Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > 2.1.1 - Cell structure > Flashcards

2.1.1 - Cell structure Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a microscope ?

A

A microscope is an instrument which enables you to magnify an object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When was the first microscope discovered ?

A

The first microscopes developed were light microscope in the 16th and 17th century

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the cell theory ?

A
  • Both plant and animal tissue is composed of cells
  • Cells are the basic unit of all life
  • Cells only develop from existing cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does a light microscope work ?

A

A light microscope uses visible light and lenses to generate magnified images of small objects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two lenses in a light microscope ?

A

Objective lens and the eyepiece lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do the two lenses in a light microscope allow ?

A

They allow for higher magnification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the sample preparation for a light microscope

A
  • Samples are stained with coloured stains that bind to certain chemicals of cell structures
  • Samples may also be sectioned and embedded in wax ; this helps with preserving structure whilst cutting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the four main ways to prepare samples ?

A
  • Dry mount
  • Wet mount
  • Squash slide
  • Smear slide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a dry mount ?

A
  • Specimen is cut into very thin slices with a sharp blade

- Specimen is then placed on a slide with a cover slip on top

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a wet mount ?

A
  • Specimens are suspended in a liquid
  • A cover slip is placed at an angle
  • It allows for aquatic samples to be viewed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are squash slides ?

A

A wet mount is prepared, then a lens tissue is used to gently press down the cover slip

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are smear slides ?

A

The edge of a slide is used to smear the sample, creating a thin, even coating on another slide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is differential staining ?

A

It can distinguish between two types of organisms that would otherwise be hard to identify

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the two types of differential staining?

A
  • Gram stain technique

- Acid fast technique

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Gram stain technique ?

A
  • It is used to separate gram positive and gram negative bacteria.
  • Crystal violet is applied to a bacterial specimen and then iodine, to fix the dye. The slide is then washed with alcohol.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What would the results be for the gram stain technique ?

A
  • Gram positive bacteria will appear blue/purple, they are susceptible to penicillin
  • Gram negative bacteria will lose the stain because they have thinner cell walls, they are not susceptible to penicillin. They are then stained with safranin dye, which will make them appear red.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is Acid fast technique ?

A
  • This technique is used to identify Mycobacterium, which have cell walls with a higher lipid content, this prevents dyes from readily binding to cells.
  • A lipid solvent is used as a primary stain to carry Carbolfuchin dye into the cells.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What would the results be for the acid fast technique ?

A
  • Acid fast bacteria retain Carbolfuchin and appear pink

- Non Acid fast bacteria lose Carbolfuchin but retain methylene blue so they appear blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is magnification ?

A

Magnification is how many times larger the image is seen compared to the actual size of the object being viewed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How do you calculate magnification ?

A
  • Magnification = Image size ÷ actual size
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is Resolution ?

A
  • Resolution is the ability to see individual objects as separate entities
  • The higher the resolution the more details are visible
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is electron microscopy ?

A

In electron microscopy, a beam of electrons with a wavelength of less than 1 nm is used to illuminate the specimen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the advantages of electron microscopy ?

A
  • It allows for more detail of the cells ultrastructure to be seen
  • It can allow magnifications of up to x 500,000 and still have clear resolution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the disadvantages of electron microscopy ?

A
  • Very expensive
  • Can only be used in a carefully controlled environment
  • Specimens can become damaged by the electron beam
  • The preparation process is very complicated and can lead to artefacts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is an Artefact ?

A
  • Artefacts are structures that are produced due to the preparation process
  • Such as a bubble trapped under the cover slip
  • They appear in both light and electron microscopes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is Transmission Electron Microscopy ?

A
  • A beam of electrons is transmitted through a specimen and focused to produce an image
  • It has the best resolution and a resolving power of 0.5 nm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is Scanning Electron Microscopy ?

A
  • A beam of electrons is sent across the surface of a specimen and the reflected electrons are collected to create an image
  • It has a resolving power from 3-10 nm, so resolution isnt as good
  • Produces 3D images of surfaces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is fluorescent microscopy ?

A

In fluorescent microscopy, a higher light intensity is used to illuminate a specimen that has been treated with a fluorescent chemical

29
Q

What is fluorescence ?

A
  • It is the absorption and radiation of light

- Light of a lower wavelength and lower energy is emitted and used to produce a magnified image

30
Q

What is Laser Scanning Confocal Microscopy ?

