Chapter 13 - Genomes, genes and alleles Flashcards
what are the base pairs?
adenine and thymine
cytosine and guanine
what makes up a nucletide
1 base
1 deoxyribose sugar
1 phosphate group
the base in a nucleotide is connected to a..
sugar
2 hydrogen bonds hold which pair of bases?
adenine and thymine
3 hydrogen bonds hold which pair of bases?
cytosine and guanine
what is chromatin
the matter of DNA in the nucleus of a cell
how does DNA become chromosomes
DNA strands in chromatin wrap around histone proteins. this makes nucleosomes which then come together to from chromosomes.
what is a genome
a complete set of autosomes + an X & Y chromosome
what is a telomere
the end of a chromosome
what is a centromere
where two chromatids are held together
what are sister chromatids
chromatids that have replicated themselves and are attached at the centromere
define metacentric
centromere is in the middle
define submetacentric
centromere is closer to one end
define acrocentric
centromere is very close to one end
what does prokaryotic cells have as DNA
circular molecules of DNA rather than chromosomes
what is the P and Q arm of a chromosome
the P arm of a chromosome is the shorter arm and the Q arm is the longer arm
what is a karyotype
a photograph of the chromosomes in a genome
how are karyotypes arranged
by size, banding pattern and centromere position
define polyploidy
having more than 2 of each chromosome in a set
e.g: 3 of each chromosome = triploidy
define aneuploidy
where there are not an appropriate number of chromosome for a single numbered chromosome
e.g: trisomy
what is trisomy
having 3 of a specific numbered chromosome
what is a block deletion
where a part of a chromosome is missing
what is monosomy
where the is only 1 chromosome instead of 2 for a specific numbered chromosome
what is disorder is trisomy-21
three 21 chromosomes
down syndrome
