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A-level Biology > 2.1.1 - Cell structure > Flashcards

2.1.1 - Cell structure Flashcards

1
Q

Name the different types of microscopes ?

A
  • Light microscope
  • Transmission electron microscope
  • Scanning electron microscope
  • Laser scanning confocal microscope
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2
Q

What are the features of a light microscope ?

A
  • Uses visible light to view specimen
  • Uses glass lenses to focus light/ magnify the specimen
  • Specimen mounted on a glass slide and held in water/wax/oil
  • Light is able to pass through specimen
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3
Q

Explain how a light microscope produces an image ?

A
  • The specimen is placed on a glass slide on the stage
  • Visible light ( from light bulb/ mirror ) passes through the specimen
  • The objective lens produces a magnified image which is magnified again by the eye piece lens
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4
Q

What are the features of an electron microscope ?

A
  • Uses a beam of electrons to view specimen
  • Electrons are focused using electromagnets
  • Specimen has to be inside a vacuum ( to allow electrons to pass through without deflection/ absorption )
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5
Q

Explain how a transmission electron microscope produces an image ?

A

A beam of electrons is focused using electromagnets and passed through a very thin specimen producing a high resolution image

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6
Q

Explain how a scanning electron microscope produces an image ?

A
  • A beam of electrons is bounced/ reflected off the surface of a specimen
  • The scattered/ reflected electrons are collected by a detector and a 3D image of the surface of the specimen is formed
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7
Q

What are the features of a laser scanning conical microscope ?

A
  • A higher light intensity is used to view specimen
  • Uses a laser to focus light/ magnify the specimen
  • The specimen is treated with a fluorescent chemical/ dye
  • Light is absorbed and re-emitted by the specimen
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8
Q

Explain how a laser scanning cofocal microscope produces a magnified image ?

A
  • The microscope moves a spot of focused light across the specimen
  • This causes fluorescence from the components labelled with a ‘dye’
  • The emitted light from the specimen is filtered through a pinhole aperture producing a magnified image
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9
Q

Why is light filtered through a pinhole aperture during laser scanning cofocal microscopy ?

A
  • This allows only light radiated from very close to the focal plane to be detected
  • Light emitted from other parts of the specimen would reduce resolution and cause blurring
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10
Q

Do you know how to prepare microscope slides using an eyepiece graticule and micrometer ?

A

Yes

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11
Q

What is staining ?

A

The process of dyeing specimen to increase contrast or identify specific components

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12
Q

Why is staining used during light microscopy ?

A
  • The interior of cells and cell structures are often transparent
  • Staining is used to increase contrast and allow components to be visible so they can be identified
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13
Q

What is differential staining ?

A

The process of distinguishing between two types of organism or organelles of an organism ( that would otherwise be hard to identify ) by using more than one dye

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14
Q

How do you represent cell structures seen under a light microscope ?

A
  • Draw solid confident lines
  • Do not use any form of shading
  • Label or identifiable organelles visible
  • Draw all detail visible
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15
Q

What is the equation for magnification ?

A

magnification = ( image size ) / ( object size )

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16
Q

Do you know how to do magnification calculations ?

A

Yes

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17
Q

Define the term ‘magnification’ ?

A

Magnification - How many times larger the image in comparison to the size of the object

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18
Q

Define the term ‘resolution’ ?

A

Resolution - The ability to see individual objects as separate entities instead of as one

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19
Q

What are the differences in magnification and resolution between a light microscope, TEM and SEM ?

A
  • Light microscope has up to 2000x magnification with a resolution of 200nm
  • Electron microscope has a magnification of over 500,000x and very high resoltion
  • TEM have a better resolution 0.5nm ( more detailed images produced ) in comparison to SEM
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20
Q

What are the differences in images produced between the TEM and SEM ?

A
  • TEM produces very high resolution 2D images ( very detailed ) of thin specimen
  • SEM produces slightly lower resolution 3D images of the surface of the specimen
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21
Q

List the differences between a light and electron microscope ?

A
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22
Q

Label the cell ?

A
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23
Q

What is the function of the nucleus ?

A

It contains coded genetic information in the form of DNA molecules that are associated with proteins called histones forming chromatin which forms chromosomes

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24
Q

What is the nucleolus ?

A

An area within the nucleus that is responsible for the production of ribosomes

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25
Q

What is the function of the nucleolus ?

A

It responsible for producing ribosomes

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26
Q

What is the nuclear envelope ?

A

A double membrane that surrounds the nucleus

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27
Q

What is the function of the nuclear envelope ?

A

It protects the nucleus from damage in the cytoplasm

28
Q

What are nuclear pores ?

A

They are gaps/ holes in the nuclear envelope

29
Q

What is the function of nuclear pores ?

A

It allows molecules to move in and out of the nucleus

30
Q

What is the rough and smooth endoplasmic reticulum ?

A
  • A network of membranes enclosing flattened sacs called cisternae
  • The SER has no ribosomes attached to its surface
  • The RER has ribosomes bound to its surface
31
Q

What is the function of the rough endoplasmic reticulum ?

A

It is responsible for the synthesis and transport of proteins

32
Q

What is the function of the smooth endoplasmic reticulum ?

A

It is responsible for lipid and carbohydrate synthesis and storage

33
Q

What is the Golgi apparatus ?

