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Genetics Lecture > Protein Structure and the Genetic Code (G) > Flashcards

Protein Structure and the Genetic Code (G) Flashcards

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1
Q

What is a polypeptide?

A

A chain of covalently linked amino acids

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2
Q

What does each mRNA specify?

A

It specifies a particular amino acid sequence of a particular polypeptide

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3
Q

What is a protein in comparison to a polypeptide?

A

It is a structure made of one or more polypeptides that has a distinct function within an organism

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4
Q

What is E. coli RNA polymerase?

A

It is a protein made of six interacting polypeptides

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5
Q

What is the function of RNA polymerase?

A

To synthesize RNA

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6
Q

What are amino acids?

A

They are individual monomers that make up a polypeptide

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7
Q

What is the basic structure of all amino acids?

A

There is a central carbon atom that is covalently bonded to a hydrogen atom, an amino group, a carboxyl group, and a side chain/R group

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8
Q

What is the purpose of a side chain/R group?

A

The side chain is variable in the composition of amino acids
This variation distinguishes one amino acid from another

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9
Q

How many different amino acids are there?

A

20 amino acids, all with a different side chain

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10
Q

Certain side chains share similar chemical properties. What are the four broad groups amino acids are separated into?

A
  1. Acidic side chains
  2. Basic side chains
  3. Uncharged polar (hydrophilic)
  4. Nonpolar (hydrophobic)
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11
Q

How are amino acids linked together?

A

Peptide bonds

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12
Q

How is a peptide bond formed?

A

By linking the carboxyl group of one amino acid to the amino group of another

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13
Q

How many peptide bonds can each amino acid make? Why?

A

Two peptide bonds
This is because each amino acid has one carboxyl and one amino group

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14
Q

What is the orientation of all amino acids and polypeptides?

A

The amino groups are directed toward one end of the polypeptide and the carboxyl groups are directed toward the other end

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15
Q

What is found at the ends of a polypeptide?

A

There is an amino acid with a free amino group in one end
There is an amino acid with a free carboxyl group at the other end

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16
Q

What is the end with a free amino group called?

A

Amino terminus
N terminus

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17
Q

What is the end with a free carboxyl group called?

A

Carboxyl group
C terminus

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18
Q

What is a polypeptide’s conformation?

A

It acquires a unique 3D shape after being synthesized (i worded this weird mb)

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19
Q

How are conformations formed in polypeptides?

A

By interactions between different functional groups within the amino acids

20
Q

What is the conformation of polypeptides dependent on?

A

On the amino acid sequence of the polypeptide

21
Q

What is considered the primary structure of a polypeptide? Why?

A

The amino acid is considered the primary structure because conformation is dependent on it

22
Q

What are the different levels of conformation?

A

Secondary
Tertiary
Quarternary

23
Q

What is secondary structure?

A

The conformation within a particular area of one polypeptide

24
Q

What is tertiary structure?

A

The overall conformation of one polypeptide

25
Q

What is quarternary structure?

A

The overall conformation of a protein that contains two or more polypeptides

26
Q

What kind of structures are found on a protein consisting of one polypeptide?

A

Primary
Secondary
Tertiary
(NO quarternary)

27
Q

Where is a protein’s function acquired?

A

From its conformation

28
Q

What happens to a protein’s function if its conformation is lost?

A

The function will also be lost

29
Q

How is each amino acid specified?

A

It is specified by a group of three bases called a codon

30
Q

What are the other names for codons?

A

Triplet codons
Triplets

31
Q

Why is the order of bases in codons important?

A

Each codon specifies a different amino acid
EX: The codon CCA specifies a different amino acid than CAC or ACC

32
Q

If codons are a genetic language, what are the bases in the gene/mRNA and what are the codons?

A

The bases would be considered the alphabet and the codons would be the words

33
Q

What do codons (the “words”) make up?

A

The genetic code

34
Q

What does translation do to the genetic code?

A

It turns it into the amino acid sequence of a polypeptide

35
Q

How mano possible codons exist?

A

64 codons

36
Q

How many codons code for amino acids?

A

61 codons

37
Q

There are 61 codons for amino acids but only 20 amino acids. What does that mean?

A

That means most amino acids are encoded by more than one codon

38
Q

Which amino acids are encoded by a single codon?

A

Methionine and tryptophan

39
Q

Why is the genetic code considered to be degenerate?

A

Because an amino acid may be encoded by more than one codon

40
Q

Which codons do not encode amino acids?

A

UGA
UAA
UAG

41
Q

What is the function of the three codons that do not encode amino acids?

A

They function as translation termination signals
STOP codons

42
Q

What does the codon AUG labeled as?

A

Methionine
Start

43
Q

What is the rule for the codon AUG?

A

All AUG codons specify methionine, but not all AUG codons are translation start signals

44
Q

Which AUG codon is considered the START codon?

A

Only the first AUG in an mRNA can be the start codon
Any other AUG is considered to be methionine

45
Q

What is the genetic code sometimes referred to as? Why?

A

The universal code
This is because the genetic code is almost identical in all organisms

46
Q

What are some exceptions to the universal code?

A

Variations have been found in the mitochondrial DNA of many eukaryotes, and in some bacterial and protists species

Genetics Lecture (17 decks)

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