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Cell Structure and biological membranes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are membrane bound organelles

A

Organelles have membranes around the outside

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2
Q

Describe the structure of the nucleus

A

Surrounded by a double membrane called a nuclear envelope

Nucleolus containing RNA

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3
Q

Describe the function of the nucleus

A

Is the control centre of the cell.

Stores the organism genotype

Transmits genetic information

Provides the instructions for protein synthesis

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4
Q

Describe the rough endoplasmic reticulum structure

A

This is a System of membrane containing fluid filled cavities that are continuous with the nuclear membrane. It’s coated with ribosomes

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5
Q

Rough endoplasmic reticulum function

A

Intracellular transport system
Provides large surface area for ribosomes which assemble amino acids into proteins which are transported to the Golgi apparatus for modification

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6
Q

Describe the smooth endoplasmic reticulum structure

A

System of membranes containing fluid filled cavities , continuous with the nuclear membrane

No ribosomes on its surface

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7
Q

Describe smooth endoplasmic reticulum function

A

Contains enzymes that catalysed reactions involved with lipid metabolism

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8
Q

Describe the Golgi apparatus structure

A

Consists of a stack of membranes bound flattened sacs . Secretory vesicles being materials to and from the Golgi apparatus

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9
Q

Golgi apparatus function

A

Proteins are modified. The proteins are packaged into vesicles that are pinched off and then stored in the cell or moved to the plasma Membrane, to be incorporated or exported

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10
Q

Describe the mitochondria structure

A

These may be spherical , rod shaped or branched . Surrounded by two membranes with a fluid space in between them . The inner part of a mitochondria is a fluid filled matrix

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11
Q

Describe the function of the mitochondria

A

Site of ATP production during aerobic respiration. They are self replicating . They’re abundant in cells where much metabolic activities take place .

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12
Q

Describe the chloroplasts structure

A

Large organelles found only in plant cells . They’re surrounded by a double membrane or envelope

They contain loops of DNA and starch grains

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13
Q

Describe chloroplasts function

A

Site of photosynthesis

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14
Q

Describe the vacuole structure

A

Surrounded by a membrane called the tonoplast and contains fluid

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15
Q

Describe the vacuole function

A

Filled with water and solute and maintains cell stability - turgid

Helps support

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16
Q

Describe lysosomes structure

A

Small bags formed from the Golgi apparatus . Each is surrounded by a single membrane

They contain digestive enzymes

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17
Q

Describe lysosomes function

A

They can engulf old cell organelles and foreign matters and digest them

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18
Q

Describe the cilia and undulipodia structures

A

Surrounded by the cell surface membrane . Each contains micro tubes. They are formed from the centrioles

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19
Q

Describe cilia and undulipodia function

A

Acts as an antenna. It contains receptors and allows the cell to detect signals about its immediate environment

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20
Q

Describe ribosomes structure

A

Small spherical organelles made of ribosomal RNA made on the nucleus. As two separate subunits which pass through the nuclear envelope into the cell cytoplasm and then combine

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21
Q

Describe ribosomes function

A

Bound to the exterior of RER mainly for synthesising proteins that will be exporters outside the cell

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22
Q

Describe the centrioles structure

A

Consists of two bundles of micro tubes at right angles to each other . The micro tubes are made from tubulin proteins subunits and are arranged to form a cylinder

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23
Q

Describe the centrioles function

A

Are involved in the formation of cilia and undulipodia

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24
Q

Describe the cytoskeleton structure

A

A network of protein structures with in the cytoplasm and consists of a rod like microfilaments made of subunits of the protein acetic . They are enzymes and have a site to allow ATP

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25
Q

Describe the cytoskeleton function

A

The protein microfilaments give support and mechanical strengths , keeps the cell shape stable and allows cell movements

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26
Q

Describe cellulose structure

A

Made from bundles of cellulose fibres

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27
Q

Describe cellulose function

A

Strong and can Prevent plant cells from bursting when turgid . Provides strength and support

Maintains the cell shape

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28
Q

Describe making and secreting proteins

A

mRNA copy of the instructions for protein is made in the nucleus

mRNA leaves the nucleus through a nuclear pore

mRNA attaches to a ribosomes on the RER . Ribosomes read the instruction to assemble the protein

Protein molecules are pinched off in a vesicles and travels towards the Golgi apparatus

