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BIO HL > A2.2 Cell Structure > Flashcards

A2.2 Cell Structure Flashcards

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Biology 101 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
Q

what is the role of the nucleus

A

control and direct the activities of the cell, along with containing DNA

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24
Q

what is the role of the cell membrane

A

the barrier controlling entry and exit from the cytoplasm

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24
Q

what are the 4 structures common to all living cells

A

plasma membrane
cytoplasm
DNA
ribosomes

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25
Q

what are organelles

A

unit of the cells substructure that have a special function

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26
Q

what are features of prokaryotes

A

very small
have a single loop of DNA(nucleoid)
no membrane bound organelles inside

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27
Q

what structures are always found in prokaryotes

A

cell wall
cell membrane
cytoplasm
chromosome
food store
70s ribosomes

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28
Q

what structure are sometimes found in prokaryotes

A

pili
capsule
plasmid
flagellum

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29
Q

what is the role of pili

A

enables the cell to attach to surfaces

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30
Q

what is the role of flagellum

A

used for movement of the bacterium

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31
Q

what is the role of the capsule

A

helps the cell from dehydrating and adheres to other surfaces

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32
Q

difference between 70s ribosomes and 80s ribosomes

A

70s are smaller and found in bacteria
80s are larger and found in eukaryotic cells

33
Q

where is DNA found in prokaryotes

A

found in nucleoids which is a loop of DNA
Can also be found in plasmids which is smaller and replicate independently

34
Q

what organelles are present in eukaryotes

A

nucleus
mitochondria
ribsomes
ER
golgi apparatus
lysosomes

35
Q

what features are present in eukaryotic cells but not considered as organelles

A

cytoskeleton
plasma membrane

36
Q

what are features of the nucleus

A

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
Q

what are features of mitochondria

A

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
Q

what is the role of mitochondria

A

adapted for production of ATP by aerobic cellular respiration

39
Q

what are ribosomes and their features

A

tiny structures with no membrane
can be free or bound to the ER
they are the site where proteins are made

40
Q

difference between free and bound ribosomes

A

free synthesises proteins within the cell
bound synthesizes proteins that are secreted from the cell or become integral proteins

41
Q

What is the Endoplasmic Reticulum

A

network of folded(flattened) membranous sacs that are interconnected
connected to the membrane of the nuclear envelope

42
Q

What is the difference between bound SER and RER

A

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
Q

what is the golgi apparatus

A

modifies polypeptides into their functional state
sorts concentrates and packs proteins into vesicles

44
Q

what is the structure of the golgi apparatus

A

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
Q

what is the role of lysosomes

A

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
Q

what are features of the lysosomes

A

tiny spherical vesicles bound by a single membrane
contains concentrated mixture of digestive enzymes

47
Q

what is the cytoskeleton

A

a network of fibers extending throughout the cytoplasm
organizes the structures and activities of the cell

48
Q

what are the three main types of fiber in the cytoskeleton

A

microtubules
microfilaments
intermediate filaments

49
Q

what are microtubules

A

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
Q

what are microfilaments (actin filaments)

A

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
Q

what are the different function of life

A

homeostasis
metabolism
nutrition
movement
excretion
growth
sensitivity
reproduction

52
Q

what is homeostasis

A

maintenance of a constant, stable environment

53
Q

what is metabolism

A

the network of interdependent and interacting chemical reactions occurring in living organisms

54
Q

what is nutrition

A

process by which organisms take in, and make use of food

55
Q

what is movement

A

moving from one place to another

56
Q

what is excretion

A

metabolic waste is eliminated from an organism

57
Q

what is growth

A

increase in size,mass or number of cells

58
Q

what is sensitivity

A

recognise an respond to changes in environmental conditions

59
Q

what is reproduction

A

formation of new individuals by sexual or asexual means

60
Q

what feature do plant cells have that other eukaryotic cells do not

A

plastids such as chloroplasts and amyloplasts

61
Q

what features do plant and fungi have that animal cells dont

A

cell wall
made of cellulose in plants
made of chitin in fungi

62
Q

what features do animal cells have that plant and fungi dont

A

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
Q

difference between cilia and flagella

A

cilia made of microtubules, shorter and more numerous
flagella less numerous and long

64
Q

what are hyphae

A

fungi form threadlike structures with no walls between the cells, resulting in multiple nuclei not divided into separate cells

65
Q

what are a collection of hyphae known as

A

mycelium

66
Q

How are skeletal muscle fibers an example of atypical cell structure

A

fusion of multiple cells which results in a single large cell that has multiple nuclei

67
Q

How are RBC’s atypical

A

they discard their nucleus and mitochondria, increasing surface area and making them smaller

68
Q

How are sieve tubes an example of atypical cell structure

A

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
Q

what is a micrograph

A

a photograph taken through a microscope to show a magnified image of an item

70
Q

What is endosymbiotic theory

A

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
Q

what organelles are believed to have originated from endosymbiotic theory

A

mitochondria and chloroplasts

72
Q

what is the evidence for the endosymbiotic theory

A

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
Q

what is a tissue

A

a group of similar cells that are specialised to perform a particular function

74
Q

what is an organ

A

a collection of different tissues which perform a specialised and coordinated function

75
Q

how do cells differentiate when they all have the same genes

A

different sets of genes are expressed according to history and signals received from the environment

76
Q

what controls how cells specialize

A

controlled by the immediate environment of the differentiating cell and the cells position in the developing organism

77
Q

what is a proteome

A

the totality of proteins expressed within a cell, tissue or organism at a certain time.
Means its unique to each individual

78
Q

what does the genome do

A

instructs the expression of proteins

79
Q

what is the result of specialisation of cells

A

due to division of labour, increased efficiency is acheived
However, specialised cells are now completely dependent on the acitvities of other cells

80
Q

due to the amount of species that are multicellular, what does it suggest

A

it is relatively easy to evolve with few barriers

81
Q

what are the advantages of multicellularity

A

larger body sizes and cell specialisation

82
Q

what could have led to multicellularity

A

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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