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Biology Module 2 Foundations In Biology > Chapter 2 Basic Components Of Living Systems > Flashcards

Chapter 2 Basic Components Of Living Systems Flashcards

1
Q

What are the different techniques for preparing samples?

A

There are four different techniques which can be used including: A dry mount, A wet mount, A squash slide and A smear slide

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2
Q

How do you prepare a dry mount?

A

The specimen being viewed is whole or sliced thinly, known as sectioning. The specimen is placed onto the slide with a cover slip placed over the top, no dye is used during this process. For example, hair, pollen, muscle or plant tissue can be viewed in this way.

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3
Q

How do you prepare a wet mount slide?

A

The specimen is suspended in a liquid like water or immersion oil. The cover slip is placed over the top at an angle to reduce air bubbles. For example, aquatic samples can be viewed this way.

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4
Q

How do you prepare a squash slide?

A

A wet mount is first prepared, then lens tissue is used to gently press down the cover slip. Potential damage to the cover slip can be avoided by squashing the sample between two microscope slides. This is a good technique for soft sample, like root tip samples for observing cell division.

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5
Q

How do you prepare a smear slide?

A

The edge of the slide is used to smear the sample, creating a thin even coating on another slide. A cover slip is then placed over the sample. For example, this can be used to view blood.

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6
Q

Why is staining used to view biological specimens?

A

Staining makes components in a cell more visible and improves contrast

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7
Q

What are the rules when doing a scientific drawing?

A

Ensuring to add a title, label magnification, using a sharp pencil on plain white paper, drawing smooth unbroken lines, no shading, proportions are correctly drawn, labelled lines drawn with a ruler without heads and should not cross another, only drawing what you can see and the drawing should be large.

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8
Q

What is magnification?

A

How many times larger the image is, compared to the actual size of the specimen

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9
Q

What is the resolution?

A

The ability to distinguish between two close together objects.

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10
Q

Why does an electron microscope have a greater resolution compared to light microscopes?

A

Electron microscopes use smaller wavelengths

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11
Q

What is the magnification equation?

A

Image size
—————
Actual size

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12
Q

How do you calculate the magnification of a sample using a scale bar?

A

Measure the actual length of the scale bar and then divide by the length that it actually represents.

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13
Q

How is an electron microscope used to view a specimen?

A

-Specimen is illuminated by a beam of electrons
-Beam is focused by electromagnetic lenses
-The specimen and beam are in a vacuum as air particles can interfere with the electrons
-The image is then viewed on a screen

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14
Q

What are the two types of electron microscope?

A

Transmission electron microscope (TEM)
Scanning electron microscope (SEM)

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15
Q

How does a transmission electron microscope work?

A

Electromagnets are used to focus a beam of electrons, which is then transmitted through the specimen. Denser parts of the specimen absorb more electrons and therefore appear darker on the final image. The image produced is 2D.

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16
Q

What are the advantages and disadvantages of using a transmission electron microscope?

A

Advantages include: A higher resolution image is produced, which means internal structures within cells are able be seen
Disadvantages: Only can be used with very thin specimens or thin sections of the object being observed.
They are unable to observe live specimens due to the vacuum as all oxygen and water must be removed
Risk of artefacts being introduced due to the lengthy process required in preparing samples.
They dont produce a colour image.

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17
Q

What is the resolving power and magnification on a transmission electron microscope?

A

Resolving power: 0.5nm
Magnification: x500,000

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18
Q

How does a scanning electron microscope work?

A

An electron beam is sent across the surface of the sample, this beam then reflected from the specimen and the electrons are detected forming an image.
This means 3D images can be produced.

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19
Q

What are the advantages and disadvantages of the scanning electron microscope?

A

Advantages: Can be used on thick or 3D specimens and allows the external, 3D structure of the specimen to be observed.
Disadvantages: Give a lower resolution than TEM
They cannot be used to observe live specimens and dont produce a colour image.

