2.1 CELL STRUCTURE Flashcards

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1
Q

what is magnification?

A

the number of times larger an image appears, compared with the size of the object

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2
Q

what is resolution?

A

the clarity of an image; the higher the resolution, the clearer the image

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3
Q

what are some key feature of optical microscopes?

A

Relatively cheap and easy to use, portable and can study whole living specimens, use visible light that has a wavelength of between 400 and 700 nm

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4
Q

what are some key feature of laser scanning microscopes?

A

Uses laser beams to scan something which is usually tagged with fluorescent dye
The laser causes the dye to give off light, the light is focused through a pinhole onto a detector which is connected to a computer, generating an image (3D)

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5
Q

what are some key feature of Transmission electron microscopes?

A

Use electromagnets to focus a beam of electrons which is transmitted through the specimen
Denser parts absorb more electrons so they look darker
They can only be used on thin specimens which have been chemically fixed ((dehydrated and stained))
2D image produced

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6
Q

what are some key feature of Scanning electron microscopes?

A

Scans a beam of electrons across the specimen
This knocks off electrons from the specimen which are gathered in a cathode ray tube to form an image, it shows the surface but they are lower resolution

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7
Q

what is the maximum resolution for an optical, Transmission electron and scanning electron microscope?

A
  1. 2 um
  2. 0002um
  3. 002 um
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8
Q

what stains are used for light and electron microscopes?

A

For Light Microscopes a dye is used like methylene blue or eosin, it is taken up by some parts high contrasts the different structures (multiple stains can be used at once)
For Electron Microscopes objects are dipped in heavy metals (like lead, the metal ions scatter the electrons creating a contrast as some show up darker

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9
Q

what is a cytoplasm?

A

contains a network of protein threads running through it

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10
Q

what are the four functions of the cytoskeleton?

A
  • The microtubules and micro filaments support the organelles keep them in position
  • They help to strengthen the cell and maintain its shape
  • They’re responsible for movement of materials within the cell
  • The proteins of the cytoskeleton can also cause the cell to move (whole cell)
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11
Q

what is the plasma 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 of many lipids and proteins

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12
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

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13
Q

what is the cell wall?

A

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

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14
Q

what is the nucleus?

A

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

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15
Q

what if the function of the nucleus?

A

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

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16
Q

what is a lysosome?

A

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

17
Q

what is the function of a lysosome?

A

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

18
Q

what is 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. Not surrounded by membrane

19
Q

what is the function of a ribosome?

A

The site of protein synthesis

20
Q

what is the rough ER?

A

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

21
Q

what is the function of the rough ER?

A

Folds and processes proteins that have been made at the ribosomes

22
Q

what is the smooth ER and what is its function?

A

Similar to rough ER, but with no ribosomes, synthesis and processes lipids

23
Q

what is a vesicle and what is it’s function?

A

A small fluid-filled sac in the cytoplasm, surrounded by membrane and it transports substances in and out of the cell and between organelles. Some are formed by the Golgi body or the ER while others are at the cell surface

24
Q

what is the golgi apparatus and its function?

A

A group of fluid-filled, membrane bound, flattened sacs. Vesicles are often seen at the edges of the sacs. It processes and packages new lipids and proteins. It also makes lysosomes

25
Q

what is a mitochondira ?

A

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

26
Q

what is the function of a 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

27
Q

what is a chloroplast?

A

A small flattened structure found in plant cells. Surrounded by a double membrane, also has internal membranes called thylakoids membranes which are stacked up to form grana which are linked by lamellae (Thin,flat pieces of thylakoids membrane)

28
Q

what is the function of a chloroplast?

A

Site of photosynthesis. Some parts take place in grana and other parts happen in the stromatolites (thick fluid)

29
Q

what is a centriole and its function?

A

Small hollow cylinders made of microtubules (found in animal cells but only some plant cells), involved in separation of chromosomes during cell division

30
Q

what is a cili and its function?

A

Small hair-like structures on surface membrane of animal cells, microtubules allow the cilia to move. This movement is used by the cell to move substances along the cell surface

31
Q

what is a flagellum and it’s function?

A

Flagella on Eukaryotic cells are like cilia but longer. They stick out from the surface and are surrounded by plasma membrane, microtubules contract and the flagellum move. They are used I’ve outboard motors to propel it forwards

32
Q

how are proteins made and secreted?

A
  1. mRNA copy of the instructions (gene) for insulin is made in the nucleus
  2. mRNA leaves the nucleus through a nuclear pore
  3. mRNA attaches to a ribosome (RER), ribosome reads instructions to assemble the protein (insulin)
  4. Insulin molecules are pinched off in vesicles and travel towards golgi apparatus
  5. fuse with golgi apparatus
  6. golgi apparatus processes and packages insulin molecules ready for release
  7. packaged insulin molecules are pinched in vesicles from golgi apparatus and move toward plasma membrane
  8. vesicles use with plasma membrane
  9. plasma membrane opens to release insulin molecules outside
33
Q

what is an example of a prokaryote?

A

bacteria

34
Q

what is an example of a eukaryote?

A

human

35
Q

what are two differences between prokaryotes and eukaryotes?

A

P = circular DNA, extremely small, no nucleus, cell wall made of polysaccharide, few organelles, small ribosomes

E = larger cells, linear DNA, nucleus present, no cell wall, many organelles, larger ribosomes