Chromosome Structure and Organelle DNA

A comprehensive set of flashcards focused on the key vocabulary and concepts related to chromosome structure and organelle DNA, aiding in exam preparation.

Supercoiled DNA

DNA that is overwound or underwound, causing it to twist on itself and occupy less space.

Topoisomerases

Enzymes that add or remove rotations in DNA by cutting the strand and rotating the ends around each other.

Euchromatin

Less condensed chromatin that contains most of the functional genes.

Heterochromatin

Highly condensed chromatin that tends to have few genes and is very repetitive.

Histones

Small, positively charged proteins that are abundant in chromatin.

Nucleosome

The fundamental repeating unit of chromatin, consisting of DNA wrapped around a histone core.

DNase I sensitivity

The correlation of chromatin structure to transcription, where sensitive DNA can indicate gene expression.

Centromeres

The constricted region of a chromosome where spindle fibers attach.

Telomeres

The ends of chromosomes that contain highly repetitive DNA sequences.

C value

The amount of DNA per cell, technically the haploid genome size per nucleus in picograms.

Denaturation

The process by which DNA strands separate due to the breaking of hydrogen bonds.

Renaturation

The process by which separated DNA strands re-anneal through hydrogen bonding.

Gene family

Similar but not identical copies of unique DNA sequences that arose through the duplication of an existing gene.

Moderately repetitive DNA

DNA sequences that are typically 150-300 bp long and can include tandem repeat sequences.

SINEs

Short interspersed elements, such as Alu elements, which comprise part of the moderately repetitive DNA.

LINEs

Long interspersed elements, such as LINE1, which comprise a significant portion of the genome.

Microsatellite DNA

Highly repetitive DNA that consists of sequences less than 10 bp long, including those found in centromeres and telomeres.

Chloroplast DNA

DNA found in chloroplasts that is similar in structure to that of eubacteria and exhibits cytoplasmic inheritance.

Endosymbiotic theory

The hypothesis that mitochondria and chloroplasts arose from eubacteria that entered into a symbiotic relationship with ancestral eukaryotic cells.

Organelle DNA inheritance

The phenomenon where traits encoded by organelle DNA are typically inherited from the female parent in animals.

Mitochondrial fusion

The process whereby mitochondria can merge within a cell, allowing for genetic mixing in heteroplasmic cells.

Polytene chromosomes

Large chromosomes formed by repeated rounds of DNA replication without cell division, typically found in certain organisms.

Chromosomal puffs

Decondensed areas of chromatin where transcription is actively occurring.

Transcription

The process by which RNA is synthesized from a DNA template.

Organelle function genes

Genes needed for the function of mitochondria and chloroplasts, many of which are encoded in the nucleus.

Replicative segregation

The random distribution of organelles, such as mitochondria, during cell division.

Heteroplasmic cells

Cells that contain a mixture of different mitochondrial DNA, resulting from mutations or variations.

Unique-sequence DNA

Regions of DNA that contain unique genetic information, including most protein-coding genes.

Highly repetitive DNA sequences

DNA sequences that are repeated many times in the genome at telomeres and centromeres.

Hybrid genomes

Genomes that may result from horizontal gene transfer, although it is not common.

Mitochondrial genome size

The total length of mitochondrial DNA, which varies widely among different organisms.

Nuclear migration of sequences

The detection of sequences typically found in mtDNA within nuclear DNA.

Chromatin structure changes

Modifications to chromatin that can affect transcription and gene accessibility.

Antibiotic effects on organelle translation

The phenomenon where antibiotics that inhibit bacterial protein synthesis also affect mitochondria and chloroplasts.