2.1.1: Cell Structure Flashcards

1
Q

Define magnification

A

How much bigger an object is compared to its actual size

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2
Q

Define resolution

A

Ability to see individual objects as separate entities

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3
Q

Which microscope has the highest resolution and magnification?

A

TEM

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4
Q

What is magnification of TEM ?

A

X1,000,000

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5
Q

What is resolution of TEM ?

A

0.0002um

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6
Q

What is magnification of SEM ?

A

X500,000

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7
Q

What is resolution of SEM ?

A

0.002um

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8
Q

What is magnification of a light microscope ?

A

X1500

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9
Q

What is resolution of a light microscope ?

A

0.2um

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10
Q

What does a TEM do ?

A

Electromagnets focus a beam of electrons.Denser regions absorb more.

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11
Q

What does a SEM do ?

A

Beams of electrons are scattered across surface of specimen

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12
Q

Give disadvantages of electron microscopes

A
  • Non living samples
  • Specialist training
  • Expensive
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13
Q

Give 2 organelles not visible using a light microscope

A
  • Lysosomes
  • Ribosomes
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14
Q

Give 2 ways to measure cells and organelles

A
  • Eyepiece graticule + stage micrometer
  • Micrograph
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15
Q

Give scale bar equation

A

Length of scale bar = magnification x length scale bar represents

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16
Q

Give 2 advantages of differential staining

A
  • Creates a contrast using stains ( if structures are colourless and transparent)
  • Helps identify organelles ( clearer)
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17
Q

Give the 4 ways of preparing a microscope slide

A
  • Dry mount
  • Wet mount
  • Squash slide
  • Smear slide
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18
Q

Give magnification equation

A

Image = magnification x actual

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19
Q

Give an example of a stain

A

Methylene blue

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20
Q

Why are TEM black and white ?

A

No light is reflected

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21
Q

What is the function of the nucleus ?

A
  • Site of DNA replication + transcription
    -Site of ribosome synthesis
  • Contains cells genetic code
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22
Q

Give features inside the nucleus and their functions

A
  • Nuclear envelope ( double membrane)
  • Nucleoplasm (granular jelly-like material)
  • Nucleolus ( site of rRNA + ribosome production)
  • Nuclear pore (enables mRNA to leave the nucleus)
  • Chromosomes ( protein bound, linear DNA)
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23
Q

What is the function of a centriole ?

A
  • Production of spindle fibres
  • Organisation of chromosomes during cell division
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24
Q

Give 2 features of centrioles

A
  • In pairs form a centrosome ( in the center)
  • Made of microtubules
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25
Q

What is the function of the golgi apparatus ?

A
  • Carbohydrates + proteins = glycoproteins
  • Transport, modify and store lipids
  • Form lysosomes
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26
Q

What are the folded membranes on the golgi apparatus, SER and RER called ?

A

Cisternae

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27
Q

What are the function of vesicles ?

A

Transport finished products to the cell surface membrane for exocytosis

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28
Q

What are lysosomes ?

A

Bags of digestive enzymes

29
Q

What is the function of lysosomes ?

A
  • Hydrolyse phagocycotic cells
  • Break down dead cells (autolysis)
30
Q

What is the function of the cell wall ?

A

Structural strength

31
Q

What is the cell wall in plants, fungi and prokaryotes made from ?

A
  • Cellulose
  • Chitin
  • Peptidoglyan
32
Q

What is the function of a mitochondrion ?

A
  • Site of aerobic respiration
  • Site of ATP production
33
Q

Give features of a mitochondrion

A
  • Double membrane
    -Cristae (folds within inner membrane)
  • 70s ribosomes
  • Loop of mitochondrial DNA (code for enzymes needed for respiration)
  • Mitochondrial matrix
34
Q

What is the function of a ribosome ?

A

Site of protein synthesis

35
Q

Give features of a ribosome

A
  • Protein + rRNA
  • 80s (eukaryotes)
  • 70s (prokaryotes + chloroplasts + mitochondria)
36
Q

What is the function of the smooth endoplasmic reticulum ?

A

Synthesis and store of carbohydrates + lipids

37
Q

What is the function of the rough endoplasmic reticulum ?

A

Protein synthesis

38
Q

What is the function of cilia (hair like projections) ?

A
  • Stationary cilia in sensory organs
  • Mobile cilia help move/waft substances (dust) away from lungs
39
Q

What is the function of a flagella ?

A
  • Sensory organelle for chemical stimuli
  • Mobility
40
Q

What is the structure of a flagella ?

