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Cell Structure Flashcards

1
Q

What is exocytosis ?

A

Transport of material out of cell by vesicles

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2
Q

Define mesosomes

A

Structures within bacterial cells that are an inward extension of the cell membrane

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3
Q

What is endocytosis?

A

Transporting material into cell by engulfing it with its membrane

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4
Q

What is a microscope that uses pairs of convex lenses called?

A

A compound microscope

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5
Q

What is the resolution and magnification of a light microscope?

A

0.2 um

X1500

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6
Q

What is the eye piece also know as?

A

Ocular Lens

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7
Q

How do you calculate total magnification?

A

Mag of eyepiece X mag of objective lens

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8
Q

What is magnification?

A

How many times bigger the image is than real life

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9
Q

What is resolution?

A

The ability to distinguish between two adjacent points as separate structures

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10
Q

What is the equation for magnification ?

A

Drawn size / actual size

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11
Q

What is the limit of resolution?

A

The smallest distance between 2 distinct points. (After this point increasing mag doesn’t reveal more detail)

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12
Q

Why do electron microscopes have a higher resolution?

A

Shorter wavelength compared to light

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13
Q

How does an electron microscope work?

A

An electron beam gets focused by electromagnets onto specimen. Denser regions absorb electrons and appear lighter

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14
Q

What is the resolution and magnification of a TEM?

A

Mag = X500,000

Res= 0.1 nm

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15
Q

What does the condenser magnet do in a TEM?

A

Focus electron beam onto specimen

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16
Q

How must the specimen be prepared before using a TEM ?

A

Must be very thin, preserved in heavy metals and dead

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17
Q

Why must the specimen be dead for a TEM?

A

Uses vacuum

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18
Q

Why might the 0.1 non resolution be met for a TEM?

A

Lower energy beam used to not damage structure of specimen

Difficulties preparing specimen

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19
Q

What are the limitations of TEM?

A 
Time consuming 
Complex process (training needed) 
Specimen must be dead 
No color 
2D image 
Artefacts
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20
Q

What does TEM and SEM stand for?

A

Transition and scanning electron microscope

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21
Q

What are the two types of electron microscope?

A

TEM and SEM

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22
Q

How is a TEM different to a SEM?

A

TEM= electron beam goes through specimen

SEM= electrons pass along surface and are reflected back.

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23
Q

What are the advantages of using a SEM compared to a TEM?

A

3D looking image produced

Preparation is less complex

Specimen can be thick

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24
Q

What are the disadvantages of using a SEM over a TEM?

A

Lower resolution (20nm VS 0.1nm )

