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Biology Of The Cell > Week 2: Genetic Coding > Flashcards

Week 2: Genetic Coding Flashcards

1
Q

What is the genetic code?

A

The genetic code is the set of rules by which information encoded in mRNA sequences is translated into amino acids.

Each group of 3 nucleotides in RNA is called a ‘codon’.

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2
Q

How is mRNA formed from DNA?

A

DNA code is transcribed into mRNA, and pre-mRNA is adapted into mature mRNA.

This process involves splicing and other modifications.

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3
Q

What role do tRNAs play in translation?

A

tRNAs carry amino acids and act as adapters during protein synthesis.

They match codons in mRNA to the appropriate amino acids.

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4
Q

What is a codon?

A

A codon is a sequence of three nucleotides in mRNA that specifies a particular amino acid.

There are 64 possible codons for the 20 amino acids.

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5
Q

What is the significance of the AUG codon?

A

The AUG codon acts as a start codon and specifies the amino acid Methionine (Met).

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6
Q

What are stop codons?

A

Stop codons signal the end of the translation process.

The three stop codons are UAA, UAG, and UGA.

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7
Q

What is an Open Reading Frame (ORF)?

A

An Open Reading Frame (ORF) is the part of a gene that is translated into a protein.

It is defined by the presence of a start codon and a stop codon.

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8
Q

How many reading frames are there per strand of DNA?

A

There are three reading frames per strand of DNA.

This means that a single strand can be read in three different ways.

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9
Q

What is degeneracy in the genetic code?

A

Degeneracy refers to the phenomenon where multiple codons can code for the same amino acid.

This allows for more than one codon to specify a single amino acid.

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10
Q

What are aminoacyl-tRNA synthetases?

A

Aminoacyl-tRNA synthetases are enzymes that couple each amino acid to its corresponding tRNA.

Each amino acid has a specific synthetase.

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11
Q

What is the role of ribosomes in protein synthesis?

A

Ribosomes facilitate the binding of tRNAs to mRNA and catalyze the formation of peptide bonds between amino acids.

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12
Q

What is the process of polypeptide chain elongation?

A

Polypeptide chain elongation involves the binding of incoming aminoacyl-tRNA, the formation of peptide bonds, and the shifting of tRNAs through the ribosome.

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13
Q

Fill in the blank: The _______ is the reading frame that produces the correct protein sequence.

A

Open Reading Frame (ORF)

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14
Q

How fast does protein synthesis occur?

A

The rate of protein synthesis is about 2 amino acids per second.

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15
Q

What are polyribosomes?

A

Polyribosomes are clusters of ribosomes translating a single mRNA molecule simultaneously.

This increases the efficiency of protein synthesis.

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16
Q

What modifications might new polypeptide chains undergo to become functional?

A

New polypeptide chains may undergo folding, binding of cofactors, and post-translational modifications such as glycosylation or phosphorylation.

17
Q

True or False: Humans have approximately the same number of genes as proteins.

A

False

Humans have around 20,000 genes but potentially more than 6,000,000 proteins due to splicing and other factors.

18
Q

How many genes do humans have?

A

Around 20,000

Estimates for the number of proteins range from 20,000 to over 6,000,000.

19
Q

What process allows the number of proteins to exceed the number of genes?

A

Splicing

20
Q

What is the purpose of splicing?

A

Allows creation of different proteins from the same gene, saving resources and energy

21
Q

What is exon skipping?

A

A splicing mechanism that can lead to the evolution of new useful proteins

22
Q

What percentage of the genome is coding?

A

Surprisingly low

23
Q

What are some components of non-coding DNA?

A
  • Introns
  • Transcription promoters
  • Transcription enhancers/silencers
  • tRNAs
  • rRNAs
  • Heterochromatin
24
Q

Which fields study DNA, RNA, and proteins respectively?

A
  • DNA: Genomics
  • RNA: Transcriptomics
  • Proteins: Proteomics
25
Q

Why is studying DNA easier than studying RNA or proteins?

A

DNA is incredibly stable

26
Q

What significant advances have occurred since the structure of DNA was proposed?

A

Many significant advances in understanding the genetic code

27
Q

How can the genetic code be used in health and medicine?

A
  • Detect, screen and treat diseases
  • Identify genetic diseases for prevention
  • Cancer prevention
28
Q

Who pioneered the use of genetic fingerprinting?

A

Alec Jeffreys in the 1980s

29
Q

What historical understanding can be gained from the genetic code?

A
  • How ancient humans survived/thrived
  • How other animals went extinct
30
Q

Fill in the blank: DNA is studied by _______.

A

Genomics

Biology Of The Cell (23 decks)

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