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CIE AS Biology > 1 - Cell structure > Flashcards

1 - Cell structure Flashcards

(94 cards)

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1
Q

Apoptosis

A

Cell death

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2
Q

Plasma membrane also known as

A

Cell surface membrane

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3
Q

Cell surface membrane thickness

A

~7nm

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4
Q

Cell surface membrane made of:

A

Phospholipid bilayer

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5
Q

Cell surface membrane function

A

Controls movement of substances into and out of the cell

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6
Q

Largest organelle

A

Nucleus

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7
Q

Nucleus has (single/double) membrane

A

Double

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8
Q

Nucleus function

A

Contains genetic information for the synthesis of proteins, site of transcription of genes and production of mRNA

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9
Q

How is DNA protected from degradation?

A

Enzymes

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10
Q

Components within nucleus

A

Nuclear envelope, nucleolus, chromatin

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11
Q

Nuclear envelope has (___) memranes

A

2

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12
Q

Features of nuclear envelope

A

Attached to ER
2 membranes
Have nuclear pores

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13
Q

Function of nuclear envelope

A

Controls movement of substances between nucleus and cytoplasm

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14
Q

Nucleolus features

A

Densest region

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15
Q

Nucleolus function

A

Site of ribosomal RNA (rRNA) synthesis - site of ribosome assembly

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16
Q

Chromatin features

A

DNA and its associated proteins (histones)

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17
Q

Smallest organelle

A

Ribosomes

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18
Q

Ribosomes features

A

Not bound by a membrane, made of rRNA, which is synthesized in the nucleolus + some protein, has 2 subunits

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19
Q

Ribosomes size

A

25nm

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20
Q

Ribosome function

A

Site of protein synthesis

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21
Q

Two types of ribosomes:

A

80S and 70S

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22
Q

Features of 80S ribosomes

A

25nm
Found in cytoplasm and rough endoplasmic reticulum of all eukaryotes

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23
Q

Features of 70S ribosomes

A

Found in mitochondria and chloroplasts of eukaryotes, found in all prokaryotes

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24
Q

Rough endoplasmic reticulum features

A

Extensive, connected system of membranes made of cisternae (flattened membrane sacs), continuous with the nuclear envelope, runs through the cytoplasm, 80S ribosomes attached

