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Cells > Eukaryotic Cell Structure > Flashcards

Eukaryotic Cell Structure Flashcards

1
Q

What are the two main features of a Eukaryotic Cell?

A

They have a distinct Nucleus and possess membrane-bound organelles.

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2
Q

What does the Nucleus do?

A

Contains organisms hereditary material and controls cells activities.

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3
Q

What is the nuclear envelope?

A

A double membrane surrounding the nucleus, continuous with endoplasmic reticulum and often has ribosomes on its surface.

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4
Q

What is the role of the nuclear envelope?

A

It controls the entry and exit of materials in and out of the nucleus, and contains reactions taking place within.

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5
Q

What is the role of the nuclear pores?

A

Allow the passage of large molecules, such as mRNA out of the nucleus.

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6
Q

What is the nucleoplasm?

A

Granular, jelly-like material that makes up the bulk of the nucleus.

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7
Q

What do the chromosomes inside the nucleus consist of?

A

Protein-bound, linear DNA.

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8
Q

What is the nucleolus?

A

Small spherical region within the nucleoplasm. It manufactures rRNA and assembles the ribosomes.

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9
Q

What are the functions of the nucleus?

A
  • Act as a control centre of the cell through production of mRNA and tRNA and hence protein synthesis.
  • Retain genetic material of the cell in the form of DNA and chromosomes.
  • Manufacture rRNA and ribosomes.
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10
Q

What are the mitochondria and what is their role?

A

They are the sites of aerobic respiration, and are therefore responsible for the production of ATP.

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11
Q

Where are there especially high numbers of mitochondria and why?

A

In metabolically active cells, such as muscle and epithelial cells. Epithelial cells in the intestine require lots of ATP in the process of absorbing substances from the intestines in active transport.

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12
Q

What are the three main features of the mitochondria structure?

A

Double membrane - controls entry and exit of material. Inner membrane Is folded to form cristae.
Cristae - Extensions of inner membrane, which provide a large SA for enzyme attachment and other respiratory proteins.
Matrix - Contains proteins, lipids, ribosomes and DNA allowing mitochondria to control production of their own proteins.

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13
Q

What are Chloroplasts?

A

Chloroplasts are the organelles that carry out photosynthesis.

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14
Q

What does the chloroplast feature, the chloroplast envelope do?

A

Double plasma membrane surrounding the organelles, selectively allowing entry and exit of materials from the chloroplast.

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15
Q

What does the chloroplast feature, the grana do?

A

Stacks of disc like structures called thylakoids. Within the thylakoids is the photosynthetic pigment called chlorophyll. The grana are where the light absorption stage of photosynthesis takes place.

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16
Q

What does the chloroplast feature, the stroma do?

A

It is a fluid-filled matrix, where synthesis of sugars takes place. Within the stroma are other structures, such as starch grains.

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17
Q

How are chloroplasts adapted to their function of absorbing sunlight and carrying out photosynthesis?

A
  • Granal membranes provide large SA for attachment of chlorophyll, enzymes and other molecules that carry out first stage of photosynthesis.
  • Fluid of stroma possesses all enzymes needed to make sugars in second stage of photosynthesis.
  • Chloroplasts contain DNA and ribosomes allowing manufacture of proteins needed for photosynthesis.
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18
Q

What is endoplasmic reticulum?

A

The ER is an elaborate, 3-D, system of sheet like membranes, spreading through cytoplasm of the cell. The membranes enclose a network of tubules and flattened sacs called cisternae.

19
Q

What type of ER has ribosomes present on the outer surface of the membranes?

A

Rough Endoplasmic Reticulum

20
Q

What are the functions of the RER?

A
  • Provide a large SA for synthesis of proteins and glycoproteins.
  • Provide a pathway for transport of materials, especially proteins, throughout the cell.
21
Q

What is the appearance of the Smooth ER?

A

Lacks ribosomes on surface and is often more tubular in appearance.

22
Q

What are the functions of the Smooth ER?

A
  • Synthesise, store and transport lipids.

