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Biology - Mr Kelly > 3.1 - 3.4 Studying cells > Flashcards

3.1 - 3.4 Studying cells Flashcards

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1
Q

Magnification =

A

Size of image/size of real

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2
Q

Magnification

A

How many times bigger the image is when compared to the real object

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3
Q

Resolution

A

The minimum distance apart that two objects can be in order for them to appear as separate items

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4
Q

Cell fractionation

A

The process where cells are broken up and the different organelles they contain are separated out

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5
Q

Before cell fractionation can begin, the tissue is placed in a solution. The solution is:

A
  1. Cold - to reduce enzyme activity breaking down organelles
  2. Isotonic - to prevent organelles bursting or shrinking due to osmosis
  3. Buffered - so that pH does not fluctuate, to avoid changes to enzymes or organelles (prevents denaturing)
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6
Q

Describe the process of homogenation

A
  1. Cells broken up by a homogeniser to remove organelles from the cell
  2. Homogenate then filtered to remove debris
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7
Q

Describe the process of ultracentrifugation

A
  1. Test tube of filtrate placed in a centifuge and spun at a slow speed
  2. Heaviest organelles fall to the bottom, forming a pellet
  3. Supernatant is removed
  4. Supernatant put in another tube, spun faster
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8
Q

What order do the organelles come out in in ultracentrifugation?

A
  1. Nuclei
  2. Chloroplasts (plant cells only)
  3. Mitochondria
  4. Lysosomes
  5. ER
  6. Ribosomes
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9
Q

How does a Transmission Electron Microscope work? (TEM)

A
  1. Electron gun produces beam of electrons
  2. Focused on specimen by a condenser electromagnet
  3. Beam passes through specimen
  4. Variation in electrons get through, produces image on screen (photomicrograph)
    Resolving power = 0.1 nm
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10
Q

What are the limitations of a TEM?

A
  • System must be in a vacuum (no live specimens)
  • Complex staining process
  • Black and white image
  • Image may contain artefacts
  • Specimen must be very thin
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11
Q

How does a Scanning Electron Microscope work?

A
  1. Beam of electrons from above
  2. Passed back and forth in a regular pattern
  3. Electrons are scattered by the specimen, depending on the contour of the specimens surface
  4. Analyse scattered electrons and secondary electrons
  5. 3D image produced
    Resolving power = 20nm
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12
Q

What advantages does a SEM have over a TEM?

A
  • Thicker specimen
  • 3D image
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13
Q

What are the limitations of a SEM?

A
  • In a vacuum (no live specimens)
  • Complex staining process
  • Image may contain artefacts
  • Lower resolution than TEM
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14
Q

Describe the structure of the nucleus

A
  • Spherical, 10-20 nm diameter
  • Nuclear envelope = Double membrane that surrounds the nucleus
  • Nuclear pore = Hole in nuclear envelope that allows things in and out
  • Nucleoplasm = Jelly like material
  • Chromosomes = Made up of DNA
  • Nucleolus = Makes ribosomal RNA and assembles ribosomes
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15
Q

Describe the function of the nucleus

A
  • Controls production of mRNA and tRNA
  • Makes ribosomal RNA and ribosomes
  • Houses DNA
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16
Q

Describe the structure of mitochondria

A
  • Rod shaped, 1-10um length
  • Double membrane = controls in and out, inner membrane has cristea
  • Cristea = Provide large SA for attachment of enzymes and other ribosomes
  • Matrix = fluid filled inner space where DNA, proteins, lipids, ribosomes and enzymes for respiration are found
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17
Q

Describe the function of mitochondria

A

Produce energy carrier molecule ATP

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18
Q

Describe the structure of chloroplasts

A
  • Disc shaped, 1um diameter, 2-10um length
  • Chloroplast envelope = double plasma outer membrane
  • Thylakoids = discs that contain chlorophyll
  • Grana = stacks of 100+ thylakoids
  • Stroma = fluid filled matrix where second stage photosynthesis takes place
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19
Q

Describe the function of chloroplasts

A
  • Granal membrane provides large SA for attchment of chlorophyll, electron carriers and enzymes for 1st stage photosynthesis
  • Stoma fluid contains enzymes for 2nd stage photosynthesis
  • Manufactures some proteins
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20
Q

Describe the structure of Rough Endoplasmic Reticulum (RER)

A
  • Sheet like membranes spread through cytoplasm
  • Cisternae = tubules and flattened sacs
  • Ribosomes = outer surface of membranes
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21
Q

Describe the function of RER

A
  • Provide large SA for protein and glycoprotein synthesis
  • Provide pathway for transport of materials
22
Q

Describe the structure of Smooth Endoplasmic Reticulum (SER)

A
  • Similar to RER
  • No ribosomes
  • More tubular
23
Q

Describe the function of SER

A

Synthesise, store and tranport lipids and carbohydrates

24
Q

Describe the structure of the Golgi apparatus

A
  • Cisternae = stacks of membranes that make up flattened sacs
  • Vesicles = small. hollow, rounded structures
25
Q

Describe the function of the Golgi apparatus

A
  • Produce glycoproteins, secretory enzymes and lysosomes
  • Secrete carbohydrates
  • Transport, modify and store lipids
26
Q

