Molecular Genetics Flashcards
What is the structure of DNA?
A double helix with two complementary, antiparallel strands made of nucleotides.
What are the components of a nucleotide?
A five-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base (A, T, C, G).
What is Chargaff’s Rule?
The amount of adenine (A) equals thymine (T), and cytosine (C) equals guanine (G).
What is the purpose of DNA replication?
To create an identical copy of DNA before cell division.
What does “semi-conservative replication” mean?
Each new DNA molecule contains one original strand and one newly synthesized strand.
What is the function of helicase?
Unwinds and separates the DNA strands at the replication fork.
How is DNA different from RNA?
DNA: Deoxyribose sugar, double-stranded, uses thymine (T).
RNA: Ribose sugar, single-stranded, uses uracil (U) instead of thymine.
How are genes, chromosomes, and genomes related?
Gene: A segment of DNA coding for a protein.
Chromosome: A long DNA molecule containing many genes.
Genome: The entire genetic material of an organism.
What is the purpose of Primase?
Adds RNA primers.
What is the purpose of DNA Polymerase?
Adds nucleotides and proofreads.
What is the purpose of Ligase?
Joins Okazaki fragments on the lagging strand.
What are Okazaki fragments?
Short DNA segments synthesized on the lagging strand.
What are the two steps of protein synthesis?
Transcription: DNA → mRNA in the nucleus.
Translation: mRNA → Protein at the ribosome.
What are the three characteristics of the genetic code?
Universal: Same code used by all organisms.
Redundant: Multiple codons for some amino acids.
Unambiguous: Each codon codes for one amino acid.
What happens during transcription?
RNA polymerase binds to DNA.
mRNA is synthesized using complementary base pairing.
The mRNA leaves the nucleus.
What happens during translation?
Ribosome reads mRNA codons.
tRNA brings matching amino acids.
Peptide bonds form to build a protein.
What are the three types of RNA?
mRNA: Carries genetic instructions.
tRNA: Brings amino acids to the ribosome.
rRNA: Forms part of the ribosome.
Where does transcription occur?
In the nucleus.
What is a codon?
A sequence of three mRNA bases that codes for an amino acid.
What are the start and stop codons?
Start codon: AUG (Methionine).
Stop codons: UAA, UAG, UGA.
What is the difference between a somatic and germ-line mutation?
Somatic mutation: Affects body cells, not inherited.
Germ-line mutation: Affects reproductive cells, passed to offspring.
What is a point mutation?
A change in a single nucleotide.
What is a silent mutation?
A mutation that does not change the amino acid sequence
What is a missense mutation?
A mutation that results in a different amino acid being incorporated.
What is a nonsense mutation?
mutation that changes a codon into a stop codon, terminating protein synthesis early.
What is a frameshift mutation?
Insertion or deletion of nucleotides that shifts the reading frame.
How do chromosomal mutations differ from point mutations?
They affect large sections of DNA or whole chromosomes.
What causes mutations?
Spontaneous (errors in replication).
Radiation (UV, X-rays).
Chemical mutagens (cigarette smoke, pollutants).
Viruses (HPV).
How is mitochondrial DNA inherited?
Only from the mother, with no recombination.
What are the steps in making recombinant DNA?
Use restriction enzymes to cut DNA.
Insert DNA into a plasmid vector.
Seal using DNA ligase.
Introduce plasmid into bacteria for replication.
What are restriction enzymes?
Enzymes that cut DNA at specific sequences.
What is gel electrophoresis used for?
Separating DNA fragments by size.
How does electrophoresis create a DNA fingerprint?
Separates DNA fragments by size using an electric current.
Creates a banding pattern unique to an individual.
Used in forensics, paternity tests, and medical diagnostics.
What are some controversies in genetic research?
Ethical concerns over genetic modification.
Privacy concerns with DNA databases.
Economic concerns about biotech companies monopolizing genetics.
What are examples of biotechnology products?
Medicinal bacteria: Produce insulin and vaccines.
Transgenic plants: Pest-resistant crops, Golden Rice.
Transgenic animals: Goats producing human proteins.
What are risks of transgenic organisms?
Environmental risks (gene transfer to wild species).
Health risks (unknown effects of consuming GMOs).
Economic risks (farmers dependent on biotech companies).
What are transgenic organisms?
Organisms that contain DNA from another species.
What are some uses of transgenic plants?
Pest resistance, improved nutrition, and increased crop yields.
What are medicinal bacteria used for?
Producing human insulin and other pharmaceuticals.
What are examples of biotechnology products?
Medicinal bacteria: Produce insulin and vaccines.
Transgenic plants: Pest-resistant crops, Golden Rice.
Transgenic animals: Goats producing human proteins.
What are prenatal diagnostic techniques?
Ultrasound: Identifies physical abnormalities.
Amniocentesis: Analyzes fetal DNA from amniotic fluid.
Chorionic Villi Sampling (CVS): Tests for genetic diseases.
How does a DNA probe work?
A labeled DNA sequence binds to a complementary gene.
Detects genetic diseases or mutations.
What is gene therapy?
Insertion of normal genes into patients to correct genetic disorders.
What is the difference between somatic and germ-line gene therapy?
Somatic therapy: Affects only the individual.
Germ-line therapy: Alters reproductive cells, affecting future generations.
What forms the “rungs” of the DNA double helix?
A purine base pairs with a pyrimidine base (A-T, C-G).
What are purines vs primadines
purines have a double-ring structure and primadines have a single-ring structure
What sugar is found in DNA?
Deoxyribose.
What is the correct definition of a gene?
A functional sub-unit of DNA that directs protein production.
What is the correct term for all of an organism’s DNA?
Genome
What is the “central dogma” of gene expression?
DNA → RNA → Protein.
What is the role of a plasmid in genetic engineering?
A vector to carry foreign DNA into bacterial cells.
What is DNA microarray technology used for?
To analyze the activity of thousands of genes at once.
What is the purpose of a surrogate mother in cloning?
To carry and develop the cloned embryo.
What is the best method to detect Down syndrome in a fetus?
Amniocentesis.
What are the four stages of genetic engineering?
DNA Cleavage (cutting DNA with restriction enzymes).
Production of Recombinant DNA (inserting genes into plasmids).
Cloning (replicating the modified DNA in host cells).
Screening (identifying successful gene incorporation).
Why do people wear lead aprons during X-rays?
To protect reproductive cells from germ-line mutations.
