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Biology > 2.1.1 Cell Structure > Flashcards

2.1.1 Cell Structure Flashcards

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1
Q

What is magnification?

A

How many times larger an image is than the actual object itself.

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2
Q

What is resolution?

A

The degree to which it is possible to distinguish between two objects that are very close together. (The higher the resolution, the greater detail you can see.)

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3
Q

What is the equation for total magnification?

A

Eyepiece lens magnification X Objective lens magnification

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4
Q

What processes are required to prepare a slide?

A

Staining and/or sectioning.

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5
Q

What is staining?

A

Coloured dyes bind to chemicals on or in the specimen so they are visible.

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6
Q

How do you increase contrast during staining?

A

Use multiple dyes called differential staining to increase contrast.

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7
Q

What is sectioning?

A

Embedding specimens in wax which can then be sliced very thinly without distorting the structure.

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8
Q

What type of tissue is sectioning used on and why?

A

Used for soft tissue to avoid distorting structures that you want to see.

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9
Q

What is the radiation used for electron and light microscopes?

A

E= Electrons
L= Light

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10
Q

How do electron and light microscopes focus?

A

E= Magnets
L= Lenses

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11
Q

What is the magnification of light and electron microscopes?

A

E= X 2,000,000
L= X 2000

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12
Q

What is the resolving power of electron and light microscopes?

A

E= 0.2nm
L= 200nm

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13
Q

What type of microscope requires the sample to be in a vacuum?

A

Electron microscope (therefore matter must be dead).

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14
Q

How do transmission electron microscopes work?

A

Some electrons pass through the specimen and are focused on the screen or photographic plate.

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15
Q

What type of image is created by a TEM microscope?

A

A 2D, black and white image.

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16
Q

How do scanning electron microscopes work?

A

Electrons don’t pass through but cause secondary electrons to bounce off the specimens surface and reflect onto a screen.

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17
Q

What type of image is created by a SEM?

A

A 3D, black and white image.

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18
Q

What is a confocal microscope?

A

A microscope that uses lasers to scan and assemble an image.

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19
Q

What are the pros of a confocal microscope?

A
  • The specimen doesn’t have to be cut so it can be used to look at whole objects.
  • Cheap and easy to use.
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20
Q

What is an eyepiece graticule?

A

Similar to a ruler but is variable as magnification changes.

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21
Q

What is the structure of a nucleus?

A

Nucleus is surrounded by a double membrane (nuclear envelope) which has pores.
Nucleolus contains RNA.
Contains chromatin which is DNA wound around histone proteins.

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22
Q

What is the function of the nucleus?

A

Nuclear envelope separates stuff in nucleus from rest of cell.
Pores: so ribosomes can leave.
Nucleolus makes ribosomes.
Contains chromosomes.

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23
Q

What is the structure of the rough endoplasmic reticulum?

A

System of membranes with fluid filled cavities (cisternae) that continue from the nuclear envelope.
Coated in ribosomes.

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24
Q

What is function of the rough endoplasmic reticulum?

A

Intracellular transport system as the cisternae form channels.
Large surface area for ribosomes. Proteins then go through to the cisternae.

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25
Q

What is the structure of the smooth endoplasmic reticulum?

A

System of membranes with cisternae.
No ribosomes.

26
Q

What is the function of the smooth endoplasmic reticulum?

A

Contains enzymes that catalyse reactions (For lipid metabolism. E.g. synthesis of cholesterol, lipids/phospholipids, steroid hormones.)
Involved in absorption, synthesis and transport of lipids (from gut).

27
Q

What is the structure of the golgi apparatus?

A

A stack of membrane bound flattened stacks.
Secretory vesicles bring materials to and from the golgi apparatus.

27
Q

What is the function of the golgi apparatus?

A

Proteins are modified (E.g. By:
- adding sugar molecules- glycoproteins
- adding lipid molecules- lipoprotiens
- being folded into a 3D shape)
Proteins are packaged into vesicles and then stored in the cell or moved to cell surface membrane.

28
Q

What is the structure of the mitochondria?

A

Spherical, rod-shaped or branched.
2-5 micrometers long.
2 membranes with fluid filled space between.
Inner membrane = highly folded.
Inner part is a fluid filled matrix.

29
Q

What is the function of the mitochondria?

A

Site of adenosine triphosphate production during aerobic respiration.
Self-replicating
Abundant in cells where much metabolic activity occurs.

30
Q

What is the structure of chloroplasts?

A

Large organells 4-10 micrometers long.
Plants and some protists have them.
Double membrane.
Inner membrane is continuous stacks of flattened membrane sacs (thylakoids) containing chlorophyll. Each stack is called a granum. The whole matrix is called the stroma.
Contain loops of DNA and starch grains.

