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B: 3.2 Cells > 3.2.1 Cell structure > Flashcards

3.2.1 Cell structure Flashcards

(51 cards)

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1
Q

What is the main difference between fungal cells and plant cells? (2)

A

Fungal cell walls are made of chitin, instead of cellulose

Fungal cells don’t have chloroplasts

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2
Q

What is included in the structure of a nucleus? (4)

A
  • Nucleolus
  • Nuclear membrane
  • Chromatin
  • Nuclear pore
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3
Q

What does the nucleus contain within its structure to accommodate for its function? (3)

A
  • Histones
  • Linear DNA
  • One or more RNA nucleoli
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4
Q

What is the function of the nucleus? (2)

A
  • Controls protein synthesis
  • So controls the development and function of the cell
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5
Q

What components make up the structure of ribosomes?

A
  • Proteins
  • Ribosomal RNA
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6
Q

Describe the function of the rough endoplasmic reticulum (2)

A
  • Has ribosomes on its surface that produce secretory proteins (proteins that are released out of the cell)
  • These secretory proteins are sent to Golgi Apparatus for modification and packaging
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7
Q

What is the basic function of the smooth endoplasmic reticulum?

A

Involved in the production and transport of carbohydrates and lipids

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8
Q

Describe the several functions of the golgi apparatus (3)

A
  • Adds carbohydrates to proteins received from the rough endoplasmic reticulum to form glycoproteins
  • Packages proteins into golgi vesicles for secretion
  • Produces lysosomes - a type of golgi vesicle that releases lysozymes (hydrolytic enzymes)
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9
Q

What are the roles of the organelles that are involved in the production, transport and release of proteins from eukaryotic cells? (5)

A
  1. DNA in the nucleus codes for these proteins
  2. Ribosomes in the RER produce these proteins via protein synthesis
  3. Mitochondria produces the ATP that is required for protein synthesis
  4. Golgi apparatus packages and modifies these proteins into vesicles
  5. Vesicles fuse with the cell membrane and release proteins outside of cell
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10
Q

Describe the functions of lysosomes (3)

A
  • Digests material that is taken in by phagocytosis
  • Non-functioning organelles within the cell are engulfed and digested by lysosomes
  • Releases enzymes outside of the cell
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11
Q

What is the basic function of the mitochondria? (2)

A
  • Involved in aerobic respiration
  • Which produces ATP
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12
Q

What is the basic function of chloroplasts? (2)

A
  • Contains chlorophyll
  • Which absorbs light energy for photosynthesis
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13
Q

What structures are present in chloroplasts? (8)

A

Lipid droplets
Stroma
Thylakoids
Free ribosomes
Circular DNA
Starch grains
Membrane bound chromosomes
Granum

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14
Q

What is the granum that is found in chloroplasts? (1)

A

Stacked thylakoids

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15
Q

How do granum join together to form grana? (1)

A

Link together by thin pieces of membrane - lamellae

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16
Q

What is the basic function of the large vacuole? (1)

A

Contains soluble sugars, salts and pigments

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17
Q

What structures are present in all prokaryotic cells? (5)

A
  • Cell wall (made of murein - a glycoprotein)
  • Cell surface membrane
  • Free circular DNA molecule in cytoplasm
  • 70s ribosomes
  • Cytoplasm
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18
Q

What structures are only present in some prokaryotic cells? (3)

A
  • Capsule surrounding cell wall
  • One or more plasmids
  • One or more flagella
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19
Q

Describe the DNA of prokaryotic cells (4)

A
  • No nucleus is present
  • DNA is free in the cytoplasm
  • Circular DNA
  • Not attached to any histone proteins
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20
Q

Describe the properties of plasmids found in prokaryotic cells (3)

A
  • Contain antibiotic resistance genes (amongst others)
  • Plasmids are able to be passed between prokaryotes
  • Some prokaryotic cells have several plasmids, others have no plasmids
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21
Q

Compare prokaryotic and eukaryotic cells (5)

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A

Prokaryotic cells have no nucleus, whereas eukaryotic cells have a nucleus present

Prokaryotic cells have no membrane bound organelles, eukaryotic cells have membrane bound organelles

Prokaryotic cells have smaller 70s ribosomes, whereas eukaryotic cells have larger 70s ribosomes

Prokaryotic cells contain circular DNA, whereas in eukaryotic cells DNA is linear

Prokaryotic cells have a murein cell wall, whereas in eukaryotic cells the cell wall does not contain murein

22
Q

What is the difference in the type of ribosome in bacterial and human cells? (2)

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A

Bacterial cells have 70S ribosomes whereas, human cells have 80S ribosomes

23
Q

What are the two key properties of viruses? (2)

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A
  • Acellular
  • Non-living (as they contain no organelles)
24
Q

Draw the structure of a typical viral particle (3)

