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What does ‘chromo’ of chromosomes mean?
Coloured
How many chromosomes are there in human somatic (body) cells?
46
How many chromosomes are there in the sperm cells?
23
Before cell division, the chromosome is a double structure; made of two identical structures called ........................., joined together.
Chromatids
The two chromatids are held together by a narrow region called the ......................., forming a chromosome.
Centromere
Each chromatid contains one .............. molecule.
DNA
In order to prevent the DNA getting tangled up into knots, a precise scaffolding made of protein molecules is used. What are these proteins called?
Histones
The combination of DNA and proteins is called .................
Chromatin
The ................... is cylindrical in shape and is made up of eight histone molecules.
Nucleosome
.................. is a type of chromatin which is loosely coiled.
Euchromatin
.................. is a type of chromatin which is tightly coiled, as in the chromosomes seen at nuclear division.
Heterochromatin
(True or False?) During the period between divisions (interphase) the majority is in the form of heterochromatin.
False
(True or False?) The genes in the heterochromatin are mostly inactive.
True
(True or False?) Chromatin is at its most condensed in chromosomes at the metaphase stage of mitosis.
True
List two types of chromosome based on the location of centromeres!
Metacentric / Sub-metacentric / Acrocentric / Telocentric
Two identical chromatids make one............
Chromosome
