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biology > Cell Structure > Flashcards

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
Q

What are the main advantages and disadvantages of using a SEM over a light microscope?

A

Ad = higher resolution

Dis = specimen must be dead

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26
Q

Place in order of increasing resolution

TEM
light microscope
SEM

A

Light
SEM
TEM

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27
Q

When using a SEM what do the dark and light areas indicate?

A

Dark = depressions

Light = extensions

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28
Q

What is the difference between an eyepiece and scale graticule ?

A

Eyepiece graticule has no fixed scale and so must be calibrated

Scale graticule has a fixed length and acts as a ruler

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29
Q

When must a eyepiece graticule be calibrated?

A

For every new magnification

For every new microscope (will differ due to lenses)

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30
Q

What are the rules for drawing from microscope observation?

A 
Clear and unbroken lines 
Large and clear
No shading 
Correct proportion 
Pencil only
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31
Q

What is cell fractionation?

A

The process of separating cell components

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32
Q

Why might cell fractionation be used?

A

To determine the function of an organelle

To obtain a pure sample of an organelle

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33
Q

What must the solution used in cell fractionation be?

+why

A

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

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34
Q

What are the two main steps in cell fractionation?

A

Homogenisation (releasing organelles from cells)

Ultracentrifugation = separating organelles

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35
Q

What occurs during homogenisation?

A

Tissue is broken into cells, cells broken into organelles by homogeniser.

Homogenate is filtered to form filtrate

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36
Q

What is a homogenate?

A

A solution of organelles produced after a homogeniser breaks down a tissue

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37
Q

Why is the homogenate filtered?

A

To remove debris (unbroken tissue)

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38
Q

Why occurs during ultracentrifugation?

A

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.

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39
Q

What is a centrifugal force?

A

An increase in gravitational field

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40
Q

What is the supernatant?

A

The liquid fraction after cebtrifugation

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41
Q

Order these by increasing size.

Nuclei
Mitochondrion
Chloroplast 
Ribosomes 
Lysosome
A 
Nuclei 
Chloroplast
Mitochondrion 
Lysosomes 
Ribosomes
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42
Q

What does ultrastructure mean?

A

The adapted internal structure of a cell

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43
Q

Define eukaryotic cell

A

A cell with a nucleus and membrane bound organelles

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44
Q

What is the function of the nucleus ?

A

Store genetic information

Produce ribosomal RNA and ribosomes

Control mRNA and tRNA production

Control cell activities

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45
Q

What are the main components that make up the nucleus?

A

Nuclear envelope

Nuclear pores

Nucleolus

Nuclearplasm

Chromosomes

46
Q

Describe the nuclear envelope and its function

A

Double envelope, outer is continuos with the RER

Contains nuclear pores

Controls entry and exit of materials

Reactions occur within

47
Q

Describe nuclear pores and its function

A

Pores roughly 40-100 nm in diameter

Allow diffusion of large molecules in and out of nucleus

48
Q

Describe the nucleoplasm and its function

A

Granular and jelly like

Makes bulk of nucleus

49
Q

Describe the nucleolus and its function

A

Small spherical

Makes ribosomal RNA

Assembles ribosomes

50
Q

Describe the chromosomes found in the nucleus

A

Protein bound linear DNA

diffuse form so not visible

51
Q

What is the function of mitochondria?

A

Produce ATP during aerobic respiration for energy release needed for metabolic reactions

52
Q

What are mitochondria made of ?

A

Double membrane

Cristae

Matrix

53
Q

What is cristae and it’s functions?

A

Extensions of the inner membrane from mitochondrion

Provide large SA for attachment of enzymes and proteins invoked in aerobic respiration

54
Q

Describe the matrix of mitochondrion and its function

A

Semi-rigid material

Contains proteins lipids DNA and ribosomes for synthesis of own proteins (for respiration)

55
Q

How can you tell a cell has a high metabolic rate from its mitochondria?

A

Lots of large mitochondria with extensive cristae

56
Q

What is the function of chloroplast?

A

Absorb light and carry out photosynthesis

57
Q

What are the components of chloroplast?

A

Chloroplast envelope

Grana

Thylakoids

Integranal lamella

Stroma

58
Q

Describe the chloroplast envelope and its function

A

Double membrane

Highly selective entrance and exit of molecules

59
Q

Describe stroma and its function

A

Fluid filled matrix

Contains starch, DNA and ribosomes (synthesis of proteins for photosynthesis)

Synthesis of sugars

60
Q

Describe grana and its function

A

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
Q

Describe endoplasmic reticulum and its function

A

Network of tubules and flattened sacs continuous with outer nuclear membrane.

Spaces within cisternae for transportation of materials

Lamella = double membrane

62
Q

What is the difference between SER and RER?

A

Rough = ribosomes

Smooth= more tubular appearance

63
Q

What is the function of RER ?

A

Protein and glycoproteins synthesis (large SA)

transportation of materials (specifically proteins.

Process polypeptides synthesised by ribosomes

64
Q

What is the function of SER?

A

Synthesis, storage and transport of lipids and carbohydrates

65
Q

What are the functions of the Golgi apparatus?

A

Synthesis glycoproteins

Produce secretory enzymes (vesicles and lysosomes)

Secrete carbs

Transport, modify and store lipids
(Label using non-protein components)

66
Q

What analogy can be used for the Golgi apparatus?

A

A post office

Sorting , labelling and delivering materials

67
Q

What is the structure of the Golgi apparatus?

