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Cells Flashcards

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1
Q

What is a light microscope?

A

They use a pair of convex glass lenses
Resolve images that are 0.2um apart
Wavelength of light and therefore restricts the resolution

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2
Q

What is magnification and the equation?

A

Magnification is the size of the image seen through a microscope
Magnification = size of image/size of real object

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3
Q

What is resolution?

A

It is the minimum distance apart two objects can be distinguished as separate objects In an image.
(The greater the resolution the more clear the image will be.)

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4
Q

What is an Electron Microscope?

A

Can look at objects that are closer together than 0.2um
Two types: TEM ans SEM
They use a bean of electrons that are focused by electromagnets in a vacuum environment.
Transmission Electron Microscope:
- beam of electrons passes through a thin section of a specimen, areas that absorb the electrons appear darker on the electron micrograph.
Scanning Electron Microscope:
- beam of electrons passes across the surface and scatter, pattern builds a 3D image.

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5
Q

What are the limitations of electron microscopes?

A
  • Must be in a vacuum = specimens must be dead
  • complex staining process may introduce artefacts
  • specimens must be very thin
  • SEM has a lower resolving power than TEM
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6
Q

What is Cell Fractionation?

A

The process in which different parts and organelles of a cell are separated so they can be studied in detail.
Most common a method of cell fractionation is differential centrifugation.

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7
Q

What is the process of homogenation?

A
  1. Cells are blended in a homogeniser = makes a fluid called homogenate. Homogenate is then placed in a centrifuge and spun at a low speed.
  2. The heaviest (most dense) organelles (nuclei) are forced to the bottom of the tube where a thin sediment or pellet forms.
  3. Fluid at top called supernatant is transferred to another tube and spun slightly faster. So the next pellet that forms contains the next heaviest (most dense) organelles (mitochondria/chloroplasts).
  4. Process repeats with the speed increase int each time to separate the diffent densities.
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8
Q

What are the conditions necessary for homogenation?

A
  • Cold, buffered solution of the same water potential as the cells.
  • This is to prevent the organelles form bursting under osmotic pressure, inactivate any enzymes from breaking down organelles and so that the pH does not fluctuate.
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9
Q

What is the structure of the Nucleus?

A

A double membrane called the envelope containing -3000 nuclear pores which enables molecules to enter and leave.
Also contains chromatin and a nucleolus which is the site of ribosome production.
A granular jelly like material called nucleoplasm makes up the bulk of three nucleus.

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10
Q

What is the structure of the Rough Endoplasmic Reticulum?

A

It is a series of flattened sacs enclosed by a membrane with ribosomes on the surface.
RER folds and processes proteins in the ribosomes.

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11
Q

What is the structure of the Smooth Endoplasmic Reticulum?

A

System of membrane bound sacs that produce and process lipids.

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12
Q

What is the structure of the Golgi Apparatus?

A

A series of fluid filled, flattened sacs and curved sacs with vesicles surrounding the edges.
It processes and packages proteins and lipids, producing lysosomes.

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13
Q

What is the structure of a Mitochondria?

A

They are oval shaped, bound by a double membrane called the envelope.
The inner membrane is folded to form projections called cristae with a matrix on the inside containing all the enzymes needed for respiration.

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14
Q

What is the structure of centrioles?

A

Hollow cylinders contains a ring of microtubules arranged at right angles to each other.
Involved in producing spindle fibres of cell division.

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15
Q

What is the structure of ribosomes?

A

Composed of two sub units and are the site of protein production.

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16
Q

What is the structure of lysosomes?

A

Vesicles containing digestive enzymes bound by a single membrane.

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17
Q

What do prokaryotic cells such as bacteria contain?

A

Cell wall - rigid outer covering made of peptidoglycan
Capsule - protective slimy layer that helps retain moisture and adhere to surfaces
Plasmid - circular piece of DNA
Flagellum - a tail like structure that rotates to propel the cell
Pili - hair like structures which attach to other bacterial cells
Ribosomes - site of protein production
Mesosomes - infoldings of the inner membrane which contain enzymes required for respiration

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18
Q

What are viruses?

A

Non-living structures which consist of nucleic acid enclosed in a protective protein coat called the capsid and sometimes covered with a lipid envelope.

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19
Q

What are cells organised into?

A

Tissues, tissues inti organs and organs into systems

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20
Q

What is mitosis?

A

Produces identical daughter cells for growth and asexual reproduction.
All cells produced by mitosis are genetically identical.

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21
Q

What are the three stages of the cell cycle?

A

Mitosis - cell division, there are three stages of mitosis = prophase, metaphase, anaphase and telophase
Interphase - grows and prepares to divide
Cytokinesis - parent and replicated organ necks move to opposite sides of the cell and the cytoplasm divides producing two daughter cells

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22
Q

What is interphase?

A

The cells DNA is unravelled and replicates to double its genetic content.
Organelles are also replicated and ATP content is increased.

