Lecture 16 Flashcards

1
Q

Where does translation occur?

A

In the cytoplasm

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2
Q

What carries out translation?

A

The ribosomes

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3
Q

What are ribosomes?

A

Complex structures made of protein and rRNA that work like enzymes to catalyse protein synthesis

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4
Q

What are the four nucleobases in DNA

A

Adenine, cytosine, guanine and thymine

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5
Q

What are the four nucleobases in RNA

A

Adenine, cytosine, guanine and uracil

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6
Q

How many amino acids are there?

A

20

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7
Q

How is DNA read?

A

In sets of three called codons

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8
Q

What is the universal genetic code?

A

The common codon system across all life

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9
Q

What is tRNA?

A

Transfer RNA

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10
Q

What does tRNA do?

A

Reads the mRNA

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11
Q

What does the tRNA contain?

A

An anti-codon, and an amino acid attachment site

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12
Q

Why is the codon/anticodon pairing and amino acid attached so spesific?

A

To ensure the same mRNA sequence is always translated the same way to make the same protein

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13
Q

What are the three steps of translation?

A

Initiation, elongation, termination

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14
Q

What happens during initiation?

A

The ribosome, mRNA, and the first tRNA come together to form the translation initiation complex. The first tRNA always codes for met (AUG/Start)

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15
Q

What happens during elongation?

A

The ribosome moves along the mRNA, adding amino acid to the growing peptide chain

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16
Q

What happens during termination?

A

A ‘stop codon’ indicates the peptide chain has all the necessary amino acids and causes the translation complex to break apart releasing the newly formed peptide chain ready for protein folding and post-translational modification

17
Q

What is the codon redundancy?

A

There are 64 possible codons and 20 amino acids plus ‘stop’ therefore each amino acid can be coded for by multiple codons (except met and trp)

18
Q

What is the advantage of codon redundancy?

A

It allows for some flexibility in the gene sequence, without changing the protein

19
Q

What is genetic variation?

A

Differences between the same locations of DNA sequences of members of the same species. This forms alleles

20
Q

How different are humans to each other on sequence level?

A

0.1%

21
Q

Why is genetic variation important?

A

To help us determine who is who, help survival and help organisms to adapt to their environment

22
Q

What are the three different ways genetic variants can be classified?

A

Number of DNA bases involved, style of DNA sequence involved, location of the change

23
Q

What are the two genetic variants we focus on?

A

SNPs and InDel

24
Q

What is a SNP?

A

Single nucleotide polymorphism, a single base change in the DNA sequence

25
Q

What is an InDel?

A

Insertion deletion, the addition or removal of one or more bases

26
Q

What are the consequences of a non-coding variant?

A

This many change the expression of the gene as it is in the regulatory region (change the amount of protein produced)

27
Q

What are the consequences of a coding variant?

A

This may change the amino acid sequence as it is within the exon region of the gene (changed function)

28
Q

SNPs that change a codon can..?

A

Code for the same, different or a stop amino acid

29
Q

What can InDels cause?

A

A frame-shift

30
Q

What do the consequences of a missense variant depend on?

A

Where in the protein the change occurs, how chemically similar the amino acids are, whether the amino acid breaks an essential structure and the original function of the protein

31
Q

When can a genetic variant be lethal?

A

When it causes a complete loss of function

32
Q

What is haemoglobin?

A

An essential tetramer protein for transport of oxygen throughout the body

33
Q

What are the four side chains in haemoglobin?

A

2x alpha (HBA1) and 2x beta (HBB)

34
Q

What is the sickle cell anaemia mutation?

A

HBB E6V - Polar charged -> non-polar uncharged. Hb proteins clog blood vessels

35
Q

What is the methaemoglobinaemia mutation?

A

HBB H64Y - Fe2+ -> Fe3+. Unable to bind O2