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A Level OCR A Biology > 2.4 Eukaryotic cell structure > Flashcards

2.4 Eukaryotic cell structure Flashcards

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1
Q

Microscopes not only make cells visible, what also do they do?

A

they also enable us to look deep inside individual cells

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2
Q

The basic unit of all living things is the cell. What are the two fundamental types of cell?

A

prokaryotic and eukarytoic

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3
Q

What are prokaryotes?

A

single-celled organisms with a simple structure of just a single undivided internal area called the cytoplasm

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4
Q

Development of microscopes has allowed biologists to discover increasing amounts of detail of cell ultrastructure.

A

The increased knowledge of structure has led to a better understanding of cell structure

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5
Q

What is the cytoplasm composed of

A

cytosol, which is made of water, salts ad organic molecules

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6
Q

What do eukaryotic cells make up?

A

multicellular organisms like animals, plants and fungi

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7
Q

Eukaryotic cells have a much more complicated internal structure, containing what?

A

a membrane bound nucleus (nucleoplasm) and cytoplasm, which contains many membrane-bound cellular components

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8
Q

Chemical reactions are the fundamental processes of life, in cells what do they require?

A

both enzymes and specific reaction conditions

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9
Q

What does metabolism both involve?

A

1) the synthesis and the breaking down of molecules

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10
Q

What is synthesis?

A

building up

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11
Q

Different sets of reactions take place in…

A

different regions of the ultrastructure of the cell

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12
Q

Where do reactions take place?

A

in the cytplasm

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13
Q

what is the cell cytoplasm separated from?

A

the external environmnt by a cell-surface membrane

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14
Q

In eukaryotic cells, the cytoplasm is divided into many different what?

A

membrane-bound compartments, known as organelles

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15
Q

What do organelles provide

A

distinct environments and therefore conditions for the different cellular reactions

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16
Q

Membranes are _______ ________ and control the ______ of substances into and out of the ____ and ________

A

i) selectively permeable
ii) movement
iii) cell
iv) organelles

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17
Q

Membranes are effective what?

A

barriers in controlling which substances enter and exit cells

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18
Q

What is a drawback of membranes?

A

fragile

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19
Q

The nucleus contains what?

A

coded genetic information in the form of DNA molecules

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20
Q

What does DNA do?

A

direct the synthesis of all proteins required by the cell (although this protein synthesis occurs outside of the nucleus at ribosomes)

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21
Q

DNA can direct the synthesis of all proteins required by the cell. What does this mean DNA can do and why?

A

i) DNA controls the metabolic activities of the cell

ii) as many of these proteins are the enzymes necessary for metabolism to take place

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22
Q

What is often the biggest single organelle in the cell?

A

nucleus

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23
Q

Where is DNA contained and why?

A

within a double membrane called a nuclear envelope to protect it from damage in the cytoplasm

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24
Q

What does the nuclear envelope (double membrane) contain?

A

nuclear pores that allow molecules to move into and out of the nucleus

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25
Q

Why can’t DNA itself leave the nucleus to the site of protein synthesis in the cell cytoplasm?

A

it is too large

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26
Q

DNA is too large to leave the nucleus to the site of protein synthesis in the cell cytoplasm?

A

transcribed into smaller RNA molecules, which are exported via the nuclear pores

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27
Q

What do DNA associates with and what does it form?

A

i) proteins called histones

ii) a complex called chromatin

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28
Q

What does chromatin do?

A

coils and condenses to form structures known as chromosomes

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29
Q

When do chromosomes only become visible?

A

when cells are preparing to divide

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30
Q

What is the nucleolus?

A

an area within the nucleus, responsible for producing RIBOSOMES

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31
Q

What is the nucleolus composed of?

A

proteins and RNA

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32
Q

What is RNA used for?

A

to produce ribosomal RNA (rRNA) which is then combined with proteins to form the ribosomes necessary for protein synthesis

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33
Q

What is the singular for mitochondria?

A

mitochondrion

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34
Q

What are mitochondria?

A

the site of the final stages of cellular respiration, where the energy stored in the bonds of complex, organic molecules is made available for the cell to use by the production of the molecule ATP

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35
Q

The number of mitochondria in a cell is generally a reflection of what?

A

the amount of energy it uses, so very active cells usually have a lot of mitochondria

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36
Q

Mitochondria have a _______ ________

A

double membrane

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37
Q

describe the inner membrane of the mitochondria

A

highly folded to form structures called cristae and the fluid interior is called the matrix

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38
Q

What does the membrane forming the cristae in mitochondria contain?

