrane
- contain a concentrated mixture of hydrolytic enzymes
Function: breakdown of imported food vacuoles, old organelles and harmful bacteria

29
Q

Structure and function of Golgi apparatus

A

Structure: consists of flattened membranous sacs
Function: modifying and packaging polymers for secretion or for use within the cell

30
Q

Structure and function of Cell wall

A

Structure: made of polysaccharide - cellulose
Function: prevents the cell changing shape and bursting (lysis)

31
Q

Structure and function of chloroplasts

A

-biconvex in shape
- double membrane
- site of photosynthesis

Structure: Thylakoids
Function: system of branching membranes

Structure: Grana
- thylakoids arranged in flattened circular piles
Function: where chlorophylls and other pigments involved light capture are located

Structure: Stroma
Function: containing enzymes and small starch grains

32
Q

Structure and function of vacuole

A

Structure: contains cell sap - weak solution of sugars and salts
Function: maintains pressure in the cell - stop wilting

33
Q

Structure and function of tonoplast

A

Structure: membrane of the vacuole
Function: barrier between the fluid contents of the vacuole

34
Q

How do prokaryotic cells differ from eukaryotic cells ?

A

Prokaryotic cells:
- no membrane bound organelles
- no nucleus containing free-floating DNA
- DNA is circular and is not associated with proteins
- made of murein and peptidoglycan

Eukaryotic cells:
- membrane bound organelles
- nucleus
- DNA is linear and is associated with proteins
- made of cellulose and 70s ribosomes

35
Q

what is magnification ?

A

the extent to which an object has been enlarged by a microscope

36
Q

formula of magnification

A

size of image / size of specimen

37
Q

what is resolution ?

A

the ability to distinguish between points that are very close together

38
Q

what is the importance of staining specimens ?

A

provides contrast to distinguish between different structures in the sample

39
Q

what is a light microscope ?

A

A light microscope is a type of microscope that uses light to magnify the image of a specimen. It works by passing light through a specimen and focusing the light on an eyepiece or camera, which magnifies the image.

40
Q

advantages of light microscope

A
  • Inexpensive to buy and operate.
  • Relatively small
  • Both living and dead specimens can be viewed
41
Q

disadvantages of light microscope

A
  • Maximum magnification of 1500x
  • Specimen may be disfigured during preparation to be viewed under the microscope
  • The resolving power is 1 nm for biological specimens
42
Q

what is an electron microscope ?

A

The electron microscope uses a beam of electrons and their wave-like characteristics to magnify an object’s image, unlike the optical microscope that uses visible light to magnify images.

43
Q

advantages of electron microscope

A
  • has a large depth of field, which allows more of a specimen to be in focus at one time.
  • much higher resolution, so closely spaced specimens can be magnified at much higher levels.
44
Q

disadvantages of electron microscope

A
  • expensive
  • large
  • must be housed in an area free of any possible electric, magnetic or vibration interference
45
Q

what is the structure of gram positive bacteria ?

A

thick layer of peptidoglycan
no outer membrane

46
Q

what is the structure of gram negative bacteria ?

A

thin layer of peptidoglycan
outer membrane contains lipopolysaccharides

47
Q

what does the function of outer membrane in gram negative bacteria ?

A

provides additional protection and barrier against certain antibiotics

48
Q

what happens to gram positive bacteria when stained ?

A

The thick peptidoglycan layer retains the crystal violet stain. The bacteria appear purple under the microscope.

49
Q

what happens to gram negative bacteria when stained ?

A

The thin peptidoglycan layer does not retain the crystal violet stain after the decolorization step. The bacteria lose the crystal violet and instead take up the counterstain (safranin or fuchsine), appearing pink under the microscope.

50
Q

how does gram positive bacteria react with antibiotics ?

A

effective because these antibiotics target the peptidoglycan layer, disrupting cell wall synthesis. Since Gram-positive bacteria have a thick peptidoglycan layer and no outer membrane, these antibiotics can easily reach their target.

50
Q

how does gram negative bacteria react with antibiotics ?

A

more resistant
due to the presence of outer membrane, which acts as a barrier to antibiotic molecules

Topic 2: Cells, viruses and reproduction of living things (9 decks)

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