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BIO HL > A2.2 Cell Structure > Flashcards

A2.2 Cell Structure Flashcards

1
Q

What are cells

A

the basic structural units of all living organisms

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2
Q

what are unicellular organisms, and examples

A

Organisms that are made of a single cell such as prokaryotes, protists and fungi

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3
Q

What are multicellular organisms

A

organisms that are made of many cells such as mammals and plants

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4
Q

what are the components of cell theory

A

all living things are composed of cells
cell is the basic unit of life
cells come from pre existing cells

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5
Q

can there be exceptions to cell theory

A

yes

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6
Q

What is 1 meter in terms of millimeters

A

1000 mm

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7
Q

what is a thousand micrometers

A

1 mm

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8
Q

what is a thousand nanometres

A

1 micrometer

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9
Q

what is the turret in microscopes

A

where the different lenses are rotated under the lenses

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10
Q

what is the stage in microscopes

A

where the slide is placed

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11
Q

what is the condenser in microscopes

A

focuses light on the object with an iris diaphragm

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12
Q

what is the fine focus in microscopes

A

used to focus high power lenses

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13
Q

what is the coarse focus in microscopes

A

used to focus low/medium power lenses

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14
Q

what is the eyepiece graticule

A

the scale that has arbitrary units ( alighned with stage micrometer to find true dimensions)

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15
Q

a material that is being magnified should be ____?

A

sufficiently transparent for light to pass through

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16
Q

what is magnification and its formula

A

the number of times large an object appears
size of image / size of specimen

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17
Q

what is resolution

A

the amount of detail that can be seen

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18
Q

how can resolution be improved

A

shorter wavelengths give better resolution

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19
Q

how do electron microscopes work

A

they replaced light with beams of electrons so that magnification and resolution are much better
Biological material must be dead

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20
Q

what is ultrastructure

A

the fine structure of cells

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21
Q

what is cryogenic electronic microscopy

A

a technique that involves flash freezing solutions and then exposing them to electrons

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22
Q

what is freeze fracturing

A

when biological material is instantly frozen solid in liquid nitrogen and the tissue is broken up in a vacuum
A replica then made of the exposed surface( freeze etching)

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23
Q

what is fluorescence microscopy

A

when dyes are used to bind specifically to target molecules, allowing their location to be revealed.
A fluorescence microscope is used to detect the stained cells.

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24
Q

what is the role of the cytoplasm

A

provides the medium in which many metabolic reactions of the cell occur ( need to be dissolved to perform their function)