A
  • A laser scanning confocal microscope moves a single spot of focused light across a specimen. This causes fluorescence from the components labelled with the fluorescent dye. The emitted light from the specimen is then fitted through a pinhole aperture.
  • Only light radiated from very close to the focal plane is detected
  • Unwanted radiation does not pass through the pinhole and is not detected
31
Q

Key points regarding LSCM

A
  • A laser is used instead of light
  • Very high resolutions can be obtained
  • A 2D image is produced, 3D images can be produced by creating images at different focal planes
  • The beamsplitter is a dichroic mirror, which only reflects the wavelength from the laser but allows wavelengths from the sample to pass through
  • The positions of the two pinholes mean the light waves from the laser follow the same path as the light was radiated from the sample when it fluoresces. They both have the same focal plane, confocal.
32
Q

What are the key uses of LSCM ?

A
  • Used in the diagnosis of the eye
  • Being developed for use in endoscopic procedures
  • Used in the development of new drugs
33
Q

Max resolutions

A
  • Light microscope - 0.2 μm
  • TEM - 0.0005 μm
  • SEM - 0.003 - 0.01 μm
34
Q

Max magnifications

A
  • Light microscope - x1500
  • TEM - more than x1,000,000
  • SEM - less than x1,000,000 but stunning 3-D images
35
Q

Name the two main types of organisms

A

Prokaryotes and eukaryotes

36
Q

What are prokaryotes ?

A
  • Single celled organisms with a simple structure of just a single internal area called the cytoplasm, composed of cytosol.
  • Bacteria
37
Q

What are eukaryotes ?

A
  • Make up multicellular organisms e.g. animals and plants
  • Have much more complicated internal structure, containing a membrane bound nucleus (nucleoplasm) and cytoplasm, which contains many membrane bound cellular components
  • Animal and plant cells
38
Q

What are bigger, prokaryotes or eukaryotes ?

A

Eukaryotes

39
Q

Define organelles

A

Membrane bound compartments within the cell, each providing distinct environments and therefore conditions for different cellular reactions

40
Q

What is the function of the cell-surface membrane ?

A
  • It is a thin selectively permeable protein and phospholipid bilayer that controls the movement of materials in and out of the cell
  • It has receptor molecules to allow it to respond to chemicals
41
Q

What is the function of the nucleus ?

A
  • It directs the synthesis of all proteins required by the cell and controls the metabolic activities of the cell
  • DNA molecules control the cell’s activities; they associate with histone molecules to form chromatin. Chromatin coils tightly to form chromosomes.
  • The nuclear envelope protects it from damage
  • The nuclear pores allow substances such as RNA to move between the nucleus and cytoplasm.
42
Q

What is the function of the nucleolus ?

A
  • The nucleolus is an area within the nucleus that is responsible for producing ribosomes
  • It is composed of proteins and RNA
  • RNA is used to produce ribosomal RNA which is then combined with proteins to form the ribosomes necessary for protein synthesis
43
Q

What is the function of mitochondria ?

A
  • Mitochondria are the site of the final stages of cellular respiration, which is when energy is made available for the cell to use by the production of ATP
  • It has a double membrane; The inner membrane is highly folded to form cristae. The fluid inside the cristae is called the matrix.
  • They contain mitochondrial DNA, produce their own enzymes and can reproduce themselves.
44
Q

What is the function of vesicles ?

A
  • Vesicles are small fluid filled sacs in the cytoplasm surrounded by a membrane
  • Their role is to transport substances in and out of the cell and between organelles
45
Q

What is the difference between a secretory vesicle and a transport vesicle ?

A
  • A transport vesicle transports things inside the cells

- A secretory vesicle transports things outside of the cell

46
Q

What is the function of a lysosome ?

A
  • Lysosome are specialised forms of vesicles that carry around hydrolytic enzymes which are used for digestion
  • These enzymes enable the lysosome to digest invading cells or break down worn out components of the cell.
  • They also play a role in programmed cell death which is known as apoptosis
47
Q

What is apoptosis ?

A

Programmed cell death

48
Q

What is the cytoskeleton ?

A
  • The cytoskeleton is a network of fibres necessary for the shape and stability of a cell
  • Organelles are held in place by the cytoskeleton and it controls cell movement of organelles within the cell
49
Q

What are the three components of the cytoskeleton ?

A
  • Microfilaments - contractile fibres formed from the protein actin.
  • Microtubules - globular tubulin proteins polymerised to form tubes that act as a scaffold structure determining the shape of a cell. Also act as tracks for the movements of organelles.
  • Intermediate fibre - fibres that give mechanical strength to cells and help maintain their integrity.
50
Q

What is the function of the microtubules and microfilaments ?