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20
Q

What is the resolution and magnification of the scanning electron microscope?

A

Resolving power: 3-10nm
Magnification: x100,000

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21
Q

What are the preparation methods for electron microscopes?

A

-Fixing: Using chemicals or freezing
-Dehydration: passed through alcohol baths
-Staining: with heavy metals
-Sectioned: Set in resin to allow cutting of thin sections

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22
Q

What are artefacts?

A

An Artefacts is an apparent structural detail that is caused by the processing of the specimen and is thus not an actual feature of the specimen. For example, in light microscopes this might be air bubbles under the cover slip or for an electron microscope this might be the distortion of organelles.

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23
Q

Explain why artefacts are more likely to be produced when preparing samples for electron microscopy than for light microscopy.

A

Artefacts are more likely to be produced when preparing samples in electron microscopy because there is a longer processing method when preparing samples, leading to more damage of specimens. This therefore increases the likelihood of artefacts.

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24
Q

What are the important factors of membranes?

A

They are selectively permeable, control what substances enter and leave and are fragile.

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25
Q

How is the nucleus structured?

A

At the centre, the nucleolus is contained which is made up of proteins and RNA. Surrounding the nucleus is the nucleoplasm which contains chromatin which coils and condenses to form chromosomes. Then everything within the nucleus is enclosed by a double membrane envelope which is marked with perforated nuclear pores.

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26
Q

What is the nucleolus made from?

A

Made from proteins and RNA

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27
Q

What is the function of the nucleus?

A

Site of DNA replication and transcription
Contains the genetic code for each cell (DNA)
Site of ribosome synthesis

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28
Q

What is the structure of the Nuclear envelope?

A

It’s a dense spherical structure made up of two membranes (the inner and the outer) with fluid separating them. The nuclear envelope is also marked with nuclear pores which allow for the exchange of molecules.

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29
Q

How is the Mitochondria structured?

A

The Mitochondria is bounded by a double membrane envelope which contains an outer and an inner layer. The inner membrane is folded (to create a large surface area) and forms the cristae. The Mitochondria also contains a fluid interior known as the Matrix where mitochondrial DNA can be found.

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30
Q

What is the function of the Mitochondria?

A

Site of aerobic respiration
The inner membrane of the Mitochondria is coated in enzymes which catalyse the reactions of aerobic respiration and produce ATP.
Contains mitochondrial DNA which enable it to code for and produce its own enzymes needed in respiration.
Can replicate itself without nucleus
Cristae forms a surface for reactions of respiration while the matrix is the site of respiration

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31
Q

What is the function of the Matrix?

A

Site of respiration in the Mitochondria

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32
Q

What is the function of Cristae?

A

Provide a surface for reactions of respiration.

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33
Q

How is the vesicle structured?

A

Fluid filled single membrane bound sacs

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34
Q

What is the function of the vesicle?

A

Storage and transport roles in cells

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35
Q

How is the Lysosome structured?

A

Contains specialised vesicles which contain hydrolytic enzymes.

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36
Q

What is the function of the Lysosome?

A

Breaks down cellular waste (like old organelles)
Has an important role in the immune system as it breaks down pathogens ingested by WBC.
Important role in cell death (apoptosis)

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37
Q

What does apoptosis mean?

A

Cell death

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38
Q

How is the cytoskeleton structured?

A

A network of fibres in the cytoplasm of all eukaryotic cells.
The cytoskeleton has three components:
-Microfilaments
-Microtubules
-Intermediate Fibres

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39
Q

What is the function of the Cytoskeleton?

A

Maintain the shape and stability of cells, while holding organelles in place. It also controls cell movement and organelle movement.

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40
Q

What are Microfilaments?

A

Contractile fibres formed from actin, they are involved in cell movement and cell contraction during cytokinesis.

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41
Q

What are Microtubules?

A

Globular tubulin proteins form tubes making a scaffold-like structure.
They act as tracks for organelle movement. Spindle fibres are Microtubules.

