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AS- Biology > 2.1- Cell structure > Flashcards

2.1- Cell structure Flashcards

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1
Q

What are the 4 main types of microscopes?

A

Optical
Laser scanning/confocal
Transmission electron
Scanning electron

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2
Q

What is the maximum magnification of an optical microscope?

A

X1500

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3
Q

What is the maximum magnification of a laser scanning microscope?

A

X1500

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4
Q

What is the maximum magnification of a transmission electron microscope?

A

X2000000

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5
Q

What is the maximum magnification of a scanning electron microscope?

A

X200,000

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6
Q

What is the resolution of a optical microscope?

A

200nm

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7
Q

What is the resolution of a laser scanning microscope?

A

160nm

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8
Q

What is the resolution of a transmission electron microscope?

A

0.1nm

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9
Q

What is the resolution of a scanning electron microscope?

A

0.1nm

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10
Q

How do optical microscopes work?

A

They shine a light through a sample

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11
Q

What are the pros of optical microscopes?

A

Relatively inexpensive
Need mimimum training to operate
Can study living organisms

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12
Q

What are the cons of optical microscopes?

A

Low magnification and resolution

specimens often need staining to show organelles

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13
Q

How do laser scanning microscopes work?

A

they use laser beams to analyse a sample and look at different depths of the sample

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14
Q

What are the pros of laser scanning microscopes?

A

Images are higher resolution than optical microscopes

Lasers can scan to different depths

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15
Q

What are the cons of laser scanning microscopes

A

Relatively low resolution and magnification
Expensive equipment that requires high level training
Specimens require staining

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16
Q

How do transmission electron microscopes work?

A

They use electromagnets to transmit a beam of electrons through a sample.
Denser parts absorb more electrons and appear darker

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17
Q

What are the pros of transmission electron microscopes?

A

They have the highes magnification and resolution of any microscope

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18
Q

What are the cons of transmission electron microscopes?

A

large and expensive machinery needs lots of training to use
specimen must be dead
Staining is potentially hazardous

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19
Q

How does a scanning electron microscope work?

A

They fire a beam of electrons at the specimen which knocks electrons off any surface it hits. these electrons are detected to produce a 3D scan

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20
Q

What are the pros of Scanning electron microscopes?

A

Can form 3D images of a sample

Magnification and resolution is much higher then light microscopes

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21
Q

What are the cons of scanning electron microscopes?

A

Large and expensive machinery is required which needs high level training
Specimen must be dead
Specimen needs to be mounted In a vacuum

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22
Q

What is the definition of magnification?

A

How much bigger an image appears enlarged by a microscope compared to the original object viewed with a naked eye

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23
Q

What is the definition of resolution?

A

The ability to distinguish between 2 objects that are close together

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24
Q

What is the formula for magnification?

A

Image Size/Object Size

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25
Q

What are graticules?

A

scales placed in a icroscope to allow the user to measure the size of a specimen. before the specimen can be measured, the eyepiece graticule must be calibrated

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26
Q

What are the 2 different ways we can compare a slide for viewing?

A

Dry Mount

Wet Mount

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27
Q

How do we dry mound a microscope slide?

A

Take a thin slice of the specimen and place it in the middle of the slide using tweezers. then place a cover slip on top.

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28
Q

How do we wet mount a microscope slide?

A

Place a small drop of water on a slide and then place the specimen on top and cover with a cover slip.
Add stain at the edge of the slip.

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29
Q

What are 3 ways of viewing a sample that is transparent or colourless?

A

Light interference
Dark background
Staining

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30
Q

What is an ultrastrusture?

A

The detailed structure of cells that can only be seen with high magnification electron microscopes.

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31
Q

Describe the nucleus.

A

A large organelle surrounded by a nuclear envelope (double membrane), which contains many pores. The nucleus contains chromatin (which is made form DNA and proteins) and a structure called the nucleolus.

32
Q

Describe the RER.

A

A system of membranes enclosing a fluid filled space. The surface is covered with ribosomes.

33
Q

Describe the SER.

A

A system of membranes enclosing a fluid filled space. The surface is NOT covered with ribosomes.

34
Q

Describe the Golgi apparatus.

A

A group of fluid-filled, membrane-bound, flattened sacs. Vesicles are often seen at the edges of the sacs..

35
Q

Describe a flagellum.

A

Flagella on eukaryotic cells are like cilia but longer. They stick out from the cell surface and are surrounded by the plasma membrane. Inside they’re like cilia too - two microtubules in the centre and nine pairs around the edge.

36
Q

Describe a mitochondrion.

A

They’re usually oval-shaped. They have a double membrane - the inner one is folded to form structures called cristae. Inside is the matrix, which contains enzymes involved in respiration.

37
Q

Describe a lysosome.

A

A round organelle surrounded by a membrane, with no clear internal structure.

38
Q

Describe a chloroplast.

A

A small, flattened structure found in plant cells. It’s surrounded by a double membrane, and also has membranes inside called thylakoid membranes. These membranes are stacked up in some parts of the chloroplast to form grana. Grana are linked together by lamellae - thin, flat pieces of thylakoid membrane.

39
Q

Describe the plasma (cell surface) membrane.

A

The membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells. It’s made mainly of lipids and proteins.

40
Q

Describe cilia.

A

Small, hair-like structures found on the surface membraneof some animal cells. In cross-section, they have an outer membrane and a ring of nine pairs of protein microtubules inside, with two microtubules in the middle.

