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Biology > 3.2 Cells > Flashcards

3.2 Cells Flashcards

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1
Q

Structure of lysosomes

A

Contains digestive enzymes (LYSOZYMES).

Lysozyme: enzymes that hydrolyse the cell wall of bacteria.

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2
Q

Function of lysosomes

A
  • Hydrolyses material ingested by phagocytic cells.
  • Release enzyme to the outside of cell to destroy material around the cell
  • Digest worn out organelles
  • Break down cells after they have died
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3
Q

What is resolution limited by?

A

Wavelength of light.

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4
Q

Which one has a shorter wavelength; light vs electron?

A

Electron (beam) has a shorter wavelength than light.

This allows higher resolution.

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5
Q

Resolution

A

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

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6
Q

Magnification

Equation

A

= size of image / size of real object

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7
Q

Magnification

A

How many times bigger an image viewed through a microscope is, compared to a real object.

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8
Q

Cell fractionation

A

The process where cells are broken up and different organelles they contain are separated out.

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9
Q

Conditions of cell fractionation and why (3)

A
  • Cold - prevent enzyme activity that breaks down organelles.
  • Buffered - prevents proteins/enzymes from denaturing.
  • Isotonic - prevents osmosis which could cuase organelles to burst.
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9
Q

Steps of cell fractionation

A
  1. Homogenisation - breaks up cells in a tussue sample.
  2. Filtration - removes large cell debris/unbroken cells.
  3. Unltracentrifugation - separates cell organelles.

Heaviest organelles are collected at the bottom - pellet.
Fluide at the top - supernatant.

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10
Q

Strucutre of vacuoles

A

• Tonoplast: outer single membrane
• Stores sugars, mineral salts & amino acids
• Sometimes pigment which attracts pollinating insects

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11
Q

Function of vacuoles

A

• Turgidity
• Energy store / temporary food store

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12
Q

Structure of cell wall

A

• Microfibrils of cellulose
• Thin layer (middle lamella)
• Rigid & permanent

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13
Q

Function of cell wall

A

• Provides mechanical strength → prevents cells from bursting under pressure (by osmosis)

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14
Q

Structure of grana

A

• Stacks of thylakoids (thylakoids are filled with chlorophyll)

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15
Q

Function of grana

A

• First place of photosynthesis
• Provides large surface area for attachment of chlorophyll & enzymes

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16
Q

Structure of storma

A

• Fluid filled matrix
• Contains - ribosomes, DNA, starch grains

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17
Q

Function of storma

A

• Second stage of photosynthesis

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18
Q

Function of chloroplast DNA

A

• Quickly manufacture proteins for photosynthesis

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19
Q

Structure of chloroplast DNA

A
  • Circular
  • No associated with proteins
  • Shorter than nuclear DNA
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20
Q

Structure of mitochondria

A

• Double membrane - inner membrane folded = cristae
• Matrix - contains: lipids, proteins, ribosomes, mitochondrial DNA, many enzymes involved in respiration.
- DNA/ribosomes to make proteins needed for respiration.

Cristae: extensions of the inner membrane provides a large surface area for attachment enzymes & other proteins (involved in respiration).

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21
Q

Function of mitochondria

A

• Produces ATP for aerobic respiration

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22
Q

Structure of rough endoplasmic reticulum

A

• Folded membranes
• Ribosomes present on the outer surface of the membranes.

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23
Q

Function of rough endoplasmic reticulum

A

• Provides a large surface area for the synthesis of proteins & glycoproteins.
• Pathway for transport materials (especially proteins).

