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AS Biology > Protein Synthesis > Flashcards

Protein Synthesis Flashcards

(57 cards)

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1
Q

What are the two types of nucleic acid?

A

DNA and RNA

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2
Q

What are nucleic acids made up of?

A

Nucleotides

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3
Q

What is a nucleotide?

A

The monomer from which nucleic acids are formed

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4
Q

What is a nucleotide made up of?

A

Pentose sugar, nitrogenous base and a phosphoric acid

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5
Q

Are purines double or single ring bases?

A

Double

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6
Q

What bases are purines?

A

Adenine and guanine

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7
Q

Are pyrimidines double or single ring bases?

A

Single

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8
Q

What bases are pyrimidines?

A

Cytosine, thymine and uracil

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9
Q

What reaction makes up a nucleotide?

A

Condensation

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10
Q

What reaction joins nucleotides together?

A

Condensation reactions

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11
Q

What bonds hold nucleotides together?

A

Phosphodiester bonds

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12
Q

What does DNA polymerase do?

A

Catalyses the formation of a phosphodiester bond between two nucleotides

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13
Q

What is a phosphodiester bond?

A

Covalent bond between two nucleotides

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14
Q

What is a nucleic acid?

A

A very long thread-like macromolecule

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15
Q

How long are RNA molecules?

A

Relatively short - between 100 and thousands of nucleotides

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16
Q

What pentose is in RNA?

A

Ribose

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17
Q

What bases are in RNA?

A

Adenine, cytosine, guanine and uracil

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18
Q

What are the three functional types of RNA?

A

messenger RNA, transfer RNA and ribosomal RNA

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19
Q

What does mRNA do?

A

Carries a copy of a single gene to a cell’s ribosome

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20
Q

What does tRNA do?

A

Carries individual amino acids to the ribosomes during protein synthesis

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21
Q

What does rRNA do?

A

Forms the subunits of the ribosomes

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22
Q

How long are DNA molecules?

A

Very long, several million nucleotides

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23
Q

What is the pentose in DNA?

24
Q

What are the bases in DNA?

Study These Flashcards
A

Adenine, cytosine, guanine and thymine

25
How many polynucleotide strands in a DNA molecule?
Two
26
How many polynucleotide strands in a RNA molecule?
One
27
What bonds hold the polynucleotide chains together in DNA?
Hydrogen
28
Where are H bonds found in DNA?
Between complementary base pairings between strands
29
What are the complementary base pairings in DNA?
Adenine and thymine, cytosine and guanine
30
Why are DNA strands antiparallel?
So that the two strands fit together
31
Explain DNA replication
DNA helicase breaks H bonds between comp. base pairings and unwinds helix Separated strands act as a template w exposed bases Free nucleotides are attracted to complementary bases on strand and H bonds form DNA polymerase reforms phosphodiester bonds and proof reads DNA DNA ligase joins segments of DNA together
32
Why is it called semi conservative replication?
Because in the newly formed DNA molecule there is one parent strand from the original DNA molecule
33
What is the major role of DNA?
To make specific proteins
34
What is a gene?
A sequence of DNA nucleotide bases that encodes for the sequence of amino acids to form a single polypeptide chain
35
What is meant by the genetic code being universal?
The same triplets code for the same amino acids in all organisms
36
How many possible triplet combinations are possible with 4 bases?
64
37
What does degenerate mean?
Some amino acids are coded for by more than one base triplet
38
What is a codon?
Nucleotide base triplet on mRNA that encodes for a single amino acid
39
What is the antisense strand?
The polynucleotide strand in a DNA molecule that is always used in protein synthesis to determine the order of amino acids in a polypeptide
40
What is meant by non-overlapping?
Each base pairing is only used in one triplet
41
What does transcription do?
Forms a molecule of mRNA
42
Explain the process of transcription
DNA helicase unwinds helix and breaks H bonds Separated into sense and antisense strand Antisense strand used as template with exposed bases Complementary RNA nucleotides attracted to exposed bases and H bonds form RNA polymerase reforms phosphodiester bonds between RNA nucleotides and mRNA is formed Leaves nucleus via nuclear pores to fo to ribosomes
43
How many amino acids involved in protein synthesis?
20
44
Describe the structure of the tRNA molecule
One end has a site for the amino acid to join on to and the other end has anticodon specific to an amino acid
45
How are amino acids activated?
Specific enzymes join specific amino acids to their specific tRNA molecules
46
Explain translation
Ribosomes attach to the mRNA molecule and read the codons Complementary anticodons on the tRNA molecules slot into place in the ribosome and held in place by temporary H bonds Amino acids on the tRNA join together in condensation reactions to form peptide bonds tRNA molecules are then free to go back to the cytoplasm and be reused Process stops at stop codons
47
What are introns?
Non coding sections of DNA
48
What are extrons?
Coding sections of DNA
49
What is splicing?
When introns are cut out of the pre mRNA before it leaves the nucleus
50
What is a gene mutation?
A random and unpredictable change in the number or sequence of bases in a single gene
51
What are mutagens?
Factors that increase the chance of a mutation
52
What are some examples of mutagens?
Radiation like x rays and chemicals
53
What is a base deletion?
When one or more bases are lost from the sequence
54
What is a base insertion?
When one or more bases are inserted into the sequence
55
What is a base substitution?
When one or more bases are changed for a different base
56
What is a point mutation?
When a gene mutation only involves one base
57
What is sickle cell anaemia and how does it arise?
When oxygen cannot be transported efficiently because of a point mutation (base substitution) in the gene that codes for haemoglobin which causes the haemoglobin to clump togetherand form long fibres

AS Biology (17 decks)

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