A

Whip like structure

41
Q

What is the function of a chloroplast ?

A

Site of photosynthesis

42
Q

Give features of a chloroplast

A
  • Fluid filled stroma with enzymes
  • Stacks = grana
  • Double membrane
  • lamella
  • Foldings = thylakoids
  • 70s ribosomes
43
Q

Give 3 differences between prokaryotes and eukaryotes

A
  • 70s ribosomes vs 80s ribosomes
  • non membrane bound organelles vs membrane bound organelles
  • DNA contained within nucleus vs DNA not contained within nucleus
44
Q

Give 3 differences in organelles between prokaryotes vs eukaryotes

A

Prokaryotes
- plasmids
- flagella
- capsule around cell

Eukaryotes
- mitochondria
- chloroplasts
- golgi
- SER/ RER

45
Q

Give 3 differences between plant and animal cells

A
  • Plant cell = chloroplasts, plasmodesmata for exchange
  • Animal cells contain centrioles
46
Q

What is the importance of the cytoskeleton ?

A

NETWORK OF FIBRES FOR ..
- microfilaments ( cell movement of cilia+ production of flagella + cilia)
- microtubules ( scaffold like structure and mechanical strength)
- intermediate fibres ( cell support and structure)

47
Q

What is the function of a plasmid ?

A

Loops of DNA which carry a few genes

48
Q

What is the function of a slime capsule

A
  • Protects bacteria against hosts immune system
  • Prevents bacteria from drying out (desiccating)
49
Q

What are some features of prokaryote ?

A
  • Peptidoglycan cell wall
  • Pilli
  • Slimy layer made of protein
50
Q

List the membrane bound organelles (8)

A
  • vacuole
  • nucleus
  • mitochondria
  • lysosomes
  • golgi apparatus
  • SER
  • RER
  • chloroplast
51
Q

List the non-membrane bound organelles (4)

A
  • flagella
  • cilia
  • cytoplasm
  • ribosomes
52
Q

Give the 4 steps of protein production and secretion

A
  • Polypeptide chains synthesised on ribosomes of RER
  • Polypeptide chains move to cisternae in RER packaged into vesicles ,moved to the golgi apparatus via cytoskeleton
  • Proteins modified + packaged into vesicles in golgi apparatus
  • Secretory vesicles carry proteins to cell surface membrane where it fuses and releases proteins by exocytosis
53
Q

What is resolution limited by ?

A

Diffraction ( the tendency of light waves to spread as they pass close to physical structures)

54
Q

How can resolution be increased ?

A

Using beams of electrons which have a wavelength thousands of times shorter than light

55
Q

Why can structures of the same organelle look different ?

A
  • Cut in different plane
  • One cut horizontally and one cut vertically
56
Q

Name an example of an extra cellular protein secreted from a cell

A

Insulin
( Begins with mRNA copy of gene for insulin being made in nucleus)

57
Q

Give 3 organelles found in both eukaryotes and prokaryotes

A
  • Cytoplasm
  • Cell surface membrane
  • Ribosomes
58
Q

What equipment would you use to measure a specimen between 200 and 300 um in length ?

A

Eyepiece graticule and light microscope

59
Q

Give 2 things to ensure when putting a cover slip on a sample with a stain

A
  • Use a mounted needle to prevent formation of air bubbles
  • Use blotting paper to remove excess stain
60
Q

How are plants supported other than by having a cell wall ?

A
  • Air spaces give buoyancy
  • Supported by surrounding water
61
Q

Give method of calibrating the diameter of a cell nucleus with a light microscope

A

1) Use eyepiece graticule
2) Calibrate eyepiece graticule using stage micrometer and calculate length of 1 epu
3) Measure diameter f nucleus in epu
4) Take repeat measurements and calculate mean diameter in epu
5) Use calibrated epu to calculate diameter of nucleus in units describes um)

62
Q

Give a benefit of using the squash slide method

A

Allows light to penetrate tissues more easily

63
Q

Give a benefit of using the wet mount slide technique

A

Prevents dehydration of tissue

64
Q

Give 3 benefits of using a stain

A
  • Contrast is higher
  • More internal structures visible
  • Cells can be distinguished from each other
65
Q

What is the surrounding layer of the vacuole called ?

A

Tonoplast

66
Q

What DNA do chloroplasts contain ?

A

Their own circular DNA

67
Q

How does yeast divide ?

A

Budding

68
Q

Outline a role of membranes

A

Compartmentalisation