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FUNBIO > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

What is the structure of an amino acid?

A

An amino group joined to a central carbon and hydrogen, joined to an R side group, and joined to a carboxylic group.

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2
Q

What is a peptide bond?

A
  • The carbon of the carboxyl group joins with the nitrogen of the amino group through dehydration synthesis. This bond is quite rigid and joins amino acids together to make a dipeptide
  • Free N-terminal and C-terminal of a dipeptide react further to make larger polypeptides and eventually proteins
  • Peptide bond is quite rigid, but adjacent R groups can rotate
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3
Q

What is the function of a side R group?

A

This is what differentiates between different amino acids. Gives an amino acid its chemical properties and reactivity

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4
Q

Non-polar amino acids?

A
  • Their side chains are typically just hydrocarbons (H&C)
  • Not reactive
  • Hydrophobic
  • The bigger the side chain, the more hydrophobic it gets, therefore the more electronegative it gets
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5
Q

Non-polar amino acid exceptions? Why do these exceptions work?

A
  • Tryptophan (N), Cysteine (S), Methionine (S), Phenylalanine (N)
  • S & N are relatively electronegative, therefore it doesn’t increase the polarity
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6
Q

Polar amino acids?

A
  • Hydrophilic
  • Uncharged
  • More reactive
  • Oxygen in their side group. O2 is way more electronegative than N&S, so it makes it polar
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7
Q

Acidic amino acids?

A
  • Negative side chains at a neutral pH
  • Long side chains
  • Has O in their long side chain
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8
Q

Basic amino acids?

A
  • Positive side chains at a neutral pH
  • Long side chains
  • Has N in their long side chain
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9
Q

What do the different levels of protein organisation mean?

A

They’re different ways that amino acids bond together to form different protein structures for various roles in your body

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10
Q

Primary structure?

A

The linear amino acid sequence. Peptide bonds. First level of protein organisation

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11
Q

Secondary structure?

A

Primary structures bonded together. Can either be a B-pleated sheet or an a-helix. Results from hydrogen bonding between amino acids

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12
Q

Tertiary structure?

A

Secondary structures bonded together. More folding occurs due to the covalent/hydrogen bonds between amino acids, and ionic bonds between the R groups

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13
Q

Dipeptide?

A

The amino group from one amino acid can react with the carboxylic acid from a second amino acid to form a dipeptide

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14
Q

Quaternary structure?

A
  • More than 1 polypeptide

- Beta chain bonds to the alpha chain

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15
Q

Molecular chaperones?

A
  • Assist the folding of proteins

- Specialised proteins

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16
Q

Why do proteins fold?

A

To change their function

17
Q

Hsp60?

A

Transports and refolds proteins from the cytoplasm to the mitochondrial matrix

18
Q

Hsp70?

A

Recognise exposed, unfolded regions of new protein chains. It binds to these regions, protecting them until productive folding reactions can occur

19
Q

Hsp90?

A

Stabilises proteins against heat stress, aids in protein degradation, and stabilises a number of proteins required for tumour growth

20
Q

The role of an enzyme?

A

Catalyse specific chemical reactions in our body, build (synthesis), or breakdown (digest)

21
Q

How does an enzyme work?

A

Step 1: A pair of substrate molecules bind to the active site
Step 2: The substrate interacts, forming a product
Step 3: This product detaches from the active site, and bc the substrate of the enzyme hasn’t been affected, the entire process can be repeated

22
Q

What are the 7 different functions of proteins?

A

Enzymes, Structural proteins, storage proteins, transport proteins, regulatory proteins, motile proteins, Productive proteins

23
Q

What is the function of structural proteins?

A

Strength and protect cells and tissues

24
Q

What is the function of storage proteins?

A

To store nutrients

25
Q

What is the function of transport proteins?

A

Move substances between cells and across cell membranes

26
Q

What is the function of regulatory proteins?

A

Control the activities of proteins, genes, cells and tissues ex: protein kinases: control activities of other proteins hormones (insulin)

27
Q

What is the function of motile proteins?

A

Generate movement in cells and tissues ex: action/myosin muscle contractions

28
Q

What is the function of protective proteins?

A

Defend against foreign invaders ex: antibodies

29
Q

Explain the alpha helix.

A
  • a delicate coil held together by hydrogen bonding between every fourth amino acid
  • Each hydrogen bond forms between an oxygen with a partial negative charge and a hydrogen with a partial positive charge
  • elasticity due to helical shape and hydrogen bonding
30
Q

Explain the beta pleated sheet.

A
  • held together by hydrogen bonds
  • Each chain is fully extended as each has zigzag structure
  • Strong and flexible but not elastic as the distance between the pleats is fixed
31
Q

Why do proteins have different conformations?

A

Environment
- in vivo (inside) and ex-vivo (outside)
Specialised proteins
- molecular chaperons

32
Q

What determines the biological role of a protein?

A
  • It’s structure
  • Different regions of a single protein can have different functions
  • Some proteins have 2 or globular regions (domains connected by less compact regions so each domain can have different functions)
33
Q

What are 3 things that cause a protein to become denatured?

A
  • Heat
  • pH change
  • Chemical exposure
    (causes proteins to unfold so they cant complete their function- disrupts the hydrogen + ionic bonding)
34
Q

What is the lock and key model?

A
  • Enzymes are specific to the substrate they bind to
  • Specific enzyme for specific reaction
  • Shape of protein
35
Q

Proteins?

A
  • Most enzymes are proteins
  • Polymers
  • Largely determine what a cell looks like and how it functions
36
Q

What is conformation dictated by?

A

The amino acid sequence

37
Q

What enzymes break down sucrose, proteins and lipids? What enzyme builds DNA?

A 
Sucrose = sucrase
Protein = protase
Lipid = lipase
DNA = DNA polymerase
38
Q

What are the four properties of a tertiary structure?

A
  • Disulphide bonds
  • R groups are bonded through ionic bonds
  • Amino groups are bonded through hydrogen covalent bonds
  • Hydrophilic

FUNBIO (17 decks)

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