Unit 7: Gene Expression and Protein Synthesis

How are DNA and RNA similar?

• Both are nucleic acids made of nucleotides composed of a phosphate, a sugar, and a nitrogen base.

• DNA contains uracil while RNA contains thymine.

• Only DNA is found in cells.

• RNA is double-stranded like a twisted ladder.

Describe three differences between DNA and RNA.

• DNA is double-stranded; RNA is single-stranded.

• DNA contains deoxyribose; RNA contains ribose.

• DNA uses thymine; RNA uses uracil.

• DNA and RNA have identical nitrogen bases with no differences.

• RNA is found only in the nucleus and never in the cytoplasm.

What are the two parts of protein synthesis?

• Transcription and translation.

• Replication and transcription.

• Translation and mitosis.

• Replication and meiosis.

Briefly explain transcription or translation. Select the statements that correctly explain either process.

• Transcription occurs in the nucleus where mRNA copies the genes from DNA and carries the code to ribosomes.

• Translation occurs at ribosomes where amino acids are linked in a specific sequence to form a polypeptide according to mRNA instructions.

• Transcription is the process of duplicating the entire cell’s DNA before division.

• Translation is when DNA is converted into RNA inside the nucleus.

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Where does transcription take place?

• In the nucleus

• In the cytoplasm

• On ribosomes

• In the mitochondria

What is the product of transcription?

• Messenger RNA (mRNA)

• A protein

• A copy of DNA

• Transfer RNA (tRNA)

Where does translation take place?

• On ribosomes in the cytoplasm

• In the nucleus

• In the Golgi apparatus

• In lysosomes

What is the product of translation?

• A polypeptide chain, or protein

• Messenger RNA (mRNA)

• A copy of DNA

• A lipid molecule

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Turn and Talk: The genetic code on a codon chart is redundant. Explain what this means.

• Each codon can code for multiple different amino acids.

• Multiple different codons can code for the same amino acid.

• The codon chart is different for each species.

• Codons overlap so that one base is shared between adjacent codons.

Using the codon chart, identify the amino acid that is coded by the following mRNA codon UAC.

• Phenylalanine

• Tyrosine

• Cysteine

• Tryptophan