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OV1113- Biological Sciences > Chapter 1- Cytology > Flashcards

Chapter 1- Cytology Flashcards

1
Q

Who discovered the cell?

A

Robert Hook in 1663

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2
Q

What is the study of cell form known as?

A

Morphology

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3
Q

Give the scales of measurement?

A 
1cm = 0.01 = 10 to the -2m 
1mm= 0.1 cm= 10 to the -3m

Micrometere= 10 to the -6m

Nanometre= 10 to the -9m

Angstrom= 10 to the -10m

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4
Q

What does a general cell consist of?

A

An outer border which is called the plasma membrane which surrounds the cytoplasm containing organelles.

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5
Q

What are the functions of a cell membrane?

A

1- Maintains the integrity of the cell- controls what comes in and out

2- It is selectively permeable- allows certain molecules or ions to pass through it.

3- Acts as a communication site- has proteins that act as receptors, e.g hormones.

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6
Q

What is the cell membrane the same as?

A

Plasma membrane

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7
Q

What is the structure of the plasma membrane?

A

1- Has a phospholipid bilayer
2- Has protein molecules

3- Cholesterol molecules

4- Sugar groups attached to the surface- e.g, glycocalyx

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8
Q

In a phospholipid bilayer, what molecules are non polar and polar?

A

Lipids are non-polar
Water molecules are polar

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9
Q

What does non polar mean?

A

Doesn’t carry a charge

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10
Q

What is the structure of a phospholipid bilayer?

A

Contains a polar, hydrophilic head- attracted to water

Contains a non polar, hydrophobic tail- repels water

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11
Q

What is an amphipathic molecule?

A

A molecule that has both hydrophobic and hydrophilic parts.

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12
Q

What is the benefit of being amphipathic?

A

If the membrane becomes disrupted, it will automatically reform into a bilayer because of the chemical nature of these lipids, meaning the cell is able to heal itself and less likely to die.

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13
Q

What does cholesterol do?

A

1- Stabilises the phospholipid bilayer.

2- Helps maintain the right fluidity of the plasma /cell membrane.

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14
Q

How does cholesterol stabilise the phospholipid bilayer?

A

1- It makes it more rigid by decreasing its permeability to water molecules.

2- Also prevents hydrocarbon tails from joining and crystallizing- the process by which a solid forms.

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15
Q

What are the types of membrane proteins?

A

1- Integral proteins - surround the membrane

2- Peripheral proteins- Found on the surface of the membrane.

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16
Q

What are the functions of the membrane proteins?

A

1- Transports substances in and out through protein channels- some channels are passive (don’t require energy) and some require energy in the form of ATP.

2- Enzymatic activity- proteins can be in the form of enzymes which speed up the rate of chemical reactions inside the membrane.

3- Joins cells together- the proteins provide binding sites that allows cells to join.

4- Are receptors- a protein may have a binding site with a specific shape that fits the shape of a chemical messenger such as a hormone. This will allow a chain of chemical reactions to take place.

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17
Q

What is the glycocalyx?

A

The sugar coating of the cell

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18
Q

Carbohydrates are mainly attached to what type of protein?

A

Integral proteins

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19
Q

What is the function of the glycocalyx?

A

Allows cell-cell recognition to take place, e.g, enables sperm cell to recognise egg cell.

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20
Q

Name the type of junctions between cells

A

1- Sticky glycoproteins on cell surface- a bit like glue

2- Mechanical junctions

3- Specialised cell-cell junctions

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21
Q

Give some types of mechanical junctions

A

1- Ball and socket- e.g, hip shoulder.

2- Tongue and groove- this is found between the cells within the lens

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22
Q

Give some types of specialised cell-cell junctions

A

1- Occluding (tight) junctions- acts as an impermeable barrier to molecules

2 Anchoring cells- locks two cells strongly together which stops two cells being easily torn apart.

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23
Q

Where would you find anchoring junctions?

A

In tissues which are subject to a lot of mechanical pressure, e.g, skin

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24
Q

Name a type of anchoring junction?

A

Desmosomes

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25
Q

Name the type of desmosomes

A

1- Belt desmosome- goes a long way round the cell

2- Spot desmosome- a small area

3- Hemidesmosome- only links the membrane to the cytoplasm

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26
Q

What is a gap junction?

A

Forms a channel between cells which allows certain molecules to pass directly from one cell to the next.

