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CHP 2 CELLS AND MICROSCOPES Flashcards

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1
Q

what is a cell

A

the basic unit of all living things

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2
Q

what are the two types of cells

A

prokaryotic and eukaryotic cells

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3
Q

what do prokaryotic cells lack

A

membrane bound organelles

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4
Q

what are organelles

A

a specialised part of a cell that performs a particular function

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5
Q

what is the overarching difference between electron and light microscopes

A

electron- uses electrons in place of light to maginify image

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6
Q

who first described and named microscopes and when

A

Robert Hooke 1660s

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7
Q

what is the cell membrane

A

surrounds the cell controls the exchange of materials between the internal and external eviroment the membrane is ‘partially permeable’ formed from a phospholipid bilayer in both animal and plant cells

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8
Q

what is the cell wall

A

freely permeable to most substances found in plant cells but not animal cells outside the cell membrane to provide structural support

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9
Q

what are the narrow threads of cytoplasm called ?

A

plasmodesmata are surrounded by a cell membrane and connect the cytoplasm of neighbouring plant cells

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10
Q

what is the nucleus

A

contains chromatin - a complex DNA and histone proteins - aka genetic material present in eukaryotic cells - except RBC relatively large seperated by the nuclear envelope double membrane- containing many pores

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11
Q

what are nuclear pores

A

important channels for allowing mRNA and ribosomes to travel out of the nucleus as well as allows enzymes to travel and molecules to travel in

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12
Q

what is chromatin

A

the material from which chromosomes are made chromosomes are made of linear DNA tightly wound around protiens called histones

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13
Q

nucleuolos function

A

sites of ribosome production

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14
Q

mitochondria

A

site of aerobic respiration of all eukaryotic cells visible with a light microscope surrounded by a double membrane with the inner membrane folded to form cristae the matrix formed by cristae contains enzymes for aerobic respiration, producing atp small circular pieces of DNA and ribosomes are also found in the matrix

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15
Q

what are chloroplasts

A

found in the green plants of the plant - as a result of the photosynthetic pigment chlorophyll plant cells larger than mitochondria surrounded by double membrane also site of photosynthisis light dependant light intependant contain small circular pieces of dna and ribsomes to synthesise protein photosynthesis and chloroplast replication

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16
Q

what are ribsomes

A

found in all cells in the cytoplasm or as part of the rough endoplasmic reticulum ribosomes are formed in the nucleuolus - composed of almost equal amounts of RNA and proteins site of translation (in protein synthesis)

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17
Q

where is rough endoplasmic reticulum found and function

A

found in animal and plant cells surface is covered in ribosomes formed from continuous folds of membrane processes proteins made by ribosomes

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18
Q

where is the smooth endoplasmic recticulum found and what is its function

A

where:found in animal and plant cells does not have ribosomes on its surface function:involved in the production, processing and storage of lipids, carbohydrates and steriods detoxification

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19
Q

golgi apparatus

A

where:found in both plant and animal cells what:flattened sacs of membrane similar to smooth ER function:modifies proteins and lipids before packaging them into golgi vesicles proteins going through the Golgi are usually: - exported - put into lysosomes - delievered to membrane bound organelles

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20
Q

what do the golgi vesicles do?

A

transport the proteins and lipids to their required destination proteins that go through the golgi apparatus are usually exported put into lysosomes and delivered to membrane bound organelles

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21
Q

vacuole/ tonoplast function

A

a sac in plant cells surrounded by the tonoplast selectively permebale membrane in animal cells are not permenant and are small contain cell sap

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22
Q

vesicles

A

found in plants and animal cells a membrane bound sac for transport and stroage

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23
Q

function of lysosomes

A

specialised forms of vesicles that contain hydrolytic enzymes break down waste materials such as worn out organelles used extensively by cells of immune system and in programmed cell death (apoptosis)

