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Cells and organisation > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

What is an advantage of membrane-bound organelles within eukaryotic cells?

A

It means that potentially harmful chemicals are concentrated within an area.

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2
Q

Why are internal membrane/membrane is important in cells?

A

It provides a large surface area for attachment of enzymes or other reactants which are involved in metabolic processes as well as ATP synthesis. They also provide a transport system separating areas from the rest of the cytoplasm.

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3
Q

How many nanometers are in one micro meter?

A

1000

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4
Q

How many micro metres in a millimetre?

A

1000

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5
Q

What is the diameter of a nucleus?

A

10-20 micrometers

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6
Q

What is the function of the nucleus?

A

It contains the DNA which codes for protein, which with protein comprises the chromosomes.

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7
Q

What is the function of the nuclear envelope?

A

It is a double membrane which separates the DNA from the cytoplasm.

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8
Q

What is the function of the nuclear pore?

A

It allows the transport of mRNA out of the nucleus

As they are pores they allow passages of large molecules like mRNA, ribosomes and nucleotides to be transported through.

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9
Q

What is the function of the nucleolus?

A

It’s synthesises rRNA and ribosomes.

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10
Q

What is the structure of the cell membrane?

A

It is selectively permeable

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11
Q

What is the function of the cell membrane?

A

It controls the entry and exit of molecules into and out of the cell.

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12
Q

What is the function of the cytoplasm?

A

It is the site of cellular reactions.

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13
Q

What is the structure of mitochondria?

A

It is often cylindrical and 1 to 10 um in length. It consists of a double membrane, that separated by a narrow fluid filled inner membrane space, where the membrane folds inwards forming a cristae. It has an organic matrix which is a solution containing many compounds such as lipids and proteins. The mitochondria has small (70S) ribosomes and small circular DNA which enables it to produce its own protein and self replicate.

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14
Q

What is the function of the mitochondria?

A

It’s synthesises ATP in aerobic respiration
Some reactions occur in the matrix where others occur in in the membrane.
The cristae provides a large surface area for which aerobic respiration can take place as well as attachment of enzymes involved in respiration.

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15
Q

Why do metabolically active cells have a large amount of mitochondria?

A

Metabolically active cells new plentiful supply of ATP which reflects the high metabolic activity taking place

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16
Q

Why is the shape of mitochondria important?

A

It allows you to have a large surface area to volume ratio. The cylindrical shape reduces the diffusion distance between the edge and the centre making aerobic respiration more efficient.

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17
Q

Where is the highest concentration of chloroplast found within a plant?

A

In the palisade mesophyll cells.

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18
Q

What is the structure of chloroplast?

A

Each chloroplast consists of a double outer membrane which comprises the chloroplast envelope. The stroma is fluid filled which contains products of photosynthesis including lipid droplets and starch grains. They contain 70 S ribosomes and circular DNA which enables them to make their own proteins and self replicate.

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19
Q

What are the close parallel flattened sacs called found within the stroma?

A

Thylakoids

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20
Q

Why are thylakoids important for photosynthesis?

A

Within the thylakoids of photosynthesis tech pigment such as chlorophyll. Each granum comprises between two and 100 parallel sacs (thylakoids) which produces a large surface area, efficient for trapping sunlight

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21
Q

What is the function of chloroplast?

A

It is the site of photosynthesis and the thylakoids contain photosynthetic pigments e.g. chlorophyll.

22
Q

What is the endoplasmic reticulum?

A

It is an elaborate system of parallel double membranes which form flattened sacs with interconnected fluid spaces between them which are called cisternae

23
Q

What is the ER connected to?

A

Is it connected with the nuclear envelope and may link to the Golgi body.

24
Q

What are the two types of ER?

A

Rough ER and smooth ER.

25
Q

What is the structure of rough ER?

A

It has ribosomes on its outer surface.

26
Q

What is the function of rough ER?

A

It transports the proteins which have been synthesised from the ribosomes attached. Large amounts of RER are present in cells that produce large amounts of protein.

27
Q

What is the structure of smooth ER?