Describe the structure of lysosomes

A
  • Vesicles that contain enzymes
  • 50+ lysozymes per lysosome (enzymes that digest certain bacteria cell walls)
  • Up to 1um diameter
27
Q

Describe the function of lysosomes

A
  • Hydrolyse material ingested by phagocytic cells
  • Exocytosis (release enzymes to outside cell to destroy surroung material)
  • Digest wornout organelles for the reuse of chemicals
  • Autolysis (completely break down dead cells)
28
Q

Describe the structure of ribosomes

A
  • Two types = 80S (found in eukaryotic, 25nm diameter)
    = 70S (found in prokaryotic, smaller)
  • 1 large and 1 small subunit
  • Contain ribosomal RNA and protein
29
Q

Describe the function of ribosomes

A

Protein synthesis

30
Q

Describe the structure of the cell wall

A
  • Lots of polysaccharides (eg cellulose)
  • Middle lamella = glues cells together
31
Q

Describe the function of the cell wall

A
  • Provide strength to stop cell bursting
  • Mechanical strength to plant as a whole
  • Allows water to pass along it
32
Q

Describe the structure of a vacuole

A
  • Fluid filled sac
  • Tonoplast = single layer outer membrane
  • Contains mineral salts, sugars, amino acids, waste and sometimes pigments
33
Q

Describe the function of a vacuole

A
  • Supports herbaceous plants by making cells turgid
  • Sugars and amino acids may act as a temporary food store
  • Pigments may colour petals, attracting pollinators
34
Q

What is the organisation order in an organism?

A 
Organelle 
Cell
Tissue
Organ
Organ system
Organism
35
Q

What is the purpose of the cell wall of a bacterial cell?

A
  • Physical barrier
  • Excludes certain substances
  • Protects against mechanical damage
  • Protects against osmotic lysis
36
Q

What is the purpose of the capsule of a bacterial cell?

A
  • Protects bacterium from other cells

- Helps groups of bacteria stick together for protection

37
Q

What is the purpose of the cell-surface membrane of a bacterial cell?

A
  • Differentially permiable layer, controls entry and exit of chemicals
38
Q

What is the purpose of the circular DNA in a bacterial cell?

A
  • Possesses genetic information
39
Q

What is the purpose of a plasmid in a bacterial cell?

A
  • Possesses genes that may aid survival in adverse conditions
40
Q

Prokaryotic cells vs Eukaryotic cells - nucleus

A 
P = No true nucleus
E = Distinct nucleus with a nuclear envelope
41
Q

Prokaryotic cells vs Eukaryotic cells - proteins

A 
P = DNA not associated with proteins
E = DNA associated with proteins called histones
42
Q

Prokaryotic cells vs Eukaryotic cells - DNA

A 
P = Some DNA in circular plasmids
E = No plasmids, linear DNA
43
Q

Prokaryotic cells vs Eukaryotic cells - membrane

A 
P = No membrane-bounded organelles
E = Membrane-bounded organelles
44
Q

Prokaryotic cells vs Eukaryotic cells - chloroplasts

A 
P = No chloroplasts
E = Chloroplasts in plants and algae
45
Q

Prokaryotic cells vs Eukaryotic cells - ribosomes

A 
P = Smaller ribosomes (70S)
E = Larger ribosomes (80S)
46
Q

Prokaryotic cells vs Eukaryotic cells - cell wall

A 
P = Cell wall made of murein
E = Cell wall made of cellulose (or chitin in fungi)
47
Q

Prokaryotic cells vs Eukaryotic cells - capsule

A 
P = Capsule
E = No capsule
48
Q

Describe the passage of an amino acid through organelles, from the cytoplasm until it is excreted from the cell as a protein

A
  • Cytoplasm
  • RER
  • Golgi body
  • Lysosomes
49
Q

Describe how to measure the length of something under a microscope

A
  • Measure with eyepiece graticule
  • Calibrate with stage micrometer
  • Repeat and calculate the mean
50
Q

Which organelles does a prokaryotic cell have?
- Cell wall
- Cell surface membrane
- Ribosomes
- Plasmid
- Nucleic acids
- Mitochondria
- Capsid
- Choloroplasts

A
  • Cell wall (P)
  • Cell surface membrane (P)
  • Ribosomes (P)
  • Plasmid (A)
  • Nucleic acids (P)
  • Mitochondria (A)
  • Capsid (A)
  • Choloroplasts (A)
51
Q

Which organelles does a eukaryotic cell have?
- Cell wall
- Cell surface membrane
- Ribosomes
- Plasmid
- Nucleic acids
- Mitochondria
- Capsid
- Choloroplasts

A
  • Cell wall (S)
  • Cell surface membrane (P)
  • Ribosomes (P)
  • Plasmid (S)
  • Nucleic acids (P)
  • Mitochondria (P)
  • Capsid (A)
  • Choloroplasts (S)
52
Q

What organelles does a virus have?
- Cell wall
- Cell surface membrane
- Ribosomes
- Plasmid
- Nucleic acids
- Mitochondria
- Capsid
- Choloroplasts

A
  • Cell wall (A)
  • Cell surface membrane (A)
  • Ribosomes (A)
  • Plasmid (A)
  • Nucleic acids (P)
  • Mitochondria (A)
  • Capsid (P)
  • Choloroplasts (A)

Biology - Mr Kelly (17 decks)

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