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B3- CELL STRUCTURE > 3.4- EUKARYOTIC CELL STRUCTURE > Flashcards

3.4- EUKARYOTIC CELL STRUCTURE Flashcards

1
Q

What is the name for when each cell type has an internal structure that suits it for its job?

A

ultrastructure

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2
Q

What do eukaryotic cells have that prokaryotic cells do not?
(2)

A

distinct nucleus

possess membrane-bound organelles

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3
Q

What can be used to see the structure of organelles within a cell?

A

electron microscope

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4
Q

What is the most prominent feature of a eukaryotic cell?

A

nucleus

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5
Q

What does the nucleus contain?

A

organism’s hereditary material

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6
Q

What does the nucleus do?

A

controls the cell’s activities

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7
Q

What shape is the nucleus usually?

A

spherical

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8
Q

Usually what is the diameter of the nucleus?

A

between 10 and 20μm in diameter

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9
Q

What is the nuclear envelope?

A

double membrane that surrounds the nucleus

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10
Q

What does the outer membrane of the nuclear envelope continuous with?

A

endoplasmic reticulum of cell and often has ribosomes on its surface

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11
Q

What does the nuclear envelope do? (2)

A

controls entry and exit of materials in and out of nucleus

contains reactions taking within in

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12
Q

What do the nuclear pores do?

A

allow passage of large molecules

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13
Q

Example of large molecules nuclear pores allow the passage of?

A

messenger RNA out of nucleus

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14
Q

Typically how many nuclear pores are in each nucleus?

A

3000 pores

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15
Q

What is the diameter of the nuclear pores like?

A

40-100 nm in diameter

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16
Q

What is the nucleoplasm?

A

granular, jelly-like material that makes up bulk of nucleus

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17
Q

What do chromosomes consist of?

A

protein-bound, linear DNA

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18
Q

What is the nucleolus?

A

small spherical region within the nucleoplasm

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19
Q

What does the nucleolus do? (2)

A

manufactures ribosomal RNA

assembles ribosomes

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20
Q

Can there be more than one nucleolus in the nucleus?

A

yes

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21
Q

Functions of the nucleus? (3)

A

act as control centre of cell through production of mRNA and tRNA and hence protein synthesis

retain genetic material of cell in form of DNA + chromosomes

manufacture ribosomal RNA and ribosomes

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22
Q

What shape is the mitochondria usually?

A

rod-shaped

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23
Q

What is usually the length of mitochondria?

A

1-10μm in length

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24
Q

Is there a double membrane around mitochondria?

A

yes

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25
Q

What does the double membrane around mitochondria do?

A

controls entry + exit of material

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26
Q

What is done to the inner membrane of the double membrane of the mitochondria?

A

folded to from extensions known as cristae

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27
Q

What are cristae? (mitochondria)

A

extensions of the inner membrane

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28
Q

What does the cristae do in some species? (mitochondria)

A

extend across the whole width of the mitochondria

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29
Q

What do the cristae do?

mitochondria

A

provide large SA for attachment of enzymes and other proteins involved in respiration

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30
Q

What does the matrix make up? (mitochondria)

A

makes up the remainder of the mitochondrion

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31
Q

What does the matrix contain? (mitochondria)

A

protein, lipids, ribosomes, and DNA

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32
Q

What does the substances the matrix contains allow the mitochondria to do?

A

allows mitochondria to control the production of some of their own proteins

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33
Q

What is also found in the matrix? (mitochondria)

A

enzymes involved in respiration

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34
Q

What is mitochondria the site of?

A

aerobic stages of respiration

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35
Q

As mitochondria is the site of the aerobic stages of respiration, what is it responsible for?

A

production of energy-carrier molecule, ATP, from respiratory substances such as glucose

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36
Q

As mitochondria is responsible for production of ATP what may vary about mitochondria in cells that have a high level of metabolic activity? (2)

A

number and size of mitochondria

number of their cristae

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37
Q

Examples of metabolically active cells? (2)

A

muscle cells

epithelial cells

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38
Q

Why do epithelial cells in the intestines require a lot of ATP?

A

in process of absorption of substances from intestines by active transport

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39
Q

What do chloroplasts carry out?

A

photosynthesis

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40
Q

What do chloroplasts vary in?

