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Biology - Module 2 > 2.1, 2.5 Cells + Membranes > Flashcards

2.1, 2.5 Cells + Membranes Flashcards

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1
Q

What is the name of the membrane surrounding the nucleus?

A

The nuclear envelope. It consists of two lipid bilayer membranes, an inner nuclear membrane, and an outer nuclear membrane.

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2
Q

What is the nucleus?

A

A fully enclosed, nuclear membrane bound organelle containing the cell’s hereditary information, DNA and controls the cell’s growth and reproduction.

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3
Q

What are the three organelles that DNA is stored in?

A
  • Nucleus
  • mitochondria
  • chloroplast
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4
Q

What is the job of the Golgi body?

A

Responsible for transporting, modifying and packaging proteins and lipids made by the ER into VESICLES for distribution.

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5
Q

What is the function of the mitochondria?

A

This is where reparation takes place. It also holds a small amount of genetic information.

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6
Q

What is the name for organelle responsible for photosynthesis?

A

Chloroplast

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7
Q

What is a Lysosome?

A

A specialised VESICLE holding digestive enzymes which can be used to digest food, waste products and the even the cell if it needs to be disposed of.

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8
Q

What is the name of the organelle responsible for protein synthesis?

A

Ribosomes

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9
Q

What are Centrioles?

A

A barrel-shaped collection of micro-tubules made from tubulin which are vital for cell division as during mitosis, they migrate to the poles and form spindle fibres to organise the chromosomes.

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10
Q

What are vesicles?

A

Vesicles are small cell organelles that are present in cells. These organelles are small, membrane-enclosed sacs that store and transport substances to and from one cell to another and from one part of a cell to another.

The membrane is much thinner than usual, meaning it can fuse with other organelles and the plasma membrane to deposit its contents where needed.

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11
Q

What is the Smooth Endoplasmic reticulum?

A

It is folded sac-like organelle which is has a variety of metabolic functions depending on its location. Generally, it makes lipids, enzymes, steroids and helps with detoxification.
It also acts as a transitional area for vesicles that transfer proteins to various locations. SER also transports the products of RER to Golgi apparatus and other parts of the cell.

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12
Q

What is the rough Endoplasmic reticulum?

A

The type of ER with ribosomes on the surface meaning its function is in protein synthesis and the movement of those products.

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13
Q

What is the Tonoplast?

A

The membrane surrounding the vacuole

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14
Q

What is the Plasmodesmata?

A

Thin strips of shared cytoplasm between neighbouring plant cells, allowing substances to diffuse through the cytoplasm.

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15
Q

What is the middle lamella?

A

The gap between two cells which connects the two cell walls.

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16
Q

What are Eukaryotic cells?

A

Cells containing membrane bound organelles such as the nucleus.

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17
Q

What are histone proteins?

A

A protein which DNA wraps around to form chromosomes.

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18
Q

What are the four bases and state whether they are purine or pyrimidine

A

Adenine (purine) base
Thymine (pyrimidine) base
Guanine (purine) base
Cytosine (pyrimidine) base

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19
Q

What is a purine and what bases are purines?

A

It is a type of nitrogen base found in DNA that consists of 2 nitrogen-carbon rings.
-Adenine and guanine

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20
Q

What is a pyrimidine and what bases are pyrimidines?

A

It is a type of nitrogen base found in DNA which consists of only one nitrogen-carbon ring.
-Thymine
-cytosine
(both contain a Y like pyrimidine does)

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21
Q

What are phospholipids? (full answer)

A

Lipids which make up the majority of the plasma membrane. They consist of hydrophilic heads and hydrophobic tails. Within the membrane they form a phospholipid bilayer.

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22
Q

What is a phospholipid bilayer?

A

The arrangement of phospholipids in a membrane.
They face away from each other with the hydrophilic heads facing out towards water outside of the membrane, whereas the hydrophobic tails face inwards away from the water.

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23
Q

What are prokaryotic cells?

A

Cells which do not have a membrane bound organelle or nucleus

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24
Q

Why is the plasma membrane a fluid mosaic model?

A

Fluid: because the phospholipids are interchangeable with each other, allowing them to swap and move about

Mosaic: made up of a variety of different parts.

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25
Q

What is the mesosome?