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25
What are the main advantages and disadvantages of using a SEM over a light microscope?
Ad = higher resolution Dis = specimen must be dead
26
Place in order of increasing resolution TEM light microscope SEM
Light SEM TEM
27
When using a SEM what do the dark and light areas indicate?
Dark = depressions Light = extensions
28
What is the difference between an eyepiece and scale graticule ?
Eyepiece graticule has no fixed scale and so must be calibrated Scale graticule has a fixed length and acts as a ruler
29
When must a eyepiece graticule be calibrated?
For every new magnification For every new microscope (will differ due to lenses)
30
What are the rules for drawing from microscope observation?
``` Clear and unbroken lines Large and clear No shading Correct proportion Pencil only ```
31
What is cell fractionation?
The process of separating cell components
32
Why might cell fractionation be used?
To determine the function of an organelle To obtain a pure sample of an organelle
33
What must the solution used in cell fractionation be? +why
Cold= prevent gutter enzyme activity that might digest organelles Isotonic (sane water potential)= prevent osmotic lysis Buffered = prevent PH change so proteins don’t denature
34
What are the two main steps in cell fractionation?
Homogenisation (releasing organelles from cells) Ultracentrifugation = separating organelles
35
What occurs during homogenisation?
Tissue is broken into cells, cells broken into organelles by homogeniser. Homogenate is filtered to form filtrate
36
What is a homogenate?
A solution of organelles produced after a homogeniser breaks down a tissue
37
Why is the homogenate filtered?
To remove debris (unbroken tissue)
38
Why occurs during ultracentrifugation?
The filtrate I’d spin in a centrifuge at high speeds Creates a centrifugal force that drives the largest organelle to form pellets at the bottom of the test tube.
39
What is a centrifugal force?
An increase in gravitational field
40
What is the supernatant?
The liquid fraction after cebtrifugation
41
Order these by increasing size. ``` Nuclei Mitochondrion Chloroplast Ribosomes Lysosome ```
``` Nuclei Chloroplast Mitochondrion Lysosomes Ribosomes ```
42
What does ultrastructure mean?
The adapted internal structure of a cell
43
Define eukaryotic cell
A cell with a nucleus and membrane bound organelles
44
What is the function of the nucleus ?
Store genetic information Produce ribosomal RNA and ribosomes Control mRNA and tRNA production Control cell activities
45
What are the main components that make up the nucleus?
Nuclear envelope Nuclear pores Nucleolus Nuclearplasm Chromosomes
46
Describe the nuclear envelope and its function
Double envelope, outer is continuos with the RER Contains nuclear pores Controls entry and exit of materials Reactions occur within
47
Describe nuclear pores and its function
Pores roughly 40-100 nm in diameter Allow diffusion of large molecules in and out of nucleus
48
Describe the nucleoplasm and its function
Granular and jelly like Makes bulk of nucleus
49
Describe the nucleolus and its function
Small spherical Makes ribosomal RNA Assembles ribosomes
50
Describe the chromosomes found in the nucleus
Protein bound linear DNA diffuse form so not visible
51
What is the function of mitochondria?
Produce ATP during aerobic respiration for energy release needed for metabolic reactions
52
What are mitochondria made of ?
Double membrane Cristae Matrix
53
What is cristae and it’s functions?
Extensions of the inner membrane from mitochondrion Provide large SA for attachment of enzymes and proteins invoked in aerobic respiration
54
Describe the matrix of mitochondrion and its function
Semi-rigid material Contains proteins lipids DNA and ribosomes for synthesis of own proteins (for respiration)
55
How can you tell a cell has a high metabolic rate from its mitochondria?
Lots of large mitochondria with extensive cristae
56
What is the function of chloroplast?
Absorb light and carry out photosynthesis
57
What are the components of chloroplast?
Chloroplast envelope Grana Thylakoids Integranal lamella Stroma
58
Describe the chloroplast envelope and its function
Double membrane Highly selective entrance and exit of molecules
59
Describe stroma and its function
Fluid filled matrix Contains starch, DNA and ribosomes (synthesis of proteins for photosynthesis) Synthesis of sugars
60
Describe grana and its function
Make of stack of thylakoids with intergranal lamella Chlorophyll within thylakoids absorb light Large SA for attachment of chlorophyll, enzymes and electron carriers (light absorption)
61
Describe endoplasmic reticulum and its function
Network of tubules and flattened sacs continuous with outer nuclear membrane. Spaces within cisternae for transportation of materials Lamella = double membrane
62
What is the difference between SER and RER?
Rough = ribosomes Smooth= more tubular appearance
63
What is the function of RER ?
Protein and glycoproteins synthesis (large SA) transportation of materials (specifically proteins. Process polypeptides synthesised by ribosomes
64
What is the function of SER?
Synthesis, storage and transport of lipids and carbohydrates
65
What are the functions of the Golgi apparatus?
Synthesis glycoproteins Produce secretory enzymes (vesicles and lysosomes) Secrete carbs Transport, modify and store lipids (Label using non-protein components)
66
What analogy can be used for the Golgi apparatus?
A post office Sorting , labelling and delivering materials
67
What is the structure of the Golgi apparatus?
A stack of flattened sacks called cisternae More compact than SER cisternae are membrane bound Vesicles pinches off from ends
68
Describe lysosomes
Vesicles from Golgi apparatus containing digestive enzymes (protease, lipase and lysozymes) Separates potentially dangerous enzymes from rest of cell via membrane