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23
Q

What is the structure of chromosomes in mitosis?

A

Chromosomes are made of two strands joined in the middle by a centromere.
The separate strands are called chromatids.
Two strands of the same chromosome are called sister chromatids.

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24
Q

What is prophase?

A
  • chromosomes condense
  • spindle fibres form
  • nuclear membrane breaks down
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25
Q

What is metaphase?

A
  • spindle fibres attach to chromosomes
  • chromosomes line up along the equator of the cell
26
Q

What is anaphase?

A
  • centromeres divide
  • sister chromatids move to opposite poles
27
Q

What is telophase?

A
  • nuclear membranes reforms
  • chromosomes decondense
  • spindle fibres disappear
28
Q

What is cytokinesis?

A
  • cytoplasm divides
  • parent cell becomes 2 daughter cells with identical genetic information
29
Q

Calculating mitotic index?

A

Mitotic index = number of cells with visible chromosomes/total number of cells observed

30
Q

Cancer and treatments?

A

There is a mutation in the gene that controls cell division so cells divide out of control.
Treatments for cancer are designed to control the rate of cell division however can also kill healthy cells.

31
Q

Calculating the actual size of cells?

A

Actual size = size of image/magnification

32
Q

What is binary fission?

A

Where prokaryotic cells divide:
- circular DNA replicates and both copies attach to the cell membrane (plasmids also replicate)
- cell membrane then begins to grow between the two DNA molecules and begins to pinch inwards dividing the cytoplasm in two
- new cell wall forms , daughter cells have single copies of identical circular DNA and variable number copies of the plasmids.

33
Q

What are biological membranes?

A
  • partially permeable membranes composed of phospholipids that have hydrophilic heads and hydrophobic tails.
  • the main function is to control the movement of substances in and out of the cell/organelle.
34
Q

What is the fluid mosaic model?

A
  • phospholipids with hydrophilic heads pointing outwards and hydrophobic tails pointing inwards.
  • allows lipid soluble molecules to pass through the membrane.
35
Q

What is the membrane made up of?

A
  • chanel proteins
  • carrier proteins
  • cholesterol
  • glycolipids
  • glycoprotiens
36
Q

What are channel and carriers proteins?

A
  • intrinsic = integrated throughout the membrane
  • extrinsic = on the surface
  • allow large molecules and ions to pass through the membrane
37
Q

What is cholesterol in the membrane ?

A
  • makes the membrane more rigid and reduces the lateral movement of the phospholipids.
  • prevents the leakage of water and dissolved ions.
38
Q

What are glycolipids?

A
  • made up of a carbohydrate that is bound to lipids
  • act as cell surface receptors
  • help cells adhere to one another to form tissues
39
Q

What are glycoproteins?

A
  • carbohydrates attached to extrinsic proteins
  • cell surface receptors and neurotransmitters
  • form tissues
40
Q

How does temperature affect membranes?

A
  • temps below 0*C don’t have much energy = increases permeability of membrane
  • 0C to 45C = partially permeable
    -45*C + starts to break down
41
Q

What is diffusion?

A
  • Passive movement of small, non-polar, lipid soluble molecules such as CO2 and O2 from and area of high concentration to an area of low concentration.
42
Q

What are the factors affecting diffusion?

A
43
Q

What is facilitated diffusion?

A
  • requires a channel protein in the cell membrane to transport polar molecules, charged and water soluble molecules across the membrane.
44
Q

What is osmosis?

A
  • is the diffusion of water from an area of high water potential to an area of low water potential through a partially permeable membrane.
45
Q

Factors affecting the rate of osmosis?

A
46
Q

What is Active Transport?

A
  • all types of molecules through carrier proteins from an area of low concentration to an area of high concentration with the use if ATP.
47
Q

What is co-transport?

A
  • uses ions to move substances into and out of cells.
  • sodium and potassium ions are pumped out of the epithelial cells of the ileum, by active transport into into the blood leaving a lower concentration in the cell. Causing the ions to move from the lumpen by facilitated diffusion which a t the same time brings glucose and amino acids into the cell.
48
Q

Factors affecting the rate of active transport?

A
49
Q

What are bacteria and viruses?

A

Bacteria are prokaryotic cells - their genetic information is stored in circular DNA
Viruses consist of just nucleic acid enclosed in a protein coat
Viruses are dependent on a host cell
Viruses are smaller

50
Q

What is the immune response?

A
51
Q

What is the cellular and humoral response?

A
52
Q

What are the primary and secondary immune response?

A
53
Q

What is active and passive immunity?

A
54
Q

What are vaccinations?

A
55
Q

What are the ethical considerations?

A
56
Q

What is antigenic variation?

A
57
Q

What are monoclonal antibodies?

A
58
Q

What is the ELISA test?

A
59
Q

What is HIV and AIDS?

A
60
Q

Antibiotics and viruses?

A

Biology (5 decks)

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