Lecture 4

Question 1

Organic molecules; What do proteins do?

Answer 1

They give structural support, facilitate chemical reactions by acting as a catalyst. They do practically everything. They typically make up 50% of organic matter in an animal body.

Question 2

Organic molecules; What do nucleic acids do?

Answer 2

They encode & transmit, and store genetic information. There are two types of nucleic acids; DNA and RNA, which are different in structure and function.

Question 3

Organic molecules; What do carbohydrates do?

Answer 3

They provide a source of energy and make up a cell wall in; bacteria, plants and algae.

Question 4

Organic molecules; What do lipids do?

Answer 4

They make up the cell membranes, they store energy and act as signalling molecules.

Question 5

Most organic molecules are what? (think of monomers together)

Answer 5

Polymers, which are made up of monomers (single units) that are covalently bonded to make polymers. A polymer is essentially a chain/ring of monomers.

Question 6

How do you build polymers?

Answer 6

Through dehydration synthesis or a condensation reaction which means the same thing. It basically means the removal of H2O to make a longer polymer.

Question 7

How do you break down polymers?

Answer 7

Through a hydrolysis reaction which means the addition of H2O to make a smaller polymer.

Question 8

What are 8 different types of proteins?

Answer 8

1. Enzymatic proteins
2. Defensive proteins
3. Storage proteins
4. Transport proteins
5. Hormonal proteins
6. Receptor proteins
7. Contractile proteins
8. Structural proteins

Question 9

Types of proteins; What are Enzymatic proteins?

Answer 9

Selective acceleration of chemical reactions, like digestive enzymes are used as a catalyst to quicken the hydrolysis of bonds in food molecules.

Question 10

Types of proteins; What are defensive proteins?

Answer 10

They’re used to protect the body against diseases, like antibodies since they inactivate/help destroy viruses & bacteria.

Question 11

Types of proteins; What are storage proteins?

Answer 11

They store amino acids, like plants have storage proteins in their seeds. Also, ovalbumin is the protein in an egg white, which is used as an amino acid source, which would be used to develop an embryo.

Question 12

Types of proteins; What are transport proteins?

Answer 12

They transport substances, like hemoglobin which is a protein of vertebrate blood that contains iron. It transports oxygen from the lungs to other areas of the body. Another example would be other proteins that transport molecules across cell membranes.

Question 13

Types of proteins; What are hormonal proteins?

Answer 13

They coordinate an organisms’ activity, like insulin which is a hormone that’s secreted by the pancreas. Insulin causes other tissues to take up glucose, which regulates blood sugar concentration.

Question 14

Types of proteins; What are receptor proteins?

Answer 14

It’s the response of a cell responding to chemical stimuli, like receptors in the membrane of nerve cells, which detect signalling molecules that are released by other nerve cells.

Question 15

Types of proteins; What are contractile proteins?

Answer 15

Their function is to move, like motor proteins are responsible for the undulations of cilia and flagella, etc. In addition, another example would be Actin and Myosin proteins, which are responsible for the contraction of muscles.

Question 16

Types of proteins; What are structural proteins?

Answer 16

They’re for support, like collagen and elastin proteins which provide a fibrous framework in animal connective tissues.

Question 17

In proteins, what are the monomers? Explain a bit.

Answer 17

Amino acids.
Monomers compose polymers, just like amino acids compose proteins. The links between amino acids (monomers) are covalent bonds (in this case=peptide bonds).

Question 18

What are the covalent bonds between amino acid called? Explain them a bit.

Answer 18

Peptide bonds, which are formed through a condensation reaction since it generates water. These peptide bonds specifically occur between an amino acid from the amino group and one amino acid from the carboxyl group.

Question 19

What’s a dipeptide?

Answer 19

It’s a molecule made up of two amino acids.

Question 20

What’s a polypeptide?

Answer 20

It’s a molecule made up of more than two amino acids.

Question 21

What’s the primary structure of a protein?

Answer 21

It’s a sequence of linked amino acids which are linear-ly linked. Each protein has a different (unique) sequence of amino acids. Proteins are always “read” from N-terminus to C-terminus.

Question 22

What’s the secondary structure of a protein?

