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Chapter 2

This document defines terms related to genetics and DNA, and provides explanations of DNA replication, how the base sequence of DNA is conserved during replication, the process of translation in cells, a comparison of DNA transcription and translation, and the relationship between polypeptides and genes. It describes that DNA replication is semi-conservative, with one old strand and one new strand forming two identical daughter molecules. Translation is the process by which the base sequence of mRNA is converted to an amino acid sequence using tRNAs, ribosomes, and complementary base pairing between codons and anticodons. Genes contain the information to make both mRNA and polypeptides, with the genetic code being universal across all living organisms.

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77 views2 pages

Chapter 2

This document defines terms related to genetics and DNA, and provides explanations of DNA replication, how the base sequence of DNA is conserved during replication, the process of translation in cells, a comparison of DNA transcription and translation, and the relationship between polypeptides and genes. It describes that DNA replication is semi-conservative, with one old strand and one new strand forming two identical daughter molecules. Translation is the process by which the base sequence of mRNA is converted to an amino acid sequence using tRNAs, ribosomes, and complementary base pairing between codons and anticodons. Genes contain the information to make both mRNA and polypeptides, with the genetic code being universal across all living organisms.

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Term Definition

Degenerate More than one codon for an amino acid


Universal All living organisms have this code

Explain the replication of DNA


- Production of DNA is semi-conservative
- One old strand and one new strand
- Double helix separated by breaking H-bonds by helicase
- Leading strand acts as template
- A with T, C with G
- Nucleotides linked by DNA polymerase
- Daughter DNA molecules rewind
- Daughter stand identical to parent strand

Explain how the base sequence of DNA is conserved during replication


- DNA replication is semi-conservative
- DNA is split into two strands
- Nucleotides are assembled on template stand by complementary base pairing
- A with T and C with G
- Strands newly formed on each stand is identical to other template strand
- DNA polymerase used
- Base pairing ensures that the information encoded in one DNA molecule is passed to others

Explain the process of translation in cells


- Translation is the process to convert base sequence on mRNA into an amino acid sequence
- mRNA attaches to ribosome
- Many ribosomes bind to the same mRNA
- mRNA carries codons each coding for one amino acid
- tRNA each have specific anticodon
- tRNA carries specific amino acid
- tRNA anticodon binds to codon in the mRNA by complementary base pairing
- A second tRNA binds to next codon
- Two amino acids bind together
- first tRNA detaches
- ribosome moves along mRNA
- another tRNA binds to next codon
- continues until stop codon is reached
- stop codon has no corresponding tRNA, causes release of polypeptide

Compare DNA transcription with translation


- Both in 5’ to 3’ direction
- Both require ATP
- DNA is transcribed and mRNA is translated
- Transcription produces RNA and translation produces polypeptides
- RNA polymerase for transcription and ribosome for translation
- Transcription in the nucleus, translation in the cytoplasm
- tRNA needed for translation but not transcription
Explain the relationship between polypeptide and genes
- Genes contain information for making polypeptides
- Genes also contain information to make mRNA
- Stored as codon sequences
- Genetic information is transcribed to mRNA
- mRNA needed to carry genetic message out of nucleus
- Ribosomes are sites for polypeptide synthesis
- mRNA, tRNA and ribosomes essential for translation
- Translation links amino acids to make polypeptide
- Genes can be mutated and result in synthesis of wrong polypeptide
- Universality of genetic code means all organisms show same relationship between polypeptides
and genes


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