3.2 Chromosomes Flashcards
What is the structure of prokaryotic chromosomes?
Prokaryotic chromosomes typically consist of a single circular DNA molecule, described as ‘naked DNA’ because it lacks histone proteins.
What are plasmids in prokaryotes?
Plasmids are small loops of DNA separate from the main chromosome, often containing genes for specific functions such as antibiotic resistance.
Describe the structure of eukaryotic chromosomes.
Eukaryotic chromosomes consist of long, linear DNA molecules associated with histone proteins, forming a compact and organized structure.
What are homologous chromosomes?
Homologous chromosomes are pairs of chromosomes in a diploid organism that carry the same sequence of genes but may contain different alleles.
Define diploid and haploid nuclei.
Diploid nuclei have pairs of homologous chromosomes, whereas haploid nuclei contain one chromosome of each pair.
How does the sex of offspring depend on the sperm cell in humans?
The sex of the offspring is determined by whether the sperm cell contributes an X chromosome (resulting in a female) or a Y chromosome (resulting in a male).
What is a karyogram?
A karyogram is a photograph or diagram that shows the chromosomes of an organism in homologous pairs of decreasing length.
How can karyograms be used in diagnosis?
Karyograms can be used to deduce sex and diagnose chromosomal abnormalities such as Down syndrome.
What information can be found in genomic databases?
Genomic databases store sequenced genomes and related genetic information, including gene loci and associated polypeptide products.
How is the locus of a gene determined using databases?
The locus, or exact position of a gene on a chromosome, can be identified using databases like OMIM by searching for the gene name or associated disorder.
What is the significance of Cairns’ autoradiography technique?
Cairns’ technique uses autoradiography to measure the length of DNA molecules, helping to understand chromosome structure and DNA replication.
What characterizes the chromosome of prokaryotes in terms of structure and composition?
Prokaryotes have one chromosome consisting of a circular DNA molecule, often accompanied by plasmids, which are not found in eukaryotes.
Describe the relationship between sister chromatids and chromosomes during cell division.
The two DNA molecules formed by DNA replication are considered sister chromatids until the splitting of the centromere at the start of anaphase, after which they become individual chromosomes.
Compare the genome sizes of T2 phage, Escherichia coli, Drosophila melanogaster, Homo sapiens, and Paris japonica.
Genome sizes vary significantly among organisms, with T2 phage having the smallest genome and Paris japonica having a considerably larger genome compared to others like Homo sapiens and Drosophila melanogaster.
Outline the significance of diploid and haploid nuclei in eukaryotes.
Diploid nuclei have pairs of homologous chromosomes, essential for sexual reproduction, while haploid nuclei, with one chromosome of each pair, are found in gametes.