A

the enzymes used in aerobic respiration

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39
Q

Mitochondira also contain a small amount of ___, called _________ __

A

DNA, mitochondrial (mt) DNA

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40
Q

What can the mitochondria produce and how?

A

can produce their own enzymes and reproduce themselves

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41
Q

What are vesicles?

A

membranous sacs that have storage and transport roles

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42
Q

What do vesicles consist of?

A

simply of a single membrane with fluid inside

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43
Q

What are vesicles used for?

A

to transport materials inside the cell

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44
Q

What are lysosomes?

A

specialised forms of vesicles that contain hydrolytic enzymes

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45
Q

What are lysosomes responsible for

A

breaking down waste material in cells, including old organelles

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46
Q

What system do lysosomes play an important part in and why?

A

immune system as they are responsible for breaking down pathogens ingested by phagocytic cells

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47
Q

What do lysosomes also play an important role in other than the immune system?

A

programmed cell death or apoptosis

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48
Q

Where is the cytoskeleton present?

A

throughout the cytoplasm of all eukaryotic cells

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49
Q

What is the cytoskeleton?

A

a network of fibres necessary for the shape and stability of the cell

50
Q

How are organelles held in place?

A

by the cytoskeleton

51
Q

What does the cytoskeleton control?

A

cell movement and the movement of organelles within cells

52
Q

What three components to the cytoskeleton have?

A

1) microfilaments
2) microtubules
3) intermediate fibres

53
Q

What are microfilaments

A

contractile fibres formed from the protein actin

54
Q

What are microfilaments responible for?

A

cel movement and also cell contraction during cytokinesis

55
Q

what is the process cytokinesis?

A

the cytoplasm of a single eukaryotic cell is divided to form two daughter cells

56
Q

What are microtubules?

A

globular tubulin proteins polymerise to form tubes that are used to form a scaffold-like structure that determines the shape of a cell

57
Q

What do microtubules act as?

A

tracks for the movement of organelles, including vesicles, around the cell

58
Q

What are spindle fibres composed of?

A

microtubles

59
Q

What role do spindle fibres have?

A

a role in the physical segregation of chromosomes in cell division

60
Q

What do intermediate fibres do?

A

give mechanical strength to cells and help maintain their integrity

61
Q

What is integrity

A

the state of being whole and undivided.

62
Q

what is segregation?

A

the separation of pairs of alleles at meiosis and their independent transmission via separate gametes.

63
Q

The movement of cells like phagocytes depends on the activity of what?

A

actin filaments in the cytoskeleton

64
Q

what are phagocytes

A

cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells

65
Q

When do the actin filament lengths in the cytoskeleton change?

A

with the addition and removal of monomer subunits

66
Q

The rate at which these monomer subunits is added are what to each end of a filament for the filament lengths to change?

A

the rate at which these subunits are added is different at each end of a filament

67
Q

Describe the subunits for the filament lengths to change?

A

not symmetrical and can be only added if they are in the correct orinetation

68
Q

What do the subunits have to do befor they are added to one end (the minus end) of the filament but not the other end (the plus end)

A

they have to change shape

69
Q

What does the subunits having to change shape befire they are added to one end of the filament for cell movement mean?

A

the subunits are added at a faster rate at the plus end

70
Q

What dothe subunits being being added to the plus side faster therefore result in?

A

an increase in length at a faster rate in one particular direction

71
Q

What are the subunits being added or removed at either end is determined by what?

A

the concentration of subunits in the cytoplasm

72
Q

Due to the different rates of addition of subunits of filaments at either end, at certain concentrations…
what is this called

A

i) subunits will be added at one end and removed at the other
ii) treadmilling

73
Q

What does the increasing length of the filaments at one edge of a cell, the leading edge, leads to?

A

cells such as phagocytes in a particular direction

74
Q

What are centriules?

A

a component of the cytoskeleton present in most eukaryotic cells with the exception of flowering plants and most fungi

75
Q

What are centrioles composed of?

A

microtubles

76
Q

What do two associated centrioles form?

A

the centrosome

77
Q

What is the form of the centrosome involved in?

A

two centrioles form the centrosome, which is invlolved in the assembly and organisation of the spindle fibres during cell division

78
Q

In organisms with flagella cilia, what do centriules play a role in?

A

the positioning of the flagella and cilia

79
Q

What is a similarity between flagella (whip-like) and cilia (hair-like)

A

they both are extensions that produce from some cell types

80
Q

Flagella are ____ than cilia but cilia are usually present in much _____ numbers

A

i) longer

ii) greater

81
Q

What are flagella primarily used for

A

to enable cells motility

82
Q

what is motility?

