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A Level Biology > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

Electron micrograph

A

Photograph of an image seen using an electron microscope

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2
Q

What is magnification

A

The number of times larger an image appears, compared with the size of the object

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3
Q

What is the formula for magnification

A

Magnification = size of image / size of real object

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4
Q

What are organelles

A

Small structures within cells, each of which has a specific function

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5
Q

What is a photo micrograph

A

Photograph of an image seen using an optical microscope

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6
Q

What is resolution

A

The smallest distance at which separate objects can be distinguished

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7
Q

What does the cell theory state

A
  • all living things are composed of cells
  • the cell is the smallest unit of life
  • cells only arise from pre-existing cells
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8
Q

How does a light/optical microscope work

A

Uses visible light which is reflected through a specimen

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9
Q

What type of image is produced by an optical microscope

A

Magnified image of the object
- 2D
- colored
- magnification limit = 1000x
- resolution limit = 200nm

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10
Q

What are the pros of optical microscopes

A
  • cheap
  • small
  • portable
  • living specimens
  • colored image
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11
Q

Cons of optical microscopes

A
  • poor resolution
  • can’t view organelles
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12
Q

How do transmission electron microscopes (TEM) work

A
  • specimen is dehydrated and stained
  • electron beams them pass through
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13
Q

What type of image is produced by a TEM

A
  • 2D image
  • black and white image
  • magnification limit = 5,000,000x
  • resolution limit = 1nm
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14
Q

What are the pros of TEM

A
  • high magnification
  • excellent resolution
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15
Q

Cons of TEM

A
  • no living specimen (vacuum)
  • black and white
  • complex staining process
  • artifacts can result
  • large
  • expensive
  • need skill and training to use
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16
Q

How do scanning electron microscopes (SEM) work

A
  • electrons are shot at the specimen
  • electrons don’t pass through
  • electrons ‘bounce of’
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17
Q

What type of image does a SEM produce

A
  • 3D image
  • black and white (programs can add colour)
  • magnification limit = 30,000x
  • resolution limit = 10nm
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18
Q

Pros of SEM

A
  • 3D image
  • don’ need a thin section
  • high magnification
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19
Q

Cons of SEM

A
  • can’t view internal structures
  • not as high resolution as TEM
  • specimen has to be in a vacuum with a thin layer of metal
  • needs skill and training to use
  • large
  • expensive
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20
Q

How do scanning laser confocal microscopes work

A
  • uses fluorescent tags (molecules that can be attached to certain things)
  • uses laser light to scan an object
  • object is displayed on a computer screen
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21
Q

What type of image is produced by a laser scanning confocal microscope

A
  • high resolution to show high contrast
  • view movement
  • view an object a certain depth within a cell/sample
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22
Q

What are the pros of scanning laser confocal microscopes

A
  • can focus on objects at different depths
  • can observe cells as well as whole objects
  • used in medical profession
  • can use living specimens
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23
Q

Cons of laser scanning confocal microscopes

A
  • resolution lower than SEM
  • very expensive
  • limited number of wavelengths
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24
Q

