Gene Expression, Protein Synthesis, and DNA Technology: Key Concepts and Processes

How does protein synthesis relate to gene expression?

Protein synthesis is the process by which a gene is used to make a protein.

Approximately what percentage of the human genome is coding DNA?

1-2%.

About how many genes do humans have?

Approximately 20,000.

What is a gene?

A segment of DNA that codes for a protein or functional RNA.

What does it mean when a gene is 'turned on'?

The gene is being transcribed into mRNA.

Over-expressing a gene results in:

More mRNA and more protein.

What is the primary role of proteins in the body?

Perform most cellular functions.

Proteins are made of:

Amino acids.

How many naturally occurring amino acids are used to build proteins?

20.

What are the two main steps of protein synthesis?

Transcription and translation.

Where does transcription occur in eukaryotic cells?

Nucleus.

Where does translation occur?

Ribosome.

Which molecule carries genetic instructions from DNA to the ribosome?

mRNA.

Which enzyme builds mRNA during transcription?

RNA polymerase.

RNA polymerase reads DNA in which direction?

3′ → 5′.

What must bind to DNA for transcription to begin?

Promoter.

Which parts of mRNA are removed during splicing?

Introns.

Where does RNA splicing occur?

Nucleus.

What structure performs splicing?

Spliceosome.

Why can humans make many proteins with relatively few genes?

Alternate splicing.

What is the purpose of the 5′ cap on mRNA?

Protects mRNA and helps ribosome binding.

The poly-A tail primarily:

Stabilizes mRNA.

DNA is described as 'triplet.' What does this mean?

Three bases code for one amino acid.

A codon is found on:

mRNA.

An anticodon is found on:

tRNA.

What is the purpose of PCR?

Amplify a specific DNA segment.

What are the three main steps of PCR?

Denaturation, annealing, extension.

After 30 cycles of PCR, approximately how many copies are produced?

Over 1 billion.

A primer dimer indicates:

Primers bound to each other instead of DNA.

Which enzyme unwinds DNA?

Helicase.

DNA polymerase builds DNA in which direction?

5′ → 3′.

Okazaki fragments are found on the:

Lagging strand.

DNA moves toward which electrode in gel electrophoresis?

Positive.

Smaller DNA fragments move:

Faster and farther.

What is the purpose of loading dye?

Add weight and color.

DNA base pairing rules are maintained by:

Hydrogen bonds.

Which bases are purines?

A and G.