Genetics and Cell Control: Mutations, Gene Expression, and Development

What is a mutation?

A random change in DNA sequence.

What are the four nucleotide bases in DNA?

Adenine, thymine, guanine, and cytosine.

What base does RNA use instead of thymine?

Uracil.

What is a codon?

A sequence of 3 nucleotide bases on mRNA that codes for an amino acid.

What does it mean that the genetic code is degenerate?

Usually more than one codon codes for the same amino acid.

What is a nonsense mutation?

A mutation that occurs in one of the three stop codons.

What is a mis-sense mutation?

A mutation that results in a different amino acid sequence being coded for.

What is a silent mutation?

A mutation that results in a different codon but codes for the same amino acid.

What is a frame shift mutation?

A mutation caused by deletion or insertion that shifts the reading frame of the gene sequence.

What are housekeeping genes?

Genes that are constantly expressed for essential processes like respiration.

What role do transcription factors play?

They bind to DNA and regulate the rate of transcription.

What happens when a transcription factor is inhibited?

Transcription is prevented because the binding site on the TF is blocked.

How does oestrogen affect transcription factors?

Oestrogen activates transcription factors by changing their shape and releasing inhibitors.

What is the lac operon?

A section of DNA that contains a cluster of genes transcribed together, primarily in prokaryotes.

What is the function of a spliceosome?

To remove introns and splice together exons in pre-mRNA.

What is apoptosis?

Programmed cell death.

What are proto-oncogenes?

Normal genes that regulate cell growth and division, which can become oncogenes through mutation.

What is the role of Hox genes?

They regulate mitosis and apoptosis and are involved in the development of body plans.

What is the significance of homeobox genes?

They contain a conserved DNA sequence that codes for proteins involved in gene regulation.

What triggers the production of cyclic AMP?

A molecule binding to the cell surface membrane.

How does a deletion mutation affect protein synthesis?

It can cause a frame shift, altering the entire amino acid sequence downstream.

What is the primary function of mRNA?

To carry a copy of the genetic code for a protein from the nucleus to the cytoplasm.

What happens during post-transcriptional control?

Editing of primary mRNA and removal of introns to produce mature mRNA.

What is the role of tRNA in translation?

To carry amino acids to the ribosome and match them with the corresponding codons on mRNA.

What is the effect of harmful mutations?

They can lead to non-functional proteins and negatively impact the organism's phenotype.

What is the role of enzymes coded by genes?

They regulate metabolic pathways and can be affected by mutations.

What is the difference between introns and exons?

Introns do not code for amino acids, while exons do.

What is a beneficial mutation?

A mutation that results in a protein with a new and useful characteristic.

What are the two types of transcription factors?

Activators, which start transcription, and repressors, which stop transcription.

What is the normal state of a cell regarding the lac operon?

A repressor protein binds to the operator region, preventing transcription of structural genes.

What are the external stimuli that can trigger apoptosis?

Changes in light intensity, temperature, pathogen attack, lack of nutrients, and drugs.