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Term 1: Mitosis
Definition 1: Asexual reproduction that preserves the chromosome number, resulting in 1 diploid cell dividing into 2 diploid cells. Phases include Prophase, Metaphase, Anaphase, Telophase.
Term 2: Meiosis
Definition 2: Sexual reproduction that halves the chromosome number, resulting in 1 diploid cell dividing into 4 haploid cells. Involves Meiosis I (homologous chromosomes separate) and Meiosis II (sister chromatids separate). Creates genetic variation.
Term 3: Genetic Variation (Meiosis)
Definition 3: Created via crossing over (Prophase I), independent assortment (Metaphase I), and random fertilization.
Term 4: Euploid
Definition 4: Normal chromosome number.
Term 5: Aneuploid
Definition 5: Abnormal chromosome number (e.g., monosomy, trisomy).
Term 6: Trisomy 21
Definition 6: A type of aneuploidy resulting in Down syndrome.
Term 7: Turner Syndrome
Definition 7: A chromosomal abnormality with the genotype XO.
Term 8: Klinefelter Syndrome
Definition 8: A chromosomal abnormality with the genotype XXY.
Term 9: Heredity
Definition 9: The passing of traits from parents to offspring.
Term 10: Locus
Definition 10: The specific location of a gene on a chromosome.
Term 11: Allele
Definition 11: A version or variant form of a gene.
Term 12: Genotype
Definition 12: The genetic makeup of an organism (e.g., TT, Tt, tt).
Term 13: Phenotype
Definition 13: The observable physical or biochemical trait of an organism (e.g., tall, dwarf).
Term 14: Homozygous
Definition 14: Having two identical alleles for a particular gene (e.g., TT, tt).
Term 15: Heterozygous
Definition 15: Having two different alleles for a particular gene (e.g., Tt).
Term 16: Law of Dominance
Definition 16: States that a dominant allele will mask the expression of a recessive allele.
Term 17: Law of Segregation
Definition 17: States that alleles for each gene separate during gamete formation, so each gamete receives only one allele.
Term 18: Law of Independent Assortment
Definition 18: States that genes located on different chromosomes assort independently of one another during gamete formation.
Term 19: Monohybrid Cross F2 Genotypic Ratio
Definition 19: 1:2:1 (for a cross involving one trait and Mendelian inheritance).
Term 20: Monohybrid Cross F2 Phenotypic Ratio
Definition 20: 3:1 (for a cross involving one trait and Mendelian inheritance).
Term 21: Dihybrid Cross F2 Phenotypic Ratio
Definition 21: 9:3:3:1 (for a cross involving two traits and Mendelian inheritance).
Term 22: Incomplete Dominance
Definition 22: A genetic inheritance pattern where the heterozygous phenotype is a blend of the two homozygous phenotypes (e.g., Red x White = Pink).
Term 23: Co-dominance
Definition 23: A genetic inheritance pattern where both alleles are expressed equally in the heterozygote (e.g., AB blood type).
Term 24: Multiple Alleles / Polygenic Traits
Definition 24: Traits influenced by multiple genes or more than two alleles for a single gene (e.g., height, eye color, skin color).
Term 25: Pleiotropy
Definition 25: When a single gene affects multiple seemingly unrelated traits (e.g., PKU).
Term 26: Sex-linked Inheritance
Definition 26: Inheritance of traits carried on sex chromosomes, typically X-linked traits, where males are more often affected and females can be carriers.
Term 27: DNA
Definition 27: A double-stranded helix with a sugar-phosphate backbone and bases Adenine-Thymine, Guanine-Cytosine. Its primary function is to store genetic information.
Term 28: RNA
Definition 28: A single-stranded nucleic acid with bases Adenine-Uracil, Guanine-Cytosine. It carries instructions from DNA to make proteins and comes in types like mRNA, tRNA, and rRNA.
Term 29: Nucleotide
Definition 29: The basic building block of DNA and RNA, composed of a sugar, a phosphate group, and a nitrogenous base.
Term 30: DNA Replication Purpose
Definition 30: To copy DNA for cell division.
Term 31: Semi-conservative Replication
Definition 31: A model of DNA replication where each new DNA molecule consists of one old (original) strand and one newly synthesized strand.
Term 32: Helicase
Definition 32: An enzyme responsible for unwinding the DNA double helix during replication.
Term 33: Primase
Definition 33: An enzyme that synthesizes short RNA primers, which provide a starting point for DNA polymerase.
Term 34: DNA Polymerase III
Definition 34: The primary enzyme responsible for adding new nucleotides and elongating the DNA strand during replication.
Term 35: Leading Strand
Definition 35: The DNA strand that is synthesized continuously in the 5' to 3' direction during replication.
Term 36: Lagging Strand
Definition 36: The DNA strand that is synthesized discontinuously in short segments called Okazaki fragments, in the direction opposite to the overall unwinding.
Term 37: DNA Polymerase I
Definition 37: An enzyme that replaces the RNA primers with DNA nucleotides during replication.
Term 38: Ligase
Definition 38: An enzyme that seals the gaps between Okazaki fragments and other DNA segments by forming phosphodiester bonds.
Term 39: Telomerase
Definition 39: An enzyme that maintains the ends of chromosomes (telomeres) by adding repetitive DNA sequences.
Term 40: Mismatch Repair
Definition 40: A DNA repair mechanism that corrects errors not fixed by DNA polymerase proofreading after replication.
Term 41: Nucleotide Excision Repair
Definition 41: A DNA repair mechanism that removes and replaces damaged nucleotides, such as thymine dimers caused by UV radiation.
Term 42: Point Mutation
Definition 42: A mutation involving a change in a single base pair in the DNA sequence, which can affect the protein product.
Term 43: Central Dogma
Definition 43: The fundamental concept of molecular biology that genetic information flows from DNA to RNA to Protein.
Term 44: Transcription
Definition 44: The process occurring in the nucleus where DNA is used as a template to synthesize mRNA via RNA polymerase.
Term 45: RNA Polymerase
Definition 45: The enzyme responsible for synthesizing mRNA from a DNA template during transcription.
Term 46: Introns
Definition 46: Non-coding sequences within a gene that are spliced out from the mRNA transcript before translation.
Term 47: Exons
Definition 47: Coding sequences within a gene that are kept and expressed in the final mRNA molecule.
Term 48: mRNA post-transcriptional modifications
Definition 48: Includes the addition of a 5' cap and a 3' poly-A tail to the mRNA molecule.
Term 49: Translation
Definition 49: The process occurring in the cytoplasm where mRNA's genetic code is read by ribosomes and tRNA to synthesize a polypeptide chain (protein).
Term 50: Ribosome
Definition 50: A complex made of rRNA and protein that serves as the site of protein synthesis (translation).
Term 51: tRNA
Definition 51: Transfer RNA; carries specific amino acids to the ribosome and matches them to mRNA codons using its anticodon.
Term 52: mRNA
Definition 52: Messenger RNA; carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm.
Term 53: rRNA
Definition 53: Ribosomal RNA; a structural component of ribosomes and helps catalyze protein synthesis.
Term 54: Start Codon
Definition 54: AUG; the codon that initiates translation and specifies the amino acid methionine.
Term 55: Stop Codon
Definition 55: undefined