42
Q

What are Intermediate fibres?

A

Give mechanical strength to cells and help maintain integrity.

43
Q

How are Centrioles structured?

A

Made up of Microtubules which occur in pairs to form a centrosome

44
Q

In what cells are Centrioles present ?

A

They are present in most eukaryotes except flowering plants and fungi.

45
Q

What is the function of the Centriole?

A

Positioning flagella and cilia,
They are also involved in the production of spindle fibres which are essential in organising the position of chromosomes in cell division

46
Q

What is a Laser scanning confocal microscope?

A

Type of fluorescent microscope, where the image created uses a very high light intensity to illuminate the specimen which is stained with a fluorescent dye. An image is created as the microscope scans the specimen point-by-point using a focused laser beam to create a 2D image or a 3D image if different focal planes are used. As the light is emitted from the specimen it causes fluorescence.

47
Q

What are the advantages and disadvantages of using a Laser Scanning Confocal Microscope?

A

Advantages:
Can be used on thick or 3D specimens so external image can be viewed
High Resolution
Disadvantages:
Slow process, takes a long time to obtain an image
Laser can photo damage cells

48
Q

What are the uses of Laser Scanning Confocal Microscopes?

A

In development of new drugs- can take an image of the distribution of molecules in cells
Non invasive- used in diagnosis of eye diseases and endoscopic procedures
In the future with virtual biopsy’s
The fluorescent dyes allows the imaging of cell components like the cell cytoskeleton.

49
Q

What is the method of Laser Scanning Confocal microscopes?

A

1-A single spot of focussed laser light is moved across the specimen
2-This causes fluorescence from the dye to label components
3-The beam splitter is a dichroic mirror which reflects monochromatic laser light while letting other wavelengths from a sample pass through
4-Emitted light is filtered through a pinhole aperture
5-Only light from close to the focal plane is detected
6-The position of two pinholes means light from the laser follows the same path as light from the specimen- they both have the same focal plane.

50
Q

What are the organelles used in protein synthesis?

A

Protein synthesis involves the: Endoplasmic Reticulum, Ribosomes and Golgi Apparatus

51
Q

How is the Rough Endoplasmic Reticulum structured?

A

Contains a series of connected, flattened membrane bound sacs called cisternae, which are studded with ribosomes.

52
Q

What is the function of the Rough Endoplasmic Reticulum.

A

The synthesis and transportation of proteins

53
Q

How is the Smooth Endoplasmic Reticulum structured?

A

Series of connected, flattened membrane bound sacs called cisternae.

54
Q

What is the function of the Smooth Endoplasmic Reticulum?

A

Lipid and carbohydrate synthesis and storage

55
Q

How are ribosomes structured?

A

Small organelles which are not membrane bound.
They are free in the cytoplasm or bound to Rough Endoplasmic Reticulum
Composed of two subunits: proteins and rRNA

56
Q

What is the function of the ribosome?

A

Site of protein synthesis,
Acts as an assembly line for coded information from the nucleus which is used to make proteins from amino acids.

57
Q

How is the Golgi Apparatus structured?

A

A stack of membrane bound flattened sacs called cisternae
Membrane surrounds an area of fluid where the complex molecules are stored and changed.

58
Q

What is the function of the Golgi Apparatus?

A

Receives proteins from the Endoplasmic Reticulum and modifies them, packaging them into vesicles.
These may be secretory vesicles destined to leave the cell or lysosomes which stay in the cell.
May add sugar molecules to them
The packaged modified proteins in vesicles are then transported to the surface of the cell where they will fuse with the membrane and release its contents

59
Q

How are proteins synthesised?

A

Proteins are synthesised on ribosomes bound to Rough ER
They will then pass into cisternae of Rough ER and be packaged into transport vesicles
The Vesicles are then sent to the Golgi apparatus using the cytoskeleton
In the Golgi Apparatus the proteins are structurally modified and packaged into vesicles
Some proteins are carried by the secretory vesicles to the cell surface membrane, where it fuses and releases the protein by exocytosis, some proteins form lysosomes.