A
  • Support the cell’s organelles keeping them in position, strengthen the cell and help maintain its shape
  • They’re responsible for the transport of organelles and materials within the cell.
51
Q

What is the function of centrioles ?

A
  • Component of the cytoskeleton present in most eukaryotic cells.
  • Small hollow cylinders containing microtubules.
  • Two associated centrioles form the centrosome, which is involved in the assembly and organisation of the spindle fibres, and therefore the splitting chromosomes during cell division.
52
Q

What is the function of cilia ?

A
  • Small hair-like structures found on the surface membrane of some animal cells.
  • Microtubules allow the cilia to move which is used to move substances along the cell surface e.g. In the trachea to sweep dust and dirt out of the lungs.
  • Cross section appears like a wheel with an outer membrane and nine pairs of microtubules arranged in a ring around two pairs in the centre
53
Q

What is the function of the flagella ?

A
  • Long hair-like structures that stick out from the cell surface and are surrounded by the plasma membrane.
  • Used primarily to enable cell motility
  • In some cells, they are used as a sensory organelle detecting the chemical changes in the cells environment
  • Microtubules contract to make flagellum move, this is used to propel cells forward e.g. the tail of a sperm cell, this requires energy
54
Q

What is the function of a ribosome ?

A
  • It is a small organelle that either floats free in the cytoplasm or is attached to the RER
  • It is where proteins are made during protein synthesis.
55
Q

What is the function of the smooth endoplasmic reticulum ?

A
  • A system of membranes enclosing a fluid filled space

- It is used for synthesising and processing lipids and for storage

56
Q

What is the function of the rough endoplasmic reticulum ?

A
  • A system of membranes enclosing a fluid filled space with its surface covered with ribosomes
  • It is responsible for the synthesis and transport of proteins
57
Q

What is the function of the Golgi apparatus ?

A
  • The golgi body is a group of flat fluid filled sacs, sometimes seen with vesicles at the edge
  • It has a compact structure formed of cisternae and does not contain ribosomes
  • It processes and packages new lipids and proteins, it also makes lysosomes
58
Q

Where are proteins made ?

A

Mainly at the ribosomes attached to the RER. These proteins are stored in the RER until they can be processed and packaged at the golgi apparatus. Some ribosomes are free in the cytoplasm and the proteins they produce also stay in the cytoplasm.

59
Q

Making and secreting a protein (six marker)

A
  • Transcription comes first. DNA is unzipped and mRNA copies the DNA strand. It copies it using complementary base pairing and is then transported out of the nucleus via the nuclear pores and to the ribosome.
  • Ribosomes in the rough endoplasmic reticulum make proteins to be secreted this is called translation.
  • Proteins are transported from the rough endoplasmic reticulum to the Golgi apparatus. It is transported to the cis face which then takes it in
  • Golgi body then processes and modifies proteins, it could also add glucose molecules. They then move to the trans face where they are released.
  • The secretory vesicles containing the proteins are then released and move towards the plasma membrane. They leave via the trans face.
  • Vesicles fuse with the plasma membrane, possible because they both have phospholipids and then the vesicle undergoes exocytosis, exocytosis is the process of the vesicle leaving the cell through the cell membrane
60
Q

What is the cellulose cell wall ?

A

A tough yet elastic wall of cellulose that surrounds and supports the cell wall

61
Q

What is the function of the cellulose cell wall ?

A
  • The contents of the cell wall press against the cell wall, making it rigid
  • It is freely permeable
  • Defence mechanism against invading pathogens
62
Q

What is the vacuole ?

A

It is a membrane lined sac in plant cells containing cell sap

63
Q

What is the function of the vacuole ?

A
  • Large permanent vacuoles are used to maintain turgor

- If vacuoles appear in animal cells they are small and transient

64
Q

What is the tonoplast ?

A
  • The membrane of the vacuole is called the tonoplast

- It is selectively permeable

65
Q

What are chloroplasts ?

A
  • Chloroplasts are found in plant cells, in the stems and leaves and not in the roots
  • They contain DNA and ribosomes, so they are able to make their own proteins
66
Q

What is the function of the chloroplast ?

A

The chloroplasts are the organelles responsible for photosynthesis in plant cells

67
Q

What is the structure of the chloroplast like ?

A
  • They have a double membrane structure
  • The fluid enclosed in the chloroplasts is called the stroma
  • They have an internal network of membranes which form flattened sacs called Thylakoids
  • Several thylakoids stacked together are called a granum
  • The grana are joined by membranes called lamellae
68
Q

What do the grana contain ?

A

The grana contain the chlorophyll pigments, where light dependent reactions occur for photosynthesis

Biology (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions