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Cells: The Working Units of Life Flashcards

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1
Q

what does cell theory state ?

A

cells are the fundamental units of life
all organisms are composed of cells
all cells come from preexisting cells

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2
Q

What are the implications of cell theory ?

A

the functions of all cells are similar
life is continuous
the origin of life was the origin of cells

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3
Q
A
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4
Q

Are cells mostly large or small ?

A

small

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5
Q

What cells are relatively large ?

A

bird eggs, neurons, some algae, and bacterial cells

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6
Q

why are cells small ?

A

a high surface-area-to-volume-ratio is essential

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7
Q

what does the volume of a cell determine ?

A

the amount of chemical activity that takes place in the cell per unit time

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8
Q

what does the surface area of a cell determine ?

A

the amount of substances that can pass the cell boundary per unit of time

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9
Q

would a large cell have a small surface-area-to-volume-ratio or a small one ?

A

small

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10
Q

what do we use to view cells ?

A

microscopes

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11
Q

what does magnification mean ?

A

increases the apparent size

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12
Q

what does resolution mean ?

A

clarity of the magnified object (the minimum distance two objects can be apart and still be seen as two objects)

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13
Q

what are the two basic types of microscopes ?

A

light microscope and electron microscopes

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14
Q

how do light microscopes work and what is there resolution ?

A

use glass lenses and light.
resolution is 0.2 micrometres

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15
Q

how do electron miscroscopes work and what is their resolution ?

A

electromagnets focus an electron beam
resolution is 0.2 nanometres

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16
Q

what is the plasma membrane ?

A

the outer surface of every cell, and has more or less the same structure in all cells

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17
Q

what is the plasma membrane made out of ?

A

phospholipid bilayer with proteins and other molecules embedded

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18
Q

is the plasma membrane rigid ?

A

no, more like an oily fluid in which the proteins and lipids are in constant motion

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19
Q

what are the 4 features of the plasma membrane ?

A

is a selectrively permeable barrier
this allows cells to maintain a constant internal environment
important in communication and receiving signals
often has proteins for binding and adhering to adjacent cells

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20
Q

what are the two types of cell ?

A

prokaryotic and eukaryotic

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21
Q
A
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22
Q

are bacteria and archaea eukaryotes or prokaryotes ?

A

prokaryotes

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23
Q

whats the main difference between eukaryotes and prokaryotes ?

A

in eukaryotes the dna is in a membrane-enclosed compartment called the nucleus

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24
Q

do eukaryotes have other membrane enclosed compartments ?