41
Q

What is the structure of a vacuole?

A

• A fluid filled sac withi

a membrane called a tonoplast

42
Q

Describe a ribosome

A

A very small organelle that either floats free in the cytoplasm or is attached to the RER. It’s made up of proteins and RNA. It’s NOT surrounded by a membrane.

43
Q

Describe a centriole

A

Small, hollow cylinders, made of microtubules (tiny protein cylinders). Found in animal cells, but only some plant cells.

44
Q

Describe a cell wall

A

A rigid structure that surrounds plant cells. It’s made mainly of the carbohydrate cellulose.

45
Q

What is the function of the nucleus?

A

The nucleus controls the cell’s activities (by controlling the transcription of DNA). DNA contains instructions to make proteins. The pores allow substances (e.g. RNA) to move between the nucleus and the cytoplasm. The nucleolus makes ribosomes.

46
Q

What is the function of the RER?

A

Folds and processes proteins that have been made at the ribosomes.

47
Q

What is the function of the SER?

A

Synthesises and processes lipids.

48
Q

What is the function of the golgi apparatus?

A

It processes and packages new lipids and proteins. It also makes lysosomes.

49
Q

What is the function of the flagella?

A

The microtubules contract to make the flagellum move. Flagella are used like outboard motors to propel cells forward (e.g.when a sperm cell swims).

50
Q

What is the function of the mitochondria?

A

The site of aerobic respiration. where ATP is produced. They’re found in large numbers in cells that are very active and require a lot of energy.

51
Q

What is the function of the lysosomes?

A

Contains digestive enzymes. These are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down worn out components of the cell.

52
Q

What is the function of the chloroplasts?

A

Site where photosynthesis takes place. Some parts of photosynthesis happen in the grana, and other parts happen in the stroma ( a thick fluid found in chloroplasts).

53
Q

What is the function of the plasma membrane?

A

Regulates the movement of substances into and out of the cell. It also has receptor molecules on it, which allow it to respond to chemicals like hormones.

54
Q

What is the function of the cilia?

A

The microtubules allow the cilia to move. This movement is used by the cell to move substances along the cell surface.

55
Q

What is the function of the vacuole?

A 
• Permanent vacuoles are only
present in plants.
• The fluid contains water and a
variety of solutes that helps plant
cells regulate their water
56
Q

What is the function of the ribosomes?

A

To carry out protein synthesis and make proteins

57
Q

What is the function of the centrioles?

A

Involved with the separation of chromosomes during cell division.

58
Q

What is the function of the cell wall?

A

Supports plant cells

59
Q

What is the role of the nucleus in protein synthesis?

A

• Contains DNA, the cells instructions for how to make proteins which can be
thought of as a cell’s machinery.
• Genes are copied into messenger RNA (mRNA), which leaves the nucleus via
nuclear pores and attaches to a ribosome.

60
Q

What is the role of the Ribosomes in protein synthesis?

A

• ‘Reads’ the mRNA and accordingly assembles amino acids into a unique sequence.
• These amino acids make up a polypeptide, a protein consists of single or multiple
polypeptides.
• Free ribosomes in the cytoplasm produce proteins that stay in the cytoplasm.
• Ribosomes on the rough ER make proteins that are secreted from the cell.

61
Q

What is the role of the RER in protein synthesis?

A

• Proteins produced by ribosomes on the rough ER are modified (e.g. sugars added
and polypeptides folded) within the rough ER.
• The polypeptide(s) are transported to the Golgi apparatus in a vesicle.

62
Q

What is the role of the Golgi apparatus in protein synthesis?

A

• Polypeptides are further modified (e.g. by joining two or more chains of
polypeptides, adding carbohydrate branches or trimming sugars added earlier).
• The protein is now fully formed and packaged into another vesicle.
• The vesicle is ready to be transported to the cell surface membrane and secreted
(a process called exocytosis).

63
Q

What is the cytoskeleton?

A

A large network of protein fibres

64
Q

What are the 3 main functions of the cytoskeleton?

A
  • Structural support
  • Transport
  • Enabling cell movement
65
Q

What stain is used to stain cytoplasms?

A

Eosin

66
Q

What stain is used to stain DNA?

A

Methylene Blue

67
Q

What is a plasmodeselata?

A

channels for exchanging substances with adjacent cells

68
Q

What size are prokaryotes?

A

less than 2 micro metres

69
Q

What size are eukaryotes?

A

10-100 micrometres

70
Q

How is DNA different in prokaryotes?

A

DNA is circular in prokaryotes

DNA floats freely in the cytoplasm

71
Q

Do prokaryotes contain any membrane bound organelles?

A

noooo

72
Q

In prokaryotic cells, ribosommes are……….

A

smaller

73
Q

What are the 2 components of the cytoskeleton?

A

microfillaments

microtubules

74
Q

How can you stain substances to be viewed in an electron microscope?

A

They can be dipped in metals like lead which repel the ions

75
Q

Describe a vesicle.

A

A small fluid-filled sac in the cytoplasm, surrounded by a membrane.

76
Q

What is the function of vesicles?

A

Transports substances in and out of the cell (via the plasma membrane) and between organelles. Some are formed by the Golgi apparatus or the endoplasmic reticulum , while others are formed at the cell surface.

AS- Biology (12 decks)

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