A

shape and size

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41
Q

Typically what shape are chloroplasts?

A

disc-shaped

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42
Q

Typically how long is a chloroplast?

A

2-10μm long

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43
Q

Typically what is the diameter of a chloroplast?

A

1μm in diameter

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44
Q

What is the chloroplast envelope?

A

double plasma membrane that surrounds the organelle

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45
Q

How selective is the chloroplast envelope?

A

highly selective

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46
Q

What is the chloroplast envelope highly selective in?

A

in what is allows to enter and leave the chloroplast

47
Q

What is the grana? (chloroplast)

A

stacks of up to 100 disc-like structures called thylakoids

48
Q

What is within the thylakoid? (chloroplast)

A

photosynthetic pigment called chlorophyll

49
Q

What do some thylakoids have? (chloroplast)

A

tubular extensions that join up with thylakoids In adjacent grana

50
Q

What happens at the grana? (chloroplast)

A

where the first stages of photosynthesis takes place

51
Q

What is the first stage of photosynthesis? (chloroplast)

A

light absorption

52
Q

What is the stroma? (chloroplast)

A

fluid-filled matrix

53
Q

What happens at the stroma? (chloroplast)

A

where second stage of photosynthesis takes place

54
Q

What is the second stage of photosynthesis?

A

synthesis of sugars

55
Q

What is within the stroma? (chloroplast)

A

number of other structures, i.e. starch grains

56
Q

How is chloroplast adapted to its function of harvesting sunlight and carrying out photosynthesis? (3)

A

granal membranes provide large SA for attachment of chlorophyll, electron carriers and enzymes that carry out first stages of photosynthesis. these chemicals attached to membrane in highly ordered fashion

fluid of stroma possesses all the enzymes needed to make sugars in second stage of photosynthesis

chloroplast contain both DNA and ribosomes so they can quickly + easily manufacture some of the proteins needed for photosynthesis

57
Q

What is the endoplasmic reticulum?

A

elaborate, three-dimensional system of sheet-like membranes,, spreading the cytoplasm of the cells

58
Q

What is the ER continuous with?

A

outer nuclear membrane

59
Q

What do the membranes enclose? (ER)

A

network of tubules and flattened sacs called cisternae

60
Q

What are the two types of ER?

A

rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER)

61
Q

What does the RER have?

A

ribosomes present on the outer surfaces of the membranes

62
Q

What are the functions of RER? (2)

A

provide large SA for synthesis of proteins and glycoproteins

provide pathway for transport of materials, especially proteins, throughout cell

63
Q

What does the SER lack?

A

ribosomes on its surface

64
Q

How does the appearance of the SER differ from the RER?

A

often more tubular in appearance

65
Q

What are the functions of SER? (2)

A

synthesise, store and transport lipids

synthesise, store and transport carbohydrates

66
Q

What cells have a very extensive ER?

A

cells that manufacture and store large quantities of carbohydrates, proteins and lipids

67
Q

Examples of cells that have very extensive ER? (2)

A

liver cells

secretory cells- e.g. epithelial cells that line the intestines

68
Q

What is the structure of the Golgi apparatus similar to?

A

SER

69
Q

How is the structure of the Golgi apparatus different to the SER?

A

Golgi is more compact

70
Q

What does the Golgi apparatus consist of?

A

stack of membranes that make up flattened sacs, or cisternae, with small rounded hollow structures called vesicles

71
Q

What are the proteins and lipids produced by the ER passed through?

A

passed through the Golgi apparatus

72
Q

What does the Golgi do to the proteins made by the ER?

A

modifies proteins often adding non-protein components i.e. carbohydrates to them

‘labels’ them, allowing them to be accurately sorted + sent to correct destinations

73
Q

What happens once the proteins and lipids are modified by the Golgi apparatus?

A

modified proteins and lipids transported in Golgi vesicles which are regularly pinched off from ends of Golgi cisternae

74
Q

Where may the Golgi vesicles move to and what do they do?

A

move to the cell surface, where they fuse with the membrane + release contents to outside

75
Q

Functions of Golgi apparatus (5)

A

add carbohydrates to proteins to form glycoproteins

produce secretory enzymes, i.e. those secreted by pancreas

secrete carbohydrates, i.e. those used in making cells walls in plants

transport, modify + store lipids

form lysosomes

76
Q

In what cells is the Golgi apparatus well developed in?