60
Q

How is the Cell Wall structured?

A

In plants, the cell wall is made from the polysaccharide cellulose.
However, in fungi the cell wall is made from chitin- a polysaccharide containing nitrogen

61
Q

What is the function of the Cell Wall?

A

Gives the cell shape and rigidity when the contents of the cell presses against it
Provides structural support and strength to the cell
Is a defence mechanism as it protects against pathogen
Freely Permeable to solvents and solutes

62
Q

How is the vacuole structured?

A

Large and permanent
Membrane bound sacs in the cytoplasm which are filled with cell sap
Contains a membrane known as the tonoplast.

63
Q

What is the function of the Vacuole?

A

The Tonoplast membrane is selectively permeable
Has a role in the maintenance of turgor of cells so that the contents of the cell push against the cell wall and maintain a rigid framework.
Supports individual cells and whole plant

64
Q

How are Chloroplasts structured?

A

Contains a double membrane bound structure
Filled with stroma (containing enzymes for photosynthesis)
Thylakoids (flattened sacs embedded with pigment) stack to form Grana
Grana is connected by membranes called Lamellae
Contains DNA and ribosome

65
Q

What is the function of the chloroplasts?

A

The Grana contains the chlorophyll pigment, where light dependent reactions occur during photosynthesis
Starch is stored in starch granules
Can self reproduce and synthesis proteins
The internal membrane provides a large surface area needed for the enzymes, proteins and pigment molecules necessary in the process of photosynthesis

66
Q

What are the similarities between Chloroplasts and Mitochondria?

A

Both mitochondria and chloroplasts contain inner and outer membranes, DNA and ribosomes.

67
Q

How do you calibrate a microscope?

A

1)Firstly, line up the stage micrometer and eyepiece graticule whilst looking through the eyepiece
2)Then, count how many divisions on the eyepiece graticule fit into one division on the micrometer slide.
3)Each division on the stage micrometer is 10 µm, so this can be used to calculate what one division is on the eyepiece graticule at that current magnification.

For example, if two eyepiece divisions fit into one division on the micrometer, then 10/2=5 µm
Therefore, each division on the eyepiece graticule is 5 µm at this magnification.

68
Q

What is differential staining?

A

A technique which involves many chemical stains being used to stain different parts of cell in different colours.

69
Q

What are commonly used stains?

A

Crystal violet and methylene blue
Nigrosin and Congo Red

70
Q

What charge does Crystal violet and Methylene blue?

A

They are positively charged and therefore they are attracted to and stain negatively charged materials

71
Q

What charge does Nigrosin and Congo Red have?

A

They are negatively charged and consequently cannot enter the cytosol as it repels them. This creates a stained background so the cell are more visible.

72
Q

What is the magnification of a Light Microscope?

A

x1500

73
Q

What is the resolution of a Light Microscope?

A

200nm

74
Q

What are Prokaryotes?

A

Single celled organisms without a nucleus and don’t have membrane bound organelles

75
Q

What are Eukaryotes?

A

Contain membranes around their many complex organelles, these often have a specific function (eg muscle fibres) and make up multicellular organisms

76
Q

What features in a prokaryotic cell are always present?

A

Cell Wall
Plasma Membrane
Cytoplasm
Ribosomes
Circular DNA

77
Q

What features of a prokaryotic cell are sometimes present?

A

Flagella
Pili
Plasmids
Capsule
Mesosomes
Infolding plasma membrane

78
Q

What are prokaryotic organisms classed into?

A

Two evolutionary domains which evolved from a common ancestor
Archea and Bacteria

79
Q

What are extremophiles?

A

Early prokaryotic cells which were adapted to live in hostile environments like
Extreme temperatures, pH or salinity

80
Q

How is the DNA of a prokaryotic cell structured?