A

A stack of flattened sacks called cisternae

More compact than SER

cisternae are membrane bound

Vesicles pinches off from ends

68
Q

Describe lysosomes

A

Vesicles from Golgi apparatus containing digestive enzymes (protease, lipase and lysozymes)

Separates potentially dangerous enzymes from rest of cell via membrane

69
Q

Describe lysosome function

A

Hydrolysed (digest and recycle) old organelles, cell when dead and pathogens engulfed by phagocytic cells.

70
Q

What does exocytosis mean?

A

The transport of materials to outer cell environment.

71
Q

Describe the stages in the digestion of a bacterium engulfed by a phagocyte

A

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
Q

Describe ribosomes and their function

A

A large and small subunit made of ribosomal DNA and protein

Polypeptide synthesis from mRNA and amino acids

73
Q

Do ribosomes have a membrane?

A

No, found in prokaryotes

74
Q

What type of ribosomes are there ?

A

80S

70S

75
Q

Describe the cell wall and its function (eukaryotes)

A

Made of cellulose and glycoproteins (plants) or chitin, glycan and glycoproteins (fungi)

Mechanical strength, prevent osmotic lysis

76
Q

What is chitin?

A

A polysaccharide that contains nitrogen

77
Q

Describe the vacuole

A 
Fluid filled sac
Single membrane (tonoplast)

Fluid contains amino acids, mineral salts, sugars waste and pigments

78
Q

Describe the function of the vacuole

A

Make cell turgid to support herbacious parts of plant

Sugars and amino acids act a food store

Pigments attract pollinators

79
Q

How does specialisation make an organism more efficient?

A

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
Q

How do cells become specialised?

A

All cells have same genes

Genes are turned on or off (expresses or not)

Determines proteins produced and so function

81
Q

Define a cell

A

A membrane bound structure that contains biomolecules

82
Q

Define a tissue

A

A group of similar specialised cells that work together to perform a specific function

83
Q

Why are cells aggregated?

A

For optimal efficiency

Cells can transfer molecules easily

84
Q

Give examples of a tissue

A

Xylem
Phloem
Capillaries
Epithelial tissue

85
Q

Define organ

A

A combination of different tissues working together to perform a specific function

86
Q

Give an example of an organ

A

Stomach (epithelial, muscle , connective)

Leaf (epidermis ,phloem , xylem, palisade, mesophyll)

87
Q

Why are capillaries not classed as an organ when arteries and veins are?

A

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
Q

Are arteries and veins a tissue or organ?

Why?

A

Organs

Arteries and veins are made of various different tissues (muscle, elastic fibre , epithelial)

89
Q

Define organ system

A

Multiple organs working together as a single unit to perform a specific function

90
Q

Give an example of an organ system and its function

A

Digestive system (digest and process food)

Respitory (breathing and Gad exchange )

Nervous (communication)

91
Q

Define a prokaryotic cell

A

Small, simple

No nucleus or membrane bound organelles

92
Q

What does unicellular mean ?

A

Only one cell

93
Q

What are the main components found in a prokaryotic cell?

A 
Pilli
Flagellum 
Plasmids 
Ribosomes 
Cell membrane 
Cell wall
Slime capsule 
Circular DNA (nucleoid)
Cytoplasm
94
Q

What do prokaryotic cells use to transfer genetic info to other prokaryotic cells?

A

Pilli

95
Q

Define the flagellum of prokaryotic cells and its function

A

Tail like protrusion

Allows for directed movement (locomotion)

96
Q

Define the slime of prokaryotic cells and its function

A

Mucilaginous slime outer layer
May contain waste and toxins

Allows for cells to stick together
Escape phagocytosis
Prevents drying out

97
Q

Define the cell wall of prokaryotic cells and its function

A

Strengthened by murein (glycoprotein)

Prevents cell bursting

Gives mechanical strength

98
Q

Define plasmids and their function

A

Circular ring of DNA

contains additional genes such as antibiotic resistance

Can be passed into other cells (vectors)

Can reproduce themselves

99
Q

What is the anther name for circular DNA in prokaryotes?

A

Nucleoid

100
Q

Define the nucleoid of prokaryotic cells and its function

A

Circular DNA of a prokaryotic cells

Non-linear, not associated with proteins or introns

Carries genes for replication of cell and protein synthesis

101
Q

Where might you find bacteria chlorophyll?

A

Cell membrane

102
Q

What we the food reserve granules in prokaryotic cells?

A

Granules of glycogen or lipid droplets

103
Q

What does acelluar mean?

A

No cells

104
Q

What are the basic components of a virus ?

A

Capsid

RNA /DNA

enzymes

105
Q

Define the attachment proteins of viruses and its function

A

Proteins found on the outer most surface of viruses (lipid envelope or capsid)

Allow virus to identify host cells

106
Q

Define the lipid envelope of viruses and its function

A

Not always present

Helps avoid immune system

107
Q

Define the matrix of viruses and its function

A

Layer of proteins immediately under lipid envelope

Structural role

108
Q

Define the capsid of viruses and its function

A

Protein capsule

Made of capsomeres

Encloses genetic info and enzymes

109
Q

What is the genetic info in viruses stored as?

A

RNA or DNA

Not both

110
Q

What is the name of the enzyme found in viruses’ capsid and what does it do?

A

Reverse transcriptase

Catalyse DNA syntheses from RNA

111
Q

What cell structure is found in both mitochondria and prokaryotes?

A

70s ribosomes

112
Q

How do you find the mean diameter of stomata using a optical. Microscope?

A

Calibrate eyepiece graticle
Measure diameter of multiple stomata
Calculate mean

biology (28 decks)

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