27
Q

Why are cells that make up the lens joined by gap junctions?

A

Because the lens has no blood supply. By having gap junctions, nutrients can diffuse from the lens surface to cells in its interior.

28
Q

What is the cytoplasm composed of?

A

1- Cytosol- fluid that contains mostly water but also sugars, proteins, salts, etc.

2- Cytoskeleton

3- Membrane bound organelles, e.g, mitochondria

4- Inclusions- various substances that are found in some cells but not others, e.g melanin in epithelial cells.

29
Q

What does a cytoskeleton do?

A

1- Provides shape to the cell

2- Responsible for the whole cell movement

30
Q

What are the components of the cytoskeleton?

A

1- Actin filaments
2- Intermediate filaments
3- Microtubules

31
Q

What is the function of the actin filaments?

A

Supports the cell and is also involved in its movement.

32
Q

What is the structure of the actin filament?

A

Consists of two strands of actin monomers in a tight helix.

33
Q

What is exocytosis?

A

Movement of substances out of the cell.

34
Q

What is endocytosis?

A

Movement of substance into cell, e.g, phagocytosis

35
Q

What is the function of microtubules?

A

Involved with the movements within the cell

36
Q

What is the structure of microtubules?

A

It consists of proteins being arranged into long hollow tubes.

37
Q

What are the proteins in microtubules made up of?

A

Alpha and beta tubulin

38
Q

Where are microtubules located?

A

To one side of the nucleus

39
Q

Microtubules form the structural core of what cell?

A

The cillia- finger like projections that move fluids and its contents over the cell.

40
Q

What are the intermediate filaments like and how are they organised?

A

Very tough and durable and are organised as rope-like polymers.

41
Q

Where are intermediate filaments located?

A

Where cells are subjected to mechanical stress, e.g, desmosomes.

42
Q

What is the function of the mitochondria?

A

Releases energy in the form of ATP

43
Q

What is the mitochondria made up of?

A

1- A smooth outer membrane

2- An inner membrane containing cristae- which increases the surface area allowing for faster production of ATP.

3- A matrix containing enzymes

44
Q

Why does the mitochondria possess some of its own DNA?

A

So it can make some of its own proteins needed for its function.

45
Q

Describe the protein synthesis process

A

1- The proteins we make are coded in the DNA of our genes.

2- The gene’s DNA is transcribed onto mRNA.

3- The mRNA leaves the nucleus for the cell’s cytoplasm where it joins onto ribosomes located on the endoplasmic reticulum.

4- Proteins are then formed by amino acids joining together in the process of translation.

46
Q

What is the function of ribsomes?

A

Its where protein synthesis takes place.

47
Q

Where are the ribosomes located?

A

In the cytoplasm or in the endoplasmic reticulum

48
Q

What does the endoplasmic reticulum (ER) do?

A

Synthesises, folds and transports proteins.

49
Q

What is the function of the rough ER?

A

It makes proteins for membranes which are due for export from the cell.

50
Q

What is the structure of the rough ER?

A

It is a surface studded with ribosomes.

51
Q

Where would there be a high number of rough ER?

A

In cells that make protein for export, e.g, plasma cells (antibodies)

52
Q

What is the function of the smooth ER?

A

This packages and modifies lipids.

53
Q

What is the structure of the smooth ER?

A

Has no ribosomes attached

54
Q

What is the sarcoplasmic reticulum?

A

An expanded specialised region of the smooth ER for muscle cells.

55
Q

What is the function of the Golgi apparatus?

A

Modifies and packages proteins from the rough ER.

56
Q

What is the structure of the Golgi apparatus?

A

Series of flat membrane stacks associated with tiny vesicles.

57
Q

The proteins are packaged into vesicles where they can follow what pathways?

A

1- Be released from the cell by exocytosis

2- End up forming part of the cell membrane

58
Q

What are lysosomes?

A

A membrane bound organelle that contains digestive enzymes

59
Q

What are lysosomes packaged by?

A

The Golgi apparatus

60
Q

Digestive enzymes in the lysosome do what?

A

1- Digest and destroy worn out components of the cell

2- Destroy bacteria and viruses.

61
Q

What does the nucleus do?

A

Controls the activities of the cell

62
Q

What does the nucleoplasm contain?

A

1- Chromatin- unwoven DNA strands

2- Nucleolus- where ribosomes are produced

63
Q
A

OV1113- Biological Sciences (42 decks)

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