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level: 8.2 DNA and chromosomes

Questions and Answers List

level questions: 8.2 DNA and chromosomes

QuestionAnswer
What is a chromosome- Thread-like structures in nucleus - Made up of protein + single DNA molecule
Chromosome structure- Two treads joined at centromere - Each tread called a chromatid - DNA held by histones - DNA highly coiled
The coiling of the DNA molecule- Wound in histones to fix it in position - DNA-histone complex is then coiled - Coil looped further - Packed into chromosome, condensed
Differences between DNA in prokaryotes + eukaryotes- Eukaryotes: DNA longer, linear, associated with proteins, histones, forms chromosomes - Prokaryotic: DNA shorter, circular, not associated with proteins, no chromosomes
Homologous chromosomes ~ HC (huh - mo - luh - gus)- A pair of chromosomes, 1 maternal homolog1 paternal homolog - Have same gene loci - HC line up and synapse during meiosis
Diploid- Two complete sets of chromosomes - Human cells are diploid with 23 pairs (46) of chromosomes in nucleus - Each pair of chromosomes in a diploid cell is a homologous chromosome set
Alleles meaning- Different forms of genes - Each gene exists in 2, or usually more, different forms - Each individual inherits 1 allele from each parent - These 2 allele may the same or different
When alleles from parent are different- When different, each allele has different base sequence, so different seq. amino acid, dif. polypept. - Changes in base sequence of gene produces new allele (mutation) = different seq. amino acids = dif poly. - May not function properly or at all