Genetics Flashcards
What is a Genotype?
All genes that make up an organism’s genetic composition.
What is Helicase?
Enzyme that unwinds and unzips DNA during replication.
What does DNA Polymerase III do?
Adds bases to a new DNA strand in the 5’ → 3’ direction.
What is the function of Ligase?
Enzyme that seals nicks in DNA strands.
What is Semiconservative Replication?
DNA replication where each new molecule has one old and one new strand.
What is a Replication Fork?
The site where DNA strands are unwound and replication occurs.
What is a Primer?
Short RNA sequence added to start DNA synthesis before being replaced by DNA.
What is a Leading Strand?
Continuously synthesized DNA strand in the 5’ → 3’ direction.
What is a Lagging Strand?
Discontinuously synthesized DNA strand, made in Okazaki fragments.
What are Okazaki Fragments?
Short DNA segments synthesized on the lagging strand.
What is the role of Topoisomerase?
Relieves tension in DNA strands during replication.
What is the Central Dogma?
The flow of genetic information: DNA → transcription → mRNA → translation → protein.
What is mRNA?
Carries genetic information from DNA to ribosomes for protein synthesis.
What is tRNA?
Transfers amino acids to ribosomes during protein synthesis.
What is rRNA?
Forms the major part of ribosomes and facilitates protein synthesis.
What is Wobble?
Flexibility in base pairing at the third codon position, allowing redundancy in the genetic code.
What is Translocation?
The movement of ribosomes along mRNA to read new codons.
What is Eukaryotic Translation?
Occurs separately from transcription; AUG codes for methionine; one protein per mRNA.
What is Prokaryotic Translation?
Occurs simultaneously with transcription; mRNA can code for multiple proteins.
What is an Operon?
A cluster of genes controlled by a single promoter, common in prokaryotes.
What is an Inducible Operon?
Turned on by a substrate (e.g., lactose operon).
What is a Repressible Operon?
Turned off by excess product (e.g., tryptophan operon).
What is Phase Variation?
Bacteria switching genes on/off to change phenotype.
What is Horizontal Gene Transfer?
Transfer of DNA between bacteria, not parent to offspring.
What is Conjugation?
DNA transfer between bacteria via a pilus.
What is Transformation?
Bacteria take up foreign DNA from the environment.
What is Transduction?
Bacteriophages transfer DNA from one bacterial cell to another.
What is Generalized Transduction?
Random DNA fragments are incorporated into a phage and transferred.
What is Specialized Transduction?
Specific bacterial genes are incorporated into a virus.
What are Transposons?
Jumping genes that move within the genome.
What is a Point Mutation?
A mutation affecting a single base in DNA.
What is a Missense Mutation?
A mutation that results in a different amino acid in a protein.
What is a Nonsense Mutation?
A mutation that converts a codon into a stop codon, halting translation.
What is a Silent Mutation?
A mutation that changes the DNA sequence but not the amino acid sequence.
What is a Frameshift Mutation?
Insertion or deletion of bases altering the reading frame.
What is a Lethal Mutation?
A mutation that results in cell dysfunction or death.
What is a Back Mutation?
A mutation that reverts a gene back to its original form.
What is Photoreactivation?
Repairing DNA damage caused by UV light.
What is Excision Repair?
Enzymes remove and replace incorrect DNA bases.
What is the Ames Test?
A test that detects mutagenic and potentially carcinogenic substances.
What is the basic unit of heredity?
Gene
True or False: DNA stands for Deoxyribonucleic Acid.
True
Fill in the blank: The process of copying DNA to RNA is called _____.
Transcription
What are the four nucleotide bases in DNA?
Adenine, Thymine, Cytosine, Guanine
Which base pairs with Adenine in DNA?
Thymine
What is the function of ribosomes in protein synthesis?
To translate mRNA into protein.
True or False: All mutations are harmful.
False
What is the term for an organism’s observable traits?
Phenotype
What does the term ‘homozygous’ mean?
Having two identical alleles for a particular gene.
In a Punnett square, what do the letters represent?
Alleles of the parents.
What is the role of messenger RNA (mRNA)?
To carry genetic information from DNA to the ribosome.
Fill in the blank: The physical location of a gene on a chromosome is called its _____.
Locus
What is genetic variation?
Differences in DNA sequences among individuals.
True or False: A phenotype can be influenced by environmental factors.
True
What is the term for a segment of DNA that codes for a protein?
Gene
Which process involves the splitting of a cell’s nucleus?
Mitosis
What is the difference between a dominant and a recessive allele?
A dominant allele expresses itself even in the presence of a different allele, while a recessive allele only expresses itself when two copies are present.
Fill in the blank: The study of heredity is known as _____.
Genetics
What is a genotype?
The genetic constitution of an organism.
True or False: Chromosomes are made of DNA and proteins.
True
What does the term ‘allele’ refer to?
Different forms of a gene.
What is the purpose of genetic engineering?
To modify the genetic makeup of an organism.
Fill in the blank: A trait controlled by multiple genes is called _____.
Polygenic trait
What is the role of transfer RNA (tRNA) in protein synthesis?
To bring amino acids to the ribosome during translation.
What are chromosomes made of?
DNA and proteins.
True or False: All genes are expressed equally in all cells.
False
What is the term for the observable characteristics of an organism?
Phenotype
