Genetics Unit 2 Vocab

Linkage – Genes located close together on the same chromosome that tend to be inherited together.

Recombination frequency – The percentage of recombinant offspring used to estimate distances between genes.

Genetic mapping – The process of determining the location and relative distances between genes.

Map units (centimorgans, cM) – A unit of measurement for genetic linkage, where 1 cM = 1% recombination.

Three-point testcross – A genetic cross used to determine the relative order of three genes.

Interference – The phenomenon where one crossover event reduces the probability of another nearby.

Coefficient of coincidence – A ratio measuring the observed double crossover frequency compared to the expected.

Parental (non-recombinant) gametes – Gametes that retain the original allele combinations from the parents.

Recombinant gametes – Gametes with new allele combinations due to crossing over.

Complete linkage – The situation where no recombination occurs between genes.

Incomplete linkage – The occurrence of some recombination between linked genes.

Syntenic genes – Genes located on the same chromosome.

Physical map – A chromosome map based on actual DNA sequence distances (measured in base pairs).

Conjugation – The process of direct transfer of DNA between bacterial cells via a pilus.

Transformation – The uptake and incorporation of foreign DNA from the environment into a bacterial genome.

Transduction – The process by which bacterial DNA is transferred via a bacteriophage.

Plasmid – A small, circular DNA molecule that replicates independently of the bacterial chromosome.

F factor (fertility factor) – A plasmid that enables bacterial conjugation.

Hfr strain (high-frequency recombination strain) – A bacterium with the F factor integrated into its chromosome.

F’ (F-prime) plasmid – A plasmid that carries bacterial chromosomal genes.

Lytic cycle – A viral reproductive cycle where new phages are produced, leading to cell lysis.

Lysogenic cycle – A viral cycle where the phage DNA integrates into the host genome and replicates passively.

Prophage – Viral DNA that is integrated into the bacterial chromosome.

Generalized transduction – The transfer of random bacterial genes by a phage.

Specialized transduction – The transfer of specific bacterial genes by a lysogenic phage.

Competence – The ability of a bacterial cell to take up foreign DNA during transformation.

Transposons – Mobile genetic elements that can move between different locations in the genome.

Nucleotide – The building block of DNA and RNA, consisting of a phosphate group, sugar, and nitrogenous base.

Purines – Double-ring nitrogenous bases (adenine, guanine).

Pyrimidines – Single-ring nitrogenous bases (cytosine, thymine, uracil).

Complementary base pairing – A-T (DNA), A-U (RNA), and G-C via hydrogen bonds.

Chargaff’s rules – The observation that DNA has equal amounts of A and T, and G and C.

X-ray diffraction – A technique used by Rosalind Franklin to reveal DNA’s helical structure.

Antiparallel strands – The orientation of DNA strands, where one runs 5' to 3' and the other 3' to 5'.

Denaturation (DNA melting) – The separation of DNA strands due to heat or chemical treatment.

Renaturation (reannealing) – The reformation of double-stranded DNA from single strands.

Hyperchromic shift – The increase in UV light absorption as DNA denatures.

Supercoiling – The overwinding or underwinding of DNA to fit into the cell.

Nucleoid – The region where bacterial DNA is found in prokaryotes.

Histones – Proteins that help organize and package eukaryotic DNA into chromatin.

Semiconservative replication – Each new DNA molecule consists of one old and one new strand.

Replication fork – The Y-shaped region where DNA is unwound and copied.

Helicase – The enzyme that unwinds DNA strands.

Single-stranded binding proteins (SSBs) – Proteins that prevent reannealing of single-stranded DNA.

Primase – The enzyme that synthesizes RNA primers for DNA polymerase to begin replication.

DNA polymerase III – The main enzyme responsible for DNA synthesis in bacteria.

Leading strand – The continuously synthesized DNA strand in the 5’ to 3’ direction.

Lagging strand – The discontinuously synthesized strand that forms Okazaki fragments.

Okazaki fragments – Short DNA segments synthesized on the lagging strand.

DNA ligase – The enzyme that seals gaps between Okazaki fragments.

Topoisomerase (gyrase) – The enzyme that relieves supercoiling tension in DNA.

Telomeres – The repetitive DNA sequences at the ends of eukaryotic chromosomes.

Telomerase – The enzyme that extends telomeres, preventing chromosome shortening.

Chromatin – The complex of DNA and proteins in the nucleus of eukaryotic cells.

Nucleosome – The fundamental unit of chromatin, consisting of DNA wrapped around histone proteins.

Euchromatin – Loosely packed chromatin associated with active gene expression.

Heterochromatin – Tightly packed chromatin associated with gene repression.

Histone modification – Chemical changes to histone proteins that affect gene regulation.

DNA methylation – The addition of methyl groups to DNA, often silencing genes.

Epigenetics – The study of heritable changes in gene expression that do not involve changes in DNA sequence.

Tandem repeats – Repetitive DNA sequences that occur in a head-to-tail arrangement.

Satellite DNA – Highly repetitive DNA sequences found in centromeres and telomeres.

Transposable elements (jumping genes) – DNA sequences that can move within the genome.

Pseudogenes – Nonfunctional sequences of DNA that resemble functional genes.

Centromere – The region of a chromosome that connects sister chromatids and attaches to spindle fibers.

Kinetochore – The protein complex that forms at the centromere and interacts with spindle fibers.