DNA, Chromosomal Theory & DNA Extraction (Lecture Notes)

Vocabulary flashcards covering chromosomal theory, DNA/RNA structure, nucleotides, base pairing, Central Dogma, and DNA extraction methods from the lecture notes.

Chromosomal theory of inheritance

Genes are located on chromosomes and chromosomes behave like Mendel’s units in inheritance; essential for development.

Gene

A region of DNA at a locus that codes for a functional biomolecule.

Locus

A region of DNA; the location on a chromosome where a gene sits.

Walter Sutton

Scientist who proposed that chromosomes carry genes and segregate during meiosis in a mendelian manner.

Theodor Boveri

Scientist who argued that all chromosomes are necessary for proper embryonic development and that chromosomes separate during meiosis.

Meiosis

Reducing division that produces haploid germ cells (gametes).

Germ cells

Reproductive cells formed by meiosis.

Lubber grasshopper

Sutton’s model organism used to study chromosome behavior.

Sea urchin

Boveri’s model organism used to study chromosome involvement in development.

DNA

Deoxyribonucleic acid; carries genetic information; located in chromosomes.

RNA

Ribonucleic acid; can hold information temporarily; mRNA carries information from DNA to ribosome.

Genome

Total genetic information contained in an organism’s DNA.

Nucleotide

The basic unit of DNA/RNA; composed of phosphate, pentose sugar, and nitrogenous base.

Nucleoside

Pentose sugar plus a nitrogenous base (no phosphate).

Deoxyribose

5-carbon sugar in DNA; lacks the 2' hydroxyl group.

Ribose

5-carbon sugar in RNA; contains a 2' hydroxyl group.

Phosphate group

Phosphate group links nucleotides via phosphodiester bonds.

Nucleic acid

Polymers of nucleotides; DNA and RNA.

Phosphodiester bond

Bond linking the 5' phosphate of one nucleotide to the 3' hydroxyl of the next.

Polarity

Nucleic acids have strand polarity with a 5' end and a 3' end.

5' end

End of a nucleic acid strand bearing a free phosphate group.

3' end

End of a nucleic acid strand bearing a free hydroxyl group.

Nucleobase

Nitrogen-containing bases in nucleic acids.

Purines

Adenine and Guanine; two-ring nitrogenous bases.

Pyrimidines

Cytosine, Thymine (DNA), and Uracil (RNA); single-ring bases.

Adenine

Purine base; pairs with Thymine in DNA and Uracil in RNA.

Thymine

Pyrimidine base in DNA; pairs with Adenine.

Cytosine

Pyrimidine base; pairs with Guanine.

Guanine

Purine base; pairs with Cytosine.

Uracil

Pyrimidine base in RNA; replaces Thymine.

Base pairing

A pairs with T (DNA) or U (RNA); G pairs with C; governed by hydrogen bonds (2 for A-T, 3 for G-C).

Chargaff's rules

In DNA, A% ≈ T% and C% ≈ G%; base composition supports pairing (C+G content relates to stability).

Double helix

Two intertwined DNA strands proposed by Franklin, Watson, and Crick; base pairs form the rungs.

Antiparallel

DNA strands run in opposite 5' to 3' directions.

Central Dogma

Genetic information flows from DNA to RNA (transcription) to protein (translation); replication also occurs.

mRNA

Messenger RNA; carries genetic information from DNA to the ribosome for protein synthesis.

rRNA

Ribosomal RNA; component of ribosomes, essential for translation.

tRNA

Transfer RNA; carries amino acids to the ribosome during translation.

iRNA

Interfering RNA; regulatory RNAs involved in RNA interference and gene expression control.

DNA extraction

Technique to extract genomic DNA from a sample; major steps include cell lysis, protein digestion, and DNA isolation.

Cell lysis

Breaking open the cell and organelles (plant cells may require breaking cell walls) using detergents or physical methods.

Proteinase K

Enzyme used to digest proteins and break DNA–protein bonds during extraction.

DNA isolation

Process to remove lipids, proteins, sugars, and other non-DNA molecules; methods include magnetic beads, alcohol precipitation, and spin-columns.

Magnetic bead DNA isolation

DNA binds to magnetic beads; magnet is used to separate DNA from solution.

Alcohol precipitation

DNA is precipitated by adding buffers and alcohol; DNA is recovered by collection of the precipitate.

Spin-column

DNA purification using silica membranes and centrifugation to bind and wash DNA.

cpDNA

Chloroplast DNA; circular chromosome in chloroplasts; multiple copies per chloroplast; common in plants.

mtDNA

Mitochondrial DNA; circular chromosome found in mitochondria; varies in size by organism; multiple copies per mitochondrion.

nDNA

Nuclear DNA; linear chromosomes located in the nucleus; in strawberries it is octoploid; humans have two copies of each chromosome.

Karyotype

A display/diagram of chromosome size and structure used to analyze chromosome number and morphology.

Centromere

Constricted region of a chromosome where sister chromatids attach during division.

Strawberries are octoploid

Strawberries have eight complete sets of nuclear chromosomes (octoploid), with seven different chromosomes in each set.