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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 much bigger an image appears compared to the original object.

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2
Q

What is resolution?

A

The ability of a microscope to distinguish between two points that are close together.

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3
Q

What is the equation for magnification?

A

Image size= Actual size x Magnification

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4
Q

What are the advantages of TEM?

A

High resolution and magnification.
Observe internal structures.

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5
Q

What are the disadvantages of TEM?

A

Requires complex sample preparation.
Sample preparation often distorts material.
Vacuum is required.
Produces a black and white image only.
Expensive to buy and operate.
Large and needs installing.
Training typically required.
No live specimen.

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6
Q

What is the maximum resolution of a Light microscope?

A

200 nm

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7
Q

What is the maximum resolution of a TEM?

A

0.5 nm

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8
Q

What is the maximum resolution of a SEM?

A

3-10 nm

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9
Q

What is the maximum magnification of a Light microscope?

A

x2000

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10
Q

What is the maximum magnification of an Electron microscope?

A

over x500,000

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11
Q

What are the advantages of Laser scanning confocal microscopes?

A

It is non-invasive and thick specimens can be observed.

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12
Q

What are the disadvantages of Laser scanning confocal microscopes?

A

Slow process and requires training.

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13
Q

What do TEM, SEM, and LSC microscopes observe?

A

TEM-organelles
SEM-an object a certain distance in a cell
LSC-cell surfaces

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14
Q

What is an artefact?

A

An issue created in specimen preparation e.g. a bubble.

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15
Q

What is a stage micrometre?

A

A microscope with a very accurate scale in micrometres engraved on it.

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16
Q

What is an eyepiece graticule?

A

A glass disc marked with a fine scale of 1 to 100.
The scale has no unit, the relative size of dimensions increases with each increase in magnification.
The scale is calibrated using a stage micrometre.

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17
Q

What is differential staining?

A

Staining which helps distinguish between two types of organisms.

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18
Q

What is Methylene blue?

A

A positively charged dye which is attracted to negatively charged materials in cytoplasm.
It stains RNA/DNA.

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19
Q

What is Congo red?

A

A negatively charged dye which repels negatively charged cytosol.
It stains the outside of a cell, leaving the inside unstrained.

20
Q

What is Eosin?

A

Common dye that stains pink/orange.
It is a negatively charged acidic dye that binds to basic components of a cell, mainly proteins in the cytoplasm.

21
Q

What is Iodine used for?

A

A common stain used to observe plant cells.

22
Q

What is the Gram stain technique?

A

A technique used to separate bacteria into two groups, Gram-positive bacteria(e.g. Streptococcus pneumonae) and Gram-negative bacteria(e.g. Yersinia pestis).

23
Q

What is a method to permanently prepare a microscope slide?

A

Fixed with formaldehyde and dehydrated with ethanol, then impregnated with paraffin wax and thinly sliced.

24
Q

What is the cryostat method to prepare a microscope slide?

A

Frozen in N2(l) or CO2(l) and cut.

25
Q

What is acid-fast staining?

A

Staining used to differentiate species of Mycobacterium from other bacteria.
(A lipid solvent is used to carry carbolfuchsin dye into the cells, then washed with dilute acid-alcohol solution. Mycobacterium are not affected by the solution and retain the stain)

26
Q

What organelles do eukaryotes contain?

A

-nucleus
-nucleolus
-nuclear envelope
-rough endoplasmic reticulum
-smooth endoplasmic reticulum
-Golgi apparatus
-ribosomes
-mitochondria
-lysosomes
-chloroplasts
-plasma membrane
-centrioles
-cell wall
-flagella
-cilia

27
Q

What is the role of the nucleus?

A

Houses DNA and directs the synthesis of all protein required by the cell.

28
Q

What is the role of the nuclear envelope?

A

The nuclear envelope has a double membrane which contains DNA with a fluid separating the inner and outer membrane.
It has nuclear pores which allow larger molecules to move into and out the nucleus.

29
Q

What is the role of the smooth endoplasmic reticulum?

A

It makes lipids and carbohydrates needed by the cell.

30
Q

What is the role of the rough endoplasmic reticulum?

A

Flattened membrane-bound sacs studded with ribosomes.

31
Q

What is role of the Golgi apparatus?

A

Receives proteins from the rough endoplasmic reticulum and modifies them. Then packages them into vesicles to be transported.

32
Q

What is the role of mitochondria?

A

They are the site of cellular respiration where energy is stored in bonds of organic molecules.
Produces ATP.

33
Q

What is the role of lysosomes?

A

Lysosomes are specialised vesicles that contain hydrolytic enzymes.
Acts as a waste disposal system-involved in phagocytosis and apoptosis.

34
Q

What is the role of Chloroplasts?

A

The site of photosynthesis.

35
Q

What is the role of the plasma membrane?

A

It is selectively permeable and controls movement in and out of the cells-acts as a barrier.

36
Q

What is the role of centrioles?

A

Self-replicating organelles made of nine bundles of microtubules that help organise cell division.

37
Q

What is the role of the cell wall?

A

Cell wall made of polysaccharide cellulose that can function as a carbohydrate store.
It has pores called plasmodesmata for communication.

38
Q

What is the role of flagella?

A

Primarily used for mobility but also for sensing chemical changes.

39
Q

What is the role of cilia?

A

Stationary cilia-important for sensory organs.
Mobile cilia-beat in rhythmic pattern.

40
Q

What is the role of cytoskeleton?

A

Microfilaments-contractive fibres for cell movement.
Microtubules-build a scaffold-like shape for structure.
Intermediate fibres-mechanical strength/integrity.

41
Q

What is the role of permanent vacuoles?

A

Tonoplast membrane filled with cell sap and keeps plant cell firm.

42
Q

How are proteins produced and packages?

A

Proteins synthesised on the ribosomes bound to the rough endoplasmic reticulum.
Packaged into transport vesicles and then transported to cis-face of Golgi apparatus with help of cytoskeleton(microfilaments).
Protein travels through cisternae and is packaged in the trans-face.
Packaged in a secretory vesicle-vesicle reaches cell-surface membrane.
Vesicle fuses with membrane and exocytosis occurs.

43
Q

What path of organelles are used in protein production and packaging?

A

-Nucleus
-Rough endoplasmic reticulum
-Transport vesicle
-Golgi apparatus
-Secretory vesicle
-Cell-surface membrane

44
Q

What organelles do prokaryotes contain?

A

-nucleoid
-plasma membrane
-ribosomes
-flagella
-capsule
-cell wall
-pilus

45
Q

What are the differences between eukaryotic and prokaryotic cells?

A

Eukaryotic- meiosis and mitosis.
multi-cellular.
linear DNA
10-100 micrometres.
Prokaryotic- binary fission.
uni-cellular.
circular DNA.
0.1-10 micrometres.

46
Q

How does DNA differ in prokaryotic cells compared eukaryotic cells?

A

Prokaryotes have one molecule of DNA which is supercoiled to be more compact.
They are grouped into operons and genes can be switched on and off.

47
Q

How do ribosomes differ between prokaryotic and eukaryotic cells?

A

Eukaryotes have 80s ribosomes while prokaryotes have 70s ribosomes.

Biology (25 decks)

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