Lecture 10 (mitosis) Flashcards
What is a genome
It is circular DNA
- it can consist of a number of DNA molecules (eukarytic cells) or a single DNA molecule (prokaryotic cells).
All the DNA in a cell constitute its genome.
How do bacterias divide
By bacterial fission; the single bacterial chromosome is replicated
Explain briefly the process ( see notes )
What are the processes of eukaryotic cells division?
- mitosis: all cells
- meiosis : only for reproductive cells
Are all organelles of the eukaryotic cell involved in mitosis? If not, which are ?
No, not all organelles are directly involved in mitosis.
Directly invoked organelles are:
The nucleus
Nucleolus
Nuclear envelope
Cytoplasm
Cell membrane
Centrioles
What is chromatin and where is it contained
Contained in the nucleus
Chromatin is a dark material composed at 40% from DNA and 60% from proteins
What is histone
Histone is a protein that provides structural structure to chromosomes.
Nucleotides coil around histone proteins
What is the nucleosome
Histone + DNA
What are selenoid ?
DNA in nucleosome is even more compacted into more compacted structures called selenoid.
What is chromosome number and how many chromosomes are contain in each human nucleus.
Each specie as a characteristic number of chromosomes. (Eukaryotes mostly between 10 and 50)
In humans each nucleus has 46 chromosomes or 23 paires
(1 set of 23 from mother and the other from the father)
Each cell has two of each kind of chromosomes
What is the meaning of n and 2n ? How are called the maternal and paternal sets of chromosomes.
n: haploid number of chromosomes
- complete set of chromosomes necessary to define an organism
2n: diploid number of chromosomes
Reflect the equal contribution of each parent
Parental and maternal sets are called homologous pairs
How do individuals grow?
By cell division
The original genetic information is copied ( called DNA replication )
An exact copy of every chromosome is distributed to each cell
What is the cell cycle and how is it divided (phase)
The cell cycle is the cell growth and maturation as well as its division.
- Interphase
- Mitosis
- Cytokinesis ( not part of mitosis)
How are called cells that are produced by the division of parent cells ?
Daughter cells
How is divided the interphase of cell division
G1 : every daughter cell has a replication of the parent cell genetic information but only half of its cytoplasm and organelles. G1 is the phase in which the cell grow and synthesizes new organelles. ( mature)
S (synthesis phase) : chromosomes and hence DNA is copied for the next division. After the DNA is replicated it remains fully extended and uncoiled.
G2 : the final phase of interphase; the cells prepare for another division by:
Increasing their production of tubulin ( component of microtubules) and the sister chromatids shorten