Answer 22

There are interactions between stretches of amino acids that lead to the formation of a helix and B sheets. These interactions are between the carboxyl group (in one peptide bond) and the amide group (in another peptide bond). There interactions are the formation of H-bonds which are the backbone of amino acids (not R groups).

Question 23

What’s the tertiary structure of a protein?

Answer 23

It’s a 3D configuration of one polypeptide chain, usually made of various secondary structure components. It’s determined by the spatial distribution in the molecule of hydrophilic “R groups” and hydrophobic “R groups”. Ultimately it determines the function of the protein.

Question 24

Tertiary structure of a protein; What are hydrophobic amino acids?

Answer 24

They cause the polypeptide to fold.

Question 25

Tertiary structure of a protein; What are hydrophilic amino acids?

Answer 25

They permit the H-bonds to form, along with other bonds, which causes the polypeptide to hold together.

Question 26

Tertiary structure of a protein; what are H-bonds of proteins/amino acids?

Answer 26

These are formed between polar bonds. It is at the surface of the protein that these polar amino acids are located.

Question 27

Tertiary structure of a protein; what are ionic bonds?

Answer 27

It’s between the acid and base (cation & anion pair or salt-bridge).

Question 28

Tertiary structure of a protein; what are hydrophobic interactions?

Answer 28

At the centre of the protein, hydrophobic areas tend to cluster. Not at the surface. Van Der Waals/dispersive forces maintain these interactions.

Question 29

Tertiary structure of a protein; what are disulfide bridges?

Answer 29

They are covalent bonds between R groups (of cysteines), which tend to keep proteins in a specific structure. For example, linking chains in an antibody.

Question 30

What’s the quaternary structure of a protein?

Answer 30

They are proteins that are made up of more or exactly two polypeptide chains (or subunits), each of them having a tertiary structure. They come together to make a higher-order quaternary structure.

Question 31

What’s denaturation?

Answer 31

The tertiary structure of the protein determines its function. To unfold/denature proteins, the process is typically done by chemical treatments or high temperature (through breaking H-bonds). Denatured proteins lose their functional activity.

Question 32

What are purines (bases found in DNA)?

Answer 32

They have a double ring structure; Adenine and Guanine.

Question 33

What are pyrimidines (bases found in DNA)?

Answer 33

They have a single ring structure; Thymine and Cytosine.

Question 34

What are phosphodiester bonds?

Answer 34

They link nucleotides together to form a DNA strand. It’s a covalent bond that connects the 3 carbon of one nucleotide to the 5 carbon of the next nucleotide in the line through the 5 phosphate group. It’s a stable bond that can withstand stress like heat and pH, which is why DNA is so stable.

Question 35

How does complementary base paring work?

Answer 35

The bases pair through hydrogen bonds. These pairings allow the strands of DNA to be in the shape of a double helix.

Question 36

Complementary base paring: What does antiparallel mean?

Answer 36

It means that the two sugar phosphate backbones run in opposite 5’->3’. These backbones stabilize the structure through H-bonds.

Question 37

What are the complementary base paring? Name them

Answer 37

Adenine & Thymine are paired together.
%Adenine=%Thymine

Guanine & Cytosine are paired together.
%Guanine=%Cytosine

To remember: “At The Gangster’s Crib”

Question 38

Why is DNA in the form of a double helix?

Answer 38

It’s two strands because they can be used as two templates for copying, you can store more info in less space. It’s a very stable structure and protects the “blueprint” from being damaged.

Question 39

What’s the “central dogma”?

Answer 39

The processes where the genetic info in DNA is used to make a protein called “The Central Dogma” of molecular biology.

Question 40

What’s RNA? (not the purpose)

Answer 40

Ribonucleic acid. It’s a polymer that is made up of ribonucleotides. It’s bases are (A,G,U or C). U is uracil. It’s single stranded which allows it to form itself into 3D molecules.

Question 41

What’s the purpose of RNA?

Answer 41

It’s used as a messenger of information (mRNA=messenger RNA).
It’s used when translating the genetic code, which means it transfers RNA (tRNA).
It’s used to build new proteins (enzymatic function), which means ribosomal RNA (rRNA).