Biology Chp 2- Structure Of Chromosomes

chromatin

Complex of DNA and proteins

chromosome

highly coiled and condensed chromatin fibres.

Scientist that studies chromosomes

Walther Flemming

Chromatin constitutes of:

DNA 40%
Histones 60%

DNA full form

deoxyribonucleic acid

components nucleotides is made up of

phosphate
sugar (pentose)
nitrogenous bonds

four types of nitrogenous base

Adenine
Guanine
Cytosine
Thymine

histone

are the proteins that help in the coiling and packaging of DNA into structural units called nucleosomes

centromere

point of attachment of two sister chromatids

gene

specific sequences of nucleotides on a chromosome, that encode particular proteins which express in the form of some particular feature of the body

cell cycle

series of events that take place in a cell leading to duplication of its DNA and the subsequent division of the cell to produce two daughter cell

three phases of interphase

first phase (G1)
synthesis phase (S)
second growth phase (G2)

Two types of cell division

Mitosis - diploid
Meiosis - haploid

Steps of mitosis

Karyokinesis
Cytokinesis

Four phases of karyokinesis

Prophase
Metaphase
Anaphase
Telophase

cytokinesis

division of cytoplasm

meiosis

cell division that produces reproductive cells in sexually reproducing organisms

chiasma

an intersection or crossing of two tracts in the form of the letter X