A

Folds in the membrane of prokaryotes and thought to be in replace of the mitochondria in that it is where respiration occurs.

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26
Q

What are three uses of bacteria?

A
  • Food industry
  • symbiotic relationships inside your body
  • decomposing matter
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27
Q

What effect does temperature have on a membrane?

A

It increases the permeability because of the phospholipids in the membrane moving about more.

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28
Q

Who developed first, eukaryotes or prokaryotes and why

A

Prokaryotes are thought to have developed first because it is likely that the eukaryotes were made by absorbing other prokaryotes such as the mitochondria.

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29
Q

What is the cytoskeleton?

A

Microtubules which provide structure and transport substances around the cell.

30
Q

What is the name of the process by which bacterial cells divide?

A

Binary fission

31
Q

What are the main proteins which make up the cytoskeleton?

A
  • tubulin
  • actin
  • miosin
32
Q

What different substances make up the membrane?

A
  • carbohydrates
  • glycoprotein
  • integral protein
  • peripheral protein
  • channel protein
  • hydrophilic channel
  • phospholipids
33
Q

What do carbohydrates/glycoproteins look like on a membrane diagram?

A

a chain of hexagons forming a Y shape.

34
Q

What are glycoproteins/glycolipids

A
  • Carbohydrate chain attached to a protein molecule/lipid molecule
  • hydrophilic so attract water and dissolves solutes helping the cell interact with it watery environment
  • They form hydrogen bonds with the water molecules surrounding the cell and thus help to stabilise membrane structure.
  • they are used as receptor molecules, binding with hormones like insulin, which could cause the cell change the amount of sugar it takes in

-to distinguish between them,
Glycoproteins are always attached to a protein
Glycolipids are always attached to the phospholipids

35
Q

What are integral proteins?

A
  • Proteins that are embedded into the membrane and can sometimes span the entire embrace.
  • They can act as a:
  • channel
  • a carrier,
  • for cell recognition
  • a receptor
  • enzymatic proteins.
36
Q

What is a peripheral protein?

A

A protein attached to the outside of the membrane by the cytoskeleton.

They sometime function as enzymes, antigens or receptor sites for complementary hormones

37
Q

What is the hydrophilic channel protein?

A
  • They are a pore whose walls are made of proteins.
  • The function of channel proteins is to transfer water molecules and small polar molecules across the membrane. They form a water-filled passage made of hydrophilic proteins that help in the transfer of ions and small polar solutes across the membrane.
38
Q

What is a carrier protein?

A
  • A protein in the membrane which transports molecules through the membrane.
  • It does this by the solute attaching to the binding site, causing the protein to change its conformation so that the binding site of the protein is now exposed on the other side of the membrane. The solute is then released from the carrier protein
39
Q

What is a polar and non-polar molecule?

A

Polar: either side of the molecule have slightly opposing charges so that one atom is slightly electro-negative to the other (uneven distribution of electrons)

Non-Polar: Even distribution of electrons so there is an equal charge all around the molecule

40
Q

What is the ion selectivity filter of a channel protein?

A

The narrowest part of the pore which will only allow the passage of specific molecules with a particular size and charge to pass through.

41
Q

What is cholesterol used for in the membrane?

A
  • Helps to regulate fluidity of the membrane
  • maintain mechanical stability
  • Reduce the effect of temperature change on the structure of the membrane
42
Q

What is resolution?

A

The minimum distance between two points that you can still distinguish

43
Q

What is the use of a TEM (transmission electron microscope)

A

They are used to show cells ultrastructure (organelles) in detail

44
Q

What is the use of a SEM microscope?

A

Used to show the surface features of organisms, such as the stomata of plants

(scanning electron microscope, where electrons are bounced off to create a 3D image)

45
Q

What is the definition of magnification?

A

How many times an image is enlarged

46
Q

What is the magnification equation?

A

Magnification = image size/actual size

AIM triangle

47
Q

What is horizontal gene transfer?

A

the transmission of genetic material from one genome to another genome in a way other than reproduction. This is usually done when plamids move between bacterial cells.

48
Q

What is the cytoskeleton made up from?

A
  • Micro tubules made from tubulin
  • micro-filaments made of the protein actin
  • intermediate filaments
49
Q

What are the functions of the cytoskeleton?

