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Biology unit 1 > Molecules (proteins)- topic 1 > Flashcards

Molecules (proteins)- topic 1 Flashcards

1
Q

what elements do protein molecules contain?

A

-carbon
-hydrogen
-oxygen
-nitrogen
-sulfur (sometimes)

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2
Q

are proteins polymers?

A

-yes and they are formed from amino acid sub units

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3
Q

how many amino acids are there and what is the effect of this?

A

-there are 20
-this allows for infinite amino acid arrangements in a protein

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4
Q

how is the shape of a protein determined?

A

-through the sequence of amino acids

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5
Q

what is the general structure of a protein look in book and learn

A

bhdwVYIAWDK

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6
Q

how do amino acids differ?

A

-through their R groups which can range anywhere between a single hydrogen to a CH3 group

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7
Q

what happens to the R group if sulfur is present in the amino acid?

A

-the sulfur atom will be contained inside the R group

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8
Q

how are amino acids linked together? what reaction occur and where does it take place?

A

-by peptide bonds
-condensation reactions take place which involve the loss of water
-condensation reactions take place between the amino group of one amino acid and the carboxyl group of another amino acid

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9
Q

what is it called when two amino acids join?

A

-dipeptide

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10
Q

what elements are in an amino group?

A

-nitrogen bonded to two hydrogens

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11
Q

what elements are present in a carboxyl group?

A

-carbon single bonded to hydroxyl group and the carbon is double bonded to an oxygen

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12
Q

how can a peptide bond between two amino acids be broken?

A

-via a hydrolysis reaction, the release of the two amino acids with the addition of water

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13
Q

what is is called when many amino acids are joined in a chain?

A

-many can be joined in a chain through peptide bonds to form a polypeptide chain

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14
Q

what is the primary structure of protein?

A

-the primary structure of a polypeptide chain is the sequence of amino acids in the chain in which the amino acids are linked together by peptide bonds

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15
Q

look at the diagrams of each stage of protein and memorize them

A

-bdhgdgh

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16
Q

what is the secondary structure of protein? what does the ends of the polypeptide chains contain?

A

-at either end of the polypeptide chain the amino acids contain an -NH (amino group) and a -C=O (carboxyl group)
-the O of the carboxyl group has a negative charge and the H of the amino group has a positive charge, this allows the formation of hydrogen bonds that allow the secondary structures to be formed

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17
Q

what are the two secondary structures of protein?

A

-a- helix
-b-pleated sheets

18
Q

what is the a-helix secondary structure of protein consist of?

A

-in a-helix the hydrogen bonds are formed between amino acids are regular intervals in the sequence
-the bond twist the chain of amino acids cause it to spiral into a helical shape

19
Q

what does the b-pleated sheet secondary structure of protein consist of?

A

-these are more rigid and less flexible than a-helix
-they are formed by small sections of the polypeptide chain, orientated in opposite directions lying adjacent to each other
-hydrogen bond are formed between the carboxyl and amino groups

20
Q

what is the tertiary structure of amino acids?

A

-further folding of the secondary structure
-this additional folding gives protein its unique 3D shape and is consequence of the range of bonds formed between the R groups of amino acids in the chain

21
Q

what is the effect of using hydrogen bonds in the tertiary structure of protein??

A

-are numerous but are relatively weak and are easily broken

21
Q

what are the three bonds involved in the tertiary structure of protien?

A

-hydrogen bonds
-ionic bonds
-disulfide bridges

22
Q

what is the effect of using ionic bonds in the tertiary structure of protein?

A

-formed between the amino and carboxyl group in some amino acids
-they are stronger than hydrogen bonds but they are damaged by changes in pH

23
Q

what is the effect of using disulfide bridges in the tertiary structure of protein?

A

-they are covalent bonds formed between the R groups of sulfur containing amino acids
-they are very strong bond and are important to give strength to structural proteins such as collagen

24
Q

how do hydrophobic interactions further influence the tertiary structure?

A

-hydrophobic interactions involve amino acids with hydrophobic R groups which usually take position within the molecule surrounded by other parts of the polypeptide as opposed to water

25
Q

what is the quaternary structure of protein?

A

-some proteins consist of two or more polypeptide chains bonded together usually by disulfide bridges
-some quaternary proteins contain non protein groups known as prosthetic groups that are important in their function, the name of these proteins are conjugated proteins

26
Q

what are two examples of these conjugated proteins?

A

-glycoproteins which are important in membrane functions
-hemoglobin is a conjugated protein that contains four polypeptide chains an each chain is attached to an iron rich haem group which essential in the blood for the transport of oxygen

27
Q

what are the types of groups protein can be grouped into?

A

-fibrous proteins and globular proteins

28
Q

what are fibrous proteins?

A

-consist of polypeptide chains that form fibers or sheets
-the parallel chains are linked by cross bridges to form strong stable molecules and so their job is primarily structural support

29
Q

what is one example of a fibrous protein? where is it found?

A

-collagen
-each collagen ,molecule contains 3 identical a-helix polypeptide chains intertwined and held together by hydrogen bonds
-collagen is found in tendons that link muscle to bones and it is very important that is is a strong molecule so that it does not stretch when tension is applied

30
Q

what are globular proteins and what is one example of a globular protein?

A

-have metabolic role and include enzymes and antibodies which are important in the formation of proteins 3D shape
-hemoglobin is a globular protein

31
Q

what are prions?

A

-particular type of protein found in mammals in the nervous system that is involved in synaptic transmission

32
Q

what is the normal form of prions?

A

-PrP

33
Q

what happens if the normal form of prions convert?

A

-they can convert to the disease causing form (PrPsc)
-if the disease causing form is present it can act as a template causing other normal prions to convert to the disease causing prions

34
Q

how does the disease causing prions differ structurally to normal prions?

A

-the disease causing form contains more beta sheets

35
Q

what happens when the disease causing form is present in the body?

A

-it leads to a chain reaction causing the number of disease causing prions to increase meaning the prions proteins become more misfolded and changes form the PrP to the PrPsc
-over time the number pf harmful prions with tightly packed beta sheets increases to reach threshold

36
Q

what happens when the number of disease causing prions reaches the threshold?

A

-it can cause neurodegenerative disorders in the brain and eventually death

37
Q

what are the two key features of disease causing prions?

A

-they can replicate and infect

38
Q

how long does the incubation period last for disease causing pirons?

A

-5 to 20 years

39
Q

what are the three ways that the disease causing form can arise?

A

-normal form can spontaneously adopt the PrPsc form
-mutations in the DNA that codes for the prions meaning the disease form is passed from parent to offspring
-through eating prion rich contaminated foods that contain the disease causing form

40
Q

what are the three prion diseases?

A

-scrapie in sheep
-BSE or Bovine Spongiform Encephalopathy or mad cows disease that affects cattle through eating contaminated foods
-vCJD or variant Creutzfeldt- Jakob disease which is a human form of mad cows disease that is acquired by humans through eating contaminated beef products containing the disease causing form

Biology unit 1 (11 decks)

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