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Cells Flashcards

1
Q

What does resolution mean?

A

The ability to see two adjacent points as distinct entities follow magnification.

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2
Q

what does the transmission electron microscope (TEM) involve?

A

Electrons passing through a very thin specimen, and produces a high resolution image.

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3
Q

What does the scanning electron microscope involve?

A

Electrons reflecting off the surface of the image as opposed to going through it, the resolution is not as high as in a TEM.

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4
Q

What is the role of the nucleus?

A

Support and protect the DNA. In general the nucleus is the control centre of the cell.

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5
Q

What does the nucleus contain?

A

DNA in chromosomes

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6
Q

In general what is the Nucleus?

A

The control centre of the cell.

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7
Q

What is the outer membrane of the nuclear envelope encrusted with?

A

Ribosomes.

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8
Q

How do other molecules enter the nucleus from the cytoplasm?

A

Nuclear pores in the nuclear envelope (membrane).

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9
Q

What is Endoplasmic Reticulum (ER)?

A

A membrane system that extends throughout the cytoplasm.

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10
Q

What do some ER have dotted along them?

A

Ribosomes this type of ER is known as Rough Endoplasmic Reticulum (RER).

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11
Q

What is ER known as if there is no ribosomes dotted along the outside?

A

Smooth Endoplasmic Reticulum (SER).

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12
Q

What does the RER provide?

A

Scaffolding for the ribosomes to make protein.

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13
Q

What are some roles of SER?

A

The synthesis of lipids, the detoxification of drugs and carbohydrate metabolism.

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14
Q

Where are Ribosomes found?

A

Either free in the cytoplasm or attached to the outer surface of the ER.

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15
Q

What are groups of ribosomes called, and what do they create?

A

Polyribosomes, creating ‘hot spots’ for protein synthesis.

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16
Q

What can Golgi apparatus be describe as?

A

A series of curved, flattened sacs (cisternae).

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17
Q

What does Golgi apparatus do?

A

Vesicles containing newly synthesised protein pinch off from the RER and coalesce with convex edge, within the main body of the Golgi the protein are modified. Once the protein is modified vesicles containing ‘finished’ protein are pinched off from concave face. These vesicles transport protein within the cell or fuse with the cell surface membrane to release their contents outside the cell.

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18
Q

What are Lysosomes?

A

Tiny vesicles formed by the Golgi apparatus.

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19
Q

What do Lysosomes have an important role in?

A

Phagocytes, where they digest engulfed bacteria enclosed in a phagosome.

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20
Q

What cells are mitochondria present in?

A

Almost all types of animal cells.

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21
Q

How are the mitochondria enclosed?

A

Within a double membrane separated by the inner membrane which is folded to form Cristae. This give mitochondria a greater surface area.

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22
Q

What is Mitochondria?

A

The ‘powerhouse’ of the cell, it is the site of ATP synthesis during aerobic respiration.

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23
Q

What are Microtubules?

A

Hollow cylinders formed from the protein tubulin.

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24
Q

How are Cytoskeleton formed and what do they do?

A

The microtubules form Cytoskeleton, this maintains cell shape and keeps organelles anchored in place.