A

the ability of organisms and fluid to move or get around

83
Q

In some cells, what can flagella be used for?

A

used as a sensory orgonelle detecting chemical changes in the cells environement

84
Q

Cilia can be ____ or statiionary

A

mobile

85
Q

Stationary cilia are present where?

A

on the surface of many cells and have important function in sensory such as the nose

86
Q

How do mobile cilia beat?

A

in a rhythmic manner, creating a current, abd cause fluids or objects adjacent to the cell to move

87
Q

Give two examples of mobile cilia

A

1) they are present in the trachea to move mucus away from the lungs (helping tokeep the air passages clean)
2) fallopian tubes to move egg cells from the ovary to the uterus

88
Q

What does each cillium contain?

A

two central microtubles (black circles) surrounded by nine pairs of microtubles arranged like a “wheel”

89
Q

What are the nine pairs of microtubles arranged like a whell known as?

A

the 9+2 arrangement

90
Q

What causes the mobile cilia to movie in a beating motion?

A

pairs of parallel microbules slide over each other

91
Q

A key function of a cell is to synthesise proteins (including enzymes). What for?

A

internal use and for secretion (transport out of the cell)

92
Q

A significant portion of what is required for secretion?

A

internal structure of the cell

93
Q

What internal structures are closely linked and coordinate the production of proteins and their preparation for different roles within the cell

A

i) the ribosomes
ii) the endoplasmic reticulum
iii) golgi apparatus

94
Q

The cytoskeleton plays a key role in coordinating what?

A

coordinating protein synthesis

95
Q

What is the endoplasmic reticulym (ER)?

A

a network of membranes enclosing flattened sacs called cisternae

96
Q

What is cisternae

A

flattened sacs

97
Q

What is cisternae connected to ?

A

the outer membrane of the nucleus

98
Q

What are the two types of endoplasmic reticulum

A

i) smooth endoplasmic reticulum

ii) rough endoplasmic reticulum

99
Q

what is the smooth endoplasmic reticulum responsible for?

A

lipid and carbohydrate synthesis, and storage

100
Q

what is the rough endoplasmic reticulum responsible for?

A

has ribosomes bound to the surface and is responsible for the synthesis and transport of proteins

101
Q

What sort of cells have more rough endoplasmic reticulum than cells that do not release proteins?

A

secretory cells

102
Q

Where are the ribosomes located?

A

it can be free-floating in the cytoplasm or attached to endoplasmic reticulum. forming rough endoplasmic reticulum

103
Q

What are ribosomes not surrounded by?

A

a membrane

104
Q

What are ribosomes constructed with and where?

A

RNA molecules made in the nucleolus of the cell

105
Q

What are the site of protein synthesis

A

ribosomes

106
Q

What also contains ribosomes other than being free floating inthe cytoplasm or attached to endoplasmic reticulum

A

mitochondria and chloroplasts, as do prokaryotic cells

107
Q

What is the Golgi apparatus similar in strucutre to?

A

the smooth endoplasmic reticulum

108
Q

What sort of structure of the Golgi appartus?

A

a compact structure formed of cisternae and does not contain ribosomes

109
Q

What is the Golgi apparatus

A

an organelle in most eukaryotic cells formed from an interconnected network of flattened, membrane-enclosed sacs or cisternae

110
Q

What does the Golgi apparatus play a role in?

A

modifying and packaging proteins into vesicles

111
Q

What sort of vesicles could the Golgi appartus package?

A

secretory vesicles, if the proteins are destined to leave the cell, or lysosomes, which stay in the cell

112
Q

Proteins are synthesised on what ribosomes?

A

on the ribosomes bound to the endoplasmic reticulum

113
Q

After the proteins are synthesised on the ribosomes, what happens?

A

they are pass into a cisternae and are packaged into transport vesicles

114
Q

Vesicles containing the newly synthesised proteins move towards the what and how?`

A

the Golgi apparatus via the transport function of the cytoskeleton

115
Q

What do the vesicles fuse with while the proteins enter?

A

the vesicles fuse with the cis face of the Golgi apparatus

116
Q

Describe the proteins before leaving the Golgi aparatus in vesicles from its trans face

A

structurally modified

117
Q

Secretory vesicles carry proteins that are..

A

to be released from the cell

118
Q

The secretory vesicles move towards and fuse with the what after they carriend the proteins that are ? and releasing what and how in the process?

A

with the cell surface membrane, releasing their contents by exocytosis

119
Q

Some vesicles form what which contain enzymes for use in the cell?

A

lysosomes

120
Q

Some vesicles form lysosomes. What do these contain?

A

enzymes for use in the cell

A Level OCR A Biology (7 decks)

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