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Biology 1 &2 > 1&2. Proteins and Cell Membranes > Flashcards

1&2. Proteins and Cell Membranes Flashcards

1
Q

What is the SA:V ratio on a small organism?

A

Large compared to that of larger organsims

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2
Q

Why do most large organisms have a respiratory system?

A

They have a small SA:V ratio so cannot meet the requirements through diffusion over the surface alone

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3
Q

How can the rate of diffusion be increased?

A

Large surface area, steep conc gradient, thin exchange surface/short diffusion pathway

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4
Q

How is the mammalian lung adapted for rapid gas exchange?

A

Alveoli have a large SA, steep concentration gradient which is maintained by ventilation, thin walls and capillaries that run close to the alveoli create a short diffusion pathway so it is rapid

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5
Q

Describe the structure of an amino acid.

A

Amine group, central carbon with H and R group, carboxyl group

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6
Q

What type of bond holds amino acids together?

A

Peptide

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7
Q

How is the primary structure of a protein formed?

A

Individual amino acids join in condensation reactions and are held together by peptide bonds.
Also known as a polypeptide chain

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8
Q

How is the secondary structure of a protein formed and what are its features?

A

Alpha helices form as a result of the chain twisting and are held in place by hydrogen bonds formed between amine and carboxyl group.
Beta-Pleated sheets form as a result of several chains linking together with hydrogen bonds stabilising the parallel arrangement.

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9
Q

How is the tertiary structure formed?

A

Interactions between R groups fold the polypeptide chain into a unique 3D shape

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10
Q

What type of bonds maintain the tertiary structure?

A

Ionic, hydrogen and disulfide

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11
Q

How is the quaternary structure formed?

A

When several polypeptide chains link together.

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12
Q

What is a globular protein?

A

The polypeptide chain is folded into a compact spherical shape. Hydrophilic side chains on outside make them soluble.
Enzymes are an example

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13
Q

What is a fibrous protein?

A

Several polypeptide chain twisted together like a rope and held together by hydrogen bonds and cross links.
They are insoluble
Collagen is an example

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14
Q

What is the purpose of staggered cross links in a fibrous protein?

A

They hold each strand together and the staggering prevents any weak points along the strand.

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15
Q

What is a cell membrane primarily made up of?

A

A phospholipid bilayer

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16
Q

Why do phospholipids arrange in the way that they do in water?

A

Phosphate head is hydrophillic as it is slightly positive so attracted to other polar molecules i.e water
Fatty acid tails are hydrophobic as they are slightly negative

17
Q

Why does the bilayer arrange the way that it does?

A

If all the fatty acids tails turned towards the inside there would be very little space within the cell

18
Q

What other components make up the phospholipid bilayer?

A

cholesterol, glycoprotein, glycolipid, proteins that can be embedded or peripheral

19
Q

Why is the bilayer described as ‘fluid’?

A

The phospholipids are constantly moving and proteins can move round within it

20
Q

What is a glycoprotein?

A

A protein with a polysaccharide chain

21
Q

What is a glycolipid?

A

A lipid with a polysaccharide chain

22
Q

What effect does cholesterol have on the membrane?

A

Effects fluidity as it forms bonds with phospholipids making the bilayer more rigid.
More cholesterol=less fluidity

23
Q

Describe the features of diffusion.

A

High to low conc until equilibrium
Hydrophobic or small uncharged molecules move through bilayer
passive process

24
Q

Describe the features of facilitated diffusion.

A

High to low conc until equilibrium
Hydrophillic molecules or ions through channel proteins or carrier proteins
passive process

25
Q

Describe the features of osmosis

A

Movement of water molecules from a high to low conc of free water molecules/ movement of water molecules from low solute conc to high solute conc
Through bilayer or channel proteins
passive process

26
Q

Describe the features of active transport.

A

low to high conc
through carrier proteins requiring energy from ATP
active process

27
Q

Describe the features of exocytosis.

A

Bulk transport of substances out of the cell

Vesicles fuse with cell surface membrane and release their contents

28
Q

Describe the features of endocytosis.

A

Bulk transport of substances into the cell

Vesicles are created from cell surface membrane and bring their contents into the cell

29
Q

How is excess water removed from the mucus?

A
  1. Na+ actively pumped across basal membrane into tissue fluid
  2. Na+ diffuses through sodium channel in apical membrane due to change in conc
  3. Cl- diffuses down electrochemical gradient into the tissue fluid
  4. High salt conc in tissue fluid drawn water out of cells
  5. Water drawn out of mucus due to change in conc gradient (goes from high to low)
30
Q

How is water added to the mucus?

A
  1. Cl- actively pumped across basal membrane into the cell
  2. Cl- diffuses through open CFTR channel in apical membrane into the mucus
  3. Na+ diffuses down electrochemical gradient into the mucus
  4. High salt conc in mucus draws water out of cell into mucus
  5. Water taken into the cell by osmosis from the tissue fluid
31
Q

What happens in water content regulation in a person with CF?

A
  1. CFTR channel not functional or absent
  2. Na+ channel permanently open
  3. The electrochemical gradient cannot be reversed as Cl- always moves toward tissue fluid and Na+ into the cell
  4. Water is constantly removed from the mucus
32
Q

What effect does CF have on the digestive system?

A

CFTR channel is absent or not functioning so viscous mucus blocks the pancreatic duct so fewer enzymes are secreted into the small intestine.
Food is not properly digested which can lead to weight loss

33
Q

What effect does CF have on the male reproductive system?

A

Vas deferens can be missing or blocked by viscous mucus, so fewer/no sperm are released which causes infertility

34
Q

What effect does CF have on the female reproductive system?

A

A viscous mucus plug builds up in the cervix preventing sperm from swimming through to fertilise an egg in the oviduct.

35
Q

What effect doe CF have on the respiratory system?

A

Viscous mucus can not be wafted away by cilia so builds up. Bacteria are therefore not removed and so can cause lung infections as conditions are anaerobic as oxygen cannot easily diffuse through the mucus layer

Biology 1 &2 (10 decks)

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