Why do electron microscopes have a higher resolving power

A
  • light microscopes use a light beam to view the specimen
  • light beams have a long wavelength
  • low resolution
  • electron microscopes use beams of electrons
  • electrons have a short wavelength
  • high resolution
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25
What are the different parts of a light microscope
- eyepiece - tube - arm - objective lens - stage - sample clamps - corse focus - fine focus - light - base
26
Steps to making a slide
- sharp blade to cut a thin slice of tissue - use the thinnest slide allowing for max light to get through - wet mount to prevent dehydration - place stain at the edge of the sample - lower cover slip at an angle - use blotting paper to get rid of any extra - use more then one stain to improve contrast - squash slide to easier see individual cells
27
Why do you use stain
- increase contrast - identify named organelles/ more visible - clear image
28
What is differential staining
- allows for more contrast - distinguishes different organelles
29
What does iodine let you see
- light - blue/black Stains starch containing tissues
30
What does methylene blue allow you to see
- light - blue Stains nuclei of animal cells
31
What does to toluidine blue let you see
- light - various Metachromatic stain, reacts with different compounds to give different colours
32
What does gold/osmium allow you to see
- electron - B&W Electron-dense heavy metal stain used to absorb electrons
33
What does eosin allow you to see
- light - purple Proteins (cytoplasm)
34
What does sudan red allow you to see
- light - red Cell membrane
35
What does phalloidin allow you to see
- light - green Cytoskeleton
36
What does acetic orcein allow you to see
- light - red Stains nucleon of animal cells
37
What does gram allow you to see
- pink or purple Bacteria
38
What is the mnemonic for drawing biological drawings
PILATES
39
What does PILATES stand for
Pencil Individual cells (do not draw) Lines Annotate Title Enormous Scale
40
What is an eyepiece graticule
A measuring device. It is placed in the eyepiece of a microscope and acts as a ruler when you view an object under the microscope
41
What is a stage graticule
A precise measuring devise. It is a small scale that is placed on a microscope stage and used to calibrate the value of eyepiece divisions at different magnifications.
42
What structures are found in eukaryotic animal cells
- nucleus - nucleolus - mitochondrion - free ribosomes (80S) - endoplasmic reticulum (rough/smooth) - Golgi body - vesicles - lysosomes - flagellum - cilia - centrioles - cytoskeleton
43
What is the function on the nucleus, nuclear envelope and nucleolus
- separate nucleus from rest of cell - allow for some dissolved substances and ribosomes through - pores allow large substances to leave or enter the nucleus - ribosomes are made in the nucleolus - contain chromosomes
44
What is the function of the mitochondria
- ATP production in aerobic respiration - self replicating - abundant in necessary cells
45
What is the function of ribosomes
- protein synthesis
46
What is the function of the endoplasmic reticulum
Rough - intracellular transport system - large surface area for ribosomes Smooth - contain catalyst enzymes - involved in absorption, synthesis and transport of lipids
47
What is the function of the Golgi body
- proteins are modified (sugar, lipids, 3D forms) - proteins packed into vesicles which are stored or moved to plasma membrane
48
What is the function of vesicles
- transport materials from inside the cell - transport = inside cell - secretory = outside cell
49
What is the function of lysosomes
- separate hydraulic enzymes from the rest of the cell - engulf old organelles/foreign matter and digest them
50
What is the function of the flagellum
- allows the cell to move
51
What is the function of the cilia and undulipodia
- beat and move the band of mucus - nearly all cells have one acting as an antena - movement
52
What is the function of the centrioles
- cell division
53
Organelles that are found in eukaryotic plant cells
- nucleus - nucleolus - mitochondria - ribosomes (80S) - endoplasmic reticulum - Golgi apparatus - vesicles - lysosomes - flagellum - cilia - chloroplasts - permanent vacuole - amyloplasts - cell wall - plasmodesmata
54
What is the function of the chloroplast
- photosynthesis
55
What is the function of the permanent vacuole
- stores cell sap - provides structure to cells
56
What is the function of the amyloplasts
- stores amylopectin
57
What is the function of the plasmodesmata
- cytoplasmic extensions - produced as cells divide
58
What is the function of the cell wall
- provide strength and support - maintain the cell’s shape
59
What is the cytoskeleton made form
- microtubules - actin filaments - intermediate filaments
60
What is the function of the cytoskeleton
- provides strength - transport within cells - allows for cell movement
61
How does protein synthesis take place
- transcription takes place in the nucleus R.E.R - protein synthesis - proteins are folded - transport vesicle carries these protein along the cytoskeleton - modification takes place in the Golgi body - secretory vesicles carry theses proteins out of the cell - exocytosis
62
Similarities between prokaryotic and eukaryotic cells
Both have - plasma membrane - cytoplasm - ribosomes - DNA and RNA
63
Differences between eukaryotic and prokaryotic cells
Prokaryotic cells - much smaller - have less well-developed cytoskeleton - no centrioles - no nucleus - no membrane bound organelles - peptidoglycan cell wall (not cellulose) - smaller ribosomes - naked DNA
64
What else do some prokaryotic cells have
- protective waxy capsule around cell wall - small loops of DNA (plasmids) - flagella - pili
65
What is a pili
- smaller hair-like projection - enables bacteria to adhere to host cells - allows passage of plasmid DNA from one cell to another

A Level Biology (13 decks)

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