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BIOLOGY > Topic 2 - Cells, Viruses And Reproduction Of Living Things > Flashcards

Topic 2 - Cells, Viruses And Reproduction Of Living Things Flashcards

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1
Q

Why are Viruses considered to be ‘non-living’ ?

A

Viruses are non-living because they don’t reproduce on their own (need a host cell).

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2
Q

What is a virus?

A

A virus is a type of pathogen.

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3
Q

What is a pathogen?

A

A pathogen is a harmful agent which can cause disease.

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4
Q

How does a virus reproduce when it’s in a host cell?

A

It hijacks the host cell’s protein production machinery (such as ribosomes) to make copies of it’s DNA/RNA.

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5
Q

Define Magnification.

A

Magnification is a measure of how much bigger the image you see is than the real object.

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6
Q

Define Resolution/resolving power.

A
  • The Resolution of a microscope is defined as the smallest distance at which 2 small objects can still be seen as separate.
  • (In other words, the microscope’s ability to distinguish details of a small specimen).
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7
Q

How do you calculate the total magnification?

A

Eyepiece lens x Objective lens = Total magnification.

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8
Q

How you calculate Image size?

A

Image size = Actual size x Magnification.

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9
Q

What are ‘Artefacts’ In Microscopy?

A
  • When looking at a prepared sample, there may be things visible that aren’t part of the specimen, such as bubbles or dust.
  • These variables are known as Artefacts.
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10
Q

What are Transmission Electron Micrographs (TEMs) ?

A

TEMs are two-dimensional (2D) images, like those from a light microscope, but with better magnification and resolution.

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11
Q

What are Scanning Electron Micrographs (SEMs) ?

A

SEMs are three-dimensional (3D) images, with the cost of slightly lower magnification.

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12
Q

What are the advantages of using Electron Microscopes?

A

Great magnification and resolution.

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13
Q

What are the disadvantages of using Electron Microscopes?

A
  • It is impossible to look at living material using an electron microscope as the specimens have to be examined in a vacuum.
  • Specimens undergo severe treatment which may result in artefacts.
  • Very expensive
  • Very large & high maintenance.
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14
Q

What is a Eukaryote?

A

A Eukaryote is an organism consisting of cells in which the genetic material (DNA) is stored in the form of Chromosomes in a Nucleus.

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15
Q

What is a Prokaryote?

A

A Prokaryote is a single-celled organism which has neither a nucleus or other membrane-bound organelles.

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16
Q

What is the main role of the cell surface membrane?

A

The cell surface membrane regulates what substances move into and out of the cell.

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17
Q

What 2 molecules are membranes mainly made up of?

A

Lipids & Proteins.

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18
Q

How are Phospholipids arranged in the membrane?

A
  • Phospholipids form a bilayer .
  • The Hydrophilic heads point towards the water
  • The hydrophobic tails point away from the water
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19
Q

What model gives an insight to the structure and function of a cell membrane?

A

Fluid Mosaic Model.

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20
Q

What are gated channels?

A
  • Gated channels are protein channels in the cell membrane which can be open or shut depending on the conditions in the cell.
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21
Q

What are Glycoproteins?

A

Glycoproteins are proteins with a carbohydrate part added to the molecule.

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22
Q

What is Protoplasm?

A

The Cytoplasm and Nucleus together is collectively known as Protoplasm.

23
Q

What is chromatin?

A

Chromatin is a complex consisting of DNA molecules wrapped around Histone proteins.

24
Q

What is Chromatin made up of?

A

Chromatin consists of DNA molecules wrapped around Histone proteins.

25
Q

When is Chromatin used to store DNA?

A

When the cell is not actively dividing.

26
Q

What is the Nucleolus?

A

An extra dense area (found in the nucleus) consisting of almost pure DNA and protein.

27
Q

What is the primary role of the Nucleolus?

A

The production of the cell’s ribosomes.

28
Q

What can the quantity of mitochondria found in a cell tell us about the cell?

A

Whether the cell requires a lot or little energy to function.

29
Q

What does the endosymbiotic theory state?

A

The endosymbiotic theory states that some organelles (Mitochondria & chloroplasts) were once individual prokaryotic cells.