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24
Function of nucleolus
• Manufactures ribosomal RNA • Assembles ribosomes ## footnote Could be more than one in a nucleus
25
Function of nuclear pore
• Allows the passage of large molecules. ## footnote Eg. Messenger RNA
26
Structure of nuclear envelope
• Is a double membrane surrounding the nucleus. • Outer membrane is continuous with the ER of the cell.
27
Function of nuclear envelope
• Controls the entry & exit of materials.
28
Structure of smooth endoplasmic reticulum
Folded membranes.
29
Function of smooth endoplasmic reticulum
• Synthesis, store + transport lipids & carbohydrates.
30
Structure of ribosomes
- RNA - Proteins
31
Function of ribosomes
Site of protein synthesis.
32
Structure of Golgi apparatus
• Cisternae - stack of membranes that makeup flattened sacs • Vesicles - small round hollow structures
33
Function of Golgi apparatus
• Modifies molecules → adds carbohydrates to proteins (glycoproteins) • Transport, modify and store lipids • ‘Labels’ molecules for them to be accurately sorted & sent to correct destinations • Forms lysosomes
34
Structure of vesicles
Fluid filled sac
35
Function of vesicles
- Transports substances around the cell. - (some) Fuse with cell membrane
36
Flagellum
Move away from danger and towards food.
37
Capsule
- Slime/mucus layer. - Protection from excessive water loss. - Protection from host’s immune system.
38
Plasmid
Gives the bacteria resistance to harmful chemicals.
39
Pili
For attachment to other cells or surfaces and interaction with other bacteria.
40
Ribosomes (prokaryotic)
70s ## footnote Eukaryotic cells - 80s
41
Circular DNA
Possesses genetic information for the replication of bacterial cell. Is not associated with histones.
42
Cell wall
Contains murine (glycoprotein) - Protection - Maintain cell shape - Prevent cells from bursting
43
Attachment proteins
Bind to receptors on host cell
44
Viral RNA
Holds genetic material.
45
Lipid envelope
Protection ## footnote Lipid layer is taken from host cell.
46
Enzyme in virus
Reverse transcriptase ## footnote Converts RNA to DNA
47
Capsule VS Capsid
Capsule: bacteria Capsid: virus
48
Scanning electron microscope (SEM)
Detects electrons that bounce off the surface of the sample 3D image of outer surface.
49
Transmission electron microscope
Electron beam passes through a thin section of the specimen. Detects electrons transmitted through sample surface. High resolution image (photomicrograph) of internal structure.
50
Strengths of optical microscope
- Better portability - Can view living specimens - Colour images
51
Strengths of SEM
- Easier sample preparation - Reduced risk of artefacts
52
Strengths of TEM
- Better magnification (vs SEM) - Better resolution (vs TEM) - 3D or internal imaging
53
Limitations of TEM & SEM
- Complex staining process - may lead to artefacts. - No colour. - Non-living specimens - Extremely thin sample (not SEM)
54
DNA contains the code for…
… proteins
55
What can be used to identify starch grains in plant cells?
Iodine in potassium iodide.
56
Mitosis
Part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical opines of DNA produced by the parent cells during DNA replication. ## footnote - Nucleus divides into two - Mass of DNA and cell is unchanged
57
Interphase
- Organelles & **DNA** replicates - Checks replicated DNA + repairs errors ## footnote Mass of DNA doubles (and mass of cell). 90% of cell cycle.
58
Cytokinesis
Cell divides into two (cytoplasm divides). ## footnote Two genetically identical daughter cells are made - Mass of DNA & cell = parent cells
59
Prophase
1. Chromatin condenses into chromatids (visible under microscope). 2. Each chromosomes is made up of two sister chromatids joined at the centromere. 3. Nucleolus disappears + nuclear envelope breaks down (chromosomes float free). 4. Spindle fibres form at centrosomes. ## footnote Plant cells do not have centrosomes but still make spindle fibres
60
Metaphase
Spindle fibres attach to the centromeres (of each chromosome). And the chromosome line up in the equator.
61
Anaphase
1. Spindle fibres shorten. 2. Sister chromatids are pulled to opposite ends of the cell. ## footnote Requires ATP.i
62
Telophase
1. Chromatids reach the cell poles and de-condense back to chromatin. 2. Nucleolus + nuclear envelope reforms. 3. Spindle fibres breaks down. Two nucleus but still in same cytoplasm.
63
Cancer
A group is diseases caused by a growth disorder of cells. Result of damage to the genes that regulate mitosis and the cell cycle. ** Leads to uncontrolled growth and cell division of cells ** ## footnote Uncontrolled cell division → tumour → cancer
64
Treatment of cancer
** Treatment aims to control rates of cell division.** - Prevents DNA replication. - Inhibits metaphase of mitosis by interfering its spindle formation.
65
Problems with cancer treatment
Disrupts the cell cycle of normal cells. ## footnote However, as cancer cells divide much more rapidly, affects are quite low.
66
Homologous pair of chromosomes
Two chromosomes that carry the same gene_s_.
67
Cell wall - plants
Microfibrils of cellulose
68
Cell wall - fungi
Chitin.
69
Eukaryotic cells VS prokaryotic cells
Eukaryotic cells are… … the cells are much smaller … no membrane bound-organelles … smaller ribosomes … no nucleus … no cell wall made of murein Prokaryotic cells have… … plasmids … a capsule around the cell … flagella
70
Cell division (prokaryotic)
Binary fission
71
Cell division (virus)
Do not undergo cell division as they are non-living. Viruses replicate inside of the host cells they invade by injecting their nucleic acid in a cell.
72
Diploid
2n To pairs of every chromosome.
73
Mitotic index =
_The number of cells in mitosis_. *100 The total number of cells
74
Importance of sodium ions
Sodium ions are involved in the co-transport of glucose/amino acids in the small intestine.
75

Biology (6 decks)

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