31
Q

What is the function of chloroplasts?

A

Site of photosynthesis.
1st stage: Light being trapped occurs in the grana. Water is split to supply hydrogen ions.
2nd stage: H reduced CO2 to make carbs (occurs in the stroma)

32
Q

What is the structure of a vacuole?

A

Surrounded by a membrane: tonoplast- contains fluid.

33
Q

What is the function of a vacuole?

A

Plant cells.
Filled with water, solutes and maintains cell stability as when full it pushes against wall.
Supports plant.

34
Q

What is the structure of lysosomes?

A

Small bags containing enzymes formed in the golgi apparatus.
Abundant in phagocytes so they can engulf pathogens.

35
Q

What is the function of lysosomes?

A

Keep the enzymes separate from the rest of cell.
Engulf old cell organelles and digest them.

36
Q

What is the structure of cilia and undulipodia?

A

Protrusions from the cell and are surrounded by cell surface membrane.
Contains microtubules.
Formed by centrioles.

37
Q

What is the function of cilia and undulipodia?

A

Move mucus.
Acts as antenna on cells- signals and contains receptors.

38
Q

What is the structure of ribosomes?

A

Small, spherical organelles, 20 micrometers in diameter.
Made of ribosomal RNA.
Made in nucleus (as 2 units) pass through the nuclear envelope then combine.
Some in cytoplasm and others in RER.

39
Q

What is the function of ribosomes?

A

On RER used for synthesising proteins.
Free in cytoplasm used as site of assembly of proteins to be used in the cell.

40
Q

What is the structure of centrioles?

A

Made of microtubules.
9 triplets of microtubules make hollow bundles.
Eukaryotic cells (Not flowering plants or fungi)
Found in pairs.

41
Q

What is the function of centrioles?

A

Before cell divides, the spindles, made of threads of tubulin forms from the centrioles.
Chromosomes attach to middle of spindle and motor proteins walk along them.

42
Q

What is the structure of a cell wall?

A

Made of cellulose.
Freely permeable, but rigid.

43
Q

What is the function of a cell wall?

A

Strong and prevents cells from bursting when turgid.
Also help maintain cell shape.
Permeable and allow solutions to go through.

44
Q

What is the function of the cytoskeleton?

A

Cellular movement (cilia and flagella)
Form tracks inside cells for organelles to move along.
Strength and support- ‘scaffolding’ to keep cell shape and strengthen.

45
Q

What are microtubules?

A

Small, tubular structures in the cytoplasm.
Diameter of around 25nm.
Composed of globular proteins.
Arranged in spirals.
Centrioles, cilia and flagella are made of them.

46
Q

What are microfilaments?

A

Small, rodlike structure present in numbers in the cytoplasm of many eukaryotes.
Diameter of 5-8nm.
Can assemble and disassemble to help cells change shape.
Made of protein which allows them to move.

46
Q

What is structure of flagella?

A

Made of microtubules.
9 pairs of microtubules surrounding 2 central ones.
Found on the surface of cells (Pro and Eukaryotes)
Singular (one)

47
Q

What is the function of flagella?

A

Enable cell motility.
Some detect chemical changes in an environment.

48
Q

What is the structure of cilia?

A

Made of microtubules.
Ring of 9 pairs of microtubules around 2 central microtubules.
Stationary cilia are found on the surface of cells (E.g. ciliated epithelial cells)

49
Q

What is the function of cilia?

A

Mobile cilia beat rhythmically to make a current which makes things move.

50
Q

What is the size of prokaryotes and eukaryotes?

A

P= 0.1-10um
E= 10-100um

51
Q

Where is genetic material found in prokaryotes and eukaryotes?

A

P= Nucleoid and plasmids
E= Linear chromosomes in the nucleus.

52
Q

Do prokaryotes and eukaryotes have organelles?

A

P= No
E= Many

53
Q

What is the size of ribosomes in prokaryotes and eukaryotes?

A

P= Smaller (70s)
E= Larger (80s)

54
Q

Where does respiration take place in prokaryotes and eukaryotes?

A

P= Mesosomes
E= Mitochondria

55
Q

What are flagella like in prokaryotes and eukaryotes?

A

P= Simple, no microtubules.
E= Complex, microtubules.

56
Q

Where does photosynthesis take place in prokaryotes and eukaryotes?

A

P= Unstacked membranes
E= Chloroplasts (plant cells only)

57
Q

What are examples of prokaryotes and eukaryotes?

A

P= Bacteria
E= Plant, animal and fungi.

58
Q

What is endosymbiont theory?

A

Mitochondria and chloroplasts were once prokaryotic cells that were engulfed but not digested. This began a symbiotic relationship where they both provided each other something.

Biology (3 decks)

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