30
Q

What is the evidence for the endosymbiotic theory?

A
  • Mitochondria & Chloroplasts have their own circular DNA (like prokaryotic cells)
  • Mitochondria & chloroplasts divide by binary fission (like prokaryotic cells)
  • Mitochondria & Chloroplasts are approximately the same siize as prokaryotic cells.
31
Q

What are Centrioles made up of?

A

Each centriole is made up of a bundle of 9 tubules.

32
Q

What is the Cytoskeleton?

A

The cytoskeleton is a 3D web-like structure that fills the cytoplasm.

33
Q

What is the Cytoskeleton made up of?

A

The cytoskeleton is made up of microfilaments (protein fibres) and microtubules.

34
Q

What is the role of the Cytoskeleton?

A

The Cytoskeleton gives the cytoplasm structure, keeping the organelles in place.

35
Q

What type of ribosomes do Eukaryotes contain?

A
  • 80S and 70S Ribosomes
  • (70S ribosomes found in Chloroplasts &
    Mitochondria)
36
Q

What type of ribosomes do Prokaryotes contain?

A
  • 70S Ribosomes.
37
Q

What is the role of the Rough Endoplasmic Reticulum?

A
  • RER has 80S Ribosomes imbedded in its membrane which synthesise proteins.
  • The RER transports these proteins within the cell or outside the cell (exocytosis)
38
Q

What is the role of the Smooth Endoplasmic Reticulum?

A
  • The SER is involved in the synthesis and transport of Steroids and Lipids.
39
Q

How do Proteins get from the Rough Endoplasmic Reticulum to the Golgi Apparatus?

A
  • A vesicle forms around the Protein being transported.
  • The Vesicle is pinched off the RER
  • The Vesicle travels and fuses with the Cisternae of the Golgi Apparatus, releasing the Protein.
40
Q

What is the Golgi Apparatus made up of?

A

Flattened stacks of membrane called Cisternae.

41
Q

What is the Role of Lysosomes?

A
  • Lysosomes break down dead organelles in to molecules that can be re used.
  • Lysosomes can also break down food content in single-celled organisms.
  • Lysosomes also destroy bacteria.
42
Q

Describe the structure of Lysosomes.

A
  • Lysosomes are membrane bound organelles
  • They are vesicles containing Digestive Enzymes.
43
Q

How is a dead organelle broken down by a Lysosome?

A
  • A membrane vacuole forms around the dead organelle
  • The Lysosome fuses with this vacuole, releasing the Digestive Enzymes which break down the dead organelle.
44
Q

What is the Tonoplast?

A

The Tonoplast is the membrane that surrounds the Vacuole in a Plant Cell.

45
Q

What are Plasmodesmata?

A

Plasmodesmata are microscopic channels in the Plant Cell Wall.

46
Q

What is the role of Plasmodesmata?

A

Plasmodesmata allow communication and transport between plant cells.

47
Q

In plant cells, what is the Vacuole filled with?

A

The Vacuole is filled with Cell Sap.

48
Q

What is the role of the Cell Sap in the Plant Vacuole?

A
  • Cell Sap is a solution which allows water to move in to it via osmosis.
  • This causes the Vacuole to expand and the cytoplasm around it to be pushed against the Cell Wall under high pressure
  • This results in the Plant Cell becoming turgid.
49
Q

What are Chloroplasts?

A

Chloroplasts are organelles which are the site of Photosynthesis in Plant Cells.

50
Q

What is the role of Amyloplasts?

A

Amyloplasts store Starch.

51
Q

What is the role of the Cell Wall in Bacteria?

A

The Cell Wall in Bacteria prevents the cell from swelling and bursting.

52
Q

What do all Bacterial Cell Walls contain a layer of?

A

All Bacterial Cell Walls contain a layer of Peptidoglycan.

53
Q

What is the role of the Capsule/Slime layer which surrounds SOME bacterial cells?

A
  • Capsules/Slime layers protect the bacterium from Phagocytosis by White blood cells
  • The Capsule also covers cell markers on the cell membrane of the bacterium, making it harder for the immune system to identify the bacterium.

BIOLOGY (10 decks)

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