Protein Synthesis and Genetic Engineering Study Guide

In what phase of the cell cycle does protein synthesis take place?

G1 and G2 phases

What is the process called that converts DNA into RNA?

transcription.

Where does transcription occur in eukaryotes and prokaryotes?

In eukaryotes, transcription occurs in the nucleus; in prokaryotes, it occurs in the cytoplasm.

What enzyme adds nucleotides to the template strand during transcription?

RNA Polymerase.

What sugar does DNA use? What sugar does RNA use?

DNA uses deoxyribose sugar and RNA uses ribose sugar.

What is messenger RNA?

Messenger RNA (mRNA) carries instructions from DNA to the ribosomes for protein synthesis.

What is ribosomal RNA?

Ribosomal RNA (rRNA) forms the core structure of ribosomes and helps in protein synthesis.

What do transfer RNAs do?

Transfer RNAs (tRNAs) carry amino acids to the ribosome during protein synthesis.

How is mRNA edited before it leaves the nucleus?

Introns are removed and exons are joined together.

What is a ribozyme?

A ribozyme is an RNA molecule that can catalyze chemical reactions.

What does RNA interference (RNAi) do?

RNAi blocks gene expression and is used by scientists to study gene function and develop therapies.

What is the process called that uses RNA to synthesize proteins?

translation.

What is the ratio of nucleotides to amino acids?

The ratio is 3:1, as each amino acid is coded by a sequence of three nucleotides (a codon).

What is a codon?

A group of three consecutive nucleotides on mRNA that codes for a single amino acid.

Why is the genetic code described as redundant?

Because multiple codons can specify the same amino acid, providing protection against mutations.

What is the start codon and how many stop codons are there?

AUG, three stop codons: UAA, UAG, UGA.

Where are ribosomal subunits assembled?

within the nucleolus in eukaryotic cells.

What is associated with the ribosome besides RNA?

Ribosomal proteins

What are the three binding sites on a ribosome?

The A site (aminoacyl), P site (peptidyl), and E site (exit).

What is the primary role of tRNA?

To translate mRNA codons into amino acids and add the correct amino acid to the growing polypeptide chain.

What are the three nucleotides at the bottom of the tRNA called?

anticodon.

What are the three stages of translation?

Initiation, elongation, and termination.

What codon appears on the A site during initiation?

The start codon AUG

What is the longest stage of translation?

Elongation is the longest stage because it involves repeated processes of codon recognition and amino acid addition.

How much energy is used per peptide bond formed?

The formation of each peptide bond requires the equivalent of 4 ATP molecules.

At what stage do protein release factors bind to the mRNA codon?

termination stage

What is the difference between the protein release factor and other tRNAs?

The protein release factor terminates translation, whereas tRNAs bring amino acids to the ribosome.

Where does translation take place in the cell?

Translation takes place on ribosomes in the cytoplasm.

What is a polyribosome?

A polyribosome is a group of ribosomes attached to a single mRNA molecule.

What is the rough endoplasmic reticulum (RER)?

The rough endoplasmic reticulum is the ER with ribosomes attached.

Where do proteins go to receive sugar attachments after they are made?

Golgi apparatus

What is the evidence for the 'RNA World' theory?

RNA can store genetic information and catalyze chemical reactions, unlike DNA.

What is a mutation?

A mutation is a change in the DNA sequence, which can be caused by replication errors or exposure to mutagens.

What is a point mutation?

A point mutation is a genetic alteration of a single nucleotide base.

Why are insertion/deletion mutations considered worse than substitution mutations?

They cause a frame-shift, altering the reading frame of codons.

What is the mutation rate in humans?

Approximately 1 in 10 billion nucleotides per generation.

Why are most point mutations considered neutral?

They often occur in non-coding regions or do not change the protein produced.

What is the role of mutations in evolution?

Mutations create genetic variation, which is necessary for natural selection.

What did Linus Pauling discover using the amino acid sequences of hemoglobin?

Mutation rates are proportional to evolutionary distance.

Why are mitochondrial mutation rates evidence of human evolution?

They provide a genetic timeline for human divergence from other species.

Do all cells in a multicellular organism transcribe the same genes?

No, different cells express different sets of genes despite having the same DNA.

What is a transcription factor?

A transcription factor is a protein that regulates gene transcription by binding to DNA.

What is an operon?

An operon is a group of genes regulated together by a single promoter.

What is the promoter site in an operon?

The specific DNA sequence where RNA polymerase binds to initiate transcription.

What attaches to the promoter site to transcribe the genes?

RNA polymerase with transcription factors.

What can block the promoter site?

Repressor proteins can bind to the operator, blocking RNA polymerase.

What can release the block on the promoter site?

Inducers can cause repressor proteins to release from the promoter site.

What is the 'on' switch for the lac operon?

The presence of lactose.

How many genes are in the lac operon?

The lac operon contains three genes: lacZ, lacY, and lacA.

What molecule attaches to a histone to prevent gene transcription?

Methyl groups attach to histone tails to turn genes off.

What tool do scientists use to transfer small amounts of liquids?

Pipettes are used for transferring small amounts of liquids.

What instrument would you use to transfer 5 microliters of liquid?

You would use a micropipette, specifically a P20 for 5μl.

What tool do scientists use to separate DNA fragments by size?

Gel electrophoresis separates DNA fragments using an electric field.

What is the overall charge of a DNA molecule?

The overall charge of DNA is negative.

What pulls the DNA during gel electrophoresis?

An electric field pulls the DNA.

Why do smaller DNA fragments move faster in gel electrophoresis?

Smaller fragments experience less resistance in the gel.

Why do you include a DNA marker in gel electrophoresis?

A DNA marker provides a reference for estimating the size of unknown DNA fragments.

What is a plasmid?

A plasmid is a small, circular DNA molecule independent of chromosomal DNA.

How do humans use plasmids?

Humans use plasmids for cloning, transferring, and manipulating genes.

What enzyme do scientists use to cut DNA at specific sites?

Restriction enzymes are used to cut DNA at specific sites.

What is the first restriction enzyme discovered in E. coli?

The first restriction enzyme discovered is EcoRI.

What gene is included on a plasmid for isolation on ampicillin?

An ampicillin resistance gene.

What gene do scientists use to make a molecule glow red?

The gene for a red fluorescent protein (RFP).

What is the process of putting foreign DNA into a bacterial cell called?

The process is called transformation.

What turns on the arabinose operon in pARA-R plasmid?

Adding arabinose to the growth medium turns on the arabinose operon.