Chromosomes and Cell Division Flashcards
What are the tops of chromosome arms called?
Telomeres
What is euchromatin?
- Less dense
- Expressed DNA
What is heterochromatin?
- More dense
- Suppressed DNA
How is DNA packaged in a protein?
Wrapped around histone proteins
What does the combination of DNA and histone proteins being wrapped around each other produce?
Nucleosomes
What are the 6 stages of mitosis
- Interphase
- Prophase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
What 3 things happen at prophase?
- Chromosomes condense
- Nuclear membrane disintegrates
- Spindle fibres form
What 3 things happen at metaphase?
- Chromosomes align on the metaphase plate
- Spindle fibres attach at centriole
- Maximum condensation of chromosomes
What 3 things happen at anaphase?
- Sister chromatids separate at centromere
- Separate longitudinally
- Move to opposite ends of the cell
What 2 things happen at telophase?
- New nuclear membrane forms
- Each pole has 46 chromosomes
What happens at cytokinesis?
Cytoplasm separates
What are 2 examples of an extragenic sequence?
- A tandemly repeated DNA sequence
- Highly repeated interspaced DNA sequences
What is the charge of histone proteins?
Positive
How many base pairs and histones make a nucleosome?
- 146 base pairs
- 8 histones
What DNA links histones together?
Linker DNA
What structure is formed by the packaging of nucleosomes?
Solenoid
What is the point of DNA packaging with histones? (3 points)
- Histones positive so neutralise negative DNA
- DNA takes up less space
- Inactive DNA can be packaged away
What is the karyotype?
Number and appearance of chromosomes in a eukaryotic cell
What does metacentric mean?
Where the centromere is in the middle of the chromosome
What does sub-metacentric mean?
Centromere is on one half of the chromosome
What does acrocentric mean?
Centromere is almost at 1 end of the chromosome
What does FISH stand for
Fluorescent in Situ Hybridisation
What is the process of FISH
- Take a fragment of the DNA sequence you are interested in
- Labelled using a fluorescent dye
- Denature DNA in cell of interest
- Fluorescent marker then binds to target sequence, shows up under light
What else can be labelled using a FISH technique?
Telomeres