A

A compact structure formed of cisternae which does not contain ribosomes

34
Q

What is the function of the Golgi apparatus ?

A

It is responsible for modifying proteins and ‘packaging’ them into vesicles ( eg. secretary vesicles or lysosomes )

35
Q

What are ribosomes ?

A

They are small granules made up of proteins and ribosomal RNA

36
Q

Where are ribosomes found in a cell ?

A
  • Free-floating in the cytoplasm
  • Bound to the surface of the rough endoplasmic reticulum
37
Q

What is the function of ribosomes ?

A

They are the site of protein synthesis

38
Q

Label the mitochondrion ?

A
39
Q

What is the function of the mitochondria ?

A

The site of aerobic cellular respiration

40
Q

Explain the structure of the mitochondria ?

A
  • Mitochondria have a double membrane, an inner and outer membrane
  • The foldings of the inner membrane are called cristae and the fluid interior the mitochondrial matrix
  • The inner membrane contains enzymes needed for aerobic respiration
  • Mitochondria contain small amounts of DNA called mitochondrial DNA and ribosomes
  • This allows mitochondria to produce they own enzymes and proteins
41
Q

What are vesicles ?

A

They are membranous sacs that have transport and storage roles

42
Q

What is the function of vesicles ?

A

They transport and store materials inside of the cell

43
Q

What are lysosomes ?

A

They are specialised vesicles that contain hydrolytic enzymes called lysozymes

44
Q

What is the function of lysosomes ?

A
  • They are responsible for breaking down waste material in cells and old organelles
  • They are responsible for breaking down pathogens ingested by phagocytic cells
45
Q

What is the cytoskeleton ?

A

A network of fibres necessary for the shape and stability of the cell

46
Q

What is the function of the cytoskeleton ?

A
  • It provides mechanical strength to cells
  • It aids transports within cells
  • It holds organelles in place and allows cell/ organelles to move within the cell
47
Q

What are the three components of the cytoskeleton ?

A
  • Microfilaments
  • Microtubules
  • Intermediate fibres
48
Q

What are microfilaments and what is their function ?

A
  • They are contractile fibres formed by the protein actin
  • They are responsible for cell movement and contraction during cytokinesis
49
Q

What are microtubules and what are their function ?

A
  • They are a scaffold-like structures
  • They are responsible for determining the cell shape and tracking the movement of organelles around the cell
50
Q

What are intermediate fibres and what are their function ?

A
  • They are fibres
  • They are responsible for providing mechanical; strength to cells and helping maintain their integrity
51
Q

What are centrioles ?

A

A component of the cytoskeleton present in most eukaryotic cells ( except flowering plants / fungi )

52
Q

What is the function of centrioles ?

A
  • Two associated centrioles forma centrosome
  • This is responsible for the assembly and organisation of the spindle fibres during cell division
53
Q

Explain how the various organelles work together to produce and secrete proteins ?

A

1 ) Proteins are synthesised by ribosomes bound to RER
2 ) They pass into RER’s cisternae and are packaged into transport vesicles
3 ) Vesicles move towards the Golgi apparatus vi the transport function of the cytoskeleton
4 ) The vesicles fuse with the Golgi apparatus and the proteins enter. The protein are structurally modified before leaving the Golgi apparatus is vesicles
5 ) Secretory vesicles move towards and fuse with the cell surface membrane before releasing proteins by exocytosis
5 ) Some vesicles form lysosomes contain enzymes used by the cell

54
Q

Label the cell ?

A
55
Q

What is the cell wall made up of ?

A
  • Cellulose in plants
  • Chitin in fungi
56
Q

What is the function of the cell wall ?

A
  • It is freely permeable so allows for the passing of substances in and out of the cell
  • It provides mechanical strength to cell and helps maintain its shape
  • It acts as a defence mechanism and protects the cell against invading pathogens
57
Q

What is the vacuole ?

A

They are membrane-lined sacs in the cytoplasm contains cell sap

58
Q

What is the function of the vacuole ?

A
  • It is responsible for maintaining turgor pressure within the cell and keeping it rigid
  • It is selectively permeable and allows for the passage of small molecules in and out of the vacuole
59
Q

What is the membrane of the vacuole made of ?

A

Tonoplast

60
Q

Label the chloroplast ?

A
61
Q

What is the function of chloroplasts ?

A

It is the site of photosynthesis

62
Q

Explain the structure of chloroplasts ?

A
  • Chlorplasts have a double membrane, an inner and outer membrane
  • The guild enclosed within is called the storma
  • Geranium are stack of disc-shaped sacs called thylakoids
  • Grana are joined by lamellae
  • Grana contain chlorophyll-pigments where light-dependant reactions occur during photosnyethsis
  • Chlroplasts contain small amounts of DNA and ribosomes so can make their own enzymes and proteins required for photosynthesis
63
Q

What is a flagella ?

A

They are tail-like structures

64
Q

What is the function of the flagella ?

A

They enable cell mobility/ locomotion

65
Q

What is the function of cilia ?

A
  • Stationary cilia play an important role in sensory organs
  • Mobile cilia beat in a rhythmic pattern and cause fluids/ objects adjacent cell to move
66
Q

Lis the similarities and differences between prokaryotic and eukaryotic cells ?

A

A-level Biology (31 decks)

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