A

Single strand of circular DNA which is packaged in a single supercoiled chromosome
Genes are grouped into operons (a number of genes which can be turned on or off)

81
Q

What is the cell wall in prokaryotic cells made from?

A

Peptidoglycan
A glycopeptide which is a complex polymer made up of sugars and amino acids

82
Q

How is the Flagella in Prokaryotic cells structured?

A

The flagella is thinner than the equivalent structure of eukaryotes and rotates to allow movement.
This power supplied to become mobile comes from chemiosmosis not ATP
Attached to the cell membrane by a basal body and rotated by a molecular motor

83
Q

How is DNA structured in a eukaryotic cell?

A

DNA is linear enclosed in a nucleus existing as multiple single supercoiled chromosomes packaged around a histone protein

84
Q

What is Gram Staining?

A

Another common use of differential staining which is used to identify a type of bacteria

85
Q

What is the process of Gram Staining?

A

Crystal violet is added, then iodine to fix the stain. Alcohols are then used to wash away any stain that’s hasn’t bound because otherwise the entire image will appear dark.
Gram-positive bacteria appear blue/purple as the stain is retained due to the really thick peptidoglycan cell wall absorbing the dye.
However Gram- negative bacteria cannot absorb Crystal violet as the peptidoglycan cell wall is thin, so the stain is not retained. Consequently, the counterstain Safranin is used to turn them red.

86
Q

Why is the process of Gram-staining important?

A

Being able to distinguish if an infection is caused by a gram-positive or negative bacteria helps medics prescribe appropriate antibiotics

87
Q

How is DNA structured in an eukaryotic cell?

A

In an eukaryotic cell, the DNA is tightly wrapped around proteins called histones to form chromatin. DNA is also linear which means the ends of the DNA molecules in a chromosome cant form a loop.

88
Q

What is the function of the nucleolus?

A

The nucleolus is responsible for making ribosomes from ribosomal RNA and proteins.

89
Q

How is Flagella structured in Eukaryotic cells?

A

Whip like structure

90
Q

What is the function of Flagella in eukaryotic cells?

A

Mobility or used as a sensory organelle for chemical stimuli

91
Q

How is cilia structured in eukaryotic cells?

A

Hair-like projections out of cells

92
Q

What is the function of cilia in eukaryotic cells?

A

Mobile cilia help to move substances in a sweeping motion.
Stationary cilia is important in sensory organs (eg nose)

93
Q

What is the size of a ribosome found in an eukaryotic cell?

A

80s (larger than prokaryotes- 25nm)

94
Q

What is the size of a ribosome found in prokaryotic cells?

A

70s (smaller ribosome found in prokaryotic cells, mitochondria and chloroplasts)

95
Q

What is meant by the term fluorescence?

A

An emission of light that has been absorbed

96
Q

Why are lasers used to provide illumination in Laser Confocal Microscopy?

A

They increase the intensity of light

97
Q

Explain the purpose of the pinhole aperture in Confocal Microscopy?

A

This means scattered light/ light from outside the focal plane is eliminated reducing blurring and increasing resolution.

98
Q

Why can’t Laser Confocal Microscopy be used for deep tissue imaging?

A

The idea of light penetration of the sample is limited.

99
Q

Which of the following is a feature of both light and confocal microscopy?
-Can be used to observe ribosomes
-Can be used with live tissue
-Obtain images using laser light
-Require a great deal of training to use

A

Can be used with live tissue

100
Q

Which of the following statements are true?
1- Microtubules are part of the 9+2 formation in bacterial flagella
2- Microtubules can be prevented from functioning from a respiratory inhibitor
3- Microtubules are involved in moving chromosomes from the equator to the poles of the cell during mitosis

A

Microtubules can be prevented from functioning from a respiratory inhibitor
Microtubules are involved in moving chromosomes from the equator to the poles of the cell during mitosis

Biology Module 2 Foundations In Biology (5 decks)

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