2.1.1 - CELL STRUCUTRE Flashcards

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1
Q

List the components of a eukaryotic animal cell

A
  • plasma (cell surface) membrane
  • rough endoplasmic reticulum (RER)
  • nucleolus
  • nucleus
  • smooth endoplasmic reticulum (SER)
  • lysosome
  • ribosome
  • nuclear envelope
  • Golgi apparatus
  • cytoplasm
  • mitochondrion
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2
Q

List the components of a eukaryotic plant cell

A
  • plasma (cell surface) membrane
  • rough endoplasmic reticulum (RER)
  • nucleolus
  • nucleus
  • smooth endoplasmic reticulum (SER)
  • lysosome
  • ribosome
  • nuclear envelope
  • Golgi apparatus
  • cytoplasm
  • mitochondrion
  • CHLOROPLAST
  • CELL WALL
  • VACUOLE
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3
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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4
Q

What is the function of the cell wall?

A

Supports plant cells

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5
Q

What is the function of the nucleus

A

Controls the cell’s activities (by controlling 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

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6
Q

What is the function of 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

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7
Q

What is the function of ribosomes?

A

The site where proteins are made

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8
Q

What is the function of the Rough Endoplasmic Reticulum (RER)?

A

Folds and processes proteins that have been made at the ribosomes

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9
Q

What is the function of the Smooth Endoplasmic Reticulum (SER)?

A

Synthesises and processes lipids

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10
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

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11
Q

What is the function of the Golgi apparatus?

A

Processes and packages new lipids and proteins. Also makes lysosomes

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12
Q

What is the function of the mitochondrion?

A

The site of aerobic respiration, where ATP is produced. Found in large numbers in cells that are very active and require a lot of energy

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13
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)

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14
Q

What is the function of the centriole?

A

Involved with the separation of chromosomes during cell division

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15
Q

What is the function of cilia?

A

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

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16
Q

What is the function of the flagellum?

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)

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17
Q

Describe the structure of the Rough Endoplasmic Reticulum (RER)

A
  • System of membranes enclosing a fluid-filled space
  • The surface is covered with ribosomes
18
Q

Describe the structure of the Smooth Endoplasmic Reticulum (SER)

A
  • A system of membranes enclosing a fluid-filled space
  • The surface has no ribosomes
19
Q

Describe the structure of the mitochondria

A
  • Oval-shaped
  • Double membrane —> inner membrane folded to form structures called cristae
  • Inside is the matrix, which contains enzymes involved in respiration
20
Q

Describe the structure of the chloroplasts

A
  • Small, flattened structure in plant cells
  • Double membrane
  • Has membranes called thylakoid membranes
  • Thylakoids stack up to form grana
  • Grana are linked together by lamellae (thin, flat pieces of thylakoid membrane
  • Contains thick fluid called stroma
21
Q

Explain the steps behind protein production/synthesis

A
  • Proteins are made at the ribosomes
  • Ribosomes on the RER make proteins that are excreted or attached to the cell membrane. Free ribosomes make proteins that stay in the cytoplasm
  • new proteins at the RER are folded and processed (e.g. sugar chains are added) in the RER
  • Proteins then transported from RER to the Golgi apparatus in vesicles
  • At Golgi, proteins may undergo more processing (e.g. sugar chains trimmed or more added)
  • The proteins enter more vesicles to be transported around the cell (e.g. glycoproteins in mucus move to the cell surface and are secreted)
22
Q

What is the cytoskeleton

A

A network of protein threads running through the cytoplasm

  • in eukaryotic cells, protein threads arranged as microfilaments (small solid strands) and microtubules (tiny protein cylinders)
23
Q

What is the function of the cytoskeleton?

A
  • Microtubules + microfilaments support the cell’s organelles, keeping them in position
  • Help strengthen cell + maintain shape
  • Responsible for movement of materials within the cell (e.g. movement of chromosomes when they separate during cell division depends on contraction of microtubules in the spindle
  • Proteins of the cytoskeleton can cause cell to move (e.g. movement of cilia + flagella caused by cytoskeletal protein filaments that run through them)
24
Q

State the characteristics of prokaryotic cells

A
  • small (less than 2 µm diameter)
  • circular DNA
  • no nucleus (free DNA)
  • cell wall made of polysaccharide - but not cellulose or chitin
  • few organelles and no membrane-bound organelles (no mitochondria)
  • flagella (if present) made of the protein flagellin, arranged in a helix
  • small ribosomes

e.g. E. coli bacteria

25
Q

State the characteristics of eukaryotic cells

A
  • larger cells (10-100 µm diameter)
  • linear DNA
  • nucleus (DNA inside nucleus)
  • no cell wall (animals), cellulose cell wall (plants), chitin cell wall (fungi)
  • many organelles - has membrane-bound organelles
  • flagella (if present) made of microtubule proteinsarranged in a ‘9 + 2’ formation
  • larger ribosomes

e.g. human liver cell

26
Q

What is the equation for magnification?

A

Magnification = Image size/Actual size

27
Q

Define magnification

A

How much bigger the image is than the specimen (actual size)

28
Q

Define resolution

A

How well a microscope distinguishes between two points that are close together

29
Q

How do light microscopes operate?

A
  • They use light to produce photograms
30
Q

What is the max resolution and magnification of a light microscope?

A

Resolution: 0.2 µm
Magnification: x 1500

31
Q

How does a Laser Scanning Confocal Microscope operate?

A
  • use laser beams to scan a specimen, which is tagged with fluorescent dye
  • laser causes dye fluoresce (give off light)
  • light then focused through a pinhole onto a detector
  • detector hooked up to computer to generate image (can be 3D)
  • can look at objects at different depths in thick specimens
32
Q

What is the maximum resolution and magnification of a Laser Scanning Confocal Microscope?

A

Resolution:
Magnification:

33
Q

What are the two kinds of electron microscope?

A
  • Transmission Electron Microscope (TEM)
  • Scanning Electron Microscope (SEM)
34
Q

How does a TEM operate?

A
  • use electromagnets to focus a beam of electrons which is transmitted through the specimen
  • denser parts of the specimen absorb more electrons, which make them look darker on the image
35
Q

What are the advantages and disadvantages of TEMs?

A

+ provide high resolution images
- can only be used on thin specimens

36
Q

What is the maximum resolution and magnification of TEMs?

A

Resolution: 0.0002 µm
Magnification: more than x 1 000 000

37
Q

How does a SEM operate?

A
  • scans a beam of electrons across the specimen
  • knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image
38
Q

What are the advantages and disadvantages of SEMs?

A

+ can be 3D and show specimen surface
- give lower resolution images

39
Q

What is the maximum resolution and magnification of SEMs?

A

Resolution: 0.002 µm
Magnification: less than x 500 000

40
Q

Explain the Dry Mount method of preparing a microscope slide

A
  • take thin slice of thick specimen
  • use tweezers to pick up specimen and put it in the middle of a clean slide
  • place a cover slip on top
41
Q

Explain the Wet Mount method of preparing a microscope slide

A
  • pipette a small drop of water onto the slide
  • use tweezers to place the specimen on the water drop
  • stand the slip upright on the slide, next to the water droplet, then title and lower it so it covers the specimen (BE CAREFUL OF AIR BUBBLES)
  • once the slip is in position, add a stain (it’ll get drawn under the slip, across the specimen)
42
Q

Why is it sometimes necessary to stain an object before viewing it through a microscope?

A

Sometimes the object being viewed may be completely transparent, making the whole thing look white

  • different stains to make different things show up (e.g. eosin stains cell cytoplasms + methylene blue stains DNA)