A

yes, in which specific chemical reactions occur

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25
what has allowed the diversification of the functions in eukaryotic cells, and their specialisation into tissues ?
membrane enclosed compartments within the eukaryotic cells. in these compartments, specific chemical reactions occur
26
are prokaryotes small or large ?
very small
27
how are prokaryotic cells found ?
as individuals (single cells), but often found in chain or clusters
28
Prokaryotes are very successful. This is because they ...
can live off a diversity of energy sources and some can tolerate extreme conditions
29
what are the features of a prokaryotic cells ?
are enclosed by a plasma membrane their dna is contained in a nucleoid
30
what does the cytoplasm consist of ?
cytosol (water and dissolved material), and suspended particles
31
what are ribosomes ?
these are the sites of protein synthesis
32
what is a prokaryotic cell made up of ?
cell wall plasma membrane nuceloid ribosomes cytoplasm capsule
33
what is the cell wall of a prokaryotic cell made of ?
peptidoglycan and outer membrane (absent in some bacteria)
34
some prokaryotes swim by the means of ...
flagella
35
what is flagella made of ?
made of the protein flagellin
36
some bacteria have pili. these are ...
hairlike structures projecting from the surface
37
what does pili help bacteria do ?
adhere to other cells
38
some rod-shaped bacteria have a ... made of the protein ...
cytoskeleton actin
39
how many times larger are eukaryotes compared to prokaryotes ?
upto x10
40
what are the membrane-enclosed compartments within eukaryotes called ?
organelles
40
41
each organelle has a ...
specific role in cell functioning
42
what does an animal cell consist of ?
plasma membrane, nucleus, nucleolus, free ribosomes, ribosomes (bound to the ER), mitochondrion, SER, RER, golgi apparatus, centrioles, peroxisome and the cytoskelton.
43
what does a plant cell consist of ?
cell wall, plasma membrane, nucleus, nucleolus, free ribosomes, RER, SER, golgi apparatus, vacuole, mitochondrion, chloroplast, plasmodesmata, peroxisome
44
how were organelles first studied ?
using light microscopy
45
what do we do to separate organelles for study by chemical methods ?
use cell fractionation
46
order these in from most dense to least dense: golgi, nuclei, mitochondria
nuclei, mitochondria, golgi
47
what do ribosomes consist of ?
ribosomal RNA (rRNA) and more than 50 different protein molecules
48
where are ribosomes found in eukaryotic cells ?
free in the cytoplasm, attached to endoplasmic reticulum, or inside mitochondria and chloroplasts
49
where are ribosomes found in eukaryotic cells ?
float freely in the cytoplasm
50
what are the 4 features of the nucleus ?
contains the DNA site of DNA replication site where gene transcription is turned on or off assembly of ribosomes begins in a region called the nucleolus
51
how many membranes is the nucleus surrounded by and what is this called ?
two membranes-nuclear envelope
52
what do the nuclear pores within the envelope do ?
they control the movement of molecules between the nucleus and cytoplasm
53
what do some large molecules (e.g. proteins) require in order to cross the nuclear envelope ?
must have a certain amino acid sequence known as a nuclear localization signal (NLS) to cross
54
in the nucleus, DNA combines with proteins to form ... in long, thin threads called ...
chromatin chromosomes
55
when are individual chromosomes visible in the light microscope ?
before cell division as chromatin condenses
56
what surrounds the chromatin ?
nucleoplasm
57
what is the nuclear matrix and what does it do ?
is a network of structural proteins and helps organise the chromatin
58
what 5 things does the endomembrane system include >
the plasma membrane, nuclear envelope, endoplasmic reticulum, golgi apparatus, and lysosomes (tiny, membrane-surrounded vesicles shuttle substances between the various components)
59
what is the endoplasmic reticulum ?
network of interconnected membranes in the cytoplasm -it has a large surface area
60
61
whats the difference between the SER and the RER ?
ribosomes are attached to the RER
62
newly made proteins enter the RER lumen where they are ...
modified, folded and transported to other regions
63
what are the 4 features of the SER ?
are more tubular and have no ribosomes chemically modifies small molecules such as drugs and pesticides important in the hydrolysis of glycogen in animal cells synthesis of lipids and steriods
64
what are the 4 features of the golgi apparatus ?
composed of flattened sacs (cisternae) and small membrane-enclosed vesicles they receive proteins the RER-can further modify them concentrates, packages and sorts proteins in plant cells, polysaccharides for cell walls are synthesized here
65
what does the cis region of the golgi apparatus do ?
receives vesicles from the ER-a piece of the ER that "buds" off
66
what takes place at the trans region ?
vesicles bud off from the golgi apparatus and are moved to the plasma membrane or other organelles
67
68
where do primary lysosomes come from ?
originate from the golgi apparatus
69
what do primary lysosomes contain ?
digestive enzymes-macromolecules are hydrolysed into monomers
70
how are food molecules hydrolysed ?
food molecules enter the cell by phagocytosis and a phagosome is formed. phagosomes then fuse with primary lysosomes to form secondary lysosomes. enzymes in the secondary lysosome thenhydrolyse the food molecules
71
what is meant by autophagy ?
lysosomes digesting cell material
72
cell ... are freqeuntly ... and replaced by new ones
components destroyed
73
what takes place in the mitochondria ?
energy in fuel molecules is transformed to the bonds of energy rich atp - cellular respiration
74
cells that require a lot of energy will have a lot of ...
mitochondria
75
how many membranes does mitochodnria have ?
2
76
what does the inner membrane of mitochondria do ?
folds inward to form cristae. this creates a large surface area for proteins involved in cellular respiration reactions .
77
what does the mitochondrial matrix contain ?
enzymes, DNA and ribosomes
78
where can we find plastids ?
only in plants and some protists
79
what is chloroplast ?
site of photosynthesis.
80
what is photosynthesis ?
when light energy is converted to the energy of chemical bonds
81
how many membranes does chloroplast have ?
2
82
what are the 3 features of a chloroplast ?
granum thylakoid stroma
83
what is grana ?
grana are stacks of thylakoids- made of circular compartments of the inner membrane
84
what are thylakoids ?
contain chlorophyll and other pigments that harvest light energy for photosynthesis
85
what is stroma ?
a fluid in which grana are suspended. it contaisn DNA and ribosomes
86
what are the two other plastids ?
chromoplasts and leucoplasts
87
what do chromoplasts contain ?
red, orange, and yellow pigments - this gives colour to flowers
88
what do leucoplasts do ?
store starches and fats
89
what do peroxisomes do ?
collect and break down toxic byproducts of metabolism such as hydrogen peroxide using specialized enzymes
90
where are glyoxysomes found and what do they do ?
found only in plants and lipids are converted to carbohydrates for growth
91
what cells contain vacuoles ?
plants and protists cells
92
93
what do vacuoles do ?
store waste and toxic compounds-some may deter herbivores provide structure for plants cells-water enters the vacuole by osmosis. This creates turgor pressure Store anthocyanins (pink and blue pigments) in flowers and fruits. the colours attract pollinators vacuoles that are in seeds have digestive enzymes to hydrolyse stored food for early growth
94
95
what are the 5 things a cytoskeleton does ?
supports and maintains cell shape holds organelles in position moves organelles involved in cytoplasmic streaming interacts with extracellular structures to hold the cell in place
96
what are the three components of the cytoskeleton ?
microfilaments intermediate filaments microtubules

Biological principles (8 decks)

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