Vesicles fuse the the Golgi apparatus

Golgi apparatus processes and packages protein molecules ready to release

Packaged proteins molecules are pinched off in vesicles from the Golgi apparatus and move toward the plasma membrane

Vesicles fuse with the plasma membrane

Plasma membrane opens to releases proteins molecules outside - exocytosis

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29
Q

Proteins can be modified by

A

Adding sugar molecules to make glycoproteins

Adding lipids molecules to make lipoproteins

Being folded into their 3D shape

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30
Q

What are motor proteins

A

Carry things along

Drag organelles from one part of the cell to another

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31
Q

Describe micro filaments

A

Gives support and strength

Allows cell to move

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32
Q

Describe intermediate filaments

A

Anchor the nucleus

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33
Q

Describe micro tubules

A

Provides shape and support helps substances move through the cytoplasm

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34
Q

Cilia are ? And can be found in large numbers

Eg ?

A

Smaller

Ciliates epithelial cells eg airways

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35
Q

Undulipodia are ? And occur as ? Structures

Eg ?

A

Longer

Single

Sperm

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36
Q

In prokaryotic cells we call the protrusions ?

A

Flagella

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37
Q

Describe prokaryotic cells

A

No nucleus

DNA circular

Smaller

Less developed cytoskeleton

No centrioles

Flagella

DNA is naked

Mesosome

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38
Q

Describe eukaryotic cells

A

Nucleus

DNA linear

Larger

Well developed cytoskeleton

Centrioles

Membrane bound organelles

Cellulose

Cilia , undulipodia

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39
Q

What is resolution

A

Is the ability To distinguishes between 2 points

Enables you to see things Jan greater detail

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40
Q

What is magnification

A

The number of times larger an object is compared with the original

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41
Q

What’s the magnification equation

A

Size of image / actual size

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42
Q

What is the magnification triangle

A

Image on top

Magnification and actual size at the bottom

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43
Q

What are stains and why do we stain things

A

Stains are coloured chemicals that bind to molecules in or on the specimen

Make it easier to see

44
Q

An example of a stain

A

Iodine in potassium iodine solutions stains the cellulose in plants cell walls yellow and starch granules blue / black

45
Q

How do you observe prepared specimens

A

Dehydrate the specimen

Embedding them in wax to prevent distortion during slicing

Using special instruments to make very thing slices called sections

They are stained and mounted in a special chemical to preserve them

46
Q

Optical (light ) microscopes

How it works and examples of what you see

A

Uses visible light ( focused beam ) to magnify objects

Large structures inside the cell
Eg cell wall
Mitochondria

47
Q

What’s the magnification and resolution of optical microscopes

A

M- x1500- x2000

R- 200nm

48
Q

Optical microscopes

Ads and disads

A

Ads

  • relatively cheap
  • easily to use
  • portable to use in lab and field study

Disads

  • cannot see small organelles
  • limited resolutions
  • low magnification
49
Q

Laser scanning microscopes

How it works and examples of what you can see

A

Use laser light to scan an object point by point and assemble by compute the image displayed

-structures in depth eg cells in the retina

50
Q

Laser scanning microscopes

Magnification and resolution

A

M- x2009

R-633nm , high

51
Q

Laser scanning microscopes ads and disads

A

Ads

  • build up clean three dimensional images
  • high resolutions
  • assist diagnosis for eye problems

Disads

  • expensive
  • not portable
52
Q

Transmissions electron microscopes

Magnification and resolution

A

M- x2000000

R- 0.2nm

53
Q

Transmission electron microscopes

How it works , what can they see

A

Beam of electrons pass through the specimen which is stained with metal salts . Some electrons pass through and are focused on the screen . The electrons form a black and white image

Smaller structures e.g. Ribosomes

54
Q

Transmission electron microscopes

Ads and disads

A

Ads

  • most powerful magnification
  • wide range of applications
  • images are high quality and detailed
  • easy to operate with special training

Disads

  • large and expensive
  • laborious sample preparation
  • images are black and white
55
Q

Scanning electron microscopes

How it works and examples of what you see

A

Electrons do not pass through the specimen, which is whole but causes secondary electrons to bounce off the surface and focused onto a screen , this gives 3D image , has to be placed in a vacuum

