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Biology > Mr P bio 5 cells > Flashcards

Mr P bio 5 cells Flashcards

1
Q

what is the purpose of the nucleus?

A

contains the DNA necessary for controlling the cell

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2
Q

what is the structure of the nucleus?

A

surrounded by a double membrane which is perforated by pores called nuclear pores (to allow passage of large molecules such as RNA), in nucleus is the nucleolus and chromatin

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3
Q

what is the function of the nucleolus?

A

site of ribosomal RNA synthesis

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4
Q

what is chromatin? (in nucleus)

A

made of DNA and coiled around protein, during cell division chromatin comes together and forms the thread like structures called chromosomes

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5
Q

is the mitochondrion made from a double or single membrane?

A

double

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6
Q

what are the folds in a mitchondrion called?

A

cristae

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7
Q

what do cristae do?

A

increase the surface area for enzymes for respiration

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8
Q

what is the name of the flattened sacs that are a part of the golgi and endoplasmic reticulum?

A

cisternae

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9
Q

what is the function of the rough endoplasmic reticulum?

A

transports proteins throughout the cell

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10
Q

what type of cells contain lots of RER?

A

cells which make a lot of proteins i.e. secrete enzymes or antibodies

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11
Q

what is the function of the Smooth endoplasmic reticulum?

A

to synthesize lipids, carbs and steroids

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12
Q

what is the structure of ribosomes? (3)

A

made up of two sub units, contain ribosomal RNA and protein, very small only 25nm in diameter

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13
Q

what is the function of the Golgi apparatus?

A

it sorts modifies and packages molecules (like proteins) produced by the cell, into vesicles

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14
Q

what is the structure of the golgi?

A

composed of flattened sacs made of membranes. the sacs are fluid filled and pinch off smaller sacs (vesicles) at their ends

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15
Q

what is the function of the lysosomes?

A

used to break down unwanted structures within the cell

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16
Q

what is the structure of the lysosomes?

A

bound by a single membrane and have no internal structure, contain a large number of hydrolytic enzymes

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17
Q

what is the function of the cell membrane?

A

controls the passage of molecules in and out of the cell

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18
Q

what is the structure of the cell membrane?

A

made up of phospholipids, proteins and carbs

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19
Q

what are microvilli?

A

finger like projections of the cell membrane, which increase the SA of the cell membrane greatly

20
Q

what is the structure of centrioles?

A

hollow fibers made of microtubules

21
Q

what do two centrioles at right angles to each other form?

A

a centrosome

22
Q

what is the cytoskeleton made up of?

A

microtubules

23
Q

what is the function of the cytoskeleton?

A

to provide support and movement to the cell

24
Q

what are the cilia?

A

hair-like projections made from microtubules

25
Q

what do cilia allow?

A

movement of substances over the cell surface

26
Q

what do flagella consist of?

A

microtubules

27
Q

what is the flagella’s function?

A

contract to provide cell movement (e.g. in sperm cells)

28
Q

what is the process of binary fission? (briefly)

A

the cells contents doubled any plasmids undergo DNA replication, the parent cell divides into two cells with the cytoplasm split roughly between the two cells, the two daughter ells each contain a single copy of the circular DNA molecule and a variable number plasmids

29
Q

why can viruses not be described as cells?

A

they have no cell membrane

30
Q

what do viruses need to be able to synthesise protein or DNA to make coped of itself?

31
Q

what is the structure of a virus? (2)

A

contains genetic material- DNA, RNA, single or double stranded, surrounded by a protein coat called a capsid, some have an outer envelope of cell membrane which originates aspart of the host cell

32
Q

do specimens have to be living or dead when using a light microscope?

33
Q

how are specimens made visible for viewing under a light microscope?

A

stained with a coloured dye

34
Q

what is the magnification of a light microscope limited to?

35
Q

what can be viewed with a light microscope?

A

individual cells and large structures such as the nucleus

36
Q

why is the light microscope magnification limited?

A

by using more lenses a light microscope can magnify by a larger amount but the problem is at these higher magnifications the microscope loses resolution

37
Q

how does an electron microscope work?

A

uses beams of electrons which behave like waves and can be easily produced and detected

38
Q

what can you view with an electron microscope?

A

very small wavelength so objects as small as a ribosome (20nm)

39
Q

what is the highest magnification of an electron microscope?

40
Q

what are the limitations of an electron microscope?

A

specimens must be fixed in resin, viewed In a vacuum and must be dead
specimens can be damaged by electron beam
specimens must be stained with an electron-dense chemical
the specimen preparation could cause the creation of observed objects that were due to the preparation process and weren’t originally there

41
Q

why is a light microscope better In some cases than an electron?

A

costs much less and electron only produces black and white images

42
Q

what are the 2 types of electron microscope?

A

transmission and scanning

43
Q

how are transmission and scanning electrons different?

A

transmission= best resolution, 2D
scanning= poorer resolution, 3D

44
Q

describe the process of cell fractionation

A
  1. tissue is homogenised in an ice cold, isotonic buffered solution to break open cells releasing the organelles into the solution
  2. the mixture can then be filtered to remove any large pieces of tissue not broken up by the homogeniser producing a solution of suspended organelles
  3. the solution is now centrifuged at low speed. larger organelles are forced to bottom of tube into a pellet and pellet removed and resuspended if needed
  4. solution now centrifuged at higher speed and smaller organelles forced to the bottom of the tube into a pellet. pellet removed and resuspended if required
  5. process can be repeated many times, increasing speed and separating organelles based on density
45
Q

why does tissue have to be homogenised in an ice cold, isotonic, buffered solution?

A

ice cold= reduce the action of enzymes that would damage the organelles
isotonic= prevent the net movement of water into or out the organelles due to osmosis (same water potential)
buffered= to stop. pH change which would denature proteins

46
Q

what is a eukaryotic cell?

A

the DNA of eukaryotes is enclosed within a nucleus

47
Q

explain why it may be impossible to identify organelles within a cell using an optical microscope?

A

because the resolution isnt high enough as the wavelengths of light are too long

Biology (19 decks)

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