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24
what is the role of the nucleus
control and direct the activities of the cell, along with containing DNA
24
what is the role of the cell membrane
the barrier controlling entry and exit from the cytoplasm
24
what are the 4 structures common to all living cells
plasma membrane cytoplasm DNA ribosomes
25
what are organelles
unit of the cells substructure that have a special function
26
what are features of prokaryotes
very small have a single loop of DNA(nucleoid) no membrane bound organelles inside
27
what structures are always found in prokaryotes
cell wall cell membrane cytoplasm chromosome food store 70s ribosomes
28
what structure are sometimes found in prokaryotes
pili capsule plasmid flagellum
29
what is the role of pili
enables the cell to attach to surfaces
30
what is the role of flagellum
used for movement of the bacterium
31
what is the role of the capsule
helps the cell from dehydrating and adheres to other surfaces
32
difference between 70s ribosomes and 80s ribosomes
70s are smaller and found in bacteria 80s are larger and found in eukaryotic cells
33
where is DNA found in prokaryotes
found in nucleoids which is a loop of DNA Can also be found in plasmids which is smaller and replicate independently
34
what organelles are present in eukaryotes
nucleus mitochondria ribsomes ER golgi apparatus lysosomes
35
what features are present in eukaryotic cells but not considered as organelles
cytoskeleton plasma membrane
36
what are features of the nucleus
largest organelle surrounded by double layered membrane known as nuclear envelope which contains nuclear pores contains chromosomes which may appear as chromatins contains nucleoli which is the site where sub units of the ribosomes are formed
37
what are features of mitochondria
relatively large and present in large numbers has a double membrane, inner membrane folds to form cristae the matrix is the fluid inside that contains enzymes, ribosomes and DNA
38
what is the role of mitochondria
adapted for production of ATP by aerobic cellular respiration
39
what are ribosomes and their features
tiny structures with no membrane can be free or bound to the ER they are the site where proteins are made
40
difference between free and bound ribosomes
free synthesises proteins within the cell bound synthesizes proteins that are secreted from the cell or become integral proteins
41
What is the Endoplasmic Reticulum
network of folded(flattened) membranous sacs that are interconnected connected to the membrane of the nuclear envelope
42
What is the difference between bound SER and RER
RER has bound ribosomes and continuous with the nuclear envelope SER is continuous with the RER and lacks ribosomes. Main function is synthesis of phospholipids and cholesterol
43
what is the golgi apparatus
modifies polypeptides into their functional state sorts concentrates and packs proteins into vesicles
44
what is the structure of the golgi apparatus
stack like collection of flattened membranous sacs one side is formed by fusion of membranes of vesicles, other side is formed by vesicles swellings which get pinched off
45
what is the role of lysosomes
contains enzymes which digest large molecules when they are old or damaged can be used for immunity by digested pathogens breakdown of foreign matter involved in 'programmed cell death' and self digestion
46
what are features of the lysosomes
tiny spherical vesicles bound by a single membrane contains concentrated mixture of digestive enzymes
47
what is the cytoskeleton
a network of fibers extending throughout the cytoplasm organizes the structures and activities of the cell
48
what are the three main types of fiber in the cytoskeleton
microtubules microfilaments intermediate filaments
49
what are microtubules
the thickest class of fibres straight,unbranched,hollow,cylindrical made of the protein tubulin used to move chromosomes during cell division organelles moved with motor proteins along microtubules support and maintain shape of the cell
50
what are microfilaments (actin filaments)
thinnest fiber made of solid rods of actin each filament is a twisted double chain of actin molecules, designed to resist tension used to divide the cell during cell division, and maintain and change cell shape
51
what are the different function of life
homeostasis metabolism nutrition movement excretion growth sensitivity reproduction
52
what is homeostasis
maintenance of a constant, stable environment
53
what is metabolism
the network of interdependent and interacting chemical reactions occurring in living organisms
54
what is nutrition
process by which organisms take in, and make use of food
55
what is movement
moving from one place to another
56
what is excretion
metabolic waste is eliminated from an organism
57
what is growth
increase in size,mass or number of cells
58
what is sensitivity
recognise an respond to changes in environmental conditions
59
what is reproduction
formation of new individuals by sexual or asexual means
60
what feature do plant cells have that other eukaryotic cells do not
plastids such as chloroplasts and amyloplasts
61
what features do plant and fungi have that animal cells dont
cell wall made of cellulose in plants made of chitin in fungi
62
what features do animal cells have that plant and fungi dont
animal cells have centrioles two centrioles create a centrosome which grow spindle fibers before an animal cell replicates They also have cilia and flagella for movement
63
difference between cilia and flagella
cilia made of microtubules, shorter and more numerous flagella less numerous and long
64
what are hyphae
fungi form threadlike structures with no walls between the cells, resulting in multiple nuclei not divided into separate cells
65
what are a collection of hyphae known as
mycelium
66
How are skeletal muscle fibers an example of atypical cell structure
fusion of multiple cells which results in a single large cell that has multiple nuclei
67
How are RBC's atypical
they discard their nucleus and mitochondria, increasing surface area and making them smaller
68
How are sieve tubes an example of atypical cell structure
sieve plates are connected to companion cells known as plasmodesmata which help service and maintain them, meaning sieve plates have no nucleus or organelles
69
what is a micrograph
a photograph taken through a microscope to show a magnified image of an item
70
What is endosymbiotic theory
suggests some organelles in eukaryotic cells were once free living prokaryotes which became incorporated into a host cell both parts would have then become integrated through natural selection leading to an endosymbiotic relationship
71
what organelles are believed to have originated from endosymbiotic theory
mitochondria and chloroplasts
72
what is the evidence for the endosymbiotic theory
chloroplast and mitochondria reproduce like prokaryotes they contain circular DNA, like prokaryotes contain 70s ribosomes transcribe mRNA from their DNA, like prokaryotes similar in size to prokaryotes they have double membrane, which suggests they were engulfed by endocytosis
73
what is a tissue
a group of similar cells that are specialised to perform a particular function
74
what is an organ
a collection of different tissues which perform a specialised and coordinated function
75
how do cells differentiate when they all have the same genes
different sets of genes are expressed according to history and signals received from the environment
76
what controls how cells specialize
controlled by the immediate environment of the differentiating cell and the cells position in the developing organism
77
what is a proteome
the totality of proteins expressed within a cell, tissue or organism at a certain time. Means its unique to each individual
78
what does the genome do
instructs the expression of proteins
79
what is the result of specialisation of cells
due to division of labour, increased efficiency is acheived However, specialised cells are now completely dependent on the acitvities of other cells
80
due to the amount of species that are multicellular, what does it suggest
it is relatively easy to evolve with few barriers
81
what are the advantages of multicellularity
larger body sizes and cell specialisation
82
what could have led to multicellularity
strong selective pressures favoring it ( clusters of cells were less likely to be predated) , few genetic changes necessary or a combination of the two

BIO HL (23 decks)

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