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25
Rough endoplasmic reticulum functions
Site of protein synthesis, protein modification (e.g. protein folding), protein transport to Golgi apparatus
26
Smooth endoplasmic reticulum features
Endoplasmic reticulum without ribosomes, continuous with rough ER
27
Function of smooth endoplasmic reticulum
Site of lipid and steroid synthesis
28
Golgi body features
Made of cisternae, layered appearance, no connection between members, not continuous with nuclear envelope, swellings at end of sacs for vesicle formation, constantly being formed and broken down
29
Golgi body functions
Modification of proteins and lipids, packaging molecules into vesicles for transport, formation of secretory vesicles for release of protein out of the cell, formation of lysosomes
30
How is the Golgi body being formed:
Transport vesicles from rough endoplasmic reticulum on cis face
31
Golgi body being broken down to form:
Secretory vesicles and lysosomes on trans face
32
List the structures involved in protein production + secretion, in order
Ribosome, rough endoplasmic reticulum, transport vesicle, Golgi body, secretory vesicle, cell surface membrane
33
Steps of protein production and secretion
1: synthesis of proteins at ribosomes/RER 2: transport vesicle buds off at RER and fuses with Golgi body 3: Modification of protein at Golgi body 4: Separation of secretory vesicle from Golgi body 5: Fusion of the vesicle with cell surface membrane
34
Steps of protein production and secretion
1: synthesis of proteins at ribosomes/RER 2: transport vesicle buds off at RER and fuses with Golgi body 3: Modification of protein at Golgi body 4: Separation of secretory vesicle from Golgi body 5: Fusion of the vesicle with cell surface membrane 6: Contents released - secretion of protein by exocytosis
35
Lysosomes features
Very small, spherical sacs
36
Lysosome function
Contains hydrolytic enzymes/lysosomes - break down unwanted structures (worn out organelles or dead cells - NOT dead organelles) via hydrolysis in an acid environment
37
Function of lysosomes in white blood cells
Digest bacteria
38
Mitochondria features
Relatively large organelle, double membrane, cristae, matrix, 70S ribosomes + small circular DNA, divide by binary fission
39
Cristae
Folded inner membrane in mitochondria
40
Matrix
Interior solution in mitochondria
41
How do mitochondria divide?
Binary fission
42
Mitochondria function
Site of aerobic respiration - synthesise ATP or produce energy in the form of ATP - release energy
43
Chloroplast features
Relatively large, oval shaped, two membranes, thylakoid (flattened membrane sacs), grana (thylakoid stacks), stroma (interior solution), 70S ribosomes + small circular DNA + starch grains, divide by binary fission
44
Chloroplast function
Site of photosynthesis
45
Cell wall features
Thick, rigid layer made of cellulose (in plants), fully permeable (because there are gaps between fibres)
46
Cell wall functions
Provide structural support, prevent bursting, limit cell size
47
Plasmodesmata features
Strands of cytoplasm passing through channels
48
Plasmodesmata functions:
Allow substances to pass from cell to cell without passing through cell walls
49
Vacuoles + tonoplast features
Commonly found in plant cells. Large, permanent, central. Surrounded by a partially permeable membrane called tonoplast.
50
Vacuoles + tonoplast functions
Store of cell sap, stores waste products, pushes chloroplasts to edge of cell, gives turgidity to the cell
51
Cell sap contents
Water, ions, minerals, salts, pigments, sugars
52
Centriole shape
Cylindrical
53
Pair of centrioles
Centrosome
54
Centrioles + centrosomes features
Centrioles cylindrical, made of 9 groups of 3 microtubules, not found in plant cells
55
Centrioles function:
Involved in cell division (replicates before each cell division and moves to opposite poles. centrioles found in pairs at right angles from each other. forms centrosome), modified centrioles also found elsewhere (e.g. in flagella/cilia. act as a microtubule organising centre - organises + assembles microtubules)
56
Centrosomes function
MTOC (microtubule organising centre), organises/assembles microtubules for the formation of spindle fibres at opposite poles during cell division/mitosis
57
Microtubule features
Very small (~25nm) Made from tubulin - form dimers - dimers polymerise to form long 'protofilaments' - 13 protofilaments = 1 microtubule Long, rigid, hollow tubes Formed + broken down at Microtubule Organising Centres
58
Microtubule functions
Make up cytoskeleton (together with actin filaments) - provides mechanical support - acts as an intracellular transport system for movement of vesicles or other components Makes up spindle fibres and centrioles used in cell division
59
Cilia features
Only found in eukaryotes Smaller in diameter than microvilli Moves rhythmically Complicates structure made of microtubules
60
Cilia function
Movement
61
Microvilli features
Only found in animal cells Found on epithelial cells in the intestines and kidneys Finger-like extensions of the cell surface membrane
62
Microvilli functions
Increase surface area of cell for: - Absorption - Secretion of enzymes - Digestion at the cell surface - Excretion of waste substances
63
3 types of microscopes
Light microscope, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM)
64
3 types of microscopes
Light microscope, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM)
65
Magnification definition
Number of times an image is enlarged compared with the actual size of the object
66
Resolution definition
Ability to distinguish between two points clearly as separate (units in nm).
67
Maximum resolution:
Shortest distance between 2 separate points 1/2 wavelength used
68
What determines resolution?
Shorter wavelength - higher resolution
69
Can a ribosome be seen by a light microscope?
No
70
Advantages of light microscopes
Live specimens can be used, image can be coloured
71
Wavelength of light microscope
400-700nm
72
Highest magnification of light microscope
x1500
73
Maximum resolution of light microscope
200nm
74
Source of electromagnetic radiation in electron microscope:
Free electrons
75
Wavelength of electron microscope
Approximately 1nm
76
Highest magnification of electron microscope
x250 000
77
Max resolution of electron microscope
0.5nm
78
Disadvantages of electron microscope
Only dead material can be examined (because vacuum environment is needed), images are black and white.
79
Which type of electron microscope is used for viewing the surface of specimens?
Scanning electron microscope
80
Which type of electron microscope is used for viewing the inside of cells?
Transmission electron microscope
81
Radiation in a light microscope travels through:
Air
82
Radiation in an electron microscope travels through:
Vacuum
83
Prokaryote cell characteristics
Unicellular Relatively small (1-5μm) Simpler in structure Divide by binary fission
84
What do all bacteria not have?
Membrane-bound organelles Nucleus
85
What all bacteria have:
Plasma membrane Cytoplasm Peptidoglycan cell wall 70S ribosomes Circular DNA DNA is "naked" + not associated with proteins
86
What is only present in some bacteria?
Plasmids Pili Flagellum Capsule Mesosomes (infoldings of plasma membrane)
87
What is a plasmid?
Small, circular DNA that codes for non-essential proteins. Several may be present
88
What are pili?
Involved in sexual reproduction, for attachment to other cells/surfaces
89
What is a capsule (with reference to prokaryotes)?
Outer coat for additional protection Attach to surfaces
90
What is a mesosome and what does it do?
An infolding of plasma membrane. Function = for photosynthesis/nitrogen fixation
91
Similarities between prokaryotes, mitochondria and chloroplasts
Similar size (1-5μm) Small, circular DNA 70S ribosomes Divide by binary fission
92
Virus size
20-300nm
93
Virus features:
Nucleic acid core (RNA or DNA) Capsid (protein coat) Some have outer envelope made of phospholipids (NOT cell surface membrane because derived from host)
94
Why are viruses non-cellular?
All parasitic Can only reproduce by infecting living cells Uses protein synthesising machinery of host cell to replicate

CIE AS Biology (2 decks)

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