69
Describe lysosome function
Hydrolysed (digest and recycle) old organelles, cell when dead and pathogens engulfed by phagocytic cells.
70
What does exocytosis mean?
The transport of materials to outer cell environment.
71
Describe the stages in the digestion of a bacterium engulfed by a phagocyte
1) lysosome pinches off end of Golgi apparatus (contains protease, lipase and lysozymes) 2) phagocytic cell that has engulfed pathogen fuses with lysosome 3) enzymes hydrolyse pathogenic material 4) soluble product diffuse into cytoplasm 5) insoluble products are egested when membrane of lysosome fuses with membrane of cell
72
Describe ribosomes and their function
A large and small subunit made of ribosomal DNA and protein Polypeptide synthesis from mRNA and amino acids
73
Do ribosomes have a membrane?
No, found in prokaryotes
74
What type of ribosomes are there ?
80S 70S
75
Describe the cell wall and its function (eukaryotes)
Made of cellulose and glycoproteins (plants) or chitin, glycan and glycoproteins (fungi) Mechanical strength, prevent osmotic lysis
76
What is chitin?
A polysaccharide that contains nitrogen
77
Describe the vacuole
``` Fluid filled sac Single membrane (tonoplast) ``` Fluid contains amino acids, mineral salts, sugars waste and pigments
78
Describe the function of the vacuole
Make cell turgid to support herbacious parts of plant Sugars and amino acids act a food store Pigments attract pollinators
79
How does specialisation make an organism more efficient?
Cells evolve to perform particular function Perform function effectively as have adapted Organism works more efficiently because one cell can’t carry out all functions at optimal levels (However, become dependent as they lose ability to carry out other functions)
80
How do cells become specialised?
All cells have same genes Genes are turned on or off (expresses or not) Determines proteins produced and so function
81
Define a cell
A membrane bound structure that contains biomolecules
82
Define a tissue
A group of similar specialised cells that work together to perform a specific function
83
Why are cells aggregated?
For optimal efficiency Cells can transfer molecules easily
84
Give examples of a tissue
Xylem Phloem Capillaries Epithelial tissue
85
Define organ
A combination of different tissues working together to perform a specific function
86
Give an example of an organ
Stomach (epithelial, muscle , connective) Leaf (epidermis ,phloem , xylem, palisade, mesophyll)
87
Why are capillaries not classed as an organ when arteries and veins are?
Capillaries are only made of epithelial cells so are a tissue Arteries and veins are made of various different tissues (muscle, elastic fibre , epithelial)
88
Are arteries and veins a tissue or organ? | Why?
Organs Arteries and veins are made of various different tissues (muscle, elastic fibre , epithelial)
89
Define organ system
Multiple organs working together as a single unit to perform a specific function
90
Give an example of an organ system and its function
Digestive system (digest and process food) Respitory (breathing and Gad exchange ) Nervous (communication)
91
Define a prokaryotic cell
Small, simple No nucleus or membrane bound organelles
92
What does unicellular mean ?
Only one cell
93
What are the main components found in a prokaryotic cell?
``` Pilli Flagellum Plasmids Ribosomes Cell membrane Cell wall Slime capsule Circular DNA (nucleoid) Cytoplasm ```
94
What do prokaryotic cells use to transfer genetic info to other prokaryotic cells?
Pilli
95
Define the flagellum of prokaryotic cells and its function
Tail like protrusion Allows for directed movement (locomotion)
96
Define the slime of prokaryotic cells and its function
Mucilaginous slime outer layer May contain waste and toxins Allows for cells to stick together Escape phagocytosis Prevents drying out
97
Define the cell wall of prokaryotic cells and its function
Strengthened by murein (glycoprotein) Prevents cell bursting Gives mechanical strength
98
Define plasmids and their function
Circular ring of DNA contains additional genes such as antibiotic resistance Can be passed into other cells (vectors) Can reproduce themselves
99
What is the anther name for circular DNA in prokaryotes?
Nucleoid
100
Define the nucleoid of prokaryotic cells and its function
Circular DNA of a prokaryotic cells Non-linear, not associated with proteins or introns Carries genes for replication of cell and protein synthesis
101
Where might you find bacteria chlorophyll?
Cell membrane
102
What we the food reserve granules in prokaryotic cells?
Granules of glycogen or lipid droplets
103
What does acelluar mean?
No cells
104
What are the basic components of a virus ?
Capsid RNA /DNA enzymes
105
Define the attachment proteins of viruses and its function
Proteins found on the outer most surface of viruses (lipid envelope or capsid) Allow virus to identify host cells
106
Define the lipid envelope of viruses and its function
Not always present Helps avoid immune system
107
Define the matrix of viruses and its function
Layer of proteins immediately under lipid envelope Structural role
108
Define the capsid of viruses and its function
Protein capsule Made of capsomeres Encloses genetic info and enzymes
109
What is the genetic info in viruses stored as?
RNA or DNA Not both
110
What is the name of the enzyme found in viruses’ capsid and what does it do?
Reverse transcriptase Catalyse DNA syntheses from RNA
111
What cell structure is found in both mitochondria and prokaryotes?
70s ribosomes
112
How do you find the mean diameter of stomata using a optical. Microscope?
Calibrate eyepiece graticle Measure diameter of multiple stomata Calculate mean

biology (28 decks)

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