Mitosis Meiosis And Chromosome Abnormality Flashcards
What is a nucleosome?
DNA wrapped around eight histone proteins
What is chromatin?
Network of DNA and proteins that make up chromosomes during interphase
What is heterochromatin?
Highly condensed and genetically inactive, mostly occurs at centromere
What is euchromatin?
Lighter staining, relatively open structure where genes can be accessed and are active
What is a telomere?
Cap at the end of a chromosome
What is an autosome?
Any chromosome that is not a sex chromosomes
Which 3 features are used to classify chromosomes?
Size, banding pattern, centromere position
What are the 4 types of centromere position?
Telocentric, acrocentric, submetacentric, metacentric
What are the 4 stages of mitosis?
Prophase, metaphase, anaphase, telophase
How does meiosis increase diversity?
Crossing over/recombination - leads to new combinations of DNA.
One of chromosome pair from each parent contributes to fertilisation.
Random alignment of homologous pairs at equator of cell during metaphase.
How is mitosis different to meiosis?
Only one division.
Two daughter cells produced, not four.
Chromosome number is diploid, not haploid.
Occurs in somatic cells, not germline.
Used for growth and repair, not sexual reproduction.
Daughter cells are all genetically identical.
What is Rett syndrome?
Mutations in genes encoding proteins controlling structure of chromatin
What is ATRX syndrome?
Mutation of a protein that can unwind DNA and influence expression of genes
What is ploidy?
Wrong number of complete chromosome sets
What is aneuploidy?
Specific additional or missing chromosomes
