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B8- DNA, GENES AND PROTEIN SYNTHESIS > 8.1- GENES AND THE GENETIC CODE > Flashcards

8.1- GENES AND THE GENETIC CODE Flashcards

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Biology 101 flashcards
1
Q

What is a gene?

A

section of DNA that contains coded information for making polypeptide + functional RNA

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2
Q

What is the coded information in the form of in a gene?

A

specific sequence of bases along DNA molecule

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3
Q

What do polypeptides make up?

A

proteins

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4
Q

As polypeptides make up proteins, what do genes determine?

A

genes determine proteins of organism

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5
Q

What are enzymes an example of?

A

proteins

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6
Q

What do enzymes control?

A

control chemical reactions

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7
Q

As enzymes control chemical reactions, what are they responsible for?

A

organism’s development + activities

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8
Q

What determines the nature + development of all organisms?

A

genes + environmental factors

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9
Q

What is the particular position of a gene on a section of DNA called?

A

locus

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10
Q

What can a gene code for? (2)

A

amino acid sequence of polypeptide
or
functional RNA, including ribosomal RNA + transfer RNAs

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11
Q

How many genes does one DNA molecule carry?

A

carries many genes

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12
Q

Why did scientists suggest there must be a minimum of three bases that codes for each amino acid: number of amino acids?

A

only 20 different amino acids regularly occur in proteins

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13
Q

Why did scientists suggest there must be a minimum of three bases that codes for each amino acid: what each amino acids must have?

A

each amino acid must have its own code of bases on DNA

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14
Q

Why did scientists suggest there must be a minimum of three bases that codes for each amino acid: number of bases?

A

only 4 different bases (adenine, guanine, cytosine + thymine) present in DNA

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15
Q

Why did scientists suggest there must be a minimum of three bases that codes for each amino acid: what if each base coded for a different amino acid?

A

if each base coded for a different amino acid, only 4 different amino acids could be coded for

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16
Q

Why did scientists suggest there must be a minimum of three bases that codes for each amino acid: what if a pair of bases were used for an amino acid?

A

using pair of bases, 16 (4^2) different codes possible, which is still inadequate

17
Q

Why did scientists suggest there must be a minimum of three bases that codes for each amino acid: what if three bases were used for an amino acid?

A

three bases produces 64 (4^3), more than enough to satisfy requirements of 20 amino acids

18
Q

As the code has three bases for each amino acid, what is each one called?

A

a triplet

19
Q

As there are 64 possible triplets and only 20 amino acids, what follows?

A

some amino acids coded for by more than one triplet

20
Q

What are a few amino acids coded for by?

A

only a single triplet

21
Q

What are most of the amino acids coded for by?

A

between two and six triplets each

22
Q

Why is the code known as a ‘degenerate code’?

A

most amino acids coded for by more than one triplet

23
Q

How is a triplet always read?

A

in one particular direction along the DNA strand

24
Q

What is the start of a DNA sequence always?

A

code for polypeptide always same triplet

25
Q

What does the start the DNA sequence triplet code for?

A

amino acid methionine

26
Q

What happens if the first methionine molecules doesn’t form part of the final polypeptide?

A

it’s later removed

27
Q

What do three triplets that do not code for an amino acid called?

A

‘stop codes’

28
Q

What do ‘stop codes’ mark?

A

end of polypeptide chain

29
Q

What does it mean that the code is non-overlapping?

A

each base in sequence read only once

30
Q

What does it mean the code is universal?

A

with a few minor exceptions each triplet codes for same amino acid in all organisms

31
Q

What is the code being universal indirect evidence for?

A

evolution

32
Q

What does much of the DNA in eukaryotes not do?

A

do not code for polypeptides

33
Q

What are coding sequences called?

A

exons

34
Q

What are non-coding sequences called?

A

introns

35
Q

What do some genes code for?

A

ribosomal RNA + transfer RNAs

B8- DNA, GENES AND PROTEIN SYNTHESIS (5 decks)

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