Biology 10th ICSE: Structure of Chromosomes Cell cycle and cell division Flashcards
What are chromosomes?
They are highly coiled and condensed chromatin fibres
Who studied chromosomes in animals for the first time? (hint: ‘walt___ ________’)
German Scientist Walther Flemming | 1882
A single DNA molecule is very large and thus described as a ______.
Macromolecule
What forms the ‘rungs’ of the ladder-like arrangement of the DNA?
Nitrogenous Bases
What is DNA strand composed of?
Repeating Nucleotides; composed of
- phosphate
- sugar (pentose)
- a nitrogenous base
Name 4 nitrogenous bases found in DNA
a) Adenine
b) Guanine
c) Cytosine
d) Thymine
Describe the appearance of chromatin under an electron microscope
long, thin, darkly stained fibre
What are the proteins that help in the coiling and packaging of DNA into structural units called ‘nucleosomes’
Histones
Histones are the proteins that help in the coiling and packaging of DNA into structural units called _______.
nucleosomes
What does the DNA strand wind around?
8 histone proteins called ‘The Histones Octamer’.
Combined with DNA, each complex is called a nucleosome
What are Genes?
They are specific sequences of nucleotides on a chromosome that encode proteins, which then express in the form of some particular feature of the body
State 4 needs for new cells
- Growth
- Replacement
- Repair
- Reproduction
What is the cell cycle?
The Cell Cycle is a series of events that take place in a cell leading to duplication of its DNA and subsequent division of the cell to produce 2 daughter cells.
name the phases of Interphase
- First Growth Phase G1
- Synthesis Phase S
- Second Growth Phase G2
Can the cell cycle go on endlessly?
No dumbass 🙄