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25
What are centrioles involved in and what are they important in?
The assembly of Spindle fibres, and centrioles are also important constituents of cilia and flagella.
26
What do organelle plant cells posses that animal cells do not?
Plant cell wall, Secondary cell wall, Middle lamella, Plasmodesmata, Chloroplasts and Large vacuole.
27
Where is the plant cell wall found?
Immediately outside the cell surface membrane.
28
What is the main component of Plant cell wall?
Polysaccharide Cellulose
29
How is the cellulose laid down as in a Plant cell wall?
As microfibrils, each consisting of many cellulose molecules cross linked to each other.
30
What does the loose arrangement of microfibrils in allow the cell wall to do?
Allows the cell wall to expand as the cell grows.
31
Why is the Secondary cell wall formed?
When the primary cell wall reaches full size, additional layers of cellulose can be deposited to form a secondary cell wall.
32
What is the advantage of a lattice arrangement of cellulose in the Secondary cell wall?
Gives the great strength necessary in cell wall function.
33
What are cell walls of adjacent cells linked by?
Middle Lamella.
34
What is the middle lamella larger made of?
Polysaccharides called Pectin.
35
What does Calcium Pectate form?
A 'gel' or 'cement' used to hold neighbouring cells together.
36
What is the function of the cell wall?
To provide support. They restrict the outward expansion of the cell contents (protoplast). Cell walls are fully permeable.
37
What are plasmodesmata?
Strands of cytoplasm that extend between neighbouring plant cells. Plasmodesmata provide 'gaps' to allow molecules to pass through.
38
What are chloroplasts?
Large organelle which are bounded by a double membrane which encloses the stroma.
39
What is found within stroma?
A system of membranes called thylakoids which are arranged in stacks called grana.
40
What do Thylakoids contain?
Contain chlorophyll.
41
What are chloroplasts the site of?
Photosynthesis.
42
What is the large vacuole important in?
Storage of ions and water, and plays an important part in the development of turgor for support.
43
Are fungi cells Eukaryotic or Prokaryotic organisms?
Eukaryotic.
44
What are fungi cell walls made from?
Glycoprotein Chitin
45
Do fungi cells photosynthesise?
No.
46
What are the two distinct categories of cell in the living world?
Prokaryotic and Eukaryotic.
47
Which cell is bigger, Prokaryotic or Eukaryotic?
Eukaryotic.
48
Where is the site of DNA in Prokaryotic cells?
DNA is free in the cytoplasm.
49
Where is the site of DNA in Eukaryotic cells?
DNA in inside the membrane bound nucleus.
50
Are plasmids present in both categories of cells?
No, only sometime present in Prokaryotic, not found in the Eukaryotic cell.
51
What is the cell surface membrane?
It is the boundary or interface with the outside world.
52
What are the two basic components of the cell surface membrane?
A phospholipid bilayer and protein.
53
What type of head does the phospholipid bilayer have?
Hydrophilic (water loving) head.
54
What type of tail does the phospholipid bilayer have?
Hydrophobic (water hating) tails.
55
What way is the phospholipids bilayer positioned?
The hydrophobic tails turn away from the solution and align with other tails, whereas the hydrophilic heads readily mix with the surrounding aqueous medium.
56
What is the structure of the cell surface membrane described as?
The fluid mosaic model.
57
What is the function of the phospholipid bilayer?
As well as being the backbone of the cell surface membrane, it gives the membrane the selectively or differentially permeable membrane.
58
What is the function of cholesterol?
Increasing the membrane stability by restricting the sideway movement of the phospholipid molecules at high temperatures.
59
What is the function of proteins?
They help provide stability and support. And need replaced less often than other enzymes. They also transport substances across the membrane.
60
How do proteins aid transport of substances across the membrane?
Protein create 'gaps' in the membrane which allow substances to pass. These 'gaps' are known as Channels and Carriers.
61
How do Channel proteins work?
A hydrophilic channel is created that allows polar molecules to bypass, these channels may be permanently open or controlled opening (gated)
62
How do Carrier proteins work?
These carrier specific ions and molecules across the membrane. The carrier protein can change shape to carry the substance from one side of the membrane to the other.
63
What is the function of Glycocalyx?
Act as receptor sites that particular molecules fit, they are complimentary in shape. Glycocalyx also form bonds with water molecules outside the membrane, they help stabilise the membrane.
64
There are two different types of viruses, these are...
Bacteriophages and the human immunodeficiency virus (HIV).
65
What happens in Bacteriophages?
Normally have a DNA core, the DNA replicates itself to form more viruses. In due course the bacterial cell is destroyed as it ruptures and many new viruses are released and the cycle continues.
66
What happens in the human immunodeficiency virus (HIV)?
Have a RNA core, they deliver RNA into the host cell together with the enzyme reverse transcriptase. The reverse transcriptase catalyses the synthesis of DNA from RNA. The DNA then makes new viruses by synthesising new protein coats and vital RNA. These viruses are known as retroviruses.
67
What does the HIV invade in humans and what are they important for?
A type of lymphocyte called Helper T-cells, which are important in the immune system.

Biology (Mrs Quinn) (6 decks)

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