A

It contains no ribosomes attached on its surface.

28
Q

What is the function of smooth ER?

A

It is associated with the synthesis and transport of lipids.

29
Q

What are the size of ribosomes in prokaryotic cells?

A

70S

30
Q

What are the size of ribosomes in eukaryotic cells?

A

80S and can be found singly or attached to the membrane of RER.

31
Q

What is the structure of ribosomes?

A

They consist of two subunits large and small which are assembled in the nucleolus from ribosomal RNA and protein.

32
Q

What is the function of ribosomes?

A

They are important in protein synthesis as they are the site of translation where mRNA is used to assemble the polypeptide chain.

33
Q

What is the structure of the Golgi body?

A

The structure resembles the ER but is more compact, it is a series of dynamic flattened sacs. The vesicles pinch off from the RER which then fuse with a stack of membranes which constitute the Golgi body.

34
Q

What happens at the other end of the organelle?

A

Vesicles are pinched off which contain modified proteins which could carry proteins elsewhere in the cell or move to and fuse with the cell membrane membrane, secreting the modified proteins by exocytosis.

35
Q

What are the functions of the Golgi body?

A

It produces secretory enzymes that get packaged into secretory vesicles.
Secreting carbohydrates e.g. formation of cell walls
Producing glycoproteins.
Transporting and storing lipids.
Forming lysosomes containing digestive enzymes.
Chemically modifying and packaging proteins for secretion of the cell.

36
Q

What are lysosomes?

A

They are small temporary vacuoles surrounded by a single membrane, they are secretory vesicles from the Golgi body

37
Q

What is the structure of lysosomes?

A

They contain and isolate potentially harmful digestive enzymes from the rest of the cell.

38
Q

What is the function of lysosomes?

A

They release harmful enzymes when the cell needs to recycle worn out organelles. They can be used to digest material which has been taken into the cell this process is called phagocytosis.

39
Q

What is the structure of centrioles?

A

They are two ringed microtubules making hollow cylinders positioned right angles of one another.

40
Q

What is the function of centrioles?

A

Are used in spindle formation during cell division.

41
Q

What is the structure of the vacuole in a plant cell?

A

It contains a large permanent vacuole which consist of a fluid filled sap bound by single membrane, the tonoplast. Vacuoles contains cell sap solution which stores chemicals such as glucose and amino acid and minerals and may store vitamins and pigments.

42
Q

What is the function of the vacuole?

A

Vacuoles have a major role in supporting soft plant tissues. They store ions and organic molecules and maintain osmotic pressure.

43
Q

What are the vesicles?

A

They are found in animal cells and acts as a contractile vacuole maintain osmotic pressure.

44
Q

What is the structure of the cell wall?

A

It is made from cellulose which are held together in microfibrils which aggregrated into fibres which are embedded into a polysaccharide matrix called pectin.

45
Q

What are the functions of the cell wall?

A

Transport: the gaps between the cellulose fibres allow the cell wall to be from fully permeable, water and dissolved molecules and ions can pass through. The space outside the cells through which the solution moves is the apoplast. Apoplast pathway is the main route water takes to cross the plant root.
Mechanical strength: the structure of the microfibrils and its laminated arrangement makes the cell wall very strong. When the vacuole is full of solution the cell contents is pushed against the cell wall which resists expansion and the cell becomes turgid supporting the plant.

46
Q

What is the plasmodesmata?

A

Cell walls have path in order for cell to cell communication these paths are called pits where strands of cytoplasm called plasmodesmata can pass through.

47
Q

Where is plasmodesma found?

A

It is found where there is no cellulose thickening the two cells allowing the strand of cytoplasm to run from one cell to the next.

48
Q

The network of cytoplasm in connected cells is called?

A

Symplast

49
Q

Why is this pathway important in a cell (plasmodesmata)?

A

In water transport through a plant.

50
Q

What organelles that only present in animal cells?

A

Centrioles and lysosomes

51
Q

What organelles are only present in plants cells?

A

Chloroplast, cellulose cell wall, permanent vacuole and plasmodesmata.

Cells and organisation (3 decks)

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