- Synthesise, store and transport carbohydrates.

23
Q

Which cells have a very extensive ER?

A

Cells that manufacture and store large quantities of carbohydrates, proteins and lipids. Such cells include liver and secretory cells.

24
Q

What is the Golgi Apparatus?

A

It consists of a stack of membranes that make up flattened sacs, or cisternae, with small rounded hollow structures called vesicles. Golgi sort molecules and sends them to their correct destinations.

25
Q

What are Golgi Vesicles and when do they form?

A

Golgi vesicles are pinched off the end of the Golgi apparatus, they transport the protein and lipid molecules after they’ve been modified to the cell surface where they release their contents.

26
Q

What are the functions of the Golgi apparatus?

A
  • Add carbohydrates to proteins to form glycoproteins.
  • Produce secretory enzymes
  • Secret carbohydrates, such as those used in making cell walls
  • Transport, modify and store lipids.
  • Form lysosomes.
27
Q

When are lysosomes formed?

A

When the Golgi vesicles produced by the Golgi apparatus contain enzymes such as proteases and lipases. They also contain lysozymes, enzymes that hydrolyse cell walls of certain bacteria.

28
Q

What do lysosomes do?

A

Lysosomes isolate enzymes from the rest of the cell before releasing them either to the outside, or into a phagocytic vesicle within a cell.

29
Q

What are the function of lysosomes?

A
  • Hydrolyse material ingested by phagocytic cells, such as white blood cells and bacteria.
  • Release enzymes to the outside of cell (exocytosis) in order to destroy material around the cell.
  • Digest worn out organelles so that the useful chemicals they are made of can be re-used.
  • Completely break down cells after they have died (autolysis).
30
Q

What are ribosomes?

A

Ribosomes are small cytoplasmic granules found in all cells. They may occur in cytoplasm or be associated with RER.

31
Q

What are the 2 types of ribosomes and where is each found?

A

80s - found in eukaryotic cells

70s - found in prokaryotic cells, mitochondria and chloroplasts and is slightly smaller.

32
Q

What does each sub unit of ribosomes contain?

A

Ribosomes have 2 sub-units, one larger than the other, each of which contains rRNA and protein.

33
Q

What is the key function of ribosomes?

A

They are the site of in protein synthesis.

34
Q

What does the cell wall consist of?

A

Microfibrils of the polysaccharide cellulose, embedded in a matrix.

35
Q

What do the cellulose microfibrils provide for the cell wall?

A

Microfibrils have considerable strength and so contribute to overall strength of the cell wall.

36
Q

What are the features of the cellulose cell wall?

A
  • They consist of a number of polysaccharides, such as cellulose.
  • There is a thin layer called the middle lamella, marking the boundary between adjacent cell walls and cements adjacent cells together.
37
Q

What are the functions of the cellulose cell wall?

A
  • Provide mechanical strength to prevent the cell from bursting under pressure of osmotic entry of water.
  • Give mechanical strength to plants as a whole.
  • Allow water to pass along it and so contribute to the movement of water through the plant.
38
Q

What are the cell walls of algae made up of?

A

Either cellulose or glycoproteins, or a mixture of both.

39
Q

What are the cell walls of fungi made up of?

A

They do not contain cellulose, but comprise a mixture of a nitrogen containing polysaccharide called chitin, a polysaccharide called glycan and glycoproteins.

40
Q

What are vacuoles?

A

A fluid filled sac bounded by a single membrane. The fluid is a solution of mineral salts, amino acids, sugars, wastes, and sometimes pigments such as anthocyanins.

41
Q

Where do vacuoles occur?

A

Within mature plants, there is usually one large central vacuole.

42
Q

What is the single membrane around the vacuole called?

A

Tonoplast

43
Q

What are the functions of the plant vacuole?

A
  • Support herbaceous plants, and herbaceous parts of woody plants, by making cells turgid.
  • Sugars and amino acids may act as a temporary food store.
  • Pigments may colour petals to attract pollinating insects.

Cells (19 decks)

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