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24
Q

what is a hydrolytic enzymes

A

that break down biological molecules

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25
what are centrioles?
made of microtubules (small, hollow cylinderical proteins) present in animal cells mainly, only some plant cells, not in flowering plants/fungi two centrioles at right angles form a centrosome, help chromosomes seperate during cell division
26
what is a microtubule
found in all eukaryotic cells makes up the cytoskeleton of the cell cytoskeleton- provides support and movement of the cell
27
where are microvilli found and function?
found in specialised animal cells cell membrane projections increase the surface area of cell surface memebrane and increases the rate of exchange of substances
28
what is the cillia?
hair like projections made from microtubules allows movement of substances over the cell surface
29
what are flagella?
found in specialised cells similar structure to cillia but made of longer microtubules contract for cell movement eg. sperm cells
30
What is magnification?
tells you how much bigger the image is compared to the real life object being viewed in the microscope
31
what is resolution?
the ability to distinguish between two points that are close together
32
what are some rules for drawing microscope diagrams
label single lines magnification scaling up do not colour it in use unlined paper don’t cross over lines draw in pencil
33
Do you have to draw everything under the microscope
You can draw a small cross section even
34
what are the different types of microscopes
electron microscopes light microscopes laser scanning confocal microscopes
35
how do light microscopes work
Use light to form an image limiting resolution as you cant distinguish the two points closer than the wavelength of light
36
what is the wavelength of light
500-650nm
37
what are light microscopes used to observe
eukaryotic cells, nuclei and chloroplasts
38
what can light microscopes not observe
smaller structures such as lysosomes
39
how do electron microscopes work
use electrons to form an image, have an increased resolution the beam of electrons have a much smaller wavelength than light
40
how do scanning electron microscopes work
1.scan a beam of electrons across the specimen 2. bounces off the specimen so the electrons are detected to form an image 3. a 3D image can be produced
41
what are the advantages of SEM
can be used on thick 3D specimens external 3D structures can be observed
42
What are the disadvantages of SEM
-have a lower resolution than TEM -cannot observe live specimens -Doesnt produce a colour image
43
how does a transmission electron microscope work
1. uses electromagnets to focus a beam of electrons 2. the beam of electrons is transmitted through the specimen 3. Denser parts of the specimen absorb more electrons, appearing darker on the image and creating a contrast PRODUCES A 2D IMAGE
44
what are the advantages of TEM
high resolution images are produced internal organelles can be seen
45
what are the disadvantages of TEM?
-thin specimen required -specimen must be dead and drained of water due to the vacuum -lengthy treatment to produce specimens and artefacts does not produce a colour image 2D IMAGE PRODUCED
46
What is an artefact
looks like a real structure but is actually a result of staining and preserving
47
how do laser scanning confocal microscopes work?
1. need to be stained with fluorescent dyes 2. a thick section of tissue is scanned with a laser beam 3. this is then reflected by the fluorescent dyes 4. multiple depths of tissue can be scanned to produce an image 3D IMAGE PRODUCED
48
what are the advantages of Laser scanning confocal microscopy?
can be used on thick specimens external 3D can be observed clear images with high resolution
49
What are the disadvantages of Laser scanning confocal microscopy
slow process and takes a long time to obtain an image laser can cause photo damage to cells
50
Why are microscopes used
because many structures are too small to be seen by the naked eye eg. the movement of chromosomes during mitosis can be observed under a microscope
51
how do light microscopes actually work ?
1. light is directed through the specimen on the slide 2. light is focused through several images so that an image is visible through the eyepiece 3. magnifying power can be changed by rotating the objective lens
52
main components of light microscope
The eyepiece lens The objective lenses The stage The light source The coarse and fine focus
53
why is a coverslip used on top of the specimen on the slide
To remove any air bubbles
54
Why should you start with a low power objective lens to begin with
Prevents damage to the lens or coverslip if the stage is raised too high Easier to find what you are looking for
55
How do u prevent the dehydration of the tissue
Add a droplet of water between the specimen and coverslip to prevent the cells being damaged by dehydration
56
What is a graticule?
A small disc that has an engraved ruler has no fixed units and must be calibrated(using a micrometer)
57
what are the limitations of light microscopes?
1.size of cells may appear inconsistent in different specimen slides- different planes cut in different places 2. treatment of specimens while preparing the cells could alter the structure of the cells 3. cannot observe the subcellular structures due to lower magnification
58
why is staining done?
tissues can be naturally transparent so they can let light and electrons pass through staining is used to make the tissue coloured and more visible
59
What is a photomicrograph
An image taken using a light microscope
60
What is differential staining
sometimes sections are stained with multiple dyes to ensure the different tissue come up in colour
61
How do the dyes in staining work
Absorb specific colours of light while reflecting others, depending on their chemical nature
62
Which subceullar structure does not require staining
Green chloroplasts which is their natural colour
63
who is schleiden
in 1838 said that all plants are made of cells
64
who is schwann
in 1839 said that all animal tissues are composed of cells
65
who is virchow
in 1858 said that all cells must arise from prexisting cells
66
what is the total magnification
objective lens x eyepiece lens
67
who said that cells are the basic units of life and when
theodore Schwann 1838
68
who said that animal and plants are made of cells and when
matthias schleiden in 1837
69
who said that cells only develop from other cells and when
BARTHELEMY dumortier 1832
70
whats the differences between eukaryotic and prokaryotic cells
eukaryotic: - nucleus stores genetic material - no cell wall - multicellular organisms have eukarytoic cells - have membrane bound organelles prokaryotic: - genetic material floating in the cytoplasm