A

secretory cells- e.g. epithelial cells that line intestines

77
Q

How are lysosomes formed?

A

when vesicles produced by Golgi apparatus contain enzymes such as proteases and lipases

78
Q

What else do the lysosomes contain?

A

contain lysozymes

79
Q

What do lysozymes do?

A

hydrolyse cell walls of certain bacteria

80
Q

Up to how many lysozymes can be in a single lysosome?

A

50

81
Q

What is the diameter of lysosomes like?

A

1.0 μm

82
Q

What does the lysosome do to the enzymes?

A

isolate enzymes from rest of the cell before releasing them

83
Q

Where can the lysosome release the enzymes?

A

to the outside
OR
into a phagocytic vesicle within the cell

84
Q

What are the functions of lysosomes? (4)

A

hydrolyse material ingested by phagocytic cells, i.e. white blood cells + bacteria

release enzymes to outside of cell (exocytosis) to destroy material around cell

digest worn out organelles so useful chemicals they’re made of can be re-used

completely break down cells after they have died (autolysis)

85
Q

What types of cells are lysosomes especially abundant in? (2)

A

secretory cells- i.e. epithelial cells

phagocytic cells

86
Q

What are ribosomes?

A

small cytoplasmic granules found in all cells

87
Q

How can ribosomes occur? (2)

A

in cytoplasm OR associated with RER

88
Q

What does the types of ribosome depend on?

A

depends on cells in which they’re found

89
Q

What are the two types of cells?

A

80S and 70S

90
Q

Where are all 80S ribosomes found?

A

in eukaryotic cells

91
Q

What is the diameter of 80S ribosomes like?

A

around 25μm in diameter

92
Q

Where are all 70S ribosomes found?

A

in prokaryotic cells, mitochondria and chloroplast

93
Q

What is the size of 70S ribosomes like in comparison to 80S ribosomes?

A

70S ribosomes are smaller

94
Q

How many subunits do ribosomes have?

A

two

95
Q

What are the subunits of ribosomes like?

A

one large and one small

96
Q

What do each subunit of the ribosome contain?

A

contains ribosomal RNA and protein

97
Q

In what numbers do ribosomes occur in?

A

in vast numbers

98
Q

As ribosomes occur in vast numbers what percent of dry mass of a cell do they account for?

A

25%

99
Q

What is the ribosome the site of?

A

protein synthesis

100
Q

What type of cell is cell walls a characteristic of?

A

plant cells

101
Q

What do the cell walls of plant cells consist of?

A

microfibrils of the polysaccharide cellulose, embedded in a matrix

102
Q

What characteristic do cellulose microfibrils have?

A

considerable strength

103
Q

As cellulose microfibrils have considerable strength what do they contribute to?

A

to overall strength of cell wall

104
Q

What features do cell walls have? (2)

A

consist of number of polysaccharides, i.e. cellulose

there’s a thin layer, called middle lamella, which marks boundary between adjacent cell walls + cements adjacent cells together

105
Q

What are the functions of the cellulose cell wall? (3)

A

provide mechanical strength to prevent cell bursting under pressure created by osmotic entry of water

give mechanical strength to plant as a whole

allow water to pass along it and so contribute to movement of water through plant

106
Q

What are the cell walls of algae made up of?

A

either cellulose or glycoproteins, or a mixture of both

107
Q

What are the cell walls of fungi made up of?

A

mixture of nitrogen-containing polysaccharide called chitin, a polysaccharide called glycan and glycoproteins

108
Q

What may be termed as a vacuole?

A

fluid-filled sacs bounded by a single membrane

109
Q

Within a mature plant cell what is the vacuole like?

A

one large central vacuole

110
Q

What is the single membrane around a vacuole called?

A

tonoplast

111
Q

What does a plant vacuole contain?

A

solution of mineral salts, sugars, amino acids, wastes and sometimes pigments

112
Q

Example of pigment that may be in a vacuole?

A

anthocyanins

113
Q

What are the functions of vacuoles? (3)

A

support herbaceous plants, + herbaceous parts of woody plant, by making cells turgid

sugars + amino acids may act as temporary food store

pigments may colour petals to attract pollinating insects

B3- CELL STRUCTURE (8 decks)

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