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A
  • Genetic material (DNA / RNA)
  • Capsid (protein coat)
  • Attachment proteins
25
What happens to eukaryotic cells in complex multicellular organisms? (2)
- Become specialised - Through the process of differentiation
26
What is meant by the term "resolution"? (1)
How well a microscope can distinguish between two points that are close together
27
What are the requirements for specimens in optical microscopes? (2)
- Be thin - Be stained
28
Why must the specimen be thin in optical microscopes? (1)
So that light can pass through the specimen and a single layer of cells is visible
29
Why must the specimen be stained in optical microscopes? (1)
So that the structures are visible
30
What are the two main stains we use during microscopy? (2)
- Eosin is used to highlight the cytoplasm - Iodine contained in potassium iodide solution highlights starch grains
31
What are the 5 structures that cannot be identified using an optical microscope? (5)
- Mitochondrion - Ribosome - Endoplasmic Reticulum - Lysosome - Cell-surface membrane
32
Describe how a transmission electron microscope produces a micrograph (4)
1. Specimen is stained with electron dense substances e.g. heavy metal salts 2. Beam of electrons are transmitted through the specimen 3. Staining substances deflect the electrons in the beam 4. The pattern that the remaining electrons produce as they pass through specimen is converted into an image
33
Describe how a scanning electron microscope produces a micrograph (3)
1. Specimen is coated with a thin film of heavy metal e.g. gold 2. Electron beam is scanned to and across the specimen 3. Electrons that are reflected from the surface are collected and produce an image on a viewing screen
34
Compare optical and electron microscopes (6)
Electron microscopes use a beam of electrons whereas optical microscopes use a beam of light Electron microscopes have a much greater resolution whereas optical microscopes have a relatively low resolution Electron microscopes are focused using magnets, whereas optical microscopes are focused using glass lenses In electron microscopes smaller structures are visible whereas in optical microscopes smaller structures are not visible In electron microscopes specimen must be dead whereas in optical microscopes specimen can be living Electron microscopes produce an image not in colour whereas optical microscopes produce an image in colour
35
Why do electron microscopes have a higher resolution than optical microscopes? (1)
Electrons have a shorter wavelength
36
Compare transmission electron microscopes and scanning electron microscopes (4)
TEMs have a higher resolution compared to SEMs TEMs produce images of internal structures only whereas SEMs produce images of external structures only TEMs produce a 2D image whereas SEMs produce a 3D image in TEMs, sections must be thin whereas in SEMs sections can be thicker than TEM
37
What are the three stages of cell fractionation? (3)
1. Homogenisation - breaking the cells open 2. Filtration - Removing large debris 3. Ultracentrifugation - Seperating the organelles
38
What are the properties of the homogenising solution used in ultracentrifugation? (3)
- Isotonic - Ice-cold - Buffer solution
39
Why do we need to homogenise cells in an isotonic solution during ultra centrifugation? (2)
- Prevents the osmotic movement of water into and out of the organelles - Which can cause them to burst or shrivel
40
Why do we need to homogenise cells in an ice-cold solution during ultra centrifugation? (2)
- Prevents the action of enzymes in the cell - That may cause self-digestion (or autolysis) of organelles
41
Describe the method you would use to carry out cell fractionation and ultracentrifugation (4)
1. Cells are first broke open by homogenising the tissue in an ice-cold, isotonic buffer solution using a blender 2. This solution is then filtered to remove large debris 3. Homogenate is then centrifuged at a low speed and the densest organelle i.e. nuclei forms a pellet at the bottom of tube 4. The supernatant (the liquid above the pellet) can be spun faster for a longer period of time to isolate the other organelles
42
What is the order in which cell organelles are isolated during ultracentrifugation? (5)
1. Nuclei 2. Chloroplasts (if its a plant cell) 3. Mitochondria 4. Endoplasmic reticulum (SER and RER) 5. Ribosomes
43
Describe and explain how cell fractionation and ultracentrifugation can be used to isolate an organelle from a suspension of animal cells (7)
1. Homogenise the cells to break them open 2. Filter to remove large debris 3. Use an isotonic solution to prevent damage to the organelles 4. Keep the solution ice-cold to prevent damage by enzymes 5. Use a buffer solution to prevent protein denaturation 6. Centrifuge at a lower speed to separate the nuclei 7. Re-spin the supernatant at a higher speed to pellet the organelles at the bottom
44
What organelles are only present in plant cells? (3)
- Cellulose cell wall - Chloroplasts - Vacuole
45
What is the difference in structure between the RER & SER? (1)
RER contains ribosomes on its surface, whereas, SER lacks ribosomes
46
Why may some cells have lots of mitochondria and could you give an example of a cell? (2)
- To provide energy to cells that require a large amount of ATP - E.g. muscle cells
47
What is the basic function of the cell wall? (1)
Provides support, strength and shape to the cell
48
What is meant by the term "tissues"? (1)
Group of similar specialised cells that perform a specific function and have a common origin
49
What is meant by the term "organs"? (2)
- Structure that consists of different tissues which have a specific function - E.g. stomach, which has a role in the digestion of food
50
What is meant by the term "organ system"? (1)
- Two or more organs which have a specific overall function (e.g. digestion) - E.g. stomach, liver and pancreas all form the digestive system
51
Why do we need to homogenise cells in a buffer solution during ultra centrifugation? (1)
Maintains ph so that enzymes do not denature

B: 3.2 Cells (3 decks)

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