71
what is the bacterial wall made of
peptidoglygan
72
what is the fungi cell wall made of
chitin
73
what is the plant wall made of
cellulose
74
what is the size of a prokaryote
less than 1-2 micrometers in diameter
75
what is the size of eukaryote
10-100 micrometers in diameter
76
making and secreting a protein
1. nucleus site of ribosomes and mRNA manufacture 2. ribosomes on RER make proteins to be secreted (free ribosomes make proteins to stay in the cell) 3. proteins are transported by RER to golgi body by vesicles 4. Golgi body processes, modifies and packages the proteins 5. vesicles containing proteins are pinched off the golgi body and move toward the plasma membrane 6. vesicles fuse with plasma membrane and undergo exocytosis
77
what proteins are produced to be excreted by cells (exocytosis)
- mucus - insulin -collagen -enzymes
78
what is the importance of the cytoskeleton
to include provide mechanical strength to cells aiding transport within cells and enabling cell movement eg. movement of chromosomes during mitosis and movement of vesicles
79
what is the cytoskeleton
the network of protein threads running through the cytoplasm contains: - microtubules -microfilaments -intermediate fibres
80
what is a microfilament
contractile fibre made of actin responsible for cytokinesis - solid strands that can cause some cell movement
81
what is a microtubule
made of globular tubulin proteins act as a track for transport of vesicles and organelles to travel up the cell make up spindel fibres
82
what are intermediate fibres
present for strength and have a fixed length
83
what is the difference between cillia and flagella
both are whip like appendages extending from the surface of EUKARYOTIC cells , ENABLES MOVEMENT OF THE CYTOSKELETON CILLIA- MANY FLAGELLA- ONLY ONE OR FEW
84
what is a carrier protein?
a protein on the surface of a cell that helps to transport molecules and ions across the plasma membrane (also called a carrier molecule)
85
what is the definition of cholestrol?
lipid that is an important component of cell surface membranes
86
what is a chromatid?
one of the two copies of a chromosome that are joined togther by a single centromere, before cell division
87
what is a chromosome?
a thread like structure made of protein and dna by which hereditary information is physically passed from one generation to the next
88
what is a compound light microscope?
has two lenses - objective near the specimen, eyepiece where the specimen is viewed from
89
what is chromatic abberation?
colour fringing, a common optical color distortion results in stray colour along the outline of objects
90
what is diffraction?
the bending of light as it passes close to the edge of an object
91
what is the cystol ?
aqueous interior of cells
92
what is a dry mount ?
solid specimens viewed whole or cut into thin slices with sharp blade - SECTIONING specimen placed on the slide cover slip on top eg. har, dust, pollen - viewed whole muscle tissue /plants - sectioned
93
what is a wet mount ?
specimens suspended in a liquid/ immersion oil cover slip placed at an angle eg. aqautic organisms/living organisms
94
what is a sqaush slide?
a wet mount first prepared lens tissue used to press down cover slip potential damage to coverslip- avoided by squashing sample between two microscope slides technqiue for soft samples cover slip should not be broken when pressed eg. root tip sqaushes cell division
95
what is a smear slide?
edge of a slide used to smear sample thin even coating on slide cover slip eg. blood sample
96
why should the refractive index (ability to bend light) of the medium be the same as glass in a wet mount?
in order to reduce/prevent diffraction between liquid and glass, reducing distortion of the image
97
why should the coverslip be placed at an angle in a wet mount ?
to prevent/reduce air bubbles being trapped
98
what is a negative stain technique ?
when the stains used are negatively charged repell the negative charged cytosol dyes stay outside cells cells unstained- background stained
99
what is the gram stain technique ?
seperate bacteria into gram positve and gram negative bacteria crystal violet iodine fixes the dye alchohol wash gram positive retain crystal violet stain - purple/blue gram negative thinner walls lose the stain then stained with safranin counterstain dye red
100
antibiotic penicillin cell walls
gram positve bacteria - suspecptible to this, inhibits formation of cell wall gram negative bacteria - thinner cell walls not sucesptible to pencillin
101
what is fixing
used chemicals like formladehyde to preserve specimens in as near natural state as possible
102
what is the cis face and the trans face
cis face- recieves the proteins lipids trans face - released by the organelles of the golgi
103
what is the fluid enclosed in the chloroplast called
stroma
104
what are thykaloids
internal network of membranes form flattened sacs
105
what are granum (plural grana )
several thylakoids stacked toghether
106
what joins the grana together
membranes called lamellae
107
who devloped the first compound microscope
Galileo in 1609
108
when and how was the spontaneous generation disproved
Louis Pasteur disproved the theory by demonstrating bacteria would only grow in sterile nutrient broth after it had been exposed to air
109
what is spontanteous generation theory
hypothetical process where life is produced from non-living matter in supposedly sterile enviroments
110
what is the importance of microscopes in the study of living organisms
a cell is unit of life and many organisms are unicellular most cells are too small to see without a microscope organelles are even smaller- need to be seen to determine function
111
why was the cell theory not developed before the mid 19th century?
because microscopes were too low a magnifcation to see and identify cells and cell components
112
why must specimens be thin
so light can shine through and details can be seen
113
how do you prepare a sample for staining ?
staining placed on slide and allowed to air dry heat fixed by passing through a flame specimen adhere to slide and take up stains
114
what is sectioning
specimens dehydrated with alcohols placed in mould with wax or resin form hard block thinly sliced with microtome (knife)
115
what is mounting
the specimens being secured to a microscope slide and cover slip placed on top
116
why are gram neg infections more difficult to treat than gram postitive
gram neg have thinner cell wall penicillin disrupts cell wall formation membrane prevents entry of penicillin
117
what are the basic concepts of cell theory
- both plant and animal tissue is composed of cells - cells are the basic unit of all life - cells only develop from existing cells

Biology (5 decks)

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