Smaller structures e.g. Red blood cells

56
Q

Scanning electron microscopes

Magnification and resolution

A

M- x15 to x 200000

R- o.2nm

57
Q

Scanning electron microscopes

Ads / disads

A

Ads
Easy to operate with training

Software user friendly

Works fast

Samples require minimum preparation

Disads

Expressive
Large
Training required
Small risk of radiation poising

58
Q

What is an eyepiece graticule

A

A measuring device . It is placed in the eyepiece of a microscope and acts as a ruler when you view on object under the microscopes

59
Q

What is a stage graticule

A

A precise measuring device . It is a small scale that is placed on a microscope stage and used to calibrate the values of eyepiece divisions at different magnification

60
Q

The head and the tail of the phospholipid , when there’s a big group in a line what is it called

A

Phospholipids bilayer

61
Q

The head is

A

Hydrophilic

62
Q

The tail is

A

Hydrophobic

63
Q

Why is the plasma membrane describe as being partially permeable

A

Cells form a barrier and separates the cell contents from the cell exterior environment , or separate organelles from cytoplasm , they need to allow some molecules through in or out of the cell - determines which molecule it allows through

64
Q

Role of membranes at the surface is cell/ plans membranes

A
  • separates the cell components from its external environment

May be the site of chemical reactions

Regulates transport of materials into and out of the cell

May realise chemicals that signals other cells

Has antigens

65
Q

Roles of membranes with thin the cell

A

The membrane around many organelles present in eukaryotic cells separate the organelles contents from the cell cytoplasm so that each organelle is a discrete entity and able to perform its function

66
Q

The fluid mosaic model contains

A 
Phospholipids
Glycoprotein
Glycolipids 
Extrinsic proteins 
Integral proteins 
Cholesterol 
Channel proteins 
Carrier proteins
67
Q

What is diffusion

A

The movement of water from a high concentration to a low concentration

Down the concentration gradient

68
Q

What molecules can diffuse through the membrane and why

A

Small molecules - e.g. Oxygen because they’re small enough to pass through the membrane by simple diffusion

Lipid molecules - because they dissolve in the hydrophobic fatty tails

Non charged particles - because they don’t dissolve in water

69
Q

What is facilitated diffusion

A

Movement of molecules from an area of high concentration to low concentration across a partially permeable membrane via a protein channel or carrier molecules

70
Q

Factors that affect the rate of diffusion

A 
Temperature 
Diffusion distance 
Surface area 
Size of diffusing distance 
Concentration gradient
71
Q

How does temperature affect rate of diffusion

A

As temp increase the molecules have more kinetic energy do their rate is diffusion will increase

Conversely as they lose heat their rate is diffusion will slow down

72
Q

How does distance affect diffusion rate

A

The thicker the membrane across which molecules have to diffuse the slower the rate of diffusion

73
Q

Describe how surface area affects the rate of diffusion

A

More diffusion can take place across a large surface area. Cells specialised for absorption have extensions to their cell surface membranes , increasing surface area

74
Q

Describe how the size of diffusing molecule affects surface area

A

Smaller ions or molecules diffuse more rapidly than larger molecules

75
Q

Describe how the concentration gradient affects the rate of diffusion

A

The steeper the gradient the more molecules there are on the other side of the membrane compared with the other side . The faster diffusion to the other side where there are fewer molecules down the gradient

76
Q

How does a temperature increase affect membrane structures and permeability

A

The phospholipids acquire more KE and move around more in a random way , this increases membrane fluidity

Increases permeability

An increase in membrane fluidity may effect the unfolding of plasma membrane during phagocytosis

77
Q

How does temperature and proteins affect membrane structure

A

High temperatures cause the atoms within their large molecules to vibrate and this breaks the hydrogen bonds and ionic bonds that hold their structure together, unfold and denature

Their tertiary structure changes and cannot change back

78
Q

When temperature drops , how does it affect membrane structure and permeability

A

Membranes have less permeable , however there are many unsaturated fatty acids making up the cell membrane phospholipid bilayer and as they become compressed the kinks in the tails push adjacent phospholipids molecules away . This maintains membrane fluidity

79
Q

The proportions of unsaturated and saturated fatty acids within a cell membrane determines the

A

Membrane fluidity at cold temperatures

80
Q

Effects of solvents on phospholipid

A

Organic solvents such as acetone and ethonal will damage cell membranes as they di

81
Q

Describe Cholestrol

A

Provides stability in the membrane and helps fluidity, when temperatures drop buffer effects and helps maintain the fluidity