A
  • transport of substances like proteins from the ER to the golgi body
  • Protein filaments give support and strength
  • movement through cilia (inside the body) and flagellum (bacterial cell movement)
50
Q

What motor proteins operate within the cytoskeleton?

A

Dynein and kinesin which walk and drag organelles from one part of the cell to another.

51
Q

How do motor proteins get the energy to move?

A

As they are also enzymes, they have a site that binds to and allows hydrolysis of ATP.

52
Q

What are hydrolytic enzymes?

A

The enzymes inside a lysosome that are used to recycle old organelles, kill pathogens, and kill the cell when faulty e.g. cancerous.

53
Q

What happens to a protein once it has finished at the rough ER?

A

1) membrane pinches around the protein creating a vesicle
2) Vesicle is walked up the cytoskeleton of microtubules by dynein and kinesin
3) Golgi body packages and modifies the proteins
4) Vesicles of protein are sent again along the microtubules to the cell surface membrane where it fuses with the membrane and releases proteins.

54
Q

What is the function of the centrioles?

A
  • Forms spindle fibres for mitosis

- helps in the formation of cilia and flagellum

55
Q

What is water potential?

A

The measure of the potential for water to move from one place to another.
Water moves from an area of high water potential (closer to 0) to an area of low water potential (further negative from 0)

56
Q

What is the water potential of pure water?

A

0 kpa

57
Q

What is the water potential of a solution with a high concentration of dissolved solutes compared to a low concentration?

A

High concentration= -100 kpa

low concentration= -8 kpa

58
Q

What is hypotonic, hypertonic and isotonic in relation to water potential?

A

Hypotonic: low concentration of solute, high kpa
Hypertonic: high concentration of solute, low kpa
isotonic; flat concentration gradient, equal kpa

59
Q

How are lipids transported across the plasma membrane?

A

They use simple diffusion through the phospholipid bilayer, as they are able to to dissolve in the lipid bilayer .

60
Q

How is glucose transported into the cell?

A

1) Active transport
- hydrolysis of atp

2) Facilitated diffusion
- Uses specialised carrier proteins which allow the glucose particiles to pass through which are not soluble and too large to pass through the phospholipid bilayer.

61
Q

What is the role of cholesterol in the plasma membrane?

A

Cholesterol immobilises nearby phospholipids, which maintains the fluidity and decreases the permeability. Overall increasing the mechanical stability.

62
Q

What is endocytosis?

A

How large particles are brought into the cell.
They do not pass through the plasma membrane. Instead, a segment of the plasma membrane surrounds and enclosed the particle and brings it into the cell, enclosed in a vacuole.

63
Q

What is a micelle?

A

The formation of phospholipids when surrounded by water:

They form a circle with the hydrophobic tails pointing inwards, away from the water.

64
Q

What is phagocystosis?

A

The engulfing of solid particles. Often, the engulfed particle is another cell, like when a white blood cell, which is a part of the immune system, engulfs a bacterium to destroy it.

65
Q

How do phagocytes engulf a bacterium?

A

1) A phagocyte cell such as a white blood cell approaches a bacterium.
2) The cell extends to surround the bacterium
3) The bacterium is now enclosed within a phagocyte vesicle, called a phagosome.

66
Q

What is Exocytosis?

A

How large molecules may be exported out of cells.

67
Q

How does exocytosis work?

A

1) A vesicle containing the molecules to be secreted fuses with the plasma membrane.
2) The fuse site opens, releasing the contents of the secretory vesicle.

68
Q

How is active transport in carrier proteins used to help stomata open/close?

A

1) Potassium ions are transported in to the cell using carrier proteins called a pump protein.
2) The potassium binds to the site of the carrier protein
3) ATP binds to the active site and is hydrolysed to release energy
4) This energy allows the pump pprotein to change shape so that the ions are now on the inside of the cell
5) This lowers the water potential which brings in water via osmosis.

69
Q

What is facilitated diffusion?

A

Movement of molecules acccorss a partially permeable membrane vie protein channels or carrier proteins, not requiring ATP as it is going down the concentration graidient.

70
Q

What material makes up a bacterium cell wall?

A

Peptidoglycan

Biology - Module 2 (7 decks)

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