82
Q

Describe channel proteins

A

Span the whole phospholipids bilayer - there integral proteins . Molecules containing charged ions are allowed to pass through facilitated diffusion allowed of polar molecules

83
Q

Describe Cartier proteins

A

Span the whole phospholipids bilayer . Carries larger molecules through the membrane

Eg glucose via facilitated diffusion

84
Q

Describe glycolipids

A

Lipids attached with carbs

85
Q

Describe glycoproteins

A

Proteins with carbs attached to them

86
Q

Describe what glycoproteins and glycolipids do

A

Both involved in cell signalling to allow recognition by the immune system

87
Q

Diffusion and facilitated diffusion are ? And require no ?

A

Passive

Energy

88
Q

Define active transport

A

The movement of substances against Their concentration gradient (lie to high) across a cell membrane using ATP and protein carriers

89
Q

Describe carrier proteins

A

Site to which substances binds and also has another site for ATP this energy helps carrier protein change shape.

90
Q

Describe bulk transport

A

Some cells need to transport large molecules and particles that are too large to pass through the plasma membrane . They require ATP . The energy released from hydrolysis at ATP enables the pump protein to change its shape so that three ions are now on the outside of the cell and two potassium ions are inside the cell

91
Q

What is endocytosis

A

the taking in of matter by a living cell by invagination of its membrane to form a vacuole.

92
Q

What is phagocytosis

A

Eating cells and refers to this type of intake of solid matter

93
Q

What is pinocytosis

A

If cells ingest liquids by endocytosis

94
Q

What is exocytosis

A

process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

95
Q

Define osmosis

A

Is the net movement of water molecules from a high water potential to a low water water potential through a partially permeable membrane

96
Q

What is water potential

A

Measure of the tendency of molecules to diffuse from one region to another

97
Q

What can affect the water potential of a solution and why

A

Solute molecules - water attaches because they’re polar , therefore cannot move , reducing water potential

98
Q

Describe cytolysis

A

if A lot of water molecules enter , the cell will swell and burst as the plasma membrane breaks

99
Q

Describe turgid

A

The strong cellulose cell wall will prevent bursting . The cell wall swell up to a certain size . When it’s contents push against the cell wall which will resist any further swelling , helps support

100
Q

Describe crenated

A

Animal cells shrivel and are describe as crenated

101
Q

Describe plasmolysed

A

The cytoplasm of the plant cells shrinks and the membrane pulls away from the cell wall , flaccid

102
Q

Glycoprotein functions

A

Acts as antigens

Cell receptors

Cell signals

Stabilise the cell membrane

103
Q

Factors effecting membrane structure and permeability

A

Temperature drops
Temperature increases
Proteins and temperature

104
Q

How a drop in temperature affects membrane structure and permeability

A

Less permeable
When temperature drops
• Saturated fatty acids become compressed.
• However, there are many unsaturated fatty acids making
up the cell membrane phospholipid bilayer, and as they
become compressed the kinks in their tails push adjacent
phospholipid molecules away. This maintains the membrane
fluidity.
Therefore, the proportions of unsaturated and saturated fatty
acids within a cell membrane determine the membrane’s
fluidity at cold temperatures.

Cholesterol in the membrane also buffers the effect of lowered
temperature, to prevent a reduction in the membrane’s fluidity
It does this by preventing the phospholipid molecules from
packing together too closely, because cholesterol molecules are
in between groups of phospholipid molecules.

105
Q

How a temperature increase effects membrane structure and permeability

A

More permeable
When temperature increases
The phospholipids acquire more kinetic energy and move
around more, in a random way. This increases the membrane’s
fluidity
• Permeability increases.
• It also affects the way membrane-embedded proteins are
positioned and may function. If some of the proteins that act
as enzymes in a membrane drift sideways, this could alter the
rate of the reactions they catalyse.
• An increase in membrane fluidity may affect the infolding of
the plasma membrane during phagocytosis.
• An increase in membrane fluidity may also change the ability
of cells to signal to other cells by releasing chemicals, often by
exocytosis.
The presence of cholesterol molecules buffers, to some extent,
the effects of increasing heat as it reduces the increase in
membrane fluidity.

106
Q

Effects of solvents on phospholipids

A

Organic solvents such as acetone and ethanol will damage cell membranes